An growing-period indicator of maize cultivars for mechanical kernel harvest

Abstract

: The high kernel moisture of maize ( Zea mays L.) at harvest stage limits the field-application of mechanical kernel harvesting. The breeding and selection of fast dry-down cultivars is the key to solve this problem. However, there is still a lack of such indicators for evaluating the kernel dry-down rate in China. To explore the indicators, the crop growth and the kernel dry-down of two cultivars, Xianyu 335 and Zhengdan 958, were investigated across various maize belts in China from 2014 to 2018. Between the two cultivars, there were significant varietal differences in thermal times (TT) at the stages of plant-ing–maturity (P–M), planting–25% moisture (P–25%), and maturity–25% moisture (M–25%), respectively. The TT P–M on average were 3039°C d (2752–3249°C d) for Xianyu 335 and 3090°C d (2750–3546°C d) for Zhengdan 958, with a difference value of 51°C d, and the corresponding coefficient of variations (CV) of TT P–M tivars, the TT P–25% could be considered as the growing period indicator for the breeding and selection of cultivars fitting to present mechanical kernel harvesting. In addition, this indicator might vary with region, year, or planting date, the same field and year were recommended to ensure a consistent environmental condition for measuring it. Conclusively, a new indicator (TT P–25% ) for breeding and selection of fast dry-down hybrids was proposed, which potentially prompting maize kernel harvesting in China.