Optimal Model for Dynamic Characteristics of Grain Weight Commonly Used in Wheat and Maize

To establish a common model of grain weight (GW) for at least 2 crops with wider application under different conditions, 3 cultivars of winter wheat (Triticum aestivum L.) and 4 cultivars of summer maize (Zea mays L.) were used in field experiments in 4 environments during 2006–2008. A common GW model, y= a/(1+be−cx), was proposed with normalized GW and grain filling duration for both crops. Based on the results from this study, the parameters of a, b, and c were 1.0624, 52.8653, and 6.7609 (r = 0.9916, P < 0.01), respectively. For different crop species, cultivars, and planting densities, the GW dynamic model remained a relative stable a value, which was around 1. However, the b and c values varied in different conditions. The b value changed slightly with density and shifted from 45.3379 to 66.9306 in different cultivars; whereas, the c value had small differences among different cultivars and densities. This normalized GW dynamic model could eliminate the variance of the model parameters caused by location, year, cultivar, and planting density, thus, predict GW increase reliably and easily when the GWmax, grain filling duration, and b value were determined.