A fertirrigação tornou-se uma prática comum entre os agricultores mais tecnificados, constituindo uma das alternativas mais consistentes para se garantir altas produtividades. Tradicionalmente, o manejo da fertirrigação é feito mediante o uso curvas de absorção de nutrientes e recomendações para aplicação de fertilizantes. O monitoramento da concentração dos nutrientes na solução do solo através do uso de extratores com cápsula porosa aparece como uma técnica promissora para um manejo mais adequado da fertirrigação. O objetivo desta pesquisa foi estudar a resposta da cultura do meloeiro quando submetida a diferentes concentrações controladas de nitrogênio-nitrato e potássio na solução do solo. Foram realizados, simultaneamente, dois experimentos em vasos sob condições de casa de vegetação, um com solo arenoso e outro com solo argiloso, adotando-se 13 tratamentos dispostos em delineamento inteiramente aleatorizado com 4 repetições. Os tratamentos foram definidos através de uma matriz denominada quadrado duplo e resultaram do manejo controlado das concentrações de nitrogênio e potássio na solução do solo. A cultura utilizada foi o meloeiro tipo cantaloupe, que foi irrigada por gotejamento com base nos dados de leituras tensiométricas sendo fertirrigada somente quando foi necessário, com base nos dados de concentração de nitrogênio e potássio. Foi avaliado, o comprimento da haste principal, diâmetro do caule, número de folhas, área foliar, área foliar média e matéria seca, nos solos arenoso e argiloso e o número de frutos, a produção, o peso médio dos frutos, a porcentagem rendilhamento da superfície dos frutos, o diâmetro dos frutos, a espessura e a firmeza da polpa e os sólidos solúveis totais, no solo argiloso. Foi realizada análise de variância e de regressão com o uso do SAS. Observou-se uma diferença no consumo acumulado de água de 27,6% no solo arenoso e 51,5% no argiloso. A concentração ótima de nitrogênio na solução do solo arenoso situou-se entre 100 e 180 mg L-1 e a de potássio em 468 mg L-1. As plantas do solo arenoso apresentaram baixo desempenho, indicando que as condições nutricionais não foram favoráveis ao desenvolvimento da cultura. Nos primeiros 30 dias de cultivo no solo argiloso, as melhores concentrações de nitrogênio e de potássio foram 336 e 84 mg L-1, respectivamente. A primeira planta avaliada no solo argiloso apresentou um melhor desempenho que a mesma planta avaliada no solo arenoso. No final do ciclo de cultivo das plantas do solo argiloso, a melhor concentração de nitrogênio na solução do solo foi de 336 mg L-1 e a de potássio variou 35 e 44 mg L-1. Houve baixa produção e peso médio de frutos e os frutos colhidos tiveram, em geral, baixa qualidade. As melhores características de qualidade dos frutos foram obtidos com concentrações de nitrogênio na solução do solo entre 240 e 260 mg L-1, tendo o potássio variado entre 0 e 84 mg L-1. / The fertigation has become a common practice among farmers more advanced, constituting one of the most consistent alternative to ensure high yields. Traditionally, the fertigation management makes use of the uptake nutrients curves and recommendations to fertilizers apply. The tracking of the soil solution nutrients concentration through of the use porous cup extractors appears as a promising technique for the most appropriate management of fertigation. The aim of this research was to study the response of the melon crop when subjected to different controlled concentrations of nitrogen-nitrate and potassium in the soil solution. Two experiments were conducted simultaneously in pots on condition of greenhouse, an with sand soil and another with clay, adopting 13 treatments disposing in to fully randomized design with 4 replications. The treatments were defined by a matrix called double square and resulted the management of controlled concentrations of nitrogen and potassium in the soil solution. The crop used was the cantaloupe melon, which was drip irrigated based on readings tensiometer and fertigation was carried out only when necessary based on concentration of nitrogen and potassium. Were evaluated the length of the main stem, stem diameter, leaf number, leaf area, average leaf area and dry matter in sandy and clay soils and the number of fruits, production, the average weight of fruit, the percentage of the area tracery fruit, the fruit diameter, thickness and firmness of flesh and the soluble solids in the clay soil. Were performed analysis of variance and regression using the SAS. There was a difference in consumption of water accumulated in the sandy soil of 27.6% and 51.5% in the clay. The optimal concentration of nitrogen in the solution of the sandy soil was between 100 and 180 mg L-1 and potassium in 468 mg L-1. The plants in sandy soil showed low performance, indicating that the nutritional conditions were not favorable for the development of culture. In the first 30 days of crop in clay soil, the best concentrations of nitrogen and potassium were 336 and 84 mg L-1, respectively. The first plant evaluated in clay soil had a better performance than the same plant assessed in sandy soil. At the end of the cycle of crop of plants in clay soil, the best concentration of nitrogen in soil solution was of 336 mg L-1 and potassium ranged from 35 and 44 mg L-1. There was low yield and average weight of fruits and fruits harvested, in general, were low quality. The best features of the quality of fruits were obtained with concentrations of nitrogen in soil solution between 240 and 260 mg L-1, and the potassium varied between 0 and 84 mg L-1.

Interés del estudio: Los viroides son patógenos exclusivos de plantas que infectan un gran número de especies de interés agronómico. Sin capacidad descrita para codificar proteínas, todas las fases de su ciclo vital son estrictamente dependientes de su interacción con factores del huésped. Históricamente se ha asumido que la patogénesis es consecuencia de la competencia huésped-patógeno por factores celulares implicados en el ciclo vital del viroide. En los últimos años se ha propuesto que la respuesta de silenciamiento de RNA (RNAi) del huésped frente a estos patógenos es la responsable de la respuesta patogénica de los viroides. En el presente trabajo se ha tratado de estudiar en profundidad la relación entre el mecanismo de silenciamiento de RNA y la patogénesis viroidal (en concreto del viroide del enanismo del lúpulo, HSVd). Objetivos: 1- Estudiar el proceso de patogénesis inducido por HSVd y la maquinaria de RNAi 2- Caracterizar mediante secuenciación masiva los sRNAs derivados de HSVd (vd-sRNAs). 4- Analizar la distribución diferencial de vd-sRNAs en distintos tejidos (hoja y floema). 5- Determinar las alteraciones inducidas por la infección en las vías endógenas de RNAi. Elementos de la metodología a destacar: - Uso de un sistema transgénico para estudiar el fenómeno de la patogénesis. - Uso de técnicas de secuenciación masiva para la caracterización de sRNAs. - Análisis bioinformático de los datos generados por la secuenciación masiva. Resultados logrados: - Primera publicación en la literatura de la relación de un componente de las rutas de RNAi en la patogénesis viroidal ocasionada por HSVd. - Publicación de una de las primeras secuenciaciones masivas de sRNAs derivados del HSVd. - Primera caracterización de las poblaciones de sRNAs endógenos de C.sativus, incluyendo la primera caracterización de microRNAs en esta especie. - Identificación y detección de nuevos microRNAs en C.sativus. / Martínez Arias, GE. (2011). Relación entre el silenciamiento de RNA y la patogénesis inducida por un viroide con replicación nuclear [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/11302 / Palancia

