Identifying cultivars of leguminous crops exhibiting drought resistance has become crucial in addressing water scarcity issues. This investigative study aimed to select soybean and cowpea cultivars with enhanced potential to grow under water restriction during the vegetative stage. Two parallel trials were conducted using seven soybean (AS3810IPRO, M8644IPRO, TMG1180RR, NS 8338IPRO, BMX81I81IPRO, M8808IPRO, and BÔNUS8579IPRO) and cowpea cultivars (Aracê, Novaera, Pajeú, Pitiúba, Tumucumaque, TVU, and Xique-xique) under four water levels (75, 60, 45, and 30% field capacity—FC) over 21 days. Growth, water content, membrane damage, photosynthetic pigments, organic compounds, and proline levels were analyzed. Drought stress significantly impacted the growth of both crops, particularly at 45 and 30% FC for soybean and 60 and 45% FC for cowpea plants. The BÔNUS8579IPRO and TMG1180RR soybean cultivars demonstrated the highest performance under drought, a response attributed to increased amino acids and proline contents, which likely help to mitigate membrane damage. For cowpea, the superior performance of the drought-stressed Xique-xique cultivar was associated with the maintenance of water content and elevated photosynthetic pigments, which contributed to the preservation of the photosynthetic efficiency and carbohydrate levels. Our findings clearly indicate promising leguminous cultivars that grow under water restriction, serving as viable alternatives for cultivating in water-limited environments.

Our working hypothesis was that magnesium (Mg) supplementation modulates plant performance under low water availability and improves drought tolerance in soybean genotypes. Plants of Bônus 8579, M8808 and TMG1180 genotypes were grown under field conditions and subjected to three water stress treatments (control, moderate and severe stress) and three Mg levels [0.9 (low), 1.3 (adequate) and 1.7 cmolc dm^-³ (supplementation)]. After 28 days of drought imposition, the growth parameters, osmotic potential, relative water content, leaf succulence, Mg content and photosynthetic pigments were assessed. In general, drought drastically decreased the growth in all genotypes, and the reductions were intensified from moderate to severe stress. Under adequate Mg supply, TMG1180 was the most drought-tolerant genotype among the soybean plants, but Mg supplementation did not improve its tolerance. Conversely, although the M8808 genotype displayed inexpressive responses to drought under adequate Mg, the Mg-supplemented plants were found to have surprisingly better growth performance under stress compared to Bônus 8579 and TMG1180, irrespective of drought regime. The improved growth of high Mg-treated M8808-stressed plants correlated with low osmotic potential and increased relative water content, as well as shoot Mg accumulation, resulting in increased photosynthetic pigments and culminating in the highest drought tolerance. The results clearly indicate that Mg supplementation is a potential tool for alleviating water stress in M8808 soybean plants. Our findings suggest that the enhanced Mg-induced plant acclimation resulted from increased water content in plant tissues and strategic regulation of Mg content and photosynthetic pigments.

Context: Cultivation of forage grasses intercropped with maize (Zea mays) improves soil quality and yield of subsequent crops. However, for the Cerrado of north-east Brazil, little is known about the effects of this practice on soil chemical and biological attributes and on succeeding soybean crop’s yield and nutrition. Aims: This study aimed to evaluate the influence of intercropping maize with forage grasses on soil chemical and biological properties and on the nutritional status and yield of succeeding soybean in the Cerrado of Piauí, Brazil. Methods: In the 2016/2017 cropping season, maize (M) was grown in monoculture and intercropped with Megathyrsus maximus cvs Zuri, Massai, Tanzania, and Tamani; Urochloa brizantha cv. Marandu, and Urochloa ruziziensis cv. Ruziziensis. In the 2017/2018 and 2018/2019 cropping seasons, soybean (Glycine max) was grown on the same plots. Key results: In the 2017/2018 cropping season, highest soil K concentrations in the 0–0.1 m depth were observed following M + Zuri and M + Massai. In the 2018/2019 cropping season, soybean grown after monoculture maize, M + Zuri, M + Tanzania and M + Ruziziensis promoted the highest soil basal respiration. Intercropping maize with forage grasses of the genus Urochloa increased the soil humic substances and carbon concentrations. The M + Tanzania treatment increased soybean leaf P and K concentrations in the 2017/2018 cropping season. Conclusions: Intercropping maize with forage grasses improved soil fertility and increased cumulative soybean grain yield by 15%. Implications: Maize intercropped with forage grasses, especially of the genus Urochloa, increases humic fractions and total soil organic carbon, and is thus a feasible agricultural management.

O presente trabalho procurou discutir os pressupostos teóricos, considerados em relação: a questão da preocupação com a utilização da água na irrigação, que é um recurso natural cada vez mais limitado; a questão da sustentabilidade, em especial a água residuária; e a questão do meio ambiente e sua valoração. A metodologia utilizada foi uma revisão de literatura através de documentos oficiais; publicações de revistas, jornais, artigos; documentos institucionais; além de fontes estatísticas e outros tipos de material literário que contribuísse para o enriquecimento deste estudo.

Dentre aspectos mais importantes para o sucesso da agricultura irrigada destaca-se o manejo da água aplicada. No mercado existe uma diversidade de metodologias e instrumentos para tal fim, entretanto, o monitoramento do nível de água no solo utilizando o tensiômetro tem se mostrado eficaz. Nesse trabalho foram avaliados dois métodos de manejo da irrigação, um baseado na tensão da água no solo e o outro com base da depleção da água disponível, com o objetivo de verificar qual deles promove maior produtividade de grãos para a cultura do feijoeiro (Phaseolus vulgaris L.) em um solo de textura arenosa. Os tratamentos foram compostos por cinco níveis de tensão (– 30, – 40, – 50, – 60 e – 70 kPa) e cinco níveis de depleção (30, 40, 50, 60 e 70% da AD), com quatro repetições delineados em blocos casualizados. O experimento foi desenvolvido em ambiente protegido no Departamento de Solos e Recursos Ambientais (UNESP/FCA), Botucatu - SP. Avaliou-se os parâmetros: Número de vagens por planta (NVP); Produção de vagens por planta (PVP, g); Comprimento da vagem (COMPV, cm); Número de grãos por vagem (NGV); Peso de grãos por vagem (PGV, g); Peso de 100 grãos (P100G, g) e Produção de grãos (PG, g planta^-1). Não foram evidenciadas diferenças significativas entre os métodos de irrigação, entretanto, as maiores produtividades de grãos de feijão ocorreram para a tensão de – 30 kPa, resultando em 12,10 g planta^-1 e 11,04 g planta^-1 para 40% da AD.