Study On Changes And Precaution Policy Of Rice Heat And Chilling Injury In Summer In Hubei Province

Nowadays global warming has been given much attention, and it can result in various weather disasters which impact sensitive agriculture more or less. Based on the meteorological data in Hubei province from1951to2010and the future data from2011to2050, the high-risk period of heat and chilling injuries are defined, besides, the dynamic variations of high and average temperature are studied by using mathematical statistics. From the point of climate change, the different measures were taken in different regions in order to prevent disaster and decrease the loss of rice. The main results in the article would be presented as following:1. The agro-meteorological quantitative threshold of heat injury was proposed as maximum temperature higher than35℃in3days or longer. Considered the threshold, the date from May1st to September30th could be taken to analyze the probability of the daily durative high temperature events. Based on the curve fitting of the probability a mathematics simulation model could be gotten. The next step is to find the rules of heat injury through analyzing the three parameters in the simulation model. Observed data showed that, several regions of Hubei province trends to have high temperature events more frequently, especially in east of province and Jianghan plain, for example, Macheng and Qichun, in which the maximum probability tendency ration can reach0.05day in10year. The data also showed the date when maximal high temperature occurred was brought forward obviously. More than half of the stations the date would upward1day in10year. The evaluated future data showed that, the maximum probability tendency ration in all province were increase in the future, but the date maximal high temperature occurred in different stations were had their own different rules.2. In order to considering both the maximum probability of high temperature and the length high temperature events duration, the risk of heat injury accumulation was first proposed. Based on that risk value, the Hubei province could be divided into3parts:first, east part of Hubei province and Three Gorges area, in which the heat injury occurred frequently; second, Jianghan plain in which heat injury were little; third, west part of Hubei province in which the heat injury occurred sometimes. The region which had high-temperature events frequently should be paid more attention. 3. The agro-meteorological quantitative threshold of chilling injury in summer was proposed as average temperature lower than22℃in3days or longer. Considered that threshold, the date from July21st to October31st could be taken to analyze the probability of the daily durative low temperature events. The mathematics simulation model can be gotten through analyzing the disaster events, and then the rules of chilling injury could be found. Observed data showed that, the west part of Hubei province have serious disaster, and the west part of province have little disaster. Take Huanggang and Qichun for example, the date chilling injury occurred is very late-it almost occurred in September. In the east of province the tendency ration of the date chilling injury occurred showed upward and in the west it showed downward, so the conclusion can be drew that the date chilling injury occurred in the east of province and Jianghan plain would delay but the situation in the west of province was on the opposite. Analyzing the whole province, a majority of stations the date chilling injury occurred were postponed. The evaluated future data showed that, in all stations of Hubei province the date chilling injury occurred would postponed, which showed that the probability of the chilling injury occurred is decreased in the future.4. According to the situation of point one and point three, right measures should be taken to prevent and decrease the two disasters of rice. But in the future, the heat and chilling injuries may have new changes, which should be paid more attention.In summary, the different measures should be taken in different regions according to the rules of heat and chilling injury. Appropriate seeding date should be chose in view of the two disasters in the background of climate change.