Spraying exogenous 6-benzyladenine and brassinolide at tasseling increases maize yield by enhancing source and sink capacity

Abstract

The endosperm contributes approximately 80% of the final kernel weight in maize. Plant hormones that affect cell proliferation might increase endosperm cells and establish greater kernel sink capacity, which would improve grain yield. In this study, 6-benzyladenine (BA) and brassinolide (BR) were separately sprayed at tasseling to regulate kernel endosperm cell division, and EDAH (a mixture of ethephon and diethyl aminoethyl hexanoate) was foliar applied at the jointing stage to enhance lodging resistance. The results showed that the two hormones sprayed at tasseling could hamper leaf senescence, improve photosynthesis and significantly increase the number of kernel endosperm cells by 6.2-40.4%, resulting in a high grain filling rate and high kernel weight. Additionally, the tasseling treatments increased grain yield by 2.9-16.0% in both years. There were no significant differences between EDAH and control conditions in sink capacity and yield. The correlation analysis suggested that grain weight and yield had a close correlation with the number of endosperm cells and the filling rate in the lag stage. We concluded that the lag stage played a vital role in constructing sink capacity, and treating maize with BA or BR at tasseling can apparently increase the source and sink capacity to improve the grain filling rate and yield.