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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Etude du rôle de FW2.2 dans le développement du fruit de tomate / Study of the FW2.2 role during tomato fruit development

Azzi, Lamia 16 December 2013 (has links)
Le gène FW2.2 correspond au locus de caractère quantitatif (QTL) majeur impliqué dans le contrôle de la taille finale du fruit de tomate. FW2.2 appartient à une famille multigénique et code une protéine transmembranaire de 163 acides aminés dont la fonction demeure de nos jours inconnue. Pourtant décrite comme un régulateur négatif des mitoses, par conséquent comme un régulateur de la taille du fruit et cloné plus de 12 ans auparavant, aucune fonction biochimique, physiologique ni même développementale n’a été déterminée concernant cette protéine. Ce qui est d’autant plus étonnant car aucun lien n’a été révélé entre sa fonction protéique et sa capacité à influencer le cycle cellulaire. L’analyse d’une nouvelle version du génome de la tomate nous a permis d’identifier 17 nouvelles séquences homologues à FW2.2 (que nous avons nommé FW2.2-like) et l’alignement de ces séquences nous a permis d’observer une importante conservation du motif PLAC8 commun à cette famille multigénique. L’étude phylogénétique que nous avons réalisée ne nous a donné aucune indication quant à la fonction potentielle de transporteur de métaux lourds de la protéine FW2.2 malgré le fait que sa séquence protéique présente les mêmes caractéristiques que celles décrites chez des transporteurs de métaux lourds. Des expériences d’électrophysiologie ne nous ont pas permis de confirmer son rôle de transporteur, mais des dosages de contenu minéral réalisés sur des péricarpes de fruits de tomate présentant des niveaux d’expression différents pour FW2.2 nous ont permis d’observer une différence de stockage du cadmium dans le péricarpe de ces fruits. Nous avons également étudié le rôle de la protéine FW2.2 dans le développement des plantes en utilisant des lignées de plantes et des lignées cellulaires surexprimant le gène FW2.2. Ceci nous a mené à l’hypothèse que la protéine FW2.2 pouvait être impliquée dans la voie de signalisation des brassinostéroïdes. Pour terminer, nous avons tenté de comprendre quels mécanismes de régulation étaient déclenchés par FW2.2 en recherchant ses partenaires potentiels par le biais de l’application de la technique du Split-Ubiquitin. / The FW2.2 gene corresponds to the major Quantitative Trait Locus (QTL) governing fruit size in tomato. FW2.2 belongs to a multigene family and encodes a transmembrane protein of 163 amino acids whose actual function remains unknown. Although described as a negative regulator of cell divisions and consequently as a regulator of fruit size, any definitive biochemical, physiological and developmental function assigned to FW2.2 is still lacking although the gene was cloned more than twelve years ago. Especially the fundamental question of what kind of link is there between the FW2.2 protein function and cell cycle regulation is all even more relevant. The analysis of the recently released genome of tomato identified 17 new sequences related to FW2.2 (SlFW2.2-like genes) and the protein sequence alignments showed the conservation of the PLAC8 motif common to this multigene family. Our phylogenetic studies did not give any clues relative to the FW2.2 function even though it presents sequence characteristics described for heavy metal transporters. Electrophysiology experiments did not allow the confirmation of the ion transporter function but a total ion content measurement on tomato fruit pericarps differing by their levels of FW2.2 expression showed a difference in the fruit pericarp cadmium content. We also investigated the role of the FW2.2 protein on the plant development using plant and cell lines that overexpress this gene and it appeared that this protein may be involved in the brassinosteroid signal pathway. The regulatory mechanisms mediated by the action of FW2.2 on mitotic activity during fruit development have also been analyzed by looking for potential partners interacting with the FW2.2 protein using the technique of split-ubiquitin.
2

Germinação e caracterização física e morfológica de frutos e sementes de Syagrus oleracea Becc / Germination and physical and morphological characterization of fruits and seeds of Syagrus oleracea Becc

