Made available in DSpace on 2016-07-18T17:46:21Z (GMT). No. of bitstreams: 1 Gabriel Toledo.pdf: 1422789 bytes, checksum: bc7db628d8c25a109a8bfd6111bb65d4 (MD5) Previous issue date: 2015-06-03 / A growing body of evidence shows that plants anticipate responses of stress as a result of signals transmitted by neighboring plants. Transmit signal of lack of water between plants is a factor that adds complexity in the dynamics of populations, communities and ecosystems. Knowing more about this ability of plants can be useful for agriculture, mainly agro-forestry systems, and for reforestation efforts. By this way, this job was done to try to find more evidences of lack of water signaling transmission. To do this, stomata aperture related parameters (leaf temperature and leaf turgor pressure) were used to find possible effects of plants under lack of water on their neighborhood. Stomatal aperture, leaf temperature and leaf turgor pressure are parameters that indicates plant water status. Two experiments were done, one measured leaf temperature, and other leaf turgor pressure. Glycine max was used as experimental model. The seedlings roots were pruned, leaving only two roots similar per plant ("split-root"). The split-root plants were arranged in sets, with 4 pots and 3 plants (with each plant roots was divided into two pots). To induce sudden lack of water, mannitol solution was used (-2MPa), applied in the first pot. Leaf temperature was monitored by thermographic camera, and the leaf turgor was monitored by magnetic probe leaf turgor pressure (ZIM-probe). Data analysis was based on graphic interpretation. Leaf temperature variation was synchronous among plants of each set. The variation of leaf turgor in the day of induction to stress was completely changed from the previous day in half of sets. The sets which turgor variation was changed also showed sync. Environmental conditions, namely air temperature, and air relative humidity, were monitored and showed no correlations with the variation in leaf temperature or leaf turgor pressure. Sync indicates that there was communication. It is possible that lack of water communication among plants increases population stability. Stability in population can increase the fitness. So, it is possible that communication of lack of water among plants is a characteristic that has been shaped by natural selection, and distributed among taxa. / É crescente o número de evidências de que plantas antecipam respostas a estresses em consequência da sinalização emitida por plantas vizinhas. Transmitir sinal de falta de água entre plantas é um fator que acrescenta complexidade na dinâmica de populações, comunidades e ecossistemas. Conhecer mais sobre essa capacidade das plantas pode ser útil para agricultura, principalmente sistemas agro- florestais, e para esforços de reflorestamento. Sendo assim, este trabalho foi realizado para tentar encontrar mais evidências da transmissão de sinal de falta de água entre plantas. Para tanto, foram utilizados parâmetros relacionados à abertura estomática (temperatura e turgor foliar) para medir os efeitos de uma planta sob falta de água sobre plantas vizinhas. A abertura estomática, a temperatura e o turgor foliar são parâmetros indicativos do status hídrico. Foram realizados dois experimentos, um medindo a temperatura, outro a pressão de turgor foliar. Foi usado Glycine max como modelo experimental. As plântulas foram submetidas à poda, deixando-se apenas duas raízes semelhantes por planta ( split-root ). As mudas foram arranjadas em séries com 4 potes e 3 plantas (cada planta ficou com suas raízes divididas entre dois potes). Para induzir falta de água repentina, foi utilizada solução de manitol (-2 MPa), aplicado no primeiro pote. A temperatura foliar foi monitorada com uma câmera termográfica e o turgor foliar foi monitorado pela sonda magnética de pressão de turgor foliar (ZIM-probe). A análise dos dados foi feita em cima da interpretação dos gráficos. A variação de temperatura foliar aconteceu de forma sincrônica entre as plantas de cada série. A variação do turgor foliar foi totalmente alterada depois do estresse em metade das repetições. Nas séries onde o turgor foi alterado houve sincronia também. As condições ambientais de temperatura do ar, e de umidade relativa do ar, foram monitoradas e não mostram correlação com as variações de temperatura e turgor foliar. A sincronia indica que tenha havido comunicação. É possível que a comunicação de falta de água aumente a estabilidade de populações. Populações mais estáveis podem ter mais chances de deixar mais descendentes para próximas gerações. Assim, é provável que a capacidade de comunicar a falta de água a outras plantas seja uma característica moldada pela seleção natural e distribuída dentre os táxons.

