Changes in grain-filling characteristics of single-cross maize hybrids released in China from 1964 to 2014

Abstract

Grain filling is the determined physiological process for the yield obtainment of cereal crops. The grain filling characteristics of 50 maize brand hybrids released from 1964 to 2014 in China were assayed across multi-environments. We found that the grain filling duration (54.46%) and rate (43.40%) at the effective grain filling phase greatly contributed to the final performance of hundred-kernel weight (HKW). Meanwhile, along with the significant increase in hundred-kernel weight (HKW), the accumulated growing degree days (GDDs) for actual grain filling period duration (AFPD) for the selected brand hybrids released between 1960s to 2010s in China had a decadal increase of 23.41°C d. However, there was a decadal increase of only 19.76°C d for GDDs of the days from sowing to physiological maturity (DPM), which was also demonstrated by the continuous decrease in the ratio between the days from sowing to silking (DS) and DPM (i.e., from 53.24% in 1960s to 49.78% in the 2010s). However, there were no significant changes in grain filling rate along with the release years of selected hybrids. Moreover, the stability of grain filling characteristics across environments also significantly increased along with the hybrid released years. We also found that the exotic hybrids showed the longer grain filling duration at the effective grain filling phase and more stability of grain filling characteristics than those of Chinese local hybrids. According to the results of this study, it was speculated that the relatively longer grain filling duration, shorter DS, the higher grain filling rate, and steady grain filling characteristics would contribute to yield improvement of maize hybrids in the future.