Climatic Suitability of Cotton and Its Changes in Henan Province

Cotton is an important economic crop for Henan Province. With long growth season, cotton is sensitive to climate change, so its climate suitability in Henan Province comes to be a valuable research. Combining previous researches and existent climatic suitability models, the cotton climatic suitability model suitable to Henan Province is established. According to homogenize principle, 46 stations in Henan province are chosen. With meteorologic data from 1960 to 2000, the cotton climatic suitability degrees of these stations during 1960—2000 are calculated and the mean is used as the general cotton climatic suitability of Henan Province. The result shows that the cotton climatic suitability degree in Henan Province has a declined tendency, particularly the latter twenty years. To explore the reason of this phenomenon, the changes and their impact on suitability of the climate elements (precipitation, sunshine hour and temperature) in the five growth seasons are analyzed. The final result shows that the decline of precipitation suitability in seedling stage is the main reason of this decline. Then the tendency and intensity of the suitability change in each station during 1980—2000 are calculated. The result shows the change situation embodies strongly regional character. The suitability change tendencies in the mountainous areas of the Nanyang Basin and in the subtropical regions south to the Huaihe River decline and in plain areas increase while the change tendencies in areas north to Huaihe River are reverse, i.e. the tendencies in most plain areas of Henan Province from Huaihe River to the Yellow River decrease and in mountainous areas increase. To areas north to the Yellow River, the character of change tendencies is like the subtropical regions:the mountainous areas have decrease tendency and the plain areas have increase tendency. From the south to the north in Henan Province the Huaihe River and Yellow River are the board line of different suitability changes tendencies. Based on the cotton climate suitability of the stations during 1980—2000, the change tendencies in Henan Province are divided into three styles:the rash increase style including Funiu mountainous areas and Taihang-Wangwu mountainous areas; the weak increase style including the Yudong Plain, Funiu-Tongbai plateau areas and the Nanyang Basin; the decrease style the rest areas. Lastly with the precipitation, sunshine and temperature data during 1980—2000 in the 46 stations the processes and reasons of the climate suitability changes in different areas are analyzed. For example, the increase of precipitation deviation in bud stage is the main reason of the suitability decrease for the Yudong Plain while the increases of temperature and sunshine hour in boll stage in the Funiu mountainous areas make the climate condition more suitable to the cotton growth.