Acúmulo de massa seca na soja em resposta a aplicação foliar com silício sob condições de déficit hídrico

The foliar fertilization with silicon has promoted several actions beneficial to plants, among them is greater drought tolerance, however, for the soybean, there is little information on these benefits in this condition. Thus, the aim of this study was to evaluate the effect of silicon on leaf, the dry matter accumulation of soybean in their reproductive stages, where the crop water stress suffered during the same. The experiment was carried out at the Plant Science Unit Aquidauana University - State University of Mato Grosso do Sul. The statistical design was a randomized block split plot with four replications. The plots were represented by cultivar 5DR615, the subplots consisted of the application (with or without) silicon, whose source was used KSi. Was measured the height and identified the development stage of all plants, separating them into stem + branches, leaves + petioles, pods capsules and seed. Foliar applications of silicon increased dry matter accumulation during the reproductive stage of soybean, where the highest values occurred in the R6 stage. Under conditions of water deficit, foliar application of silicon on soybean provided normal plant development, generating greater dry mass of stem + branches, leaves + petioles, pods capsules and seeds throughout their reproductive phase, with the highest values obtained at R6 stage (35 days after R2).A adubação foliar com silício tem promovido diversas ações benéficas às plantas, dentre elas está a maior tolerância à deficiência hídrica, contudo, para a cultura da soja, são escassas informações destes benefícios nesta condição. Assim, objetivou-se, neste estudo, avaliar o efeito da aplicação de silício, via foliar, no acúmulo de massa seca da soja em seus estádios reprodutivos, onde a cultura sofreu deficiência hídrica durante os mesmos. O experimento foi realizado no setor de Fitotecnia da Unidade Universitária de Aquidauana - Universidade Estadual de Mato Grosso do Sul. O delineamento estatístico utilizado foi o de blocos ao acaso em parcelas subdivididas, com quatro repetições. As parcelas foram representadas pela cultivar de soja 5DR615, as subparcelas consistiram na aplicação (com e sem) de silício, cuja fonte utilizada foi o KSi. Mensurou-se a altura e identificou-se o estádio de desenvolvimento de todas as plantas, separando-as em haste + ramos, folhas + pecíolos, cápsulas de vagens e sementes, para avaliação quanto ao acúmulo de matéria seca. Em condições de déficit hídrico, a aplicação foliar de silício na soja proporcionou um desenvolvimento normal das plantas, gerando maior acúmulo de massa seca de haste + ramos, folhas + pecíolos, cápsulas de vagens e sementes durante toda sua fase reprodutiva, sendo os maiores valores obtidos no estádio R6 (35 dias após R2)

Estimation of genetic divergence between braquiária ecotypes based on quantitative and qualitative descriptors

This study aimed to estimate the genetic divergence between Urochloa brizantha ecotypes based on quantitative, qualitative descriptors and their joint analysis to select the promising to release as cultivars of this species. Eight ecotypes (B1, B2, B3, B4, B5, B6, B8) and cultivar 'Marandu' of U. brizantha were implanted into pickets with 1000m2 each, with two repetitions. Five quantitative descriptors were evaluated [leaf area (ALF), length and width of leaf blades (CLF and LLF, respectively), dry mass (MS), mass of dry matter (MMS) and proportion of leaf blade in MS (PLF)] in two forage samples, being a representative of rainfall, in February 2000, and another in the dry period, in August 2000. It was measured the qualitative descriptors: shear strength (RC), volume of accumulated gas in fast and slow fraction (A and B, respectively), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF ), cellulose (CEL), lignin in sulfuric acid (LIG), silica (SIL) and in vitro digestibility of organic matter (IVOMD). There was considerable genetic divergence in U. brizantha ecotypes, especially regarding to quantitative descriptors. Based on the groupings of quantitative, qualitative descriptors and their joint analysis, the grouping containing of B1, B3 and B5 with 'Marandu' can result in promising U. brizantha ecotypesO presente trabalho objetivou estimar a divergência genética entre ecótipos de Urochloa brizantha com base na análise de descritores quantitativos, qualitativos e sua análise conjunta a fim de selecionar os promissores para liberação como cultivares desta espécie. Oito ecótipos (B1, B2, B3, B4, B5, B6, B8) e a cultivar 'Marandu' de U. brizantha foram implantados em piquetes, com 1000m2 cada, em duas repetições. Foram avaliados cinco descritores quantitativos e dez qualitativos no período seco e das águas. Os descritores quantitativos foram: área foliar, comprimento e largura das lâminas foliares, massa seca (MS) e proporção de lâmina foliar na MS. Os descritores qualitativos mensurados foram: resistência ao cisalhamento, volume de gás acumulado na fração rápida e lenta, proteína bruta, fibra em detergente neutro, fibra em detergente ácido, celulose, lignina em ácido sulfúrico, sílica e digestibilidade in vitro da matéria orgânica. Houve divergência genética entre os ecótipos de U. brizantha, especialmente em relação aos descritores quantitativos. Com base nos agrupamentos dos descritores quantitativos, qualitativos e sua análise conjunta, o agrupamento contendo de B1, B3 e B5 com 'Marandu' podem resultar em ecótipos promissores de U. brizanth

Screening of Popcorn Genotypes for Drought Tolerance Using Canonical Correlations

Getting around the damage caused by drought is a worldwide challenge, particularly in Brazil, given that economy is based on agricultural activities, including popcorn growing. The purpose of this study was to evaluate popcorn inbred lines under water stressed (WS) and well-watered (WW) conditions regarding agronomic attributes, root morphology, and leaf “greenness” index (SPAD index), besides investigating the viability of indirect selection by canonical correlations (CC) of grain yield (GY) and popping expansion (PE). Seven agronomic, six morphological root traits were evaluated and SPAD index at five different dates during grain filling. The WS (−29% less water than WW) affected significantly the GY (−55%), PE (−28%), increased the brace and crown root density, and more vertically oriented the brace and crown angles. Higher SPAD index is associated with a higher yield, and these measures were the only ones with no significant genotype × water condition interaction, which may render concomitant selection for WS and WW easier. For associating the corrections of the different traits, CC proved to have better potential than simple correlations. Thus, the evaluation of SPAD index at 29 days after the anthesis showed the best CC, and based on the previous results of SPAD index, may be used regardless of the water condition