[ES] En la actualidad, el melón (Cucumis melo L.) es un cultivo con gran impacto económico mundial que se cultiva en más de 100 países. Su adaptación a diversas regiones en todo el mundo ha dado como resultado el gran polimorfismo actualmente observado en la especie. Esta variabilidad genética es un recurso imprescindible en los programas de mejora, pues constituye un reservorio valioso de nuevos alelos. La utilización de herramientas moleculares permite la optimización de los programas de mejora convencionales, consiguiendo el desarrollo de nuevas variedades más rápidamente y adaptándose así a las exigencias del productor y las preferencias del consumidor. El desarrollo de líneas de introgresión (ILs) mediante la ayuda de técnicas moleculares que facilitan el proceso de selección, constituye una estrategia óptima para la introducción de características favorables procedentes de tipos silvestres en cultivares comerciales. En la presente Tesis Doctoral se describe el desarrollo de una colección de ILs usando la entrada Queen's Pocket melon (del grupo Dudaim) de Irak, como parental exótico donante y el cultivar español 'Piel de Sapo' (del grupo Ibericus) como parental recurrente. Durante el proceso de generación de las ILs no sólo se tuvo en cuenta el genotipado (mediante diversas técnicas como HRM, la plataforma Agena Bioscience y GBS) para optimizar la recuperación del fondo genético recurrente, el número de introgresiones y la cobertura del genoma del parental donante, sino también el fenotipo mostrado por las diferentes familias. La selección final, formada por 16 ILs, presenta un promedio de 1,4 introgresiones por IL y representa el 62,6 % del genoma del parental donante. La caracterización fenotípica de esta colección de ILs permitió la identificación de 32 QTLs (Quantitative Trait Loci) estables en los dos ambientes evaluados. De éstos, 22 QTLs corresponden a caracteres morfológicos como peso, forma, reticulado, ancho de pulpa y cavidad; 9 QTLs están relacionados con características asociadas a maduración climatérica como la presencia de la capa de abscisión, aroma y firmeza de la pulpa; y uno se refiere al contenido de sólidos solubles. Muchos de los QTLs identificados en este trabajo no han sido descritos anteriormente, lo cual constituye un valioso recurso tanto de alelos nuevos potencialmente interesantes en mejora como para el estudio de las regiones genómicas y genes implicados en el control de ciertos caracteres de interés agronómico. Por otra parte, otros QTLs confirmaron regiones previamente descritas por otros autores. En esta Tesis se describen líneas potencialmente interesantes en cuanto a presencia de aroma, tamaño reducido del fruto y/o formas más redondeadas, características buscadas en el mercado de tipos 'Piel de Sapo'. La caracterización de ese conjunto de ILs también se llevó a cabo para la resistencia a un hongo patógeno del suelo, Macrophomina phaseolina. A pesar de la moderada resistencia descrita en trabajos anteriores para el parental Dudaim, ninguna línea resultó resistente. El estudio que se presenta en esta Tesis acerca de la influencia de la temperatura en la patogenicidad de este hongo ha demostrado que la resistencia del parental es superada con temperaturas altas y por tanto, no es estable. En este cribado, tan sólo una entrada silvestre africana resultó resistente a temperaturas altas. De igual manera se realizó un ensayo de tolerancia a los hongos del suelo Monosporascus cannonballus y M. eutypoides, principales responsables del colapso del melón, que causa también muchas pérdidas económicas. Los resultados permitieron concluir que M. cannonballus presenta mayor patogenocidad que M. eutypoides y que la temperatura también afecta de forma importante a la severidad de los síntomas, apoyando estudios previos. Las dos entradas africanas y de la India que presentaron mayor tolerancia a Monosporascus spp. pueden ser de interés en futu / [CAT] A l'actualitat, el meló (Cucumis melo L.) és un conreu amb gran impacte econòmic que es cultiva en més de 100 països. La seua adaptació a diverses regions per tor el món ha donat com a resultat el gran polimorfisme que actualment observem en l'espècie. Esta variabilitat genètica és un recurs imprescindible en els programes de millora, ja que constitueix un reservori valuós de nous al¿lels. La utilització de ferramentes moleculars permet l'optimització dels programes de millora convencionals, aconseguint el desenvolupament de noves varietats més ràpidament i adaptant-se així a les exigències del productor i les preferències del consumidor. El desenvolupament de línies d'introgressió (ILs) mitjançant l'ajuda de tècniques moleculars que faciliten el procés de selecció, constitueix una estratègia òptima per a la introducció de característiques favorables vinents de tipus silvestres en cultivars comercials. En la present Tesi Doctoral es descriu el desenvolupament d'una col¿lecció d'ILs usant l'entrada Queen's Pocket melon (grup Dudaim) d'Iraq, com a parental exòtic donant i el cultivar espanyol 'Piel de Sapo' (grup Ibericus) com a parental recurrent. Durant el procés de generació de les ILs no solament es tingué en compte el genotipatge (mitjançant diverses tècniques com HRM, la plataforma Agena Bioscience i GBS) per a optimitzar la recuperació del fons genètic recurrent, el nombre d'introgressions i la cobertura del genoma del parental donant, sinó també el fenotip mostrat per les diferents famílies. La selecció final, formada per 16 ILs, presenta una mitjana de 1,4 introgressions per IL i representa el 62,6% del genoma del parental donant. La caracterització fenotípica d'aquesta col¿lecció d'ILs permeté la identificació de 32 QTLs (Quantitative Trait Loci) estables en els dos ambients avaluats. D¿aquests, 22 QTLs corresponen a caràcters morfològics com pes, forma, reticulat, amplària de polpa i cavitat; 9 QTLs estan relacionats amb característiques associades a maduració climatèrica com la presència de la capa d'abscissió, aroma i fermesa de la polpa; i un es refereix al contingut de sòlids solubles. Molts dels QTLs identificats en este treball no han sigut descrits anteriorment, cosa que constitueix un valuós recurs tant d¿al¿lels nous potencialment interessants en millora com per a l¿estudi de les regions genòmiques i gens implicats en el control de certs caràcters d'interés agronòmic. Per una altra banda, altres QTLs confirmaren regions prèviament descrites per altres autors. En esta Tesi es descriuen ILs potencialment interessants respecte a la presència d¿aroma, mesura reduïda del fruit, i/o formes més arrodonides, característiques buscades en el mercat de tipus 'Piel de Sapo'. La caracterització d¿aquesta col¿lecció d'ILs també es va dur a terme per a la resistència a un fong patogen del sòl, Macrophomina phaseolina. Malgrat la moderada resistència descrita en treballs anteriors per al parental Dudaim, cap línia resultà resistent. L'estudi que es presenta en aquesta Tesi sobre la influència de la temperatura en la patogenicitat d'aquest fong ha demostrat que la resistència del parental es superada amb temperatures altes i per tant, no és estable. En aquest estudi, tan sols una entrada silvestre africana resultà resistent a temperatures altes. També es va realitzar un assaig de tolerància als fongs del sòl Monosporascus cannonballus i M. eutypoides, principals responsables del col¿lapse del meló, que causa també moltes pèrdues econòmiques. Els resultats permeteren concloure que M. cannonballus presenta major patogenicitat que M. eutypoides i que la temperatura també afecta de forma important a la severitat dels símptomes, recolzant estudis previs. Les dues entrades africanes i la hindú que presentaren major tolerància a Monosporascus spp. poden ser d'interés en futurs programes de millora. / [EN] Nowadays, the melon (Cucumis melo L.) is a crop with great economic impact worldwide that is grown in more than 100 countries. Its adaptation to diverse regions around the world has turned out in the high polymorphism this species shows. This genetic variability is an indispensable resource for breeding programs, since it is a valuable reservoir of new alleles. The use of molecular tools allows the optimization of conventional breeding programs, achieving the development of new varieties more quickly and adapting to the demands of the producer and to consumer preferences. The development of Introgression Lines (ILs) employing molecular techniques to assist in the selection process, constitutes an optimal strategy for the introduction of favourable traits from wild types in commercial cultivars. In this PhD thesis the development of an ILs collection is described, using the Queen's Pocket melon accession (Dudaim group) of Irak as the exotic donor parental and the Spanish cultivar 'Piel de Sapo' (Ibericus group) as the recurrent parental. During the ILs generation process, not only genotyping was taken into consideration (several techniques such as HRM, the Agena Bioscience platform and GBS were used) to optimize the recovery of the recurrent genetic background, the number of introgressions and the coverage of the donor genome, but also the phenotype shown by the different families. A set of 16 ILs was finally selected, bearing an average of 1.4 introgressions per IL and representing 62.6% of the donor genome. The phenotypic characterization of this IL collection allowed the identification of 32 stable QTLs (Quantitative Trait Loci) in the two environments evaluated. Out of these, 22 QTLs correspond to morphological traits such as weight, shape, netting, flesh width and cavity; 9 QTLs are related to traits associated with the climacteric ripening such as the presence of the abscission layer, aroma and flesh firmness; and one related to the soluble solids content. Many QTLs identified in this work have not been described previously. This implies new alleles of potential interest not only in breeding but also in the study of new genomic regions and genes controlling agronomical and quality traits. On the other hand, other QTLs confirmed regions previously described by other authors. In this work, interesting lines are described in terms of the presence of aroma, reduction of fruit size and / or more rounded shapes, characteristics requested by 'Piel de Sapo' consumers. The phenotyping of this set of ILs was also carried out for searching for resistance to a pathogenic soil fungus, Macrophomina Phaseolina. Despite the moderate resistance described for the Dudaim parental in a previous work, no line was resistant. The study presented herein about the influence of temperature on the pathogenicity of this fungus, has shown that the resistance of the donor parenal is overcome with the temperature increase and therefore, is not stable. In this screening, only one African wild accession was resistant to high temperatures. In addition, an assay searching for tolerance to the fungi of the soil, Monosporascus cannonballus and M. eutypoides, the main responsible for melon collapse, was carried out. The results allowed us to conclude that M. cannonballus presents higher pathogenicity than M. eutypoides. Additionally, temperature also affected the symptoms severity, which is coherent with previous studies. Two African and one Indian accessions were the ones displaying higher tolerance to Monosporascus spp. They may be of great interest in future melon breeding programs. / Castro Alcocer, GE. (2019). APROVECHAMIENTO DE HERRAMIENTAS GENETICAS Y GENOMICAS PARA DESARROLLO DE NUEVAS POBLACIONES PARA LA MEJORA DEL MELON POR RESISTENCIA A PATÓGENOS Y CALIDAD [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/131206 / TESIS

