Effect of Brassinolide on Leaf Photosynthetic Function and Yield in Spring Maize Filling Stage

Abstract

A field experiment was conducted to investigate the effect of plant growth regulator brassinolide(BR) on the regulation of physiological activities of ear leaf, the grain filling and yield in spring maize(Zea mays L., cv. Zhengdan 958). Husks and ear leaves were treated with BR at 15 days after anthesis by foliar spraying. The results showed that the chlorophyll content, photosynthetic rate and activities of PEP carboxylaes, Ru BP carboxylase, sucrose synthase and sucrose phosphate synthase in ear leaf as well as source content in kernel were significantly reduced, while starch accumulation and dry weight of kernel were increased during grain filling. BR significantly increased the content of chlorophyll and photosynthetic rate, enhanced the activities of PEP carboxylaes and Ru BP carboxylase, definitely resulting in enhanced CO2 assimilation. BR markedly increased the activities of sucrose synthase and sucrose phosphate synthase in ear leaf. And in kernel, the accumulation of sucrose and starch as well as the grain filling rate were accelerated by BR. BR treatment significantly reduced the length of ear barren tip, and increased the number of kernels per ear, which led to higher yield. These results suggest that BR treatment at filling stage may be a good strategy to get a high yield in maize, by enhancing activity of resource, delaying sencence and stimulating the flow of assimilate from the source to the sink.