Physiological changes in soybean cultivated with soil remineralizer in the Cerrado under variable water regimes
Lucas Felisberto Pereira, Walter Quadros Ribeiro Junior, Maria Lucrécia Gerosa Ramos, Nicolas Zendonadi dos Santos, Guilherme Filgueiras Soares, Raphael Augusto das Chagas Noqueli Casari, Onno Muller, Cássio Jardim Tavares, Éder de Souza Martins, Uwe Rascher, Cristiane Andréa de Lima Guimarães, André Ferreira Pereira, Liliane Márcia Mertz-Henning, Carlos Antonio Ferreira de Sousa
The objective of this work was to evaluate the influence of the soil remineralizer fine-graded mica schist (FMS) on soybean (Glycine max) physiology, yield, and grain quality under different water regimes (WRs) in the Brazilian Cerrado. The experiment was conducted under field conditions for two years, using four WRs and three treatments: mica schist, conventional fertilization, and control. In 2017 and 2018, the following WRs were evaluated: WR1, WR2, WR3, and WR4, corresponding to a mean value of 100, 65, 44, and 28% of crop evapotranspiration replacement, respectively. Photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, effective quantum yield of photosystem II (PSII) (Fv’/Fm’), quantum yield (PSII) (ᶲFSII), and electron transport rate reduced as a function of the advanced phenological stage of soybean and the reduction in WR. Grain quality was only affected by the WR. The mica schist was statistically similar to conventional fertilization and the control in 2017 and 2018. Yield decreased due to the anticipation of soybean phenological age and WR, but there were no differences between the three treatments in 2017 and 2018. The reduction in soybean yield is attributed to stomatal closure, loss of photoprotective capacity, and damage to the photosynthetic machinery
caused by drought.