Orientador: Edson Luiz Mendes Coutinho / Coorientador: Milton José Cardoso / Banca: Carolina Fernandes / Banca: José Eduardo Cora / Banca: Takashi Muraoka / Banca: Adolfo Valente Marcelo / Resumo: O feijão-caupi é uma leguminosa importante socioeconomicamente para o Norte e Nordeste do Brasil, sendo fonte de proteína para a alimentação dessas populações. No entanto, a cultura apresenta baixa produtividade de grãos, o que se atribui a vários fatores, em especial, o manejo inadequado da adubação. Realizou-se este experimento em condições de campo, objetivando avaliar a influência da adubação com fósforo e zinco no estado nutricional da cultura e na produtividade de grãos do feijão-caupi, em um Plintossolo Háplico distrófico com baixos teores de fósforo (3,0 mg dm-3) e zinco (0,1 mg dm-3). O delineamento experimental consistiu em blocos casualizados, utilizando cinco doses de fósforo (0; 40; 80; 120 e 160 kg ha-1 de P2O5)e três doses de zinco (0; 1 e 3 kg ha-1 de Zn), usando como fonte o superfosfato triplo e o sulfato de zinco, respectivamente. As doses de P e Zn foram aplicadas a lanço na área total da parcela. Os resultados evidenciam que a adubação com fósforo e zinco aumentou a produtividade de grãos, sendo a máxima produtividade de grãos (1648 kg ha-1) obtida com a combinação de 125 kg ha-1 P2O5 e 2,6 kg ha-1 de Zn. A adição de fósforo e zinco aumentou as concentrações desses nutrientes nos grãos. O nível crítico de fósforo no solo e na folha são 6,3 mg dm-3 (Mehlich-1) e 2,01 g kg-1, respectivamente / Abstract: The cowpea is an important socioeconomically legume to the North and Northeast of Brazil, thus becoming an excellent source of protein for feeding of the population. Grain yield is influenced by several factors, in particular the inadequate fertilization. This field experiment was conducted with the objective for evaluating on a in out the effects field conditions, to evaluating the combined effects of phosphorus (P) and zinc (Zn), fertilization on the plant nutritional status and grain yield of cowpea in dystrophic haplic Plinthosol (3.0 mg dm-3 of P and 0,1 mg dm-3). The experimental design consisted of randomized blocks, with five rates of P (0, 40, 80, 120, and 160 kg ha-1P2O5), and three rates of Zn (0, 1, and 3 kg ha-1 Zn), using as sources the triple superphosphate and zinc sulphate, respectively . The fertilizers were broadcasted in the total area of the plot obtaining the The results show that fertilization with P e Zn increased grain yield, obtaining the maximum grain yield (1648 kg ha-1) with the combination of 125 kg ha-1 P2O5 and 2.6 kg ha-1 Zn. The addition of P and Zn increased the concentrations of these nutrients in the grains. The critical level of phosphorus in soil and leaf are 6.3 mg dm-3 (Mehlich-1) and 2.01 g kg-1, respectively / Doutor

Orientador: Carlos Alexandre Costa Crusciol / Resumo: O Brasil é o maior produtor mundial de cana-de-açúcar, sendo esta uma das principais culturas agrícolas cultivadas no país e de extrema importância para o cenário econômico nacional. Entretanto, ao longo das últimas safras, observou-se uma estagnação na produtividade média brasileira, consolidando-se muito abaixo do potencial genético produtivo das variedades aqui cultivadas. Diante disso, houve a necessidade de se desenvolver novas técnicas de manejo, visando aumentar os patamares de produtividade. O presente trabalho teve como objetivo avaliar o efeito da nutrição via foliar no final do ciclo vegetativo, precedendo o estádio de maturação da cana-de-açúcar, bem como os efeitos dessa aplicação associada com reguladores vegetais visando aumento do teor de sacarose por tonelada de cana no início de safra. Para tanto, dois estudos foram conduzidos: i) aplicação de nutrientes associados ou não ao maturador no final do ciclo vegetativo e em pré-maturação; ii) associação entre hormônios vegetais, nutrientes e maturador aplicados em fase antecedente à maturação da cana-de-açúcar. Os experimentos foram instalados em quatro locais diferentes, situados nos municípios de Indiaporã, Luis Antônio, Pontal e Santa Maria da Serra, todos localizados no estado de São Paulo, no período de fevereiro a maio de 2017, sendo repetidos nas mesmas localidades e época no ano de 2018. Foram avaliadas as variáveis biométricas, tecnológicas e teor nutricional foliar. O delineamento experimental utilizado ... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Orientador: Evandro Pereira Prado / Resumo: Diversos fatores podem interferir nos depósitos da pulverização em plantas sendo o tamanho de gotas e a ponta de pulverização uma das mais importantes nesse processo. Diante disso, objetivou-se avaliar como o tamanho de gotas e a ponta de pulverização afetarão a quantidade e qualidade dos depósitos da pulverização em plantas de amendoim (Arachis hypogaea L.) nos diferentes estádios de desenvolvimento. A verificação da deposição em plantas de amendoim nos estádios de desenvolvimento dos primeiros ramos (V1) e nos estádios de alongamento de ginóforos (R2) em função do tamanho de gotas (fina, média, grossa e muito grossa – experimento 1) e da ponta de pulverização (TXA 8002 VK - Cônico, TTJ 60 11002 - Plano duplo, AIXR 110025 - Plano com indução de ar, DGTJ 11002 - Plano duplo de deriva reduzida, XR 8003 - Plano de faixa ampliada – experimento 2) foram realizadas em delineamento de blocos inteiramente casualizados com 4 tratamentos e 40 repetições (experimento 1) e 5 tratamentos e 40 repetições (experimento 2), pela pulverização do corante alimentício Azul Brilhante na concentração de 1,5 g. L-1. Os valores de deposição obtidos nos experimentos foram submetidos à análise de variâncias e as médias comparadas pelo teste de Scott-Knott. A uniformidade de distribuição dos depósitos foi ajustada a regressão logística. No primeiro experimento (tamanho de gotas × estádios fenológicos) as médias de deposição no estádio V1 foram todas significativamente diferentes ente si, e no estádio R... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Several factors can interfere with spray deposits on plants. It is known that the droplet size and the spray tip are some of the most important in this process. Therefore, the objective was to evaluate how the droplet size and the spray tip will affect the quantity and quality of spray deposits on peanut (Arachis hypogaea L.) plants at different stages of development. The verification of deposition in peanut plants in the stages of development of the first branches (V1) and in the stages of elongation of gynophores (R2), depending on the droplet size (fine, medium, coarse and very coarse - experiment 1) and the spray tip (TXA 8002 VK - Conical, TTJ 60 11002 - Double plane, AIXR 110025 - Air induction plane, DGTJ 11002 - Double reduced drift plane, XR 8003 - Extended range plane - experiment 2), were carried out in a completely randomized block design with 4 treatments and 40 repetitions (experiment 1) and 5 treatments and 40 repetitions (experiment 2), by spraying the Brilliant Blue dye food at concentration of 1.5 g L-1. The deposition values obtained in the experiments were subjected to analysis of variances and their averages were compared by the Scott-Knott test. The uniformity of deposit distribution was adjusted to logistic regression. In the first experiment (droplet size × phenological stages), the deposition averages in the V1 stage were all significantly different from each other; in the R2 stage, the treatments with fine and medium droplets differed from the treatm... (Complete abstract click electronic access below) / Mestre

Iodine is an essential nutrient for humans, which is often not ingested through food in adequate quantities. Currently, Germany is once again one of the countries in which there is an iodine deficiency in the population. Women between the ages of 20 and 40 are particularly affected, a critical situation since pregnant and lactating women have an increased iodine requirement. Iodization of table salt is a widely used prophylactic measure. However, this method is not sufficient and may become less important in the future if further dietary salt reduction occurs, as nutritionists are demanding. Alternative approaches are therefore needed to improve the supply. One of these approaches is the agronomic biofortification of food crops. In this process, iodine is applied via fertilization measures during the cultivation of the plants. This gives the plants the ability to take up the mineral, which is only available in the soil to a very limited extent. In recent years, many studies have been published on the biofortification of vegetables and cereals. Foliar fertilization measures have proven to be significantly more efficient than soil fertilization measures. Nevertheless, up to now few results are available on the biofortification of fruit crops. However, fruit is also important for a healthy diet and the iodine supply of humans can only be improved if as many iodine-rich foods as possible are available. Therefore, the aim of this work was to investigate iodine biofortification of berry and tree fruit species in more detail. In order to be able to achieve this objective, trials were performed over several years with strawberries, apple and pear trees. In addition to suitable application