Research Of Water Requirement Of Tobacco In The Middle Of Yunnan Province Under Climate Change

The central region of Yunnan Province is the main cash crops production base. As the country’s largest tobacco production cultivation base, it irrigation mode for planting tobacco was still stay in the original stage. At present, seasonal drought and water shortage problem are prominent, the project of water resource and water co-exist, which also led to the efficient production of high quality tobacco is restricted in the middle of Yunnan Province. It has great significance to the available water resources planning of agricultural water resources planning and rational distribution of regional by depth researching the tobacco water requirement under the climate change in the middle of Yunnan Province. It is helpful to optimization of water resources in area management and provide a theoretical basis for the coffee industry development by mastering scientific tobacco water requirement rule.This paper based on date (1956-2013) daily meteorological data and crop coefficient of different growth period by tobacco in the middle of Yunnan Province. Calculating reference crop evapotranspiration, irrigation requirement undering the tobacco, net irrigation requirement and net irrigation requirement index in the middle of Yunnan Province within 58 years (1956-2013) is using Penman-Monteith equation recommended by Food and Agriculture Organization in 1998. Analysis of tobacco’s water demand variation characteristics in the middle of Yunnan Province within its growing season. Using the method of sliding t test and the Mann-Kendall trend test to analyze the climate changes of tobacco growing periods in central of Yunnan Province. On the ordinary Kringing Method of GIS to do spatial analysis of water demand, net irrigation requirement and net irrigation requirement index by tobacco in the middle of Yunnan Province. While using the Pearson Ⅲ type curve forecast in flat water, the dry years and the wet years tobacco under the net irrigation water requirement of three frequencies, the following conclusions can be drawn from the research:(1) The net irrigation requirement index of tobacco showed a descending tendency with the change of its growing season. With the growth of tobacco the rainy season is coming, and precipitation gradually increased, and the number of sunshine hours gradually reduced, so the index in mature of tobacco was the lowest net irrigation requirement. Natural precipitation of the other three sites are basically meet the tobacco water requirement expect Yuanmou region.(2) For the growth periods, the growth of tobacco irrigation demand index from high to low are the root extending stage, the vigorous growth stage, the mature stage. In addition, the trend of tobacco net irrigation requirement index in four regions is more consistent, and it indicates that the meteorological factors have an obviously influence on the growth of tobacco in the middle of Yunnan Province. In the 58 years the net irrigation requirement index more than zero years were 54% in the middle of Yunnan Province. It’s indicated that tobacco needed artificial irrigation in normal year.(3) In the analysis of Yunnan tobacco water requirement and net irrigation water requirement and net irrigation requirement index in space. The maximum water demand of the Yuanmou region is 428.63mm, the minimum Yuxi region is 288.57mm.The naximun net irrigation water requirement of the Yuannou region is 268.17mm, the minimum of Kunming region is 59.69mm. The maximum net irrigation water requirement index of Yuanmou region is 0.28, the minimum of Kuming region is-0.20. The results show that with the increase of latitude, the water requirement, the net irrigation water requirement and the net irrigation requirement index of flue-cured tobacco increased.(4) In the path analysis of the requirement of the meteorological factors to the net irrigation water requirement of Flue-cured tobacco. Net irrigation requirement largest flue-cured tobacco positively related meteorological factors as the daily maximum temperature. The path coefficient is 0.83. The most negative meteorological factor is precipitation. The path coefficient is-0.88. The maximum temperature and precipitation are the main meteorological factors that cause the change of the net irrigation demand index of flue-cured tobacco in middle of Yunnan. Other positive correlation factors are wind speeds, the temperature, sunshine hours, the minimum temperature. The negative correlation factors are the relative humidity, the water vapor pressure, the pressure.(5) In the use of Pearson type III curve, take use of this to simulate the precipitation of four regions in middle of Yunnan. We can draw the conclusions that four regions at the situation under various guarantee rates. They are differently corresponding with 5%,25%,50%,75%,95%. Kunming areas are -42.91mm, 41.38mm,60.08mm,64.31mm,170.59mm.Chuxiong areas are-64.83mm,52.79mm, 64.18mm,99.93mm,228.68mm. Yuxi areas are -0.53mm,58.32mm,75.97mm, 91.98mm,155.37mm.Yuanmou areas are 101.55mm,179.38mm,264.76mm, 283.29mm,344.59mm.