Predicting maize kernel sink capacity early in development

Development of maize (Zea mays L.) kernels follows a predictable pattern involving rapid increase in dry weight and large changes in water content (WC). We showed previously that final kernel weight (KW) was closely correlated with maximum WC achieved during rapid grain filling. The objectives of the current work were (i) to test if percent moisture content (MC, measured on a fresh weight basis) could be used to normalize genetic and environmental variations in kernel development shown to affect final KW and (ii) to determine whether final KW could be predicted from kernel WC prior to rapid grain filling. The data examined included results from five hybrids varying more than 2-fold in final KW grown in the field, and from previously published results. When KW and WC were expressed relative to their maximum values obtained during kernel development, a single model described the relationship between dry weight accumulation and MC for the larger seeded hybrids (199–352 mg kernel⁻¹) and published results (222–359 mg kernel⁻¹). Two smaller seeded yellow-flint popcorn hybrids, however, accumulated less dry matter per unit moisture than expected. Nonetheless, all genotypes exhibited a common developmental relationship between kernel WC (expressed as a percent of the maximum value) and MC under well-watered conditions. A new model was developed to couple this developmental relationship to final KW. This model accurately predicted final KW from kernel WC values measured prior to rapid grain filling (∼80% MC; root mean square error, RMSE, of 28.9 mg kernel⁻¹) for all hybrids examined and all published results for which KW and kernel WC data were available. The model also provided a simple means to determine whether final KW was limited by photosynthate supply during kernel development.