Physiological changes in soybean cultivated with soil remineralizer in the Cerrado under variable water regimes

Abstract: 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.

摘要：本研究旨在评估土壤再矿化剂细粒级云母片岩（fine-graded mica schist, FMS）对巴西塞拉多（Brazilian Cerrado）地区不同水分供应状况（water regimes, WRs）下大豆（Glycine max）生理特性、产量及籽粒品质的影响。本试验于大田条件下开展，为期两年，设置4种水分供应状况与3种处理：细粒级云母片岩、常规施肥与空白对照。2017年与2018年共设置WR1、WR2、WR3、WR4四种水分处理，其对应作物蒸散量（crop evapotranspiration）补灌比例分别为100%、65%、44%与28%。光合速率、气孔导度、蒸腾速率、胞间CO₂浓度、光系统II（photosystem II, PSII）有效量子产额（Fv’/Fm’）、光系统II量子产额（ᶲFSII）以及电子传递速率均随大豆生育进程推进与水分供应状况的降低而下降。籽粒品质仅受水分供应状况的影响。2017年与2018年，细粒级云母片岩处理与常规施肥、空白对照在统计学上无显著差异。产量下降归因于大豆生育期推进与水分供应状况缩减，但2017年与2018年三种处理间产量并无显著差异。大豆产量降低的原因在于干旱引发的气孔关闭、光保护能力丧失以及光合机构受损。