4.3 The implication for maize breeding
In this study, we found the subsequent impacts on grain filling of stresses episodes around flowering mainly resulted from the disturbing starch synthesis. Therefore, maize hybrids that have a high ability for starch synthesis in kernel are likely more tolerant to DS, HS and DHS. This should be received more attention in future breeding program. For example, the drought‐tolerant lentil showed stronger ability of starch synthesis in seeds (Sehgal et al., 2018). Meanwhile, we found the grain weight was also reduced by shortened grain filling duration, accelerated leaf senescence, and decreased photosynthesis in field. This also implicated the importance of delaying senescence and improving photosynthetic capacity for maize breeding. For example, the drought-tolerant hybrid maintained greater photosynthetic rates (+8-10%) compared with the conventional hybrid (Lindsey, Barker, Metzger, Mullen, & Thomison, 2018). Meanwhile, the heat-tolerant germplasm emphasized the importance of sufficient CO2 exchange rate (Neiff, Trachsel, Valentinuz, Balbi, & Andrade, 2016).