Water restriction and physiological traits in soybean genotypes contrasting for nitrogen fixation drought tolerance

Biological nitrogen fixation (BNF) is essential to the economic viability of the soybean [Glycine max (L.) Merrill] crop in Brazil, but drought may impair the BNF processes. We evaluated physiological traits of nitrogen fixation drought-tolerant (NFDT) (R01-581F, R01-416F and R02-1325) and drought-susceptible (CD 215 and BRS 317) genotypes of soybean subjected to drought or regular water supply between 45 and 55 days after emergence, in an experiment under greenhouse conditions in pots containing non-sterile soil. R01-581F had more stable photosynthetic and transpiration rates, and higher intercellular CO2 levels under drought. Drought reduced the chlorophyll concentration in all genotypes, but with less intensity in R01-581F and R02-1325. The NFDT genotypes generally showed higher concentrations of N, K and Mn in shoots, irrespective of the water condition. Exposure to drought increased total soluble sugars in nodules in all genotypes, as well as the concentrations of ureides in leaves and nodules, whereas ureides in petioles increased only in the susceptible genotypes. Drought negatively affected photosynthetic and BNF attributes; however, R01-581F showed the best performance, with potential for use in breeding programs aiming at drought-tolerant varieties.

Water restriction and physiological traits in soybean genotypes contrasting for nitrogen fixation drought tolerance

Biological nitrogen fixation (BNF) is essential to the economic viability of the soybean [Glycine max (L.) Merrill] crop in Brazil, but drought may impair the BNF processes. We evaluated physiological traits of nitrogen fixation drought-tolerant (NFDT) (R01-581F, R01-416F and R02-1325) and drought-susceptible (CD 215 and BRS 317) genotypes of soybean subjected to drought or regular water supply between 45 and 55 days after emergence, in an experiment under greenhouse conditions in pots containing non-sterile soil. R01-581F had more stable photosynthetic and transpiration rates, and higher intercellular CO2 levels under drought. Drought reduced the chlorophyll concentration in all genotypes, but with less intensity in R01-581F and R02-1325. The NFDT genotypes generally showed higher concentrations of N, K and Mn in shoots, irrespective of the water condition. Exposure to drought increased total soluble sugars in nodules in all genotypes, as well as the concentrations of ureides in leaves and nodules, whereas ureides in petioles increased only in the susceptible genotypes. Drought negatively affected photosynthetic and BNF attributes; however, R01-581F showed the best performance, with potential for use in breeding programs aiming at drought-tolerant varieties.(AU)

Influence of genotype on protein and oil concentration of soybean seeds

Aiming at evaluating genotype influence on the concentration of protein and oil, immature seeds of cultivars CD 202 and CD 206 were removed from the mother-plant, in the stage R5, and were grown in vitro, in a liquid culture medium which contained 20, 40 and 60 mM of glutamine, during eight days. Afterwards, the concentrations of oil and protein were compared to the contents of the seeds cultivated in vivo. With a higher availability of glutamine for the seed, there was an increase of protein content. The genotypes were statistically different as far as the protein concentration was concerned,which confirmed that the genotype had influence on the concentration of protein in the seed. Oil and protein concentrations were inversely related when a variation of glutamine concentration occurred.

Com o objetivo de avaliar a influência do genótipo sobre as concentrações de proteína e óleo, sementes imaturas das cultivares de soja CD 202 e CD 206 foram retiradas da planta mãe no estádio R5, cultivadas in vitro em meio de cultura líquido por oito dias, contendo 20, 40 e 60 mM de glutamina. Depois disso, as concentrações de óleo e proteína foram comparadas com as das sementes que continuaram seu desenvolvimento in vivo. Com a maior disponibilidade de glutamina para a semente, houve um aumento do conteúdo protéico nas sementes. Quanto às concentrações de proteína, os genótipos foram estatisticamente diferentes, levando a afirmar a sua influência na concentração de proteína na semente. As concentrações de proteína e óleo foram inversamente relacionadas quando variou a concentração de glutamina.

Genetic and improvement of Pigeon pea (Cajanus cajan L. Milisp) / Genética e melhoramento do guandu (Cajanus cafan L. Millsp)

The pigeon pea is a leguminous plant grown in tropical and subtropical regions. In Brazil it is found in almost all the country. It is the fifth leguminous most cultivated in the world, mainly in India with the greatest area. The plant is a great promisse as human food source, it has a high proteic content. It is also useful as animal food or green manuring. In this review work it can be enumerated the following characteristics which show the potential of pigeon pea as an alternative for agriculture exploration in Brazil, a) vigorous root system, wich confers high drough resistente; b) High genetic variability, which is a promising factor for improvement; c) presence of dwart types ideal for mechanical harvest; d) high protein content in the seeds.

O Guandu é uma leguminosa cultivada nas regiões tropicais e subtropicais. No Brasil é encontrada em quase todos os estados brasileiros, dentre as leguminosas situa-se como a quinta cultura mais produzida no mundo, estando concentrada na Índia sua maior área cultivada. Essa leguminosa é bastante promissora como fonte de alimento humano, apresenta elevado teor protéico, prestando-se ainda como planta forrageira e adubo verde. Através deste trabalho de revisão pode-se enumerar as seguintes características que evidenciam o potencial do guandu como alternativa para exploração no Brasil, a) sistema radicular vigoroso, o que lhe confere elevada resistência a seca. b) Grande variabilidade dentro da espécie, fator promissor no melhoramento dessa cultura, c) presença de tipos anões viabilizando a colheita mecânica, d) elevado teor protéico nas sementes.