Carrijo, Núbia Sousa 23 May 2011 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-11-03T16:43:45Z No. of bitstreams: 2 Dissertação - Núbia Sousa Carrijo - 2011.pdf: 957612 bytes, checksum: cbe93773d48d1a86e9cbbba954779238 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2014-11-03T16:43:58Z (GMT) No. of bitstreams: 2 Dissertação - Núbia Sousa Carrijo - 2011.pdf: 957612 bytes, checksum: cbe93773d48d1a86e9cbbba954779238 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-11-03T16:43:58Z (GMT). No. of bitstreams: 2 Dissertação - Núbia Sousa Carrijo - 2011.pdf: 957612 bytes, checksum: cbe93773d48d1a86e9cbbba954779238 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2011-05-23 / This study was aimed at characterizing the fruit and at observing if its size affects the germination and early development of seedlings of Syagrus oleracea Becc. (Arecaceae), Mineiros and Jataí (GO), measured and separated into five size classes ((T1: fruit≤4,300cm; T2: 4,300cm>fruit≤4,833cm; T3: 4,833cm>fruit≤5,367cm; T4: 5,367cm>fruit ≤5,900cm e T5: fruit>5,900cm).After the fruit collection, the physical analysis of the fruits, the seeds, the embryo and endosperm was made, on different days after sowing (0, 20, 40, 60, 80, 100, 110, 120 and 130 days after sowing). The emergence analysis and of initial development was made individually every 10 days, six evaluations performed. After stabilization of the emergency, all the seedlings were analyzed every 10 days, a total of 16 ratings. In both, in each seedling, the length of insertion to the apex of the leaf and stem diameter at ground level were measured; calculating the speed of emergence index (EVI), emergence percentage (E%) and time spent to emerge half of the fruits (T50). In germination chambers BOD types, trials were carried out with green and ripe fruits and the influence of different wavelengths of visible light in the germination process was verified. In these trials the germination speed index (GSI), germination (%G) and time spent to germinate half of the fruits (T50) were calculated. The descriptive analysis was also performed for the variables related to the size of the fruits and diaspores, followed by analysis of variance and regression equations when necessary for the characteristics evaluated. The fruits measure between 3,61 and 6,98 cm. The greater the thickness of the functional pore, the higher the germination capacity and GVI. The initial seedling development was uniform within 60 days after the stabilization of the emergence for all sizes of fruits; however, the fruit shorter than 5,367 cm higher has better performance between 60 and 150 days after the stabilization of the emergence. In nursery conditions, the higher the fruit, the greater the IVE. In the nursery, higher %E were found in fruits higher than 5.90% cm and lower %E in fruits shorter than 4,30 cm. In the laboratory, higher %G were found in fruits with length between 4,834 and 5,367 cm and lower % G between 5,368 and 5,90 cm. Ripe fruits have a higher germination capacity when compared to green fruits. Guariroba is a neutral species, for it is independent on the influence of light for the germination to occur. / O presente trabalho teve como objetivos caracterizar o fruto e verificar se o tamanho do fruto afeta a germinação e o desenvolvimento inicial das plântulas de Syagrus oleracea Becc. (Arecaceae), conhecida popularmente como guariroba. Para tanto, foram coletados frutos de guariroba nos municípios de Mineiros e Jataí (GO), mensurados e separados em cinco classes de tamanho (T1: fruto≤4,300cm; T2: 4,300cm>fruto≤4,833cm; T3: 4,833cm>fruto≤5,367cm; T4: 5,367cm>fruto ≤5,900cm e T5: fruto>5,900cm). Posteriormente à coleta dos frutos, foi realizada a análise física destes, dos diásporos, do embrião e do endosperma em diferentes dias após semeadura (0; 20; 40; 60; 80; 100; 110; 120 e 130 dias após semeadura). A análise de emergência e desenvolvimento inicial foi realizada individualmente de 10 em 10 dias, sendo realizadas seis avaliações. Após estabilização da emergência, foram analisadas todas as plântulas de 10 em 10 dias, totalizando 16 avaliações. Em ambos, foram medidos, em cada plântula, comprimento da inserção até o ápice da folha e diâmetro do colo ao nível do solo; calculando índice de velocidade de emergência (IVE), porcentagem de emergência (%E) e tempo gasto para emergir metade dos frutos (T50). Em câmaras de germinação tipo BOD foram realizados ensaios com frutos verdes e maduros assim como verificada a influência de diferentes comprimentos de onda da luz visível no processo de germinação, nestes ensaios foram calculados índice de velocidade de germinação (IVG), porcentagem de germinação (%G) e tempo gasto para germinar metade dos frutos (T50). Foi ainda realizada análise descritiva para as variáveis relacionadas ao tamanho dos frutos e diásporos, seguida de análise de variância e as equações de regressão quando necessárias para as características avaliadas. Os frutos medem entre 3,61 e 6,98cm. Quanto maior a espessura do poro funcional maior a capacidade germinativa e IVG. O desenvolvimento inicial das plântulas foi uniforme até 60 dias após a estabilização da emergência para todos os tamanhos de frutos, no entanto os frutos menores que 5,367cm obtiveram maior desempenho entre 60 e 150 dias após a estabilização da emergência. Em condições de viveiro, quanto maior o fruto, maior IVE. No viveiro foram encontradas maiores %E em frutos maiores que 5,90cm e menores %E em frutos menores que 4,30cm. No laboratório, maiores %G foram encontradas em frutos com comprimento entre 4,834 e 5,367cm e menores %G entre 5,368 e 5,90cm. Frutos maduros possuem maior capacidade de germinação quando comparados com frutos verdes. A guariroba é uma espécie neutra, pois independe da influência luminosa para ocorrência da germinação.
3