The use of biological control agents (BCAs) in the past has shown limited success as its application has often been done incorrectly, and in addition, management practices are rarely altered to incorporate BCAs. Criteria for the correct application of BCAs have been devised as part of the research, and companies selling these products may use the said criteria. Such application will ensure the correct BCAs are used and, more specifically, used under the correct conditions. The powdery mildew (PM) fungus is often seen to develop resistance to synthetic fungicides and, therefore, alternative control measures are required. BCAs as an alternative pose less risk to the environment, workers and the consumer. A pre-trial has been conducted with a range of BCAs to see if they can control powdery mildew (PM) in a greenhouse environment on hydroponically grown cucumber (Cucumis sativus L.) plants using the variety Baccara that has only a moderate tolerance to PM. The BCAs have been compared to the control (synthetic fungicide: Bravo). Comparative work includes Coyier's model, which has been modified and adapted for these trials to determine the percentage of leaf area covered by the PM infection. Furthermore, the number of fruit harvested per treatment, kilogram yield, total mass of yield and average fruit mass is also used to determine the efficacy of the BCAs as these factors have economic significance to commercial growers. The pre-trial showed promise until the fertigation computer failed, resulting in a nutrient shortage and imbalance, confirming that BCAs alone cannot control PM. Synthetic fungicides were applied until control of PM and plant nutrition was regained. BCAs were re-introduced and used until the end of crop production. The confirmation from the pre-trial has led to the inclusion of silicon in conjunction with the BCAs in the two subsequent trials (Trials 1 & 2). Silicon was applied with the BCAs as a foliar spray on a weekly basis. In trials 1 and 2, the cucumber variety, Palladium, with a high genetic tolerance to PM is used, as this variety is suited to form part of the holistic approach used for trials 1 and 2. Trial 1 showed that treatment A, containing Streptomyces griseovirdis and Streptomyces aureofaciens, had the highest yield. Both of these are bacterial BCAs and demonstrated their adaptability to varied climatic conditions, notably when low humidity was experienced. In treatment B, Trichoderma harzianum strains, Rifai and Uppington, show the slowest rate of PM development. In trials 1 and 2, the best actual PM control was obtained by two fungal based BCAs (Trial 1, treatment C was Ampelomyces quisqualis) and (Trial 2, treatment B was Trichoderma harzianum strains, Rifai and Uppington), showing that fungal BCAs have a place for this application, but the growth-enhancing properties of bacterial based BCAs make economic sense and would make them attractive to growers. Treatment A (Streptomyces spp.) had the most number of fruit for the entire growing period and the best overall yield (kg yield) again. Two of the BCA / silicon treatments have marginally better PM control compared to that of the control (E) treatment, although not statistically significant. Treatment E (control) has the highest average fruit mass in this instance but does not have the highest yield (kg yield) when compared to treatments A and B, possibly due to the growth-enhancing properties of most of these BCAs. Therefore, most of these BCA treatments give fairly inconsistent results that vary possibly according to season, humidity and temperature, making it difficult to predict their efficacy. Using combinations or weekly alternations of these BCAs with extremes of climatic adaptation will probably be the most reliable method of obtaining consistent results. Bacterial BCAs are shown to have lower humidity requirements and produce the most consistent results in terms of fruit number, yield and fruit mass and a combination of bacterial and fungal based BCAs would possibly be the best as this would control PM and yet still have the growth enhancing properties from the bacterial based BCAs. From the research, it can be said that some BCAs in trials 1 and 2 produce results similar to that of the control in terms of percentage leaf area covered by PM and some are shown to have improved yields. Results produced from certain BCA treatments are thus equal to the control; yet provide an environmentally friendly alternative to synthetic fungicides. Silicon is listed as a beneficial element rather than an essential element; however, literature claims it to be highly effective in treating PM in cucurbits. Results from trials 1 and 2 show that control of PM is possible in most cases, when a holistic approach is used. This approach includes a cucumber variety with a high PM tolerance, optimum nutrition, cultural practices and silicon in combination with the BCAs. A complete change of management practices is necessary to implement such a BCA program. / Agriculture, Animal Health & Human Ecology / M. Tech. (Nature Conservation)

The use of biological control agents (BCAs) in the past has shown limited success as its application has often been done incorrectly, and in addition, management practices are rarely altered to incorporate BCAs. Criteria for the correct application of BCAs have been devised as part of the research, and companies selling these products may use the said criteria. Such application will ensure the correct BCAs are used and, more specifically, used under the correct conditions. The powdery mildew (PM) fungus is often seen to develop resistance to synthetic fungicides and, therefore, alternative control measures are required. BCAs as an alternative pose less risk to the environment, workers and the consumer. A pre-trial has been conducted with a range of BCAs to see if they can control powdery mildew (PM) in a greenhouse environment on hydroponically grown cucumber (Cucumis sativus L.) plants using the variety Baccara that has only a moderate tolerance to PM. The BCAs have been compared to the control (synthetic fungicide: Bravo). Comparative work includes Coyier's model, which has been modified and adapted for these trials to determine the percentage of leaf area covered by the PM infection. Furthermore, the number of fruit harvested per treatment, kilogram yield, total mass of yield and average fruit mass is also used to determine the efficacy of the BCAs as these factors have economic significance to commercial growers. The pre-trial showed promise until the fertigation computer failed, resulting in a nutrient shortage and imbalance, confirming that BCAs alone cannot control PM. Synthetic fungicides were applied until control of PM and plant nutrition was regained. BCAs were re-introduced and used until the end of crop production. The confirmation from the pre-trial has led to the inclusion of silicon in conjunction with the BCAs in the two subsequent trials (Trials 1 & 2). Silicon was applied with the BCAs as a foliar spray on a weekly basis. In trials 1 and 2, the cucumber variety, Palladium, with a high genetic tolerance to PM is used, as this variety is suited to form part of the holistic approach used for trials 1 and 2. Trial 1 showed that treatment A, containing Streptomyces griseovirdis and Streptomyces aureofaciens, had the highest yield. Both of these are bacterial BCAs and demonstrated their adaptability to varied climatic conditions, notably when low humidity was experienced. In treatment B, Trichoderma harzianum strains, Rifai and Uppington, show the slowest rate of PM development. In trials 1 and 2, the best actual PM control was obtained by two fungal based BCAs (Trial 1, treatment C was Ampelomyces quisqualis) and (Trial 2, treatment B was