Quantifying individual and interactive effects of elevated temperature and drought stress on cotton yield and fibre quality

Abstract

AbstractThe individual effect of high temperatures or water‐deficit stress on cotton has been studied extensively; however, their combined effects were less studied. To that end, an experiment was imposed with a heat‐sensitive (Sumian 15) and a heat‐tolerant (PHY370WR) cultivar in 2016–2018 and two temperature regimes including ambient temperature (AT, 31.0/26.4°C) and elevated temperature (ET, 33.4/28.9°C), and three soil relative water content (SRWC) levels including (75 ± 5)%, (60 ± 5)% and (45 ± 5)% were performed. Results showed that the decline in boll number was the primary driver of yield loss, while the decreases in boll weight minimally impacted yield under drought and combined treatments. Besides, elevated temperature and drought stress performed significant interactions on boll weight (except in 2018) and seed cotton yield (except for Sumian 15 in 2017). Specifically, seed cotton yield was reduced by 23%–35% in Sumian 15 and by 8%–13% in PHY370WR under ET60 (ET with SRWC (60 ± 5)%), while the reduction was 44%–54% in Sumian 15 and 37%–43% in PHY370WR under ET45 (ET with SRWC (45 ± 5)%), which produced lower yields than any other treatment combination or any single abiotic stress factor. Furthermore, significant interactions between the two stresses were observed in fibre length of Sumian 15 and strength (except for PHY370WR in 2018) and micronaire (except for Sumian 15 in 2017 and for PHY370WR in 2018) of both cultivars. Elevated temperature exacerbated the negative impacts of drought on fibre length but offset them on fibre strength and micronaire. Finally, the economic benefit among different treatments was evaluated. Compared to the control, ET45 suffered the biggest economic loss by 2,536.7 USD ha−2 in Sumian 15 and by 2,167.8 USD ha−2 in PHY370WR, respectively. Quantifying the interactive effects of drought and elevated temperature on cotton yield and fibre quality should allow researchers to better understand the economic implications of these two stresses which often occur concurrently under field conditions.