Evaluation of climate suitability of winter wheat based on cloud model analysis— A case study of Suzhou, Anhui Province

Based on three limiting indexes (light, temperature and water), an evaluation system was set up along with its parameters for normal cloud models and the “3En” rule to evaluate the suitability of winter wheat to climatic factors. The weighted comprehensive assessment and geometric mean method were used to determine the climate suitability of winter wheat for the whole growth period, while the integral regression method was used to determine the weight coefficients for each growth stage. The calculated values were analyzed in relation to winter wheat yield in every district of Suzhou City of Anhui Province from 1954 to 2013 and the actual observed yield and its’ components from 1995 to 2013. The results showed that the trapezium cloud model was suitable for air temperature and precipitation suitability evaluation, while the left-half cloud model was suitable for sunshine suitability analysis. There was significantly positive correlation between the climate suitability of winter wheat for the whole growth period and climate-driven yield, 1000-grain weight, kernel number per ear, and plant height at milk stage in the study area. The corresponding correlation coefficients were 0.588 0 (P < 0.01), 0.756 1 (P < 0.01), 0.670 7 (P < 0.01) and 0.464 3 (P < 0.05), respectively. The correlation coefficients between the climate suitability and panicle per unit area of winter wheat were 0.558 9 (P < 0.05), 0.649 8 (P < 0.01) and 0.736 1 (P < 0.01) at returning greenjointing stage, jointingheading stage and headingmilk ripe stage, respectively. There was a significantly positive correlation between climate suitability and kernel number per ear — 0.710 7 (P < 0.01) and 0.744 2 (P < 0.01) at returning greenjointing stage and headingmilk ripe stage, respectively. The suitability of sunshine and precipitation decreased at the rates of 0.005 and 0.008 per decade. However, the suitability of temperature in the study area increased at the rate of 0.028 per decade in 1954–2013. The study laid the scientific reference for evaluating adaptability and developing response strategies of winter wheat to climatic conditions.