Trichoderma harzianum strains, Rifai and Uppington), showing that fungal BCAs have a place for this application, but the growth-enhancing properties of bacterial based BCAs make economic sense and would make them attractive to growers. Treatment A (Streptomyces spp.) had the most number of fruit for the entire growing period and the best overall yield (kg yield) again. Two of the BCA / silicon treatments have marginally better PM control compared to that of the control (E) treatment, although not statistically significant. Treatment E (control) has the highest average fruit mass in this instance but does not have the highest yield (kg yield) when compared to treatments A and B, possibly due to the growth-enhancing properties of most of these BCAs. Therefore, most of these BCA treatments give fairly inconsistent results that vary possibly according to season, humidity and temperature, making it difficult to predict their efficacy. Using combinations or weekly alternations of these BCAs with extremes of climatic adaptation will probably be the most reliable method of obtaining consistent results. Bacterial BCAs are shown to have lower humidity requirements and produce the most consistent results in terms of fruit number, yield and fruit mass and a combination of bacterial and fungal based BCAs would possibly be the best as this would control PM and yet still have the growth enhancing properties from the bacterial based BCAs. From the research, it can be said that some BCAs in trials 1 and 2 produce results similar to that of the control in terms of percentage leaf area covered by PM and some are shown to have improved yields. Results produced from certain BCA treatments are thus equal to the control; yet provide an environmentally friendly alternative to synthetic fungicides. Silicon is listed as a beneficial element rather than an essential element; however, literature claims it to be highly effective in treating PM in cucurbits. Results from trials 1 and 2 show that control of PM is possible in most cases, when a holistic approach is used. This approach includes a cucumber variety with a high PM tolerance, optimum nutrition, cultural practices and silicon in combination with the BCAs. A complete change of management practices is necessary to implement such a BCA program. / Agriculture, Animal Health and Human Ecology / M. Tech. (Nature Conservation)

Text in English with abstracts in English, Tsonga and Sepedi and keywords in English / This study was carried out to investigate the performance and quality of Cucumis metuliferus E. Mey. Ex Naudin (African horned cucumber) under protected and open environment with the aim of comparing yield and quality for the purpose of commercialisation of the crop. Therefore, the overall objective was to determine a suitable growing environment for C. metuliferus between greenhouse, shade net and open field, so that a comparative yield and quality analysis could be done for the purpose of commercialisation of the crop. Cucumis metuliferus seeds are difficult to germinate under the normal suitable environmental conditions in which most farmers operate. Germination was evaluated with respect to growth medium, scarification and seed certification. These factors ultimately control yield and fruit quality. The main aim of the study was to investigate the effect or impact of seed certification, growth medium (sand and vermiculite, peat TS1 and seedling mix) and scarification on germination success of C. metuliferus seeds. The seeds were classified under four different categories viz. treated certified, non-treated certified, treated uncertified, and non-treated uncertified. Of the 540 certified and uncertified seeds sown in the three-growth media, 80% germinated, significantly more that those that failed. The treatment combination of treated certified seeds (TC) and peat demonstrated high germination success rate of 93.6%, followed by the treatment combination of treated certified seeds (TC) and sand+ vermiculite with germination success rate of 91.3%. The treatment combination of uncertified untreated (UTU) seeds and potting mix illustrated low germination success rate at 37.2%. In general, the study results revealed that certified seeds scarified with warm water combined had a higher germination rate that unscarified seeds, irrespective of the growth media. Since the seedling root-ball integrity is essential for transplant survival, this study suggests peat and certified seeds as the best combination for propagation and good quality plants. Water scarcity, population growth and climate change are the major factors affecting agricultural productivity in the 20th century. Cucumis metuliferus grows naturally in the wild; however, its yield response to water stress, different cultivation environment and soil types, has not been assessed. A study was carried out to determine water use efficiency of the C. metuliferus grown the greenhouse, shade net and open field under varying soil types and irrigation water levels, so that a comparative analysis could be done on productivity levels. The research was conducted at the University of South Africa (Unisa) Science Campus, in Florida, Gauteng (-26.157831 S, 27.903364 E) during the 2017/2018 and 2018/2019 growing seasons. A factorial experiment with two factors – soil (loamy soil and sandy loam soil) and water stress levels (no water stress, moderate water stress and severe water stress). The pot experiments were a completely randomised design with nine (9) replicates per treatment. Data collected included total biomass, aboveground biomass, harvest index and water use efficiency. Results illustrated that treatment of moderate water stress combined with loamy soil and shade net decreased WUE from 6.2 to 1.4 kg m-3, whereas treatment combination of no water stress combined with sandy loam and open field environment demonstrated increase in WUE from 1.4 to 6.2 kg m-3. Nutritional concentration of most crops depends on factors such as amount of water, growing environment, light intensity and soil types. However, factors influencing nutritional concentration of C. metuliferus fruits is not yet known. Another objective of the study was to determine the effect of different water stress levels, soil types and growing environment (greenhouse, shade net and open field) on the concentration of nutrients in C. metuliferus fruit. Freeze-dried fruit samples were used in the quantification of ꞵ-carotene, vitamin C, vitamin E, total soluble sugars, crude proteins, total flavonoids, total phenols, macro-nutrients (Ca, Mg, P, K, Na and S), and micro-nutrients (Cu, Fe, Mn and Zn). Results demonstrated that plants grown under shade net, combined with severe water stress level and loamy soil, had increased total soluble sugars (15.8 ˚Brix) compared to other treatments. Plants under shade net environment, combined with moderate water level and loamy soil, resulted in increased crude protein content (6.31 ˚Brix). The severe water stress treatment combined with loamy soil under greenhouse conditions resulted in increased ꞵ-carotene content (1.65 mg 100 g-1 DW) when compared to other treatments. Regarding vitamin C, the treatment of no water stress combined with loamy soil under shade net environment showed higher content of (33.1 mg 100 g-1 DW). The severe water stress treatment combined with sandy loam soil under greenhouse environment, increased vitamin E content (35.1 mg 100 g-1 DW) when compared to other treatments. The treatment of open field under severe water stress level and loamy soil increased total flavonoids content (0.85 mg CE/g-1 DW) in the fruit when compared to other treatments. The results thus imply that this plant bears better-quality fruit in terms of concentration of nutrients and biochemical constituents when grown under no to moderate water stress treatment on the loamy or sandy loam substrate in the shade net and open field environment. Primary metabolites are biological compounds that are essential to the growth and development of a plant during its life cycle. They have a direct impact on the yield and biochemical constituents in plants. Quantities of the primary metabolites were determined using the LC-MS-8040 triple quadrupole mass spectrometer (Shimadzu) from fruits harvested from treatments mentioned above. The results showed that the no water stress treatment combined with sandy loam under shade net environment significantly (P≤0.05) increased asparagine content from 10×106 to 80x106 peak intensity when compared to other treatments. The severe water stress treatment combined with sandy loam soil under open field environment during the 2017/2018 season, significantly increased dopa content from 12,030 to 324,240 peak intensity, while during the 2018/2019 season, 4-hydroxyproline from 10×106 to 90x106 peak intensity the was significantly increased. The study suggests that the treatment combination of water stress levels (no water stress and severe water stress) and soil substrates (loamy soil and sandy loam) under greenhouse and shade net