Impact of climate change on cotton growth and yields in Xinjiang, China

The cotton cultivation region in Xinjiang, China, is large and plays an important role in the national economy. Understanding the impacts of climate change on cotton growth and yield will inform appropriate adaptation and mitigation measures to improve cotton productivity. The trends and significance of several variables, including collected weather (precipitation, sunshine duration, average air relative humidity, maximum temperature, minimum temperature, and average temperature) and cotton growth and yield-related (plant height at cotton flowering stage, cotton stalk weight, seed cotton yield and lint percentage) data, were tested during the cotton growth season from 1986 to 2017 at 19 agro-weather stations in Xinjiang, China Linear or non-linear single or multivariate correlations between climatic and cotton growth indices were analyzed to investigate the impacts of climate change on cotton growth and yield. The results showed that the maximum, minimum, and mean temperatures exhibited significant increasing trends at 19, 17, and 16 (out of 19) sites, respectively. Precipitation and sunshine duration demonstrated insignificant increasing trends at most sites, while relative air humidity showed significant decreasing trends at 13 sites. Plant height at the cotton flowering stage, seed cotton yield, cotton stalk weight, and lint percentage generally increased significantly at most sites. Based on Pearson's correlation, multivariate linear regression and multivariate nonlinear regression, the best equation between the cotton growth indices and climatic variables were determined. The main climatic variables affecting cotton during the flowering stage at most sites were relative air humidity and temperature, for cotton seed yield were sunshine duration, and average, maximum, and minimum temperatures. Cotton stalk weight was mainly impacted by precipitation and minimum temperature. Lint percentage was mainly affected by precipitation, sunshine duration, and average temperature. The climatic variables during the cotton growth period explained 8.1-69.9%, 8.5-75.3%, 7.1-56.1%, and 10.4-85.7% of the changes in plant height at the flowering stage, seed cotton yield, cotton stalk weight and lint percentage, respectively, across study locations. Future studies should focus on using crop models to simulate and predict of cotton growth and production using the associated climatic variables and other measured soil and cotton properties in Xinjiang, China.