Persistently smaller tassels threaten maize yield under a warming climate

Abstract

AbstractHeat waves become more serious with the warming climate, increasing the demand for developing high temperature (HT) tolerant maize germplasm. Here we compared the responses of 323 elite inbred lines released in multiple eras from both China and the United States to HT during flowering under field conditions. The newly released lines exhibit higher grain yield than the early released lines as a result of improved ear characteristics and flowering synchrony. However, the newly released lines are more susceptible to HT stress partly due to the reduced tassel size and spikelet opening angle. We identify a key threshold for spikelet/tassel (~700), over which maize can produce a stably high seed set under HT stress. According to the daily temperature during flowering, it is estimated that small-tassel (<700 spikelet/tassel) genotypes are unsuitable in 23.7% of global maize-growing regions. This work provides important information for breeding and selecting HT-tolerant maize varieties.