significantly affected the shift of primary metabolites profile of C. metuliferus fruit as opposed to individual factors, respectively. There is therefore great potential to commercialise this crop; however, there is still a great deal that is not well understood of its growth habits and biological/biochemical constituents as a future alternative crop. / Ndzavisiso lowu wu endliwe ku lavisisa hi matirhelo na khwaliti ya Cucumis metuliferus E. Mey. Ex Naudin (African horned cucumber) eka mimbangu na mavala lama sirheleriweke na hi xikongomelo xa ku kotlanisa ntshovelo na vuxopaxopi bya khwaliti hi xikongomelo xa ku endla minxaviso ya ximila. Xikongomelonkulu xa ku vona ku faneleka ku kula ka C. metuliferus exikarhi ka ti-greenhouse, nete ya ndzhuti na mimbangu ya le rivaleni ku endlela ku pfuneta nxopaxopo. Timbewu ta C. metuliferus ta nonon'hwa ku tihlukisa ehansi ka swiyimo swa mbangu leswi faneleke laha varimi va tirhaku eka tona. Ku hlukisa swi kamberiwe hi ku langutana na midiyamu ya ku kula, skarifikhexini na switifiketi swa timbewu. Swilo leswi swi lawula ntshovelo na khwaliti ya muhandzu. Xikongomelonkulu xa ndzavisiso lowu a ku ri ku lavisa hi vuyelo bya ku nyikiwa ka switifiketi, midiyamu ya ku kula (sand + vermiculite, peat TS1 and seedling mix) na skarifikhexini eka ku humelela ku hlukisa timbewu ta C. metuliferus E. Mey. ex naudin. Timbewu ti klasifayiwile ehansi ka tikhathegori ta mune to hambana, ku nga, treated certified, non-treated certified, treated uncertified, na non-treated uncertified.Hi vunharhu ka timediya leti ti ve na nhlukiso wa xiyenge hi 80%. Vuyelo byi kombise leswo treated certified na non-treated certified ti ve na ku humelela ka le henhla ka nhlukiso hi 93.6% na 91.3% hi ku landzelelana. Vuhumeleri bya nhlukiso wa le hansi ku ve timbewu ta treated uncertified hi vuyelo bya 37%. Vulehi bya 12 cm byi voniwe eka certified seedlings tanihi bya le henhla swinene. Swimilani swa unscarified na swa uncertified swi ve na timbewu ta le hansi, ta vulehi bya 3.44 cm eka vhiki ra vumune. Hikokwalaho, seed certification swi ve na vuyelo ngopfu ku tlula scarification hi majini ya le henhla swinene. Ku khomaniseka ka ximila eka bolo ya misava i swa nkoka eka ku pona no ya emahlweni ka ximila loko xi transplantiwa, kasi ndzavisiso lowu wu tlakusa leswo ku va na peat na timbewu leti nga na switifiketi tanihi ndlela yo antswa swinene ya ku kurisa swimila na ku va na swimila swa khwaliti. Ku pfumaleka ka mati, nkulo wa swilo hinkwaswo na ku cinca ka tlayimete i swa nkoka leswi khumbaka ku tirheka ka vurimi eka malembexidzana ya 20. Cucumis metuliferus yi kula hi ntumbuluko enhoveni; kambe ntshovelo wa yona wu angula eka ku kala ka mati, tindhawu to hambana ta ku rimiwa na mixaka ya misava, a swi si kamberiwa. Ku endliwe ndzavisiso ku vona ku faneleka ka mafambiselo ya ku kurisa ximila eka greenhouse, nete ya ndzhuti eka swiyimo swa mavala lama pfulekeke, leswo nxopaxopo wu ta kotlanisiwa eka tilevhele ta vuyelo bya ntshovelo loku nga endliwaka. Ndzavisiso wu endliwe eka greenhouse, nete ya ndzhuti na swiyimo swa mavala lama pfulekeke eKhempasi ya Sayense eUniversity of South Africa (Unisa) eFlorida, eGauteng (26.157831 S, 27.903364 E) hi nkarhi wa 2017/2018 na 2018/2019 hi tisizini ta ku byala. Ekspirimente leyi nga na swilo swimbirhi – ku nga misava ya loamy na misava ya misava ya sava ya loam) na levhele ya ncheleto wa mati (laha ku nga ri ku na mati kahle, laha ku nga na matinyana na laha ku kalaka mati). Xipirimente xa le mapotweni xi endliwe hi ndlela yo ka yi nga kunguhatiwangi hi ku tirhisa ku phindaphinda ka nkaye (9), na dizayini ya kona leyi nga kombisiwa laha henhla. Tipharamita ta ku pimiwa ti katsa chlorophyll content, stomatal conductance na xiyenge xa ntshovelo, xo fana na ku tirhisa mati, vuheleri bya biomass, biomass ehenhla ka bayomasi ya misava, indeksi ya ntshovelo, vulehi bya muhandzu, nhlayo ya mihandzu, na ku tirhisiwa ka mati hi ndlela yo hlayisa. Vuyelo byi kombise leswo tirhelo ra mavala lama pfulekeke swi pfanganisiwa na ndhawu yo kala mati na misava ya sava ya loam, swi ngetela nhlayo ya mihandzu. Ku tirhiwa ka swiyimo swa mavala lama nga pfuleka, swi hlanganisiwa na ndhawu yo kalanyana mati na misava ya sava ya loam, swi kombise ku tirhisiwa kahle ka mati ka le henhla hi (6. 2 kg m-3) loko swi kotlanisiwa na ku tirhiwa ku n'wana. I swa nkoka ku lemuka leswaku a ku va ngi na ku hambana ku kulu exikarhi ka misava ya sava ya loam na misava ya loam eka ntirhiso wa mati lowu ku nga water use efficiency (WUE). Kambe, misava ya sava ya loam yi kombise xiyenge xa le henhla xa WUE loko swi kotlangisiwa na misava ya loam. Hikokwalaho ku nga fikeleriwa eka mhaka ya leswo ku pfanganisa ku tirhana na mavala yo pfuleka, tilevhele ta ncheleto wa mati (kahle na le xikarhi) na misava ya sava ya loam swa bumabumeriwa eka varimi leswo ku ta fikelekeleriwa xiyenge xa le henhla xa WUE na ku humelela ka ntshovelo wa C. metuliferus. Ku hlengeletana ka tinutriyente eka ndhawu yin'we (nutritional concentration) ka swimila swi titshege hi swilo swo fana na leswi kumekaka eka mati, mbangu wa ku kula, masana ya dyambu na mixaka ya misava. Kambe, swilo swo fana na ku hlengeletana ka tinutriyente ta mihandu ya C. metuliferus a swi si tiveka. Xikongomelo xa ndzhavisiso a ku ri ku vona vuyelo bya tilevhele to hambana ta ku kala ka mati (ku pfumaleka ka mati, ku pfumalekanyana, na ku pfumaleka swinene ka mati), mixaka ya misava (misava ya loam na misava ya sava) mbangu wa ku kula (greenhouse, nete ya ndzhuti na mavala yo pfuleka) hi ku pfangana na tinutriyente eka mihandzu ya C. metuliferus E. Mey. ex naudin. Tisampuli ta mihandzu leyi nga omisiwa yi friziwa ti tirhisiwe eka ku endla vunyingi bya ꞵ-carotene, Vhitamini C, Vhitamini E, na total soluble sugars, ti-crude protein na ti-total flavonoids, total phenols, na micro-nutrients (Cu, Fe, Mn na Zn). Vuyelo bya ndzavisiso byi kombise leswo swimila leswi nga kurisiwa eka nete ya ndzhuti, swi pfanganisiwa na levhele ya nkalo wa mati swinene na misava ya loam, swi ngetele ti-soluble sugars hi (15.8 ˚Brix) loko ku kotlanisiwa na ku tirhiwa kun'wana. Swimila leswi nga hansi ka mbangu wa nete ya ndzhuti, swi pfanganisiwa na nkayivelonyana wa mati hi vuxikarhi na misava ya loam, swi ve na vuyelo bya ku ngetela crude protein content hi (6.31˚Brix). Ku tirhiwa ka nkayivelo wa mati swinene swi pfanganisiwa na misava ya loam ehansi ka swiyimo swa greenhouse swi ngetelele ꞵ-carotene content (1.65 mg/100 g-1 DW) loko swi kotlanisiwa na ku tirhiwa kun'wana. Ku tirhiwa ka ku kayivela ka mati swi pfanganisiwa na misava ya loam ehansi ka mbangu wa nete ya ndzhuti swi kombise ku ngeteleleka ka vhitamini C hi (33.1 mg 100 g-1 DW). Ku tirhiwa ka nkayivelo wa mati swinene swi pfanganisiwa na misava ya loam ehansi ka swiyimo swa mbangu wa greenhouse swi ngetelele vhitamin E hi (35.1 mg 100 g-1 DW) loko swi kotlanisiwa na ku tirhiwa kun'wana. Ku tirhiwa ka mavala lama nga rivaleni eha CE g-1 DW) loko swi kotlanisiwa na ku tirhiwa kun'wana. Ku tirhana na nkayivela mati ka levhela ya le xikarhi na misava ya sava ya loam ehansi ka mbangu wa nete ya ndzhuti swi kombise ku ngeteleleka ka Zn content (12.7 μg g-1 DW) loko swi kotlanisiwa na ku tirhiwa kun'wana. Vuyelo byi kombisa leswaku ximila lexi xi na mihandzu ya khwaliti yo antswa hi ku landza ku hlengeletana ka tinutriyeente na tikhonstituwenti ta bayokhemikali, loko xi kurisiwa ehansi na ku ka ku nga ri na nkayivela mati kumbe ku kayivelanyana ka mati, hi ku tirhisa misava ya loam kumbe misava ya sava eka nete ya ndzhuti na le ka mavala ya le rivaleni.Ti-primary betabolites ti tlhela titiviwa tanihi biological compounds leti ti faneleke eka ku kula na ku hluvuka ka ximila hi nkarhi wa vutomi bya xona. Ti na vuyelo byo kongoma eka ntshovelo na tikhonsticuwenti ta bayokhemikala eka swimila. Vunyingi bya primary metabolites swi vekiwe hi ku tirhisa LC-MS-8040 triple quadrupole mass spectrometer (Shimadzu) eka mihandzu leyi nga ntshovelo wa ku tirhiwa kun'wana loku ku nga vuriwa laha henhla. Vuyelo byi kombe leswo ku tirhana na nkala nkayivelo wa mati, swi pfanganisiwa na misava ya loam ehansi ka mbangu wa nete ya ndzhuti, swi ngetelele swinene asparagine content from 10×106 to 80x106 nsi ka nkayivelo swinene wa mati na misava ya loam, swi ngetelele ti-total mz loko swi kotlangisiwa na ku tirhiwa kun'wana. Ku tirhana na nkayivelo wa mati swinene, swi pfanganisiwa na misava ya sava ya loam ehansi ka mbangu wa mavala lama pfulekeke hi nkarhi wa sizini ya 2017/2018, swi ngetelele swinene dopa content ku suka eka 12,030 to 324,240 peak intensity, kasi hi nkarhi wa sizini ya 2018/2019 season, 4-hydroxyproline ku 10×106 to 90x106 peak intensity swi ngeteleleke swinene. Ku tirhana ko fanana ehansi ka mbangu wa greenhouse, swi ngetelele swinene acetylcarnitine content ku suka eka 3,761 to 82,841 area under the curve hi nkarhi wa sizini ya 2018/2019. Ku tirhiwa ka ku nga ri na ku kayivela ka mati ka le xikarhi swi pfanganisiwa na misava ya loam ehansi ka mbangu wa mavala lama nga rivaleni swi ngetelele swinene norepinephrine content