Regulated Deficit Irrigation of 'Montmorency' Tart Cherry

Papenfuss, Kylara A. 01 May 2010 (has links)
Regulated deficit irrigation (RDI) is the strategy of reducing irrigation rates during a specific period of growth and development, with the objective of conserving water and managing plant growth while maintaining or improving yield and fruit quality. Mature tart cherry (Prunus cerasus L. 'Montmorency') trees in a commercial orchard were subjected to a range of irrigation deficits from pit hardening to harvest during the 2007 and 2008 seasons. Irrigation treatments replaced from 62% to 96% of ETc, during that period. Midday stem water potential measurements were significantly different among treatments before harvest. However, fresh weight yield at harvest did not differ significantly among irrigation treatments in either year (P-value=0.64). In 2008 the amount of undersized fruit eliminated during packout was significantly higher in the treatments replacing 61% and 68% of ETc than in the control (P-value<0.0001), but only amounted to 2.0% and 1.4% of total yields, respectively. This small increase in undersized fruit did not significantly affect packout. Fruit quality measurements, such as soluble solids concentration and chroma of whole intact fruit, increased with the severity of the irrigation deficit. Visible surface bark damage from mechanical harvesting appeared less severe as deficit levels increased. Return bloom was not significantly affected by irrigation treatments.
4

The cloning and cellular basis of a novel tomato fruit weight gene: Cell Size Regulator (FW11.3/CSR)

Mu, Qi 15 October 2015 (has links)
No description available.
5

Fine Mapping and Characterization of fw3.2, One of the Major QTL Controlling Fruit Size in Tomato

