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

Grain filling is the physiological process for determining the obtainment of yield in cereal crops. The grain-filling characteristics of 50 maize brand hybrids released from 1964 to 2014 in China were assayed across multiple 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 parameter of 100-kernel weight (HKW). Meanwhile, along with the significant increase in HKW, the accumulated growing degree days (GDDs) for the actual grain-filling period duration (AFPD) among the selected brand hybrids released from the 1960s to the 2010s in China had a decadal increase of 23.41 degrees C d. However, there was a decadal increase of only 19.76 degrees C d for GDDs of the days from sowing to physiological maturity (DPM), which was also demonstrated by a continuous decrease in the ratio between the days from sowing to silking (DS) and DPM (i.e., from 53.24% in the 1960s to 49.78% in the 2010s). In contrast, there were no significant changes in grain-filling rate along with the release years of the selected hybrids. Moreover, the stability of grain-filling characteristics across environments also significantly increased along with the hybrid release years. We also found that the exotic hybrids showed a longer grain-filling duration at the effective grain-filling phase and more stability of the grain-filling characteristics than those of the Chinese local hybrids. According to the results of this study, it is expected that the relatively longer grain-filling duration, shorter DS, higher grain-filling rate, and steady grain-filling characteristics would contribute to the yield improvement of maize hybrids in the future.

Automated summary

This study analyzed 50 maize hybrids released in China from 1964 to 2014 and found that the duration and rate of grain filling greatly influenced the 100-kernel weight. The growing degree days for the grain-filling period increased over the years, but the days from sowing to physiological maturity did not show significant changes. Grain-filling rate did not vary with the release years. Exotic hybrids had longer grain-filling duration and more stable characteristics compared to local hybrids. The results suggest that longer grain-filling duration, shorter days to silking, higher grain-filling rate, and stable characteristics can contribute to yield improvement of maize hybrids in the future.