from 71,577 to 256,1045 peak intensity. Ndzavisiso wu pimanyete leswo mpfanganyiso wa ku tirhana na tilevhele ta ncheleteo wa mati (laha ku nga ri ku na ku kayivela ka mati na le ku nga na nkayivelo wa mati) na misava ya loam na misava ya sava ya loam) ehansi ka greenhouse na nete ya ndzhuti swi khumbe swinene ku xifta ka mihandzu ya primary metabolites profile of C. metuliferus E. Mey. ex naudin loko ku langutaniwa na tifekthara ha yin'we yin'we hi ku landzelelana.flavonoids content (0.85 mg CE g-1 DW) loko swi kotlanisiwa na ku tirhiwa kun'wana. Ku tirhana na nkayivela mati ka levhela ya le xikarhi na misava ya sava ya loam ehansi ka mbangu wa nete ya ndzhuti swi kombise ku ngeteleleka ka Zn content (12.7 μg g-1 DW) loko swi kotlanisiwa na ku tirhiwa kun'wana. Vuyelo byi kombisa leswaku ximila lexi xi na mihandzu ya khwaliti yo antswa hi ku landza ku hlengeletana ka tinutriyeente na tikhonstituwenti ta bayokhemikali, loko xi kurisiwa ehansi na ku ka ku nga ri na nkayivela mati kumbe ku kayivelanyana ka mati, hi ku tirhisa misava ya loam kumbe misava ya sava eka nete ya ndzhuti na le ka mavala ya le rivaleni.Ti-primary betabolites ti tlhela titiviwa tanihi biological compounds leti ti faneleke eka ku kula na ku hluvuka ka ximila hi nkarhi wa vutomi bya xona. Ti na vuyelo byo kongoma eka ntshovelo na tikhonsticuwenti ta bayokhemikala eka swimila. Vunyingi bya primary metabolites swi vekiwe hi ku tirhisa LC-MS-8040 triple quadrupole mass spectrometer (Shimadzu) eka mihandzu leyi nga ntshovelo wa ku tirhiwa kun'wana loku ku nga vuriwa laha henhla. Vuyelo byi kombe leswo ku tirhana na nkala nkayivelo wa mati, swi pfanganisiwa na misava ya loam ehansi ka mbangu wa nete ya ndzhuti, swi ngetelele swinene asparagine content from 10×106 to 80x106 mz loko swi kotlangisiwa na ku tirhiwa kun'wana. Ku tirhana na nkayivelo wa mati swinene, swi pfanganisiwa na misava ya sava ya loam ehansi ka mbangu wa mavala lama pfulekeke hi nkarhi wa sizini ya 2017/2018, swi ngetelele swinene dopa content ku suka eka 12,030 to 324,240 peak intensity, kasi hi nkarhi wa sizini ya 2018/2019 season, 4-hydroxyproline ku 10×106 to 90x106 peak intensity swi ngeteleleke swinene. Ku tirhana ko fanana ehansi ka mbangu wa greenhouse, swi ngetelele swinene acetylcarnitine content ku suka eka 3,761 to 82,841 area under the curve hi nkarhi wa sizini ya 2018/2019. Ku tirhiwa ka ku nga ri na ku kayivela ka mati ka le xikarhi swi pfanganisiwa na misava ya loam ehansi ka mbangu wa mavala lama nga rivaleni swi ngetelele swinene norepinephrine content from 71,577 to 256,1045 peak intensity. Ndzavisiso wu pimanyete leswo mpfanganyiso wa ku tirhana na tilevhele ta ncheleteo wa mati (laha ku nga ri ku na ku kayivela ka mati na le ku nga na nkayivelo wa mati) na misava ya loam na misava ya sava ya loam) ehansi ka greenhouse na nete ya ndzhuti swi khumbe swinene ku xifta ka mihandzu ya primary metabolites profile of C. metuliferus E. Mey. ex naudin loko ku langutaniwa na tifekthara ha yin'we yin'we hi ku landzelelana. / Thuto ye e dirilwe ka maikemišetšo a go nyakišiša tiragatšo le boleng bja Cucumis metuliferus E. Mey. Ex Naudin (phara ya seAfrika) mo tikologong yeo e šireleditšwego le ya mo lebaleng e le nepo ya go bapetša tshekatsheko ya kotollu le boleng go hola thekišo ya mabele. Maikemišetšo kakaretšo e le go humana tsela ya maleba ya go mediša C. Metuliferus dipakeng tša mokhukhutšhireletšo, nnete ya moriti le mo ditikologong tša mabala ao a bulegilego gore go nolofatšwe tshekatsheko. Go boima go mediša dipeu tša C. Metuliferus ka tlase ga maemo a tikologo ya maleba ya go tlwaelega yeo e šomišwago ke bontši bja balemi. Medišo ya dipeu e lekanyeditšwe go ya le ka sedirišwa sa go mediša dimela, go fala dipeu le go hlahlobo ya boleng bja dipeu. Dikokwana tše ke tšona di laolago kotollu le boleng bja dienywa. Nepokgolo ya thuto ye e be e le go nyakišiša khuetšo ya tlhahlobo ya polokego ya dipeu tše, sedirišwa sa go mediša dimela (mohlaba+vermiculite, peat TS1 le motswako wa dipeu) le phalo ya dipeu go kgonthišiša katlego ya go mela ga dipeu tša C. Metuliferus. Dipeu di ile tša arolwa go ya le ka magoro a mane, bjalo ka peu ya go okobatšwa ka dikhemikhale yeo e hlahlobilwego, peu yeo e sa okobatšwago gomme e hlahlobilwe, peu ya go okobatšwa e sa hlahlobjwago le peu yeo e sa okobatšwago gomme e se ya hlahlobjwa. Boraro bja didirišwa tše di laeditše katlego ya go mediša yeo e ka balelwago go 80%. Dipoelo di šupa gore dipeu tšeo di okobaditšwego di se a hlahlobjwa le tšeo di sa okobatšwago di hlahlobilwe di bile le katlego ya tlhogo yeo e ka balelwago go 93.6% le 91.3%. Tlhogo ya fase e bile go dipeu tšeo di okobaditšwego di sa hlahlobjwago ka poelo ya 37%. Dipeu tše di hlahlobilwego di laeditše botelele bja 12cm gomme e le bjona bja go di feta ka moka. Dipeu tšeo di sa falwago le go hlahlobjwa di bile le botelele bja fase bja go balelwa go 3.44 cm ka dibeke tše nne. Bjalo, tlhahlobo ya dipeu e tlišitše katlego go fetiša phalo. Ka ge mudu wa dipeu o le bohlokwa go tšhutišetšo ya maphelo a dimela, thuto ye e thekga mmutedi le tlhahlobo ya dipeu bjalo ka tlhakanyo ya go mediša dimela tša boleng bja maleba. Tlhokego ya meetse, go oketšega ga baagi, le diphetogo tša klaemete ke tšona dikokwana tše di amago tšwelelo go tša temo nakong ya bjale. C. Metuliferus E. Mey. ex naudin e mela ka lešokeng tlhagong ya yona; efela, kotullo ya yona go tlhokego ya meetse, go mehuta ya mašemo le mehuta ya mabu ga se e ahlaahlwe. Thuto e ile ya dirwa go humana mokgwa wa go bjala/mediša dimela dipakeng tša mokhukhutšhireletšo, nnete ya moriti le boemo bja lebala le le bulegilego, gore go tle go tšweletšwe tshekatsheko yeo e laetšago diphapano tša mabato a puno. Nyakišišo ye e diritšwe ka fase ga maemo a mokhukhutšhireletšo, nnete ya moriti le lebaleng le le bulegilego Yunibesithing ya Afrika Borwa (UNISA) Khamphasing ya tša Saense, go la Florida, Gauteng (-26.157831 S, 27.903364 E) ka nako ya sehla sa 2017/2018 le 2018/2019 ka dinako tša go mela. Teko ye e ithekgile godimo ga dikokwana tše pedi – mabu (monola le mohlaba) le mabato a taolo ya go nošetša (tlhokego ya meetse ya lebato la fase, tlhokego ya meetse ye e lekanetšego le tlhokego ya meetse ya lebato la godimo). Diteko di be di beilwe ka mokgwa wo o sa rulaganywago gomme teko ye nngwe le ye nngwe e boeleditšwe ga senyane (9) bjalo ka ge e laeditšwe godimo. Dipharametha tšeo di lekantšwego di akaretša dikagare tša chlorophyll, stomatal conductance le bjalo ka tšhomišo ya meetse, palomoka ya dimela, dimela tše di bonagalago ka godimo, lenaneo la puno, botelele bja enywa, palo ya enywa le tšhomišo ya meetse ke dimela. Dipoelo di tšweletša gore teko ya mo lebaleng le le bulegilego le meetse a a lekanetšego gammogo le monola di oketša palo ya dienywa. Teko ya mo lebaleng le le bulegilego go kopantšhwa le meetse ao a lekanetšego le monola, di laeditše tšhomišo ya meetse yeo e balelwago go (6.2 kg m-3) ge go bapetšwa le diteko tše di ngwe. Go bohlokwa go lemoga gore ga ga go na diphapano magareng ga mohlaba le monola tšhomišong ya meetse (WUE). Efela, mohlaba o laeditše (WUE) ya godimo ge go bapetšwa le monola. Se se bolela gore, go ka tšewa sephetho sa gore teko ya dipeu lebaleng le le bulegilego, taolo ya go nošetša dimela (ye gabotse le ye e lekanetšego) le mohlaba ke didirišwa tšeo go eletšwago balemi gore ba di šomiše go humana (WUE) ya godimo le tšweletšo ye e atlegilego ya C. metuliferus. Bontši bja phepo mo mabeleng bo hlohleletšwa ke dikokwana tša go swana le meetse, tikologo ya mo a melago gona, dihlase tša letšatši le mehuta ya mabu. Efela, dikokwana tše di huetšago bontši bja diphepo go dienywa tša C. metuliferus ga dišo di tsebjwa. Nepo ya thuto ye e be e le go nyakolla khuetšo yeo dikokwana tše di latelago; di nago le yona go bontši bja diphepo go enywa ya C. Metuliferus: mabato a meetse (tlhokego ya meetse ya lebato la fase, tlhokego ya meetse ye e lekanetšego le tlhokego ya godimo ya meetse), mehuta ya mabu (monola le mohlaba) le tikologo ya go mediša (mokhukhutšhireletšo, nnete ya moriti le lebala le le bulegilego). Diteko tša enywa yeo e omišitšwego ka setšidifatšing e ile ya šomišwa go tšweletša boleng bja ꞵ-carotene, vitamin C, vitamin E, total soluble sugars, crude proteins, total flavonoids, total phenols, le micro-nutrients (Cu, Fe, Mn le Zn). Dipoelo di šupa gore dimela tše di godišitšwego ka fase ga nnete ya moriti, go akaretša le tlhokego ya meetse ya godimo le monola di nyološitše diswikiri tše di humanegago mo dimeleng (15.8 ˚Brix) ge go bapetšwa le diteko tše dingwe. Dimela tikologong ya nnete ya moriti go akaretša le tlhokego ya meetse ye e lekanetšego le monola di ile tša nyološa phroteine (6.31 ˚Brix). Teko go tlhokego ya meetse ya godimo go akaretša le monola ka tlase ga boemo bja mokhukhutšhireletšo go nyološitše diteng tša ꞵ-carotene (1.65 mg 100 g-1 DW) ge e bapetšwa le diteko tše dingwe. Teko go tlhokego ya meetse go akaretša monola ka fase ga nnete ya moriti go nyološitše Vitamin C (33.1 mg100 g-1 DW). Teko go hlokego ya meetse ya godimo go akaretša mohlaba tikologong ya mokhukhutšhireletši