methods, the aim was to determine the iodine form (iodide and iodate) and the necessary iodine quantity. On the one hand, the measured iodine contents in the fruit and leaf tissue allowed conclusions to be drawn about the translocation of iodine in the plant. On the other hand, this made it possible to evaluate the basic suitability for iodine biofortification of the fruit crops investigated. Since iodine has a phytotoxic effect above a certain amount, the plant compatibility should also be tested. In addition, common household processing methods, such as washing or peeling the fruit, as well as fruit storage over several months, should provide information on the extent to which such measures could reduce the iodine content. Another study parameter was the soluble solids content, as there is evidence that iodine can affect the sugar content of fruit. Furthermore, a combined application of potassium nitrate and selenium was carried out and their influence on iodine and sugar content was investigated. Selenium is also an essential trace element, which is usually inadequately absorbed through the diet. The results of the investigations showed that it was possible, in principle, to raise the iodine content of strawberries, apples and pears to a level of 50 to 100 µg iodine per 100 g fresh mass. In the case of strawberries, however, this was only feasible if the plants were in their first year of cultivation and the iodine was applied by foliar fertilization shortly before harvest. In the 2nd and 3rd year of cultivation, the plants had a very dense canopy, which prevented direct wetting of the fruit. However, direct wetting of the fruit surface with the iodine solution is imperative, as this was the only way to achieve a reliably high iodine content in the fruit mass. Soil fertilization proved to be completely unsuitable in trials with strawberries and apple trees. The translocation of iodine after soil fertilization occurred mainly via the xylem transport into the strongly transpiring leaves and not into the fruits. In addition, compared to a foliar application, a significantly higher iodine application rate was required. Furthermore, experiments with apple trees cultivated in a plastic tunnel, protected from precipitation, showed that the iodine transfer via the phloem into the fruits was only marginal. With regard to the phytotoxic effect of iodine application, no consistent difference was observed between potassium iodide and potassium iodate. Both forms of iodine did not affect yield or average individual fruit weight. Damage to fruit was not observed in any variant. However, with increasing iodine levels, significant damage to leaves was noticeable. Apple and pear trees also showed early leaf fall. Iodide generally led to significantly higher iodine contents in the plant mass after foliar application, but this was also associated with high fluctuations. With iodate, it was possible to reliably achieve the targeted iodine content in the fruit mass of apple and pear trees with an application rate of 1.5 kg iodine per hectare and meter canopy height. Washing the fruit reduced the iodine content of strawberries by up to 30%. For apples and pears, this value was about 14% at harvest and about 12% after 3 months of storage. Peeled apples and pears showed a significantly reduced iodine content. 51% of the iodine in apples was bound in the fruit peel or the cuticular waxes. A reduction of 73% was determined for pears. Cold storage for 3 months resulted in a significant loss of iodine in parts of the apple peel. At this point, the release of volatile iodine compounds is probably the cause of the reduction. However, this would still have to be confirmed by further investigations. Iodine application had a negative effect on the soluble solids content of strawberries above a certain level. It was not possible to observe significant changes for pome fruit in the trials conducted. However, the application of potassium nitrate (alone and in combination with iodine) resulted in an increase. Iodine uptake remained unaffected by the combined application of potassium nitrate and selenium. However, it was shown that selenium has a comparable uptake and translocation pattern to iodine and that a combined biofortification with both minerals is, in principle, possible. Accordingly, apple and pear trees are well suited for biofortification with iodine by foliar fertilization. However, further trials in commercial orchards are necessary to implement this process. In the future, appropriately fortified fruit could make an important contribution to the alimentary iodine supply for humans.

