High Temperature Reduces the Viability of Pollen from Upland Cotton in China

Abstract

The viability of pollen grains from upland cotton (Gossypium hirsutum L.) has an important influence on fertilization and fiber yield and quality, and high temperature adversely affects cotton pollen grain development. However, the effects of high temperature on the vigor of pollen grains and cultivars having pollen grains resistant to high temperature in different regions have not been reported. The purpose of this study was to evaluate how high temperatures influence the viability of pollen from upland cotton and determine the high‐temperature risk to pollen vigor in upland cotton cultivars in major cotton‐producing regions in China. In this study, pollen grain germination was performed in vitro by culturing pollen grains in medium to detect cotton pollen grain viability. Pollen germination rates decreased significantly when the maximum daily temperature was ≥35°C for three consecutive days. The resistance of pollen vigor to high temperatures significantly differed among cultivars. According to the average annual number of days with temperatures ≥35°C from June to August in the main cotton‐producing areas in China within a 10‐yr period, the risk of high temperature affecting pollen vigor can be divided into five levels. Seventeen cultivars (lines) resistant to high temperatures were selected from 206 upland cotton cultivars, and four simple sequence repeat (SSR) markers were found to be associated with pollen germination rates under high temperature. This study clarified the degree of high‐temperature risk in major cotton‐producing areas in China and provided guidance for the selection of suitable heat‐resistant cultivars.Core Ideas Pollen germination rates decreased significantly when the maximum daily temperature was ≥35°C for three consecutive days. The heat resistance index was calculated to evaluate the differences in the heat resistance among the different cultivars. Resistance of pollen vigor to high temperature significantly differed among cultivars. Four simple sequence repeat markers associated with pollen germination rates under high temperature were identified.