Mepiquat chloride application increases lodging resistance of maize by enhancing stem physical strength and lignin biosynthesis

Lodging is a major adversity which limits maize grain yields and quality, especially under dense population. The present study was conducted to determine the efficacy of mepiquat chloride, a potential anti-gibberellic plant growth retardant on plant height, the physical strength of stem, lignin content and its relationship with lodging resistant in maize crop. Maize seeds were dressed with mepiquat chloride at the rate of 0 (MC0), 2.0 (MC1), 2.5 (MC2), and 3.0 (MC3) g kg(-1) during 2015-2016. Our results showed that mepiquat chloride treatments enhanced the culm physical strength, as revealed by enhanced rind puncture strength and stalk bending strength, increased dry weight per cm, stern diameter, and lignin accumulation resulting in strong lodging resistance. A significant and negative correlation was detected between stalk bending and rind puncture strength with lodging rate. Moreover, the lodging rate, plant height, intemodes length and gravity center height were significantly reduced following a dose-response trend, and MC2 and MC3 treatments resulted in relatively shorter plants, compared to control treatment. In addition, the grain yield, lignin contents and activities of lignin-related enzymes were enhanced by mepiquat chloride, and the MC2 (2.5 g kg(-1)) treatment showed the best effect of all treatments. The correlation analysis revealed that lignin accumulation was negatively and significantly correlated with lodging rate of the maize crop. Our results imply that plant height obviously, as well as the culm physical strength and lignin are closely associated with the lodging resistance in maize, and the decreased plant height, enhanced culm morphological characteristics and lignin content could strengthen the resistance of crops to lodging.