go nyološitše diteng tša vitamin E (35.1 mg/100 g-1 DW) ge e bapetšwa le diteko tše dingwe. Teko ya go se hlokege ga meetse, go akaretša le monola tikologong ya lebala le le bulegilego e nyološitše palomoka ya diteng tša phenolic (6.4 mg GAE/g-1 DW) ge e bapetšwa le diteko tše dingwe. Teko lebala le le bulegilego ka fase ga hlokego ya meetse ye godimo go akaretša monola go okeditše diteng tša flavonoids (0.85 mg CE g-1 DW) mo dienyweng tša gona ge e bapetšwa le diteko tše dingwe. Teko go hlokego ya meetse ye e lekanetšego le mohlaba ka fase ga nnete ya moriti di laeditše go oketšega ga diteng tša Zn (12.7 μg g-1 DW) ge e bapetšwa le diteko tše dingwe. Dipoelo di laetša gore semela se se thunya boleng bjo bo kgodišago bja dienywa ge go lebeletšwe bontši bja diphepo le dikokwana tša dikhemikhale ge di medišwa mo go sa hlokegago meetse go yela go mo go hlokegago meetse ka go lekanela, go šomišitšwe monola goba mohlaba mo nneteng ya moriti le mo lebaleng le le bulegilego. Dimetabolite tša motheo di tsebjwa bjalo ka motswako wa tlhago wo o lego bohlokwa go kgolo le tlhabollo ya dimela maphelong a tšona. Di na le khuetšothwii go dikokwana tša puno le khemikhale ya hlago ya dimela. Bontši bja dimetabolites tša motheo di humanwe ka go šomiša LC-MS-8040 triple quadrupole mass spectrometer (Shimadzu) ya go tšwa dienyweng tšeo di bunnwego ditekong tše di šetšego di boletšwe. Dipoelo di laeditše gore teko ya hlokego ya meetse ya lebato la fase go akaretša le mohlaba tikologong ya nnete ya moriti; e nyološitše asparagine content go tloga go 10×106 go ya go 80x106 peak intensity ge e bapetšwa le diteko tše dingwe. Tlhokego ya meetse ya lebato la fase e akaretša le monola tikologong ya lebala le le bulegilego ka nako ya sehla sa 2017/2018, 4-hydroxyproline go tšwa go 10×106 go ya go 90x106 area under curve e ile ya nyušwa. Teko ya go swana le ye tikologong ya mokhukhutšhireletšo e ile ya oketša dikagare tša acetylcarnitine go tšwa go 3,761 go ya go 82, 841 peak intensity ka nako ya sehla sa 2018/2019. Teko go tlhokego ya meetse ye e lekanetšego go akaretšwa le monola tikologong ya lebala le le bulegilego e nyološitše dikagare tša norepinephrine go tloga go 71,577 go ya go 256,1045 peak intensity. Diteko di šupa gore ge go kopantšwe taolo ya mabato a go nušetša (tlhokego ya meetse ya lebato la fase le tlhokego ya meetse ya lebato la godimo) le (monola le mohlaba) ka fase ga boemo bja mokhukhutšhireletšo le nnete ya moriti go ile gwa ama katološo ya dimetabolites tša motheo tša enywa ya C. metuliferus ge di bapetšwa le kokwana ye nngwe le nngwe. / College of Agriculture and Environmental Sciences / Ph. D. (Agriculture)

Este trabalho teve como objetivo avaliar o efeito da utilização de película comestível, ácido ascórbico e cloreto de cálcio sobre a conservação do melão \'Amarelo\' minimamente processado. Primeiramente, visando à obtenção de um produto conveniente foram estudados os aspectos microbiológicos e os efeitos dos tratamentos sobre a taxa respiratória e a produção de etileno de produtos de melão durante o armazenamento refrigerado. Os frutos depois de selecionados, lavados e higienizados em solução de dicloroisocianurato de sódio dihidratado (200ppm) tiveram a polpa cortada em cubos (3cm de aresta), que foi imersa em solução de dicloroisocianurato de sódio dihidratado (100ppm) e drenada. A seguir, foram divididos em 4 lotes, cujos cubos foram imersos nas soluções de cloreto de cálcio a 1%, ácido ascórbico a 1% e película a base de alginato (1%) e um lote foi deixado sem tratamento, o qual serviu de testemunha. Após a segunda drenagem, os melões tratados foram acondicionados em bandejas de tereftalato de polietileno (PET) e armazenados a 5°C. Verificou-se que, em todos os tratamentos, houve redução da taxa respiratória ao longo do período de armazenamento e foi detectada baixa produção de etileno. Quanto à qualidade microbiológica, as contagens de bactérias psicrotróficas e de bolores e leveduras mantiveram-se dentro dos limites aceitáveis. Não foi detectada a presença de microrganismos do grupo coliformes e de Salmonella, mostrando que o processamento foi realizado de forma adequada. No segundo experimento estudou-se o efeito dos tratamentos químicos quanto à manutenção dos parâmetros físicos e químicos dos melões \'Amarelo\' minimamente processados. Verificou-se perda de massa de 0,34% durante todo o período de armazenamento. O ácido ascórbico fornecido pelo tratamento levou a um aumento na acidez nos frutos. O uso de película a base de alginato de sódio resultou em melões com menores teores de sólidos solúveis e de acidez titulável, menores pH e grau de solubilização da pectina, melhor sabor, além de coloração mais escura da polpa, em decorrência da cor da solução filmogênica. Os tratamentos químicos estudados pouco afetaram as características físicas e químicas dos produtos de melão e não estenderam a sua vida útil. No terceiro experimento avaliou-se a manutenção da qualidade sensorial, utilizando provadores treinados, através do método da Análise Descritiva Quantitativa (ADQ), bem como a aceitação do produto pelo consumidor. A ADQ mostrou que os tratamentos testados não apresentaram efeito no prolongamento da vida útil dos melões \'Amarelo\' minimamente processados. O teste de consumidor indicou que os melões tratados com cloreto de cálcio e com ácido ascórbico foram os melhor aceitos pelos provadores e revelou que não houve diferença quanto à intenção de compra. No quarto experimento estudaram-se alternativas para o aproveitamento das cascas e das sobras de polpa de melões minimamente processados. Da casca foram desenvolvidos três produtos, compota, doce e glaceado; e com as sobras de polpa foram elaboradas geléias. O teste sensorial indicou que todos os produtos elaborados, com exceção do doce de melão, obtiveram boa aceitabilidade por parte dos julgadores, com índice de aceitabilidade acima de 80%. / This work aims to evaluate the effect of the use of edible film, ascorbic acid and calcium chloride on the conservation of minimally processed melon. In order to obtain a convenient product, the microbiological aspects have been studied in order to evaluate the effect of the treatments on the respiratory rate and ethylene production of melons during the refrigerated storage. The fruits were selected, washed and sanitized in sodium dichloroisocianurate dehydrated solution (200ppm). The pulp of the fruits was cut in cubes (3cm of edge), immersed in sodium dichloroisocianurate dehydrated solution (100ppm) and drained and consequently it was divided in four lots. These cubes were immersed in calcium chloride (1%), ascorbic acid (1%) and alginate film (1%) and a lot was left without any treatment, which served as control. After the second drainage, the melons were placed in trays of polyethylene terephtalate (PET) and stored at 5°C. It has been verified that in all the treatments there was a reduction of the respiratory rate during the storage and the low ethylene production was detected. Concerning the microbiological quality, psychotropic bacteria, molds and yeasts counts were within acceptable limits and fecal bacteria group and Salmonella were not detected which demonstrates that the processing was carried out adequately. The second experiment was studied in order to evaluate the effect of the chemical treatments on the maintenance of the physical and chemical parameters of minimally processed melons. It was verified that the loss of mass was 0.34% during the storage. The ascorbic acid supplied for the treatment suffered an increase of acidity of fruits. The edible coating of sodium alginate resulted in melons with fewer contents of soluble solids and titratable acidity, lesser pH and degree of pectin solubilization, better flavor, and pulp with darker coloration, which results the color of the film solution. It was concluded that the chemical treatments affected the physical and chemical characteristics of minimally processed melons a little and they did not extend the product\'s shelf-life. In the third experiment, the maintenance of the sensorial quality, using trained panelists, through the Quantitative Descriptive Analysis Method (QDA), as well as the acceptance of the product for the consumer has been evaluated. The QDA showed that the treatments were not presented to be effective in the prolongation of the shelf-life of minimally processed melons. The consumer test indicated that the melons treated with calcium chloride and ascorbic acid were more accepted by the panelists and showed that there was no significant difference about buying intention. The fourth experiment was intended to study alternatives for the exploitation of the peels and the pulp\'s leftovers of minimally processed melons. With the peels, three products were developed: compote, candy, icing candy and jellies were made with the leftovers of the pulp. The sensorial test indicated that all the elaborated products, except for the candy made of melon peel, showed good acceptability for panelists, with rate of acceptability above of 80%.