Zhang, Na 20 June 2012 (has links)
No description available.
6

A Genomic Approach Toward Understanding Fruit Size Regulation in Apple

Khalil Jahed (13163247) 27 July 2022 (has links)
<p> Fruit size is a polygenic trait controlled by multiple genomic regions each with small effect. The complex nature of fruit size regulation makes it challenging to dissect individual genes responsible for phenotypic variation. Though recent advances in high-throughput genome sequencing technology in conjunction with improved statistical and computational methods empowered science to explicitly understand the genetic basis underlying multiple fruit quality traits, much of the work that has been done through classical quantitative trait loci (QTL) approach resulted in reduced resolution and instability when evaluating in different genetic backgrounds and different environments. To increase the precision and improve the stability of QTL analyses and to identify genes controlling fruit size, we performed a set of multiple quantitative and molecular genetic analyses to elucidate the underlying genetic architecture of fruit mass. A total of nine genomic regions associated with fruit mass were identified, two of which are novel to this study; markers Md14_26050918 and Md14_26050904. Detected QTLs explained ~ 42% of the total genetic variation of which ~ 20% is explained by the two novel QTLs. Regions responsible for fruit mass variation appear to be under strong additive and epistatic genetic control. These regions exhibited high stability across-family as well as across-years and showed accurate genomic prediction across-family. Additionally, we identified the apple gene family of putative fw2.2 orthologs, naming them Cell Number Regulators (CNRs) genes (MdCNRs). Three CNRs (MdCNR1-3) showed increased expression at early fruit growth in small-fruited crabapple, associating with reduced relative cell production rate (RCPR), suggesting that alteration in cell number that leads to a subsequent reduction in fruit size is probably due to reduced cell division most likely due to changes in CNRs regulation. Furthermore, our study revealed that reduced fruit size is partially due to the shortened cell expansion period after which cell expansion ceases in the small-fruited crabapple species. Together, these data will advance our understanding of dissecting fruit mass genetic architecture and have high potential to be deployed for marker-assisted selection and further breeding approaches. </p>
7

Desenvolvimento, produção e qualidade de frutos de abacateiro cv. \"Hass\" sobre dois porta-enxertos nas condições edafoclimáticas da região central do Estado de São Paulo / Growth, fruit yield and quality of \'Hass\' avocado budded onto two rootstocks in the central region of São Paulo State

Ana Flávia Garcia Moraes 10 September 2014 (has links)
A produção comercial brasileira de abacates ocorre em pomares implantados sobre porta-enxertos oriundos de sementes, o que resulta em grande desuniformidade das plantas com relação a tamanho da copa, produção, qualidade de frutos e suscetibilidade a patógenos do solo, principalmente Phytophthora cinnamomi, agente causal da podridão radicular, principal doença da cultura. Enquanto em outros países já é adotado o uso de porta-enxertos com características superiores que são propagados clonalmente visando minimizar esses problemas, no Brasil estes materiais ainda não foram avaliados. Durante os anos de 2010 a 2013 foi conduzido um experimento na Fazenda Jaguacy, município de Bauru, SP, com o objetivo de avaliar o desenvolvimento, produção e qualidade de frutos de abacateiro \'Hass\' sobre dois porta-enxertos, sendo um proveniente de sementes (\'Seedling\') (T1) e o outro da cultivar Dusa obtido por propagação clonal (T2). O experimento foi conduzido seguindo um delineamento em blocos casualizados, com dois tratamentos, 5 repetições e 10 plantas por parcela, totalizando 100 plantas em avaliação. O desenvolvimento vegetativo foi obtido pela medição da altura e diâmetro das plantas, utilizados para o cálculo do volume de copa. A produção foi avaliada a partir da contagem e pesagem de todos os frutos de cada planta e também pelo cálculo da eficiência produtiva e da alternância produtiva entre anos. A qualidade dos frutos foi avaliada a partir da massa, diâmetro e comprimento individual de uma amostra de 200 frutos por tratamento. Os dados foram submetidos à análise da variância, considerando nível de significância de 5%. Nenhuma diferença significativa foi observada entre os tratamentos para volume de copa, produção média, produção acumulada e número de frutos. Para as variáveis de eficiência produtiva, massa, comprimento, diâmetro e relação C:D de frutos ocorreram diferenças significativas que indicaram a superioridade do porta-enxerto clonal \'Dusa\' para plantas de \'Hass\' quando comparadas ao \'Seedling\'. / Avocado production in Brazil takes place in orchards established onto Seedling rootstocks, with large heterogeneity among plants regarding tree size, fruit yield and quality and susceptibility to soil pathogens, mainly Phytophthora cinnamomi that causes avocado root rot and is by far the main disease affecting this crop worldwide. While clonally obtained rootstocks are used in other countries to minimize such disadvantages, in Brazil such materials have not been yet evaluated. During 2010 to 2013 a trial was conducted in Fazenda Jaguacy farm, in Bauru county, with the aim to evaluate plant growth, fruit yield and quality of \'Hass\' avocados onto two rootstocks, a Seedling type (T1) and the \'Dusa\' clonal rootstock (T2). The trial was established after a completely randomized block design, with two treatments, 5 repetitions and 10 trees per plot, with a total of 100 measured trees. Tree size was evaluated by measurements of plant height and diameter, which were utilized to compute canopy volume. Fruit yield was obtained from counting and weighing all the fruits harvested at once from each tree, and also the yield efficiency and alternate bearing index were calculated. Fruit quality was determined from individual measurements of fruit weight, diameter (D) and length (L) on a 200-fruit sample randomly collected from each rootstock. Data was submitted to analysis of variance with a 5% significance level. No significant differences were observed among treatments for canopy volume, mean fruit yield, cumulative yield and fruit number. There were significant differences for yield efficiency, fruit weight, length, diameter and L:D ratio supporting the better performance of \'Dusa\' clonal rootstock on \'Hass\' scion as compared to the Seedling rootstock.
8

