Evaluation Of High Temperature Stress On Rice Based On Field Temperature And Station Temperature

Rice is one of three main grain crops in China,the exuberant growth period of rice is mainly concentrated in the summer and the rice often be injured by high temperature heat damage.In order to determine the occurrence of heat injury in rice field and take measures to avoid or decrease the loss of heat injury in time,this study put forward the idea and method of calculating rice field tremperatiore by using station temperature to judge the heat injury.The raw data was meteorological data of the station and the synchronous recorded temperature data of rice field from July to October 2016 and from June to Selptember 2017 in Shouxian weather station,this data was used to analyze the measiured temperature change law of different heights in rice field and the influence of different treatments on rice temperature under high temperature conditions.The mathematical model between the station temperature and the canopy and infrared temperature of the rice field was established respectively in the day and night through the multiple regression analysis,then the optical calculation model was selected and tested,then the calculation model was tested during the high temperature period in that year.The transmit MODIS remote sensing data during the test period of two years was downloaded and the LST temperature was extracted from this data,then selected the correspounding period of the ground infrared temperature data and established statistical relation of these two temperatures to simulate the ground infrared temperature,at the same time we extracted the planting area of Anhui Province to invert the ground infrared temperature of rice field.Here are some main results:(1)The canopy temperature was the highest of all the measured temperatures in the rice field,followed by infrared temperature and the ground temperature,the average temperature difference was about 0.9°C.The soil temperature was the lowest compared with other temperatxore levels,the average temperature difference with rice canopy was about 3-4°C.(2)Some processing methods such as water spraying or fertilization on rice under the condition of high temperature could effectively relieve the rice heat damage.The spray effect was best,followed by spraying on the leaf fat,and then the water irrigating treatment,all of these methods could reduce the temperature of the rice field,relieve the heat imjury and improve the yield of rice.(3)The rice planting area of Anhui Province were extracted through the time series vegetation index from S-G filter.2229600hm2 of rice was planted in Anhui.Compared with the data of planting area from the statistical yearbook,the relative deviation was 1.58%.The correlation coefficient between the infrared temperature and remote sensing LST was about 0.8,which could be preferably used to invert rice infrared temperature of Anhui Province.(4)When the temperature data were divided into day and night,the simulation effect of their mathematical model was good generally,the accuracy of temperature simulation of the linear regression equation which had the station temperature and humidity as the independent variable was better overall at night,however in the daytime the simulation effect of the power equation which had the station temperature as independent variable was the best.The calculation model was tested during the high temperature period in two years respectively,the temperature calculated by the optimal model of the rice field was closer to the measured temperature than the station temperature,judgment of the heat injury situation according to the calculated temperature was more in line with the actual situation of rice field than station temperature.