Effects of Short-Term High Temperature on Cotton Yield and Fiber Quality of Different Cultivars

To explore the effects of short-term high temperature on cotton yield and fiber development, pot experiments were carried out in 2015 and 2016 in a climate chamber using two cotton cultivars, which were HY370WR (high-temperature tolerant) and Sumian 15 (high-temperature sensitive), under two temperature regimes (26 ¡æ (30/22 ¡æ), CK; 34 ¡æ (38/30 ¡æ), HT) for 5 days. The results showed that the short-term high temperature stress reduced the fiber length and decreased the yield by increasing the shedding rate. The fiber length of PH370WR and Sumian 15 was decreased by 4.1% and 6.7%, and the decrease in fiber length was significantly lower for PHY370WR than Sumian15. Fiber strength and micronaire variation width between the two cultivars were not significant. The variation range of yield per plant and boll weight under high temperature was significantly different between the two cultivars (yield per plant: PHY370WR -14.6%, Sumian 15 -20.3%; boll weight: PHY370WR -3.4%, Sumian15 -5.8%). The variation of the shedding rate was significantly higher than that of boll weight, but the difference between varieties was not significant (PHY370WR 13.5%, Sumian 15 15.1%). Boll weight was the main reason causing the difference in yield between the two cultivars under high temperature. Compared with Sumian 15, subtending leaves of cotton boll in PHY370WR had higher net photosynthetic rate and could maintain a longer time. Therefore, PHY370WR had stronger source capacity than Sumian 15 under short-term high temperature stress, which was the key reason for the difference in yield between the two cultivars under short high temperature.