Aminoethoxyvinylglycine (AVG) Application During Mid-Vegetative Growth Perturbs Maize Ear Development and Increases Individual Sink Capacity.

Modulation of ethylene biosynthesis or perception through chemical or genetic approaches has been proposed as a strategy to mitigate the response of maize to yield limiting environmental stresses. The effects of timing and magnitude of ethylene modulation on maize grain yield, however, are poorly documented. This study was initiated in 2009 to investigate the impact of ethylene biosynthesis inhibition on maize ear development through application of aminoethoxyvinylglycine (AVG) during mid-vegetative growth stages (V8-V12).

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.