Embora não seja reconhecido como um nutriente essencial, o silício (Si) reduz a severidade de oídios em diversas espécies vegetais quando acumulado na parte aérea. Contudo, apesar deste efeito benéfico ser amplamente relatado na literatura, ainda pouco se sabe dos mecanismos envolvidos. Este estudo avaliou o efeito das aplicações foliar e radicular de silicato de potássio, uma importante fonte de Si solúvel, na severidade de oídio e na indução de mecanismos de defesa pós-infecção em meloeiro. Os efeitos na doença foram avaliados em plantas inoculadas artificialmente ou naturalmente mantidas em casa de vegetação através da mensuração da dinâmica da epidemia e de seus componentes. Os resultados indicaram que tanto aplicações foliares como radiculares de silicato de potássio reduziram a área abaixo da curva de progresso da doença em 65% e 73%, respectivamente, comparadas ao tratamento controle sem aplicação. Tal redução foi resultado da alteração dos seguintes componentes epidemiológicos: eficiência de infecção, taxa de expansão da colônia, área da colônia, produção de conídios por área colonizada e taxa de progresso da epidemia. Contudo, a aplicação radicular foi mais eficiente que a foliar em atrasar o início da epidemia e em reduzir todos os componentes epidemiológicos, exceto a eficiência de infecção. A maior eficiência do silicato de potássio quando aplicado via raiz decorreu da maior concentração foliar do Si, a qual induziu uma antecipação (efeito priming) e um aumento da intensidade de expressão de mecanismos de defesa, fenômenos que não foram detectados no tratamento foliar. A aplicação radicular resultou na alteração de enzimas envolvidas na produção e catabolismo de espécies reativas de oxigênio, onde foi verificado aumento na atividade das enzimas superóxido dismutases e redução na atividade das enzimas catalases, principalmente nas primeiras 96 horas após a inoculação. O efeito priming também foi observado para as enzimas peroxidases, 1,3(4)-glucanases e quitinases e para o acúmulo de compostos fenólicos. Neste tratamento também ocorreu aumento na concentração de lignina em resposta à inoculação, contudo a concentração de malondialdeído foi reduzida, indicando que o Si aplicado nesta forma aliviou o estresse oxidativo sobre os lipídeos das membranas celulares da planta. Por outro lado, quando o silicato de potássio foi aplicado via foliar apenas a deposição de lignina aumentou comparado ao tratamento controle. Assim, depreende-se que os mecanismos de atuação do Si no controle da doença quando aplicado nesta forma, são distintos e envolvem, segundo a literatura, a formação de uma barreira físicoquímica sobre a cutícula resultado da polimerização do silicato de potássio. Tomados em conjunto, os resultados deste estudo evidenciaram que o Si tem papel ativo na modulação do sistema de defesa da planta, mas que sua efetividade depende de sua presença na forma solúvel no interior da planta, obtido por meio de sua absorção via raiz. Não obstante, os efeitos do silicato de potássio aqui relatados permitem concluir que a incorporação do produto a um sistema de manejo integrado, principalmente se fornecido via sistema radicular, terá efeitos positivos tanto na redução da epidemia de oídio como no meio ambiente, neste caso em função da redução no uso de fungicidas. / Silicon (Si) is not considered an essential nutrient of plants, but when it accumulates in the shoots it reduces powdery mildew severity on several species. However, despite this beneficial effect being widely reported in the literature, the mechanisms involved are still little understood. In this study, the effects of both foliar and root applications of potassium silicate, an important soluble source of Si, on the severity of powdery mildew and on the induction of postinfection defense mechanisms of melon were evaluated. Treatment effects were assessed by measuring the epidemics dynamic and its components in both artificially and naturally inoculated plants kept in the greenhouse. Results showed that the area under the disease progress curve was reduced by 65% and 73%, respectively by foliar and root application of potassium silicate, compared to control plants that were not supplied with potassium silicate. This effect accrued from the reduction of the infection efficiency, colony expansion rate, colony area, conidia production per colonized area and the epidemic progress rate. However, root application was more effective than foliar application on both delaying the onset of the epidemic and reducing most epidemic components, except for the infection efficiency. The greater efficiency of potassium silicate in controlling the disease when supplied via roots by irrigation correlated with higher foliar concentrations of Si which induced both a priming effect and increased expression of key defense responses. These phenomena, however, were not observed when potassium silicate was sprayed on leaves. Root supply of Si altered the activity of enzymes involved in the production and catabolism of reactive oxygen species, resulting in the increased activity of superoxide dismutase and reduced activity of catalases mainly in the first 96 hours after inoculation. Root application also primed the activity of peroxidases, 1,3(4)-glucanases, chitinases and the accumulation of phenolic compounds. Lignin concentration also increased in response to inoculation while the concentration of malondialdeide reduced indicating that Si decreased the oxidation of lipids of the plant cell membranes. In contrast, when Si was sprayed on the leaves, only an increase in lignin deposition was observed compared to the control treatment. Thus, it appears that the mechanisms of powdery mildew control in this case are distinct and, according to literature data, could include the formation of a physical-chemical barrier on the cuticle as the result of potassium silicate polymerization. Taken together, the results showed that Si plays an active role in modulating the host defense system, but only when present in the soluble form inside the plant which can be achieved by root uptake. Nevertheless, the effects of potassium silicate reported here allowed concluding that the inclusion of this compound in an integrated management system, mainly if supplied via roots, will render positive effects both on reducing the disease in melon plants and on the environment, in this case through reducing the use of fungicides.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-20T12:00:31Z No. of bitstreams: 1 Cleidio da Paz Cabral.pdf: 307888 bytes, checksum: 839bdb2400d1038e8ac0b20e10e22398 (MD5) / Made available in DSpace on 2017-02-20T12:00:31Z (GMT). No. of bitstreams: 1 Cleidio da Paz Cabral.pdf: 307888 bytes, checksum: 839bdb2400d1038e8ac0b20e10e22398 (MD5) Previous issue date: 2009-02-27 / Bacterial fruit blotch caused by Acidovorax avenae subsp. citrulli (Schaad et al.) Willems et al. is an important melon (Cucumis melo L.) disease which causes fruit value reduction and high production losses reaching 100% in rainy season. At the present there are not effective methods of controlling this disease in Brazil, and therefore research for finding alternative control methods is essential. It was studied the effect of resistance inducers for controlling bacterial fruit blotch in ‘yellow’ melon (AF4945) and ‘Pele de Sapo’ (Nilo), evaluating different application periods (10 and 15 days after plant emergency), inducer dosages (acibenzolar-S-metil- ASM - 25; 50 and 75 mg a.i. L-1; Agro-Mos® - 0.5; 1.0 and 1.5 c.p. L-1; Ecolifeâ - 2; 3 and 4 mL c.p. L-1) and plant physiology in soil supplemented or not with NPK observing plant height, fresh and dry shoot biomass and enzymatic activity. The best period for inducers application was 10 days after plant emergency. For both genotypes, ASM (50 mg a.i. L-1) and Ecolifeâ (3 mL c.p. L-1) increased incubation period until 12 and 8 days; and reduced disease incidence by 87.5 and 60%; disease index by 95.7 and 88%; and area under disease progress curve by 93.7 and 74.5%. The two inducers independent of NPK level reduced plant height, fresh and dry shoot biomass until 24.5; 41.4 and 34.2%, respectively. Onlythe peroxidase activity was detected at 5, 10 and 45 days after inducer application. Although ASM (50 mg i.a. L-1) and Ecolifeâ (3 mL p.c. L-1) had affected plant development they significantly reduced bacterial fruit blotch in both melon types, ‘yellow’ and ‘Pele de Sapo’, and should be used for the integrated management of this disease. / A mancha-aquosa causada pela bactéria Acidovorax avenae subsp. citrulli (Schaad et al.) Willems et al. é uma importante doença para a cultura do meloeiro ocasionando depreciação do valor comercial do fruto e grandes perdas na produção, que podem atingir até 100% em períodos chuvosos. Não se dispõe até o momento de medidas efetivas de controle dessa doença no Brasil o que torna imprescindível à realização de pesquisas que visem à obtenção de métodos alternativos de controle. Foi estudado o efeito de indutores de resistência no controle da mancha-aquosa em meloeiros Amarelo (AF4945) e Pele de Sapo (Nilo), em diferentes épocas de aplicação (10 e 15 dias após a emergência das plântulas) e dosagens (acibenzolar-S-metil – ASM - 25; 50 e 75 mg i.a. L-1; Agro-Mos® - 0,5; 1,0 e 1,5 p.c. L-1; Ecolifeâ - 2; 3 e 4 mL p.c. L-1); e na fisiologia da planta em solo com ou sem NPK, avaliando-se altura (AL), biomassa fresca e seca da parte aérea (BFPA, BSPA), e atividade enzimática. A melhor época para aplicação dos indutores foi dez dias após a emergência das plântulas. Considerando os dois genótipos, ASM (50 mg i.a. L-1) e Ecolifeâ (3 mL p.c. L-1) elevaram o período de incubação em até 12,6 e 8 dias e reduziram a incidência da doença em 87,5 e 60%; índice de doença em 95,7 e 88%; e área abaixo da curva de progresso da doença em 93,7 e 74,5%, respectivamente. Esses dois indutores, independente do nível de NPK, reduziram a AL,BFPA e/ou BSPA em até 24,5; 41,4 e 34,2%, respectivamente. Apenas a atividade de peroxidase foi detectada aos 5, 10 e 45 dias após a aplicação dos indutores. ASM (50 mg i.a. L-1) e Ecolifeâ (3 mL p.c. L-1) mesmo tento afetado o desenvolvimento de plantas de meloeiro, apresentaram redução significativa da intensidade da mancha aquosa tanto em meloeiro tipo Amarelo quanto Pele de Sapo, podendo ser inseridos no manejo integrado da mancha-aquosa.

The response of cucumber (Cucumis sativus L.) plants to various root and shoot environments (solution depth, temperature, ionic strength, nitrogen and calcium level and light intensity) were studied. Cucumber plants were grown in continuously circulating-solution in a heated-glasshouse. Dry weights of leaves, stems and roots, leaf area, leaf number, root length and root number were measured as well as uptake of potassium, calcium and nitrogen. The relationship between shoot and root in terms of functional equilibrium equations was also examined. The results presented show that: 1. Shoot growth of cucumber plants was reduced if grown in solutions of less than 50mm in depth; 2. When roots were grown in shallow solution depths at 1 or 5mm the dry weight allocated to the root increased. The ratio of root number/root length(no./cm) also increased. Lowering solution temperature to 12.5±2.5°C enhanced the production of root number relctive to root length, and 5 and 2% of full strength and 5% of full strength nitrogen level solution stimulated the growth of root length relative to root number; 3. Under low solution temperature treatment leaf number was maintained at the expense of leaf area. Under low total ionic strength and low nitrogen solution, enhanced root length growth was at the expense of leaf area growth; 4. Low solution temperature enhanced the dry weight allocated to the stem relative to the leaf. Low total ionic strength and low nitrogen solution increased the dry weight allocated to the leaf relative to the stem; 5. The specific activity of root, represented by specific absorption rate, increased when the shoot was under light stress and, the specific activity of shoot, represented by unit shoot rate, increased when the root was under nitrogen-stress; 6. The form of equation developed by Thornley (ΔM = fmΔW, where ΔM is the increment in weight of element M and ΔW the increment in total plant dry weight during a time period Δt with fm a constant) showed a better relationship than the equation developed by Davidson [root mass x rate(absorption) ∝ leaf mass x rate(photosynthesis)] and subsequently used by Hunt in the form of mass ratio(root/shoot) ∝ l/activity ratio; 7. The equation developed by Chung et al, total plant weight/(leaf number/leaf area) ∝ total "k"/(root number/root length), where k represents the total contents of elements or compounds, showed a good approximation of the relationship between shoot and root under all the environmental stresses imposed with the exception of calcium uptake. The results support the concept that the activity of the root or shoot in carrying out its function is influenced by the demand created by the opposite organ and appears to be a better assumption than that which proposes that the activity of an organ is solely dependent on its own size.