This diploma thesis is focused on foliar fertilization. It is nowadays one of the most widespread types of application of commercial fertilizers. Concern of this thesis is the study of plant cuticles as a thin layer on the leaves. These thin membranes are responsible for regulation of water transport and nutrients. Further function of plant cuticles is the mechanical protection of the outer part of the plant. Plant cuticles were characterized by fluorescence spectroscopy, classical optical microscopy and profilometry. The main aim of this thesis is the optimization and verification of experimental methodology aimed to the transport of commercial humic product through plant cuticles by simple diffusion techniques. The results obtained by presented diffusion techniques of humic product through plant cuticles were correlated with the same diffusion experiments through synthetic membranes with defined pore size and density. The study on transport of commercial humic product was realized in hydrogel medium by two different diffusion methods – non-stationary diffusion technique and diffusion couple. The important part of this diploma thesis is the characterization of supported hydrogel matrix by rheology tests, mercury intrusion porosimetry and scanned electron microscopy. Conclusions of this diploma thesis could be used for improving of efficiency of foliar fertilization.

Orientador: Silvia Rodrigues Machado / Resumo: A busca pela compreensão dos mecanismos que permitem que espécies vegetais ocupem ambientes distintos tem atraído a atenção de inúmeros pesquisadores, especialmente no contexto de mudanças climáticas. Neste sentido, características morfológicas, anatômicas e fisiológicas têm sido usadas com frequência para investigar respostas das plantas a diferentes condições ambientais. Miconia ligustroides, um representante de Melastomataceae, exibe extremo polimorfismo em cerrado (stricto sensu) e floresta estacional semidecídua (Mata Atlântica). Com o objetivo de verificar como as características foliares variam nesta espécie em reposta ao ambiente, e compreender como essas respostas podem interferir na distribuição da espécie em ambientes contrastantes, exemplares de M. ligustroides foram estudados e comparados. Para isso, amostras de folhas completamente expandidas foram coletadas e processadas para estudos aos microscópios de luz e eletrônico de varredura, de acordo com técnicas usuais. Trocas gasosas, fluorescência da clorofila a e luminosidade incidente foram avaliadas in loco utilizando-se o analisador de gás infravermelho portátil (IRGA-modelo LI 6400 XT, Li-cor). Foram realizados registros do microclima e análises físico-químicas do solo nas áreas de estudo. Plantas desses dois ambientes mostraram variações quanto ao hábito e características morfológicas e anatômicas das folhas, além de diferenças nos índices de trocas gasosas e fluorescência da clorofila a. No cerrado, as plant... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The search for understanding the mechanisms that allow plant species to occupy different environments has attracted the attention of countless researchers, especially in the context of climate change. In this sense, morphological, anatomical and physiological characteristics have been used frequently to investigate plant responses to different environmental conditions. Miconia ligustroides, a representative of Melastomataceae, exhibits extreme polymorphism in cerrado (stricto sensu) and seasonal semideciduous forest (Atlantic Forest). In order to verify how the leaf characteristics vary in this species in response to the environment, and to understand how these responses can interfere in the distribution of the species in contrasting environments, specimens of M. ligustroides were studied and compared. For this, samples of fully expanded leaves were collected and processed for studies under light and scanning electron microscopes, according to usual techniques. Gas exchanges, chlorophyll a fluorescence and incident luminosity were evaluated on the spot using the portable infrared gas analyzer (IRGA-model LI 6400 XT, Li-cor). Records of the microclimate and physical-chemical analyzes of the soil in the study areas were carried out. Plants from these two environments showed variations in habit and morphological and anatomical characteristics of the leaves, in addition to differences in gas exchange rates and chlorophyll a fluorescence. In the cerrado, the plants showed a shrubb... (Complete abstract click electronic access below) / Mestre