Desenvolvimento, produção e qualidade de frutos de abacateiro cv. \"Hass\" sobre dois porta-enxertos nas condições edafoclimáticas da região central do Estado de São Paulo / Growth, fruit yield and quality of \'Hass\' avocado budded onto two rootstocks in the central region of São Paulo State

Moraes, Ana Flávia Garcia 10 September 2014 (has links)
A produção comercial brasileira de abacates ocorre em pomares implantados sobre porta-enxertos oriundos de sementes, o que resulta em grande desuniformidade das plantas com relação a tamanho da copa, produção, qualidade de frutos e suscetibilidade a patógenos do solo, principalmente Phytophthora cinnamomi, agente causal da podridão radicular, principal doença da cultura. Enquanto em outros países já é adotado o uso de porta-enxertos com características superiores que são propagados clonalmente visando minimizar esses problemas, no Brasil estes materiais ainda não foram avaliados. Durante os anos de 2010 a 2013 foi conduzido um experimento na Fazenda Jaguacy, município de Bauru, SP, com o objetivo de avaliar o desenvolvimento, produção e qualidade de frutos de abacateiro \'Hass\' sobre dois porta-enxertos, sendo um proveniente de sementes (\'Seedling\') (T1) e o outro da cultivar Dusa obtido por propagação clonal (T2). O experimento foi conduzido seguindo um delineamento em blocos casualizados, com dois tratamentos, 5 repetições e 10 plantas por parcela, totalizando 100 plantas em avaliação. O desenvolvimento vegetativo foi obtido pela medição da altura e diâmetro das plantas, utilizados para o cálculo do volume de copa. A produção foi avaliada a partir da contagem e pesagem de todos os frutos de cada planta e também pelo cálculo da eficiência produtiva e da alternância produtiva entre anos. A qualidade dos frutos foi avaliada a partir da massa, diâmetro e comprimento individual de uma amostra de 200 frutos por tratamento. Os dados foram submetidos à análise da variância, considerando nível de significância de 5%. Nenhuma diferença significativa foi observada entre os tratamentos para volume de copa, produção média, produção acumulada e número de frutos. Para as variáveis de eficiência produtiva, massa, comprimento, diâmetro e relação C:D de frutos ocorreram diferenças significativas que indicaram a superioridade do porta-enxerto clonal \'Dusa\' para plantas de \'Hass\' quando comparadas ao \'Seedling\'. / Avocado production in Brazil takes place in orchards established onto Seedling rootstocks, with large heterogeneity among plants regarding tree size, fruit yield and quality and susceptibility to soil pathogens, mainly Phytophthora cinnamomi that causes avocado root rot and is by far the main disease affecting this crop worldwide. While clonally obtained rootstocks are used in other countries to minimize such disadvantages, in Brazil such materials have not been yet evaluated. During 2010 to 2013 a trial was conducted in Fazenda Jaguacy farm, in Bauru county, with the aim to evaluate plant growth, fruit yield and quality of \'Hass\' avocados onto two rootstocks, a Seedling type (T1) and the \'Dusa\' clonal rootstock (T2). The trial was established after a completely randomized block design, with two treatments, 5 repetitions and 10 trees per plot, with a total of 100 measured trees. Tree size was evaluated by measurements of plant height and diameter, which were utilized to compute canopy volume. Fruit yield was obtained from counting and weighing all the fruits harvested at once from each tree, and also the yield efficiency and alternate bearing index were calculated. Fruit quality was determined from individual measurements of fruit weight, diameter (D) and length (L) on a 200-fruit sample randomly collected from each rootstock. Data was submitted to analysis of variance with a 5% significance level. No significant differences were observed among treatments for canopy volume, mean fruit yield, cumulative yield and fruit number. There were significant differences for yield efficiency, fruit weight, length, diameter and L:D ratio supporting the better performance of \'Dusa\' clonal rootstock on \'Hass\' scion as compared to the Seedling rootstock.
9

