Effects of Plant Growth Regulators and Nitrogen Management on Root Lodging Resistance and Grain Yield under High-Density Maize Crops

Abstract

Lodging is one of the main factors causing yield loss of maize under high-density planting conditions. Root lodging as an important lodging type has received little attention. Plant growth regulators (PGRs) and nitrogen fertilizer can coordinate the relationship between root lodging and yield. This two-year field experiment was conducted with two nitrogen levels of N225 (225 kg ha−1) and N300 (300 kg ha−1) at a high planting density (90,000 plants ha−1) during the maize growth season from 2019 to 2020. Plant growth regulator (Yuhuangjin, the mixture of 3% DTA-6 and 27% ethephon) was sprayed at the V8 stage. The results showed that PGRs significantly decreased plant height, improved root distribution and dry weight, enhanced photosynthetic rate and activities of photosynthetic carboxylase in ear leaves, and improved root bleeding sap and root activities after the silking stage. N225 combined with PGRs reduced the occurrence of root lodging and was conducive to photosynthate accumulation and root nutrient supply; it coordinated root regulation and morphological and physiological shoot functions, and played a crucial role in reducing root lodging and improving maize yield.