Increasing nitrogen availability during the seed-filling period improves grain weight and grain industrial quality in soybean under drought

ERGO VERÓNICA V.; SALVAGIOTTI, FERNANDO; CARRERA C. S.

Santa Fé

Congreso; XXXIII Reunión Argentina de Fisiología Vegetal. 2021. Santa Fé, Argentina.; 2021

Sociedad Argentina de Fisiología Vegetal

Increasing o maintaining crop productivity and quality under drought conditions is one of the main challenges for agriculture in a climatic change scenario. The objective of this study was to evaluate the increase in nitrogen (N) availability in the seed-filling period in soybean on grain weight (Gweight), protein and oil concentrations (Gprotein and Goil, respectively) in irrigated-plots and droughtconditions in genotypes contrasting in Gprotein. We conducted field experiments testing two nontransgenic genotypes: high (HP) and low (LP) Gprotein. Treatments included two water levels: irrigated- and drought-plots (with a soil water content≤ 25% of field capacity from R5, beginning grain filling), and two N levels: unfertilized-plots and fertilized-plots (600 kg.N.ha-1 equally split at vegetative, beginning bloom, and beginning pod). Regardless of water and N levels, the HP genotype, exhibited greater Gweight (18%) and Gprotein (5%), and lower Goil (4%) than the LP genotype. In irrigated-plots, N fertilization decreased Gweight (17%) compared to non-fertilized treatment, decreasing protein and oil contents at similar rates (~20%), without significant impact on Gprotein and Goil. Drought-treatments, independently of the genotype, reduced 38% the Gweight,41% the protein content and 52% the oil content, increasing Gprotein by 7%. Interestingly, in these plots reductions of Gweight, protein and oil contents were slightly higher without N fertilization compared to fertilized treatments in both genotypes, but more pronounced in HP. Based on these results we hypothesized that under drought conditions fertilization addition mitigated the decrease N supply from other sources (i.e. soil, biological fixation and/or remobilization), and thus increasing Gprotein.