Fitorreguladores para reduzir abscisão de frutos em abacateiros \'Quintal\' e \'Margarida\' cultivados sob sequeiro / Plant growth regulators to reduce fruit fall in rainfed \'Quintal\' and \'Margarida\' avocados

Baptista, Edypol Guilherme 19 May 2017 (has links)
A cultura do abacateiro vem ganhando expressividade, contudo, a abscisão natural de frutos representa um entrave, pois o desprendimento dos mesmos, pelo aumento dos níveis de etileno e diminuição de auxinas ocorre intensamente nas cultivares \"Quintal\" e \"Margarida\". Em 2014 e 2015 foi conduzido um experimento nas fazendas Santa Cecilia e Santa Elisa, nos municípios de Bernardino de Campos e Timburi-SP com o objetivo de avaliar em condições de sequeiro, o efeito de diferentes fitorreguladores na abscisão, produção, alternância produtiva, tamanho, formato e qualidade pós-colheita de frutos de abacateiros \"Quintal\" e \"Margarida\". Os tratamentos foram: T1: Água e espalhante; T2: 25 mg.L-1 de Ester isopropílico de ácido 2,4-D diclorofenoxiacético; T3: 45 mg.L-1 de AVG aplicados em novembro de 2013 e de 2014; e T4: Fosfito de potássio na dose de 400 ml.100 litros-1 de água aplicado entre dezembro de 2013 e janeiro de 2014 e dezembro de 2014 e janeiro de 2015, em intervalos de 15 dias. O ensaio foi conduzido em delineamento de blocos casualizados, com 4 tratamentos, 4 repetições de duas árvores cada, totalizando 32 plantas em avaliação para cada cultivar. Os dados foram submetidos à análise da variância pelo teste de Fisher a 5% de significância e as variáveis que não atenderam os supostos desta, foram submetidas a análises não paramétricas pelo teste de Friedman e Kruskal-Wallis. A aplicação de aminoethoxivinilglicina (AVG), um mês antes da segunda queda fisiológica dos frutos, reduz a abscisão e altera o formato de abacates \'Quintal\'. Na cultivar \'Margarida\', o uso de fosfito de potássio aumenta a fixação de frutos e o de 2,4-D altera o formato dos mesmos. Nenhum efeito da aplicação dos fitorreguladores foi observado para as variáveis de qualidade pós-colheita em ambas as cultivares. / Avocado cultivation is becoming very important in Brazil, although the abundant natural fruit drop represents a serious constraint in some cultivars such as \'Quintal\' and \'Margarida\', which exhibit high fruit drop rates due to increased ethylene synthesis and a reduction of internal auxin levels. In the 2014- 2015 period this experiment were conducted at Santa Elisa and Santa Cecilia farm placed at Bernardino de Campos and Timburi city, in São Paulo state, with the propose to value the effects of different plant growth regulators (PGRs) at fruit drop, at the production, at the on/off production phenomenon, at the form and at the size, and also, at the post-harvest quality of \'Quintal\' and \'Margarida\' cultivars planted in dry field. The following treatments were applied in December, before the second natural fruit drop: T1: water (control); T2: 25 mg.L-1 of isopropilic ester of 2,4-D diclorofenoxiacetic acid; T3: 45 mg.L-1 of AVG, and T4: 3 sprayings of 400 ml.100 L-1 potassium phosphite in biweekly intervals from mid-December thru mid-January, in each year. The trial was conducted following a randomized complete block design, with four replications and two plants per plot, with a total of 32 trees under evaluation for each cultivar. Data analyses were performed by parametric (Fisher) and by nonparametric (Friedman and Kruskal Wallis) for variables that did not fit the normal distribution. AVG application about one month after the second natural fruit fall set this occurrence but modified the form of \'Quintal\' avocados. In the \'Margarida\' cultivar, sprayings with 2,4-D modified the form of the fruits and the application of potassium phosphite grow the flower fixation. No effect on postharvest quality attributes were observed among the treatments.
10

