气象干旱对中亚棉花产量的影响

极端干旱事件频发对中亚棉花生产具有重要影响。本文利用乌兹别克斯坦赞格阿塔实验站棉花大田试验数据评估了APSIM-Cotton模型的适用性,根据CMIP6气候模式模拟的SSP1-2.6、SSP3-7.0和SSP5-8.5等3种共享社会经济路径下的气候变化数据集,分析了2021—2090年SPEI-3干旱指数的变化特征,进而利用APSIM-Cotton模型模拟了考虑CO₂肥效作用的气象干旱对棉花产量的影响。结果表明：APSIM-Cotton模型能够准确模拟乌兹别克斯坦塔什干地区的生育期和产量变化趋势;未来塔什干地区呈现温度明显升高、干旱发生频率明显增加的特征;气象干旱将导致棉花产量下降,SSP1-2.6、SSP3-7.0和SSP5-8.5等3种排放情景下,严重气象干旱导致2021—2050年棉花产量较1961—1990年分别下降28.0%、29.6%和32.1%,2061—2090年棉花分别减产31.5%、33.1%和35.7%,在SSP3-7.0和SSP5-8.5情景下,极端气象干旱导致2061—2090年棉花产量分别下降41.3%和54.2%;CO₂浓度升高可提高棉花产量,贡献率为14.9%~25.0%,但浓度达到750 µmol/mol以上时,棉花增产幅度将不再持续增加。

Effect of meteorological drought on cotton yield in Central Asia

Frequent occurrence of extreme drought events has great impacts on cotton production in Central Asia. In this study, data from field experiments designed for different sowing densities and irrigation levels at the Zangiata experimental station in the Tashkent of Uzbekistan were adopted for calibration and validation. Using the CMIP6 climate change datasets for three shared socioeconomic pathways (SSP1-2.6, SSP3-7.0 and SSP5-8.5), we analyzed the variations in the standardized precipitation evapotranspiration index in three-month steps (SPEI-3) within the growing seasons from May to August during the period from 2021 to 2090 and simulated the changes in cotton yields under meteorological drought conditions using the APSIM-Cotton model considering CO₂ fertilization. The results showed that the APSIM-Cotton model accurately simulated the cotton yield in Tashkent, and the relative errors between the simulated and measured yields were lower than 10.4% in both the calibration and validation years. Both temperature and drought frequency are expected to increase in the future during the cotton growing period in Tashkent. For the SSP3-7.0 and SSP5-8.5 scenarios, the percentages of severe drought are 36.7% and 40.0% from 2021 to 2050, respectively, and the percentages of extreme drought are 66.7% and 86.7% from 2061 to 2090, respectively. Severe meteorological droughts under three emission scenarios (SSP1-2.6, SSP3-7.0, and SSP5-8.5) would cause reductions of 28.0%, 29.6%, and 32.1% in cotton yields from 2021 to 2050, respectively, compared with the period 1961-1990. Severe meteorological droughts under the SSP1-2.6 scenario would result in a reduction of 31.5% in cotton yield from 2061-2090. Under the SSP3-7.0 and SSP5-8.5 scenarios, severe meteorological droughts would result in reductions of 33.1% and 35.7% in cotton yield, respectively, and extreme meteorological droughts would cause reductions of 41.3% and 54.2% in cotton yields, respectively. CO₂ has a certain fertilization effect. The rise in CO₂ concentration would increase the cotton yield by 14.9% to 25.0%; however, the increase in yields will not be sustained at concentrations above 750 µmol/mol. The results will provide scientific data for planting strategies for cotton in Central Asia that account for climate change and a reference for the future cooperation mode of the cotton industry between China and Central Asian countries.