Physiological mechanisms of slow canopy wilting in early maturity group soybeans were identified and the underlying QTLs were mapped and confirmed to protect soybean yield under drought in the field.

Salinity is a limiting factor that can affect plant growth and cause significant losses in agricultural productivity. This study provides an insight about the viability of partial root-zone irrigation (PRI) system with saline water supported by a biochemical approach involving antioxidant responses. Six different irrigation methods using low and high salt concentrations (S1-0.5 and S2-5.0 dS m) were applied, with or without PRSI, so that one side of the root-zone was submitted to saline water while the other side was low salinity water irrigated. The results revealed different responses according to the treatments and the PRSI system applied. For the treatments T1, T2 and T3, the PRSI was not applied, while T4, T5 and T6 treatments were applied with PRSI system. Lipid peroxidation, proline content, and activities of SOD, CAT, APX, GR and GSH in tomato plants subjected to PRSI system were analyzed. Plant growth was not affected by the salt concentrations; however, plants submitted to high salt concentrations showed high MDA content and Na accumulation when compared to the control plants. Plants submitted to treatments T4, T5 and T6 with PRSI system exhibited lower MDA compared to the control plants (T1). Proline content and activities of SOD, CAT, APX, GR and GSH content were maintained in all treatments and tissues analyzed, with only exception for APX in fruits and GSH content, in roots. The overall results showed that PRSI system could be an applicable technique for saline water supply on irrigation since plants did not show to be vulnerable to salt stress, supported by a biochemical approach involving antioxidant responses.

ResumoO objetivo deste estudo foi avaliar o efeito da adubação fosfatada, com e sem aplicação foliar de zinco na produção de alface americana. O experimento foi conduzido no Instituto Federal do Triângulo Mineiro (IFTM), campus Uberaba, em área de campo. O delineamento experimental foi de blocos casualizados, em esquema fatorial 5 x 2, com quatro repetições. Foram avaliadas cinco doses de fósforo (50%, 75%, 100%, 150%, 200% da quantidade recomendada de P 2 O 5 ) com ou sem aplicação foliar de zinco (0,5 kg.ha -1 ). Houve efeito signiicativo para as características massa fresca total e massa fresca comercial da planta apenas em relação ao fator doses de fósforo. Conclui-se que para a alface americana, cultivar Lucy Brown, cultivada na região de Uberaba-MG não se recomenda a utilização de adubo foliar à base de zinco, já que este não proporciona diferenças signiicativas na produtividade da cultura e deve-se aumentar a adubação fosfatada em 50% da dose atualmente recomendada. Palavras-chave: Adubação; Lactuca sativa L.; Massa fresca AbstractPhosphorus doses for producing iceberg lettuce with and without foliar application of zinc. This study aimed to evaluate the effect of phosphate fertilization, with and without foliar application of zinc for producing iceberg lettuce. The experiment was conducted in the Federal Institute of Triângulo Mineiro (IFTM), campus Uberaba, in the ield area. The experimental design was randomized blocks, in a 5 x 2 factorial scheme with 4 replications. Five phosphorus doses were evaluated (50%, 75%, 100%, 150%, 200% of the recommended amount of P 2 O 5 ) with or without foliar application of zinc (0.5 kg.ha -1). There was a signiicant effect for the characteristics total fresh mass and commercial fresh mass of the plant only regarding the factor phosphorus levels. We conclude that for iceberg lettuce, Lucy Brown cultivar, grown in the region of Uberaba, Minas Gerais, Brazil, it is not recommended to use a zinc-based foliar fertilizer, since this does not provide signiicant differences in crop yield and phosphate fertilization must have a 50% increase in the currently recommended dose.

The objective of this study was to evaluate the relationship between agronomic traits and physiological traits of seeds in segregating soybean populations by canonical correlation analysis. Seven populations and two commercial cultivars in three generations were used: F plants and F seeds; F plants and F seeds, and F seeds and plants. The following agronomic traits (group I) were evaluated: number of days to maturity, plant height at maturity, insertion height of first pod, number of pods, grain yield, and oil content. The physiological quality of seeds (group II) was evaluated using germination, accelerated aging, emergence, and emergence rate index tests. The results showed that agronomic traits and physiological traits of seeds are not independent. Intergroup associations were established by the first canonical pair for the generation of F plants and F seeds, especially between more productive plants with a larger pod number and high oil content and seeds with a high germination percentage and emergence rate. For the generation of F plants and F seeds, the first canonical pair indicated an association between reduced maturity cycle, seeds with a high emergence percentage and a high percentage of normal seedlings after accelerated aging. According to the second canonical pair, more productive and taller plants were associated with seed vigor. For the generation of F seeds and plants, the associations established by the first canonical pair occurred between seed vigor and more productive plants with high oil content and reduced maturity cycle, and those established by the second canonical pair between seeds of high physiological quality and tall plants.