Most of the fields planted with clonal tea in Malawi are deficient in micronutrients. This was evident in leaf analysis data collected in 2007 from 170 mature clonal tea fields of some of the tea estates in Malawi, which showed very high incidences of B, Zn and Cu deficiencies. Current fertiliser recommendations have emphasised much on macronutrients, such as N, Pand K, but little attention has been paid to micronutrient elements despite continuous removal through harvesting. A study was therefore conducted to assess the effect of foliar applications of Cu, Zn and B containing fertilisers on yield and quality of mature clonal tea plants. Field experiments were laid out in randomised blocks in two fields planted with cultivars PC 105 and 108 at Mianga and Glenorchy estates in the Mulanje district in Malawi and were replicated four times at each site. The treatments were T1 (control, no spray), T2 [ 0.1% boric acid (190.8g B/ha)], T3 [1% copper sulphate solution (4.35kg Cu/ha)], T4 [1.25kg/ha zinc oxide (1kg Zn /ha)], T5 [0.1% boric acid, 1% copper sulphate solution, 1.25kg/ha zinc oxide], T6 [1% of Commercial micronutrient mix ( N 1.7%, P 2.3%, K 1.6%, Mg 0.25%, Fe 1288 mg/kg, Mn 1005 mg/kg, Zn 2182 mg/kg, Cu 732 mg /kg, B 8202 mg/kg, Mo 3681 mg/kg, kelp extract 75 mg/kg, amino acids 50 g/kg, phytofulvate 50 g/kg)], and T7 [2.48kg/ha zinc sulphate (1kg Zn /ha)]. Micronutrient foliar sprays affected yield significantly at Glenorchy tea estate, but had no significant effect on yield at Mianga estate. Copper sulphate solution applied at 1% concentration decreased yield, but the other foliar applications did not impact yield relative to the control at Glenorchy. Tea quality by taster’s scores was not affected at Mianga estate, whilst at Glenorchy quality was affected, with the commercial micronutrient mix giving the lowest total score. Individual parameters that contributed to the differences in total scores at Glenorchy estate included brightness, briskness, colour of liquor, colour of infusion and colour with milk. Thearubigin (TR) concentration was the only biochemical quality parameter that was affected by the micronutrient foliar sprays. The level of TR was increased in all treatments that received the foliar sprays and the control treatment gave the lowest amount of TRs at both sites. An increase in the Thearubigin/Theaflavin (TR/TF) ratio, obtained in all treatments that received the foliar sprays, provides evidence that more catechins were being converted to TRs than TFs during fermentation. Foliar levels of B, Zn and Cu were raised significantly by the application of the respective foliar sprays, except for the commercial micronutrient mix which did not significantly increase B and Zn levels at both sites, but raised Cu levels to the recommended level only at Mianga, but not at Glenorchy estate. Concentration of Cu was extremely high in tea leaves treated with copper sulphate either alone or in combination with boric acid and zinc oxide. Levels of other nutrient elements, namely N, P, K, S, Zn, Cu, Mg, Mn, Mo, Ca, Fe, B, Al and Na in the soils where different foliar sprays were applied were similar at both sites. Likewise, foliar levels of N, P, K, S, Zn, Cu, Mg, Mn, Mo, Ca, Fe, B, Al and Na were not different in all plots at Mianga, but at Glenorchy differences in foliar levels of Al and S were noted. High concentrations of Al and S in the leaves were observed in plots that received copper sulphate applied alone. High foliar concentrations of Al and Cu in leaves treated with copper sulphate could be the reason for the low yields obtained in the plots treated only with copper sulphate at Glenorchy estate. Foliar application of Cu, Zn and B in forms of 0.1% boric acid (190.8g B/ha)], 1% copper sulphate solution (4.35kg Cu/ha)], [1.25kg/ha zinc oxide (1kg Zn /ha)], 1% of a Commercial micronutrient mix (N 1.7%, P 2.3%, K 1.6%, Mg 0.25%, Fe 1288 mg/kg, Mn 1005 mg/kg, Zn 2182 mg/kg, Cu 