Delayed fruit harvest on yield, nutritional value and post-harvest quality of late maturing reed avocado (Persea Americana Mill)

Novela, Precious January 2016 (has links)
Thesis (MSc .(Plant Production)) -- University of Limpopo, 2016 / Delayed fruit harvest (DFH) or on-tree-fruit storage is a strategy being considered to extend the harvest season of late maturing ‘Reed’ avocado. However, avocado fruit growth beyond physiological maturity is accompanied by alterations in chemical and physical properties. Thus, the study aimed to investigate the effects of delayed harvest on tree productivity, mineral nutrition and post-harvest quality of late maturing ‘Reed’ avocado and further to evaluate the fruit quality response to varying ripening temperature regimes. As treatments, fruit were harvested early, mid and late in the season, with one month apart from each harvest during 2013 and 2014 seasons. Yield and fruit size were recorded at harvest. During each harvest time, two sets of fruit samples were collected to determine the fruit nutritional content while the second set was cold stored at 5.5°C for 28 days. After storage, fruit were ripened at 16, 21 or 25°C and evaluated for post-harvest disorders, pathological diseases and fruit physico-chemical properties. Yield dropped from 42 to 12 kg/tree from early to late harvest during 2013, while treatments showed no effect during 2014. Furthermore, treatments had no effect on fruit size during both seasons. Phosphorus content decreased by 40 and 23% from early to late harvest time during 2013 and 2014 seasons, respectively. Similar decreasing patterns were observed for K, Ca and Mg content. Zinc content remained constant during 2013; however, mid-season fruit maintained higher zinc levels during 2014 season when compared to early and late harvest time. Protein content was constant for early and mid-season fruit but significantly decreased during the late harvest in both seasons. Moisture content decreased from 74.0 to 65.0% from early to late harvest during both seasons. Starch, oil and ash content were high during late harvest time in both seasons; while crude fibre was high during the mid-harvest time when compared with early and late harvest time. Internal chilling injury increased with maturity and ripening temperature. In both seasons, higher temperatures induced higher anthracnose incidences during early and mid-harvest compared with late harvest time. Similarly, vascular browning was high on fruit ripened at 16°C during early and mid-harvest time but decreased on late harvest fruit during 2013. However, low ripening temperatures induced high incidences of vascular browning during 2014 season. Stem-end rot was high on fruit ripened at 16°C than 21 and 25°C during 2014 season. xvi Physico-chemical quality parameters showed similar behaviour in both seasons. Fruit lightness increased with ripening time regardless of ripening temperature during the early harvest, but remained constant during mid and late harvest. Hue angle (h0) and Chroma (C*) values were slightly reduced during ripening. Fruit ripened at 25°C had the highest respiration rate and reached a climacteric peak earlier (day 2) than fruit ripened at 21 and 16°C (day 4). Fruit firmness and weight loss were high and rapid at 25°C followed by 21 and 16°C regardless of the harvest time. Delayed harvest had no effect on yield and fruit size. Generally, nutritional content of avocado fruit increased with fruit maturity. Furthermore, fruit maturity played a major role in the response of fruit to ripening temperature. Higher temperature enhanced fruit ripening, but was conducive for development of post-harvest diseases. Keywords: Harvesting time, nutrition, yield, fruit size, ripening temperature, post-harvest quality

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