Shade stress decreased maize grain yield, dry matter, and nitrogen accumulation
Jia Gao, Zheng Liu, Bin Zhao, Shuting Dong, Peng Liu, Jiwang Zhang
Abstract
Abstract Shade stress severely limits plant growth and crop productivity. This study investigated the relationship between shade stress and nitrogen (N) accumulation in maize at different growth stages. Field experiments were conducted in 2015 and 2016 with three shading treatments: from emergence stage (VE) to physiological maturity (R6) (whole‐season shade), from six‐leaf (V6) to tassel stage (VT) (midseason shade), and from VT to R6 (late‐season shade). Ambient sunlight was used as control (CK). Two hybrids, Zhengdan958 (ZD958) and Denghai 605 (DH605), were used. This study focused on accumulation and partition of dry matter (DM) and N based on the above treatments. Shading reduced DM and N accumulation of maize, which decreased yield. In addition, 15 N stable isotope tracing revealed that shading disrupted N accumulation, partitioning, and remobilization in different organs. The contents of grain 15 N in whole‐season shade, midseason shade, and late‐season shade from ZD958 decreased by 60, 28, and 50%, respectively, compared with those in CK, and DH605 decreased by 70, 32, and 51%, respectively. Our results indicate that yield decline can be mainly attributed to DM and that N accumulation and remobilization were disrupted by shading at different maize growth stages. Shading during the vegetative stage and reproductive stage reduced N accumulation, and shading during the reproductive stage mainly promoted N transport from other organs to grain, which mitigated some of the effects of reduced N absorption.