Leaf Photosynthesis and Senescence in Heated and Droughted Field-grown Soybean with Contrasting Seed Protein Concentration

Soybean plants under heat and drought generate a multiplicity of responses in photosynthesis and senescence, impairing growth, yield, and seed quality. The goal of this study was to analyze and quantify independent and combined effects of heat and drought during seed filling on photosynthesis and senescence, and its subsequent effects on the filling duration in soybean genotypes contrasting on seed protein. Two field experiments were conducted using high and low seed protein genotypes. During seed filling plants were exposed to four treatments: control (ambient temperature and soil water content near field capacity), heat stress (HS, episodes above 32 °C 6 h d-1) during 15-d, drought stress (DS, soil water content ≤ 25% of field capacity) during the entire seed filling, and HS×DS. We found non-genotypic variation in leaf photosynthesis in both experiments. Irrigated HS, did no alter photosynthesis and senescence. Drought, regardless of heat, reduced photosynthesis, carbohydrate production and affected membranes integrity, leading to premature leaf senescence and shortening the filling duration. The magnitude of responses was similar between drought alone and stresses combined, indicating a dominant role of drought over heat. The seed filling duration was not shorter in high protein compared to low protein genotype, nor was senescence pattern altered across treatments. These results indicated that the higher seed protein content exhibited by some genotypes are not necessarily associated with an earlier onset of senescence and shortening of the filling period as suggested by previous studies analyzing genotypes differing in protein concentration.

Instituto de Fisiología y Recursos Genéticos Vegetales

Fil: Ergo, Verónica Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Estudios Agropecuarios (UDEA;. Argentina

Fil: Ergo, Verónica Vanesa. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Fil: Veas, Rodolfo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Estudios Agropecuarios (UDEA); Argentina

Fil: Veas, Rodolfo Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Fil: Vega, Claudia Rosa Cecilia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Manfredi; Argentina

Fil: Lascano, Hernán Ramiro. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Fisiología Vegetal; Argentina

Fil: Lascano, Hernán Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Estudios Agropecuarios (UDEA); Argentina

Fil: Lascano, Hernán Ramiro. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Fil: Carrera, Constanza Soledad. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Fil: Carrera, Constanza Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Estudios Agropecuarios (UDEA); Argentina