LAUSR

BACKGROUND Drought stress (DS) induced by post-silking can have a major impact on the yield and quality of maize. In this study, the effects of DS degrees after pollination, namely well-watered (WW), mild water-stressed (WS1), moderate water-stressed (WS2), on the grain filling, starch and protein metabolism, and functional properties were investigated using two waxy maize cultivars as materials. RESULTS DS decreased grain fresh weight, dry weight, and moisture content in both cultivars during grain filling, and reduced kernel number, thousand kernel weight, and grain yield at maturity. Meanwhile, the effect on grain development and yield formation gradually increased with drought aggravation. WS treatment downregulated the enzymatic activities related to starch biosynthesis during grain-filling process, accompanied by a decrease in soluble sugar and starch deposition. WS treatment increased the enzymatic activities involved in protein synthesis during grain-filling process, thereby increasing the protein content of grains. On the average, WS2 and WS3 treatments reduced the pasting viscosities and increased the gelatinization temperatures of grains, with WS3 having the greatest effect. However, the changes of setback viscosities, gelatinization enthalpy, retrogradation enthalpy, and retrogradation percentage under WS treatment were inconsistent in both cultivars. Pearson correlation analysis showed that starch content was negatively correlated with gelatinization temperatures and positively correlated with pasting viscosities in both cultivars. However, grain pasting characteristics and thermal properties have opposite correlations with protein content and starch content. CONCLUSIONS These findings suggest that post-silking DS regulated the grain-filling process and starch and protein biosynthesis, which influenced the grain yield and quality. This article is protected by copyright. All rights reserved.