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We found that application of AVG during these growth stages resulted in reduction of grain yield and striking ear abnormalities in a dose-dependent manner. Abnormal ear development was most evident at the high rate of AVG (1600 mg L-1), and was generally characterized by an approximate 50% reduction in cob length and terminated ovule development which occurred along the distal halves of abnormal ears. Average grain weights (g plant-1) were reduced by 6% with 400 mg L-1 AVG, and by 55% with 1600 mg L-1 AVG. The yield component contributing to the decrease in total grain weight was kernel number. Although total grain weight and kernel number decreased with AVG application, average individual kernel weights increased by 4.7% with 400 mg L-1 AVG, and by 12% with 1600 mg L-1 AVG. Accompanying the increase in individual kernel weight was an increase in grain protein concentration from 73 g kg-1 to 92 g kg-1.
Our literature review suggests that an increase in individual kernel weight along with an increase in grain protein concentration cannot be completely explained by drastic manipulation of the source-sink ratio. We propose that AVG applied during early development of the maize female inflorescence influences the establishment of individual sink capacity, and particularly enhances the potential of each kernel for increased endosperm protein accumulation.