Grain Dehydration Characteristics of Old and Modern Maize Hybrids and Their Response to Different Planting Densities

High grain water content at harvest stage is the main limiting factor for realizing mechanized maize in China. Under background of yield gain by density increase, it necessary to clarify effect planting increase on dehydration characteristics, which would provide theoretical support under high conditions. Therefore, this study selects five hybrids, ZD2, DY13, YD13, XY335, and DH618, released different eras that were widely promoted Inner Mongolia from 1970s 2010s. The experiment was conducted Chilechuan Modern Agriculture Expo Park, Tumed Right Banner, Baotou city, Mongolia, 2018 2019. three densities 45,000 plants ha−1 (low density), 75,000 (medium density) 105,000 (high indexes dehydration, leaf stay-green, bract cob hybrids measured analyzed. results show MCpm (moisture physiological maturity) 1990s significantly reduced 1.57 1.14 percentage points, respectively, MCh time) period 0.99 a low medium density. GDRbm (rate before maturation) GDRam after showed an increasing trend From density, 1980s 2000s could be 1.78, 1.53 1.88 points; 1.77 increased 0.101%/d, but improvement not significant. With decreased ratios relative GLAD (green area duration) SPAD (soil plant analyzer development) per old more than modern decrease rate hybrids. There direct positive correlation between rates, had no significant rate. values decreased, stay-green worsened, bracts important reason moisture