732 mg /kg, B 8202 mg/kg, Mo 3681 mg/kg, kelp extract 75 mg/kg, amino acids 50 g/kg, phytofulvate 50 g/kg), and 2.48kg/ha zincsulphate (1kg Zn /ha) to mature clonal tea did not significantly increase yields and tea tasters scores, therefore their application to clonal tea with the aim of improving yield and quality may not be necessary. Results from this study indicated that clonal tea, specifically cultivars (PC 108 and PC 105), could not give positive results in terms of yield and quality of tea due to foliar application of Cu, Zn and B within the first season of application. However, if application is aimed at raising concentrations of Cu, Zn, and B, then boric acid, zinc sulphate, zinc oxide and the commercial micronutrient mix may be used without negatively affecting yield and quality of tea significantly. Copper sulphate however, at the application concentration and frequency used, should not be done because of the observed yield decline in copper sulphate treated plots. More prolonged research is required to determine if long term applications can correct perceived deficiencies and increase yield. / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Plant Production and Soil Science / unrestricted

<p>Reductions in atmospheric deposition of sulfur (S) coupled with increases in yields of <i>Glycine Max</i> (L.) Merr. (soybean) has led to S deficiencies in Indiana. Poor nodulation due to limited S, and thus a decrease in nitrogen (N) supply, restricts the yield and quality of soybean grain (i.e., protein). Sulfur is a key component of methionine and cysteine, which are important amino acids in the nutrition of foodstuffs. The objective of the first study is to improve yield and composition of soybean through various applications of N and S. Ten N+S fertility treatments were factored by 2 planting dates (early vs. late) at West Lafayette, IN in 2018 and 2019. The same 10 N+S fertility treatments were factored by 2 varieties (Asgrow 24x7 and 34x6) at Wanatah, IN in 2018 and 2019. Soybean yield increases among the N+S fertility treatments of the May 11th planting (early) were 380 to 1006 kg ha^-1 over the untreated control, with no difference within the June 5th planting (late) in 2018. Cool and wet conditions that limited mineralization of N and S from the early planting are likely the source of yield improvements. Protein concentrations were maintained and even increased with N and S treatments that were coupled with yield improvements. The Wanatah location showed that protein levels were increased with the ATS and R4+ NS treatments, while the UAN Direct treatment had the lowest protein in both varieties, suggesting that having no source of S could limit protein development. Although variety did not affect yield, fertility improved yields with the V4R3 NS, Plant NS, R3 NS, R4+ NS, and V4 NS treatments. The yield improvements that developed with these treatments is interesting because each treatment contained a source of N equaling at least 44.8 kg N ha^-1.</p><p>Secondly, the optimal rate and timing of foliar S applications were determined at a S-deficient location (La Crosse, IN) in 2018 and 2019. Three target application timings; V4, R3, and V4 + R3, were crossed with 4 rates of foliar S at 1.12, 2.24, 4.49, 6.73 kg S ha^-1 with each application. Therefore, the sequential application (V4 + R3) received a total of 2.24, 4.49, 8.96, and 13.44 kg S ha^-1. The optimal rate with 2018 yields was 4.5 kg S ha^-1 at V4 or R3; whereas, the optimal rate was 7.9 kg S ha^-1 with the sequential V4 + R3 treatment in 2019. Leaf tissue concentrations of S were nearly deficient (0.25%) post-V4 and post-R3. Higher rates of S had greater S concentrations in the leaf; furthermore, most cases resulted in a linear increase of S concentration with the rate of S applied. Foliar applications of S also reduced N:S ratio. Protein levels in 2018 increased at an equal rate for both the V4 and the R3 timings. In 2019, at a 6 lb ac^-1 rate of S the protein levels were 39.5 and 39.8% for V4 and R3 timings, respectively. Foliar S applications at V4 vs. R3 timings had little variation in yield or protein levels, thereby resulting in flexibility for application timing for growers.</p>

No description available.