Seasonal and diurnal patterns of nonstructural carbohydrates in source and sink tissues in field maize

Carbohydrate partitioning and utilization is a key determinant of growth rate and of yield in plants
and crops. There are few studies on crops in field conditions. In Arabidopsis, starch accumulation in leaves is a negative indicator of growth rate. Here, we wished to establish if starch accumulation in leaves could potentially be a marker for growth rate and yield in crops such as maize. We characterized daily patterns of non-structural carbohydrate (NSC) at different growth stages over two seasons for maize hybrids in the field. In 27 commercial hybrids, we found a significant negative relationship between residual starch in leaves and plant growth, but not with final yield and biomass. We then focused on three typical hybrids and established a method for calculation of C turnover in photosynthetic leaves that took into account photosynthesis, leaf area and NSC accumulation. The ratios of stored NSC decreased from approximately 15% to less than 4% with ongoing ontogeny changes from V7 to 28 days after pollination. The proportion rather than absolute amount of carbon partitioned to starch in leaves at all stages of
development related well with yield and biomass accumulation. It is proposed that screening plants at an early vegetative growth stage such as V7 for partitioning into storage may provide a prospective method for maize
hybrid selection. Our study provides the basis for further validation as a screening tool for yield.