The Risk Of Rice Chilling Injury And Index Insurance In Northeast Under The Variation Of Planting Area

As one of the most important food crop in Northeast China,rice had good quality and a large market demand.With the warming of the climate,it provided certain thermal conditions of rice expansion in Northeast China.In order to identify potential rice expansion areas in northeast China based on thermal resources,we assessed the risk of chilling injury in the plantable regions,and explored methods to develop the chilling index insurance products.This study used 104 meteorological station data from 1981-2010 and temperature data from 5 km×5 km grid meteorological datasets,based on 80% of guarantee rare,analyzed the spatial distribution of rice heat resources,the changes of rice cultivation potential range and the spatial transformation of rice maturity type,in 1980 s,1990s and 2000 s.In the potential rice planting area,based on the technical standard on rice cool damage evaluate,grids data,systematically explored the changes in transfer matrix of delayed chilling injury in typical years,the frequency of delayed chilling injury,and the annual fluctuations of chilling injury in the provinces during in Northeast China.Then,we based on 32 agro-station growth period data,used the k-Nearest Neighbor arithmetic,and reckoned booting and flowering date of each grids and spatial-temporal risk of sterile type of chilling injury.Finally,we selected Jiaohe,Jilin province as the research experiment of sterile type injury index insurance.The main conclusions of this paper were as follows:Annual accumulated temperature about 10? presented upward trend and average growth rate at 104.44?·d/10 a from 1981 to 2010.In addition to the south of Liaoning and Mohe of Heilongjiang province,the length of rice growth shorten.For the increase of accumulated temperature and growth period,2000 s was reduced by 59.45% compared with 1980 s in the region of unplantable area.In the region of potential plantable area,the rice of extremely-early maturing and early maturing scope was decreased,middle-later maturing and later maturing expanded from north to west.The frequency and intensity of delayed chilling injury of rice showed a downward trend in Northeast China.However,in some parts of the region,there were still chilling injury aggravated in some areas.The delayed chilling injury grade transfer matrix showed that some part of grids changed from no chilling damage to mild or moderate even serious grades for temperature fluctuation in 1981,1990,1990 and 2010 respectively.Among the light,moderate and severe delayed type of chilling injury,the severe delayed type chilling had a maximum frequency and scope,the highest serious chilling frequency occurred in 1980 s,and 1.78% area had 100% frequency of occurred severe chilling injury and the lowest in all chilling grades occurred in 2000 s.The overall trend of risk level was downward trend and the risk of flowering stage is higher than that of booting stage in Northeast China.We defined the risk of chilling injury from 0 to 5,according to the degree of risk.In the booting stage and flowering stage,the average risk level of sterile type chilling injury in the northeast China during the 1980 s,1990s,and 2000 s was 2.60,2.50,2.11,2.79,2.68,2.42 respectively.The risk of sterile type of chilling injury from high to low was Eastern Inner Mongolia > Heilongjiang > Jilin > Liaoning Provinces.Jiaohe city,with complicated landform and relatively high risk of chilling injury,was selected as the study area for sterile type of chilling injury index insurace.Based on the relationship between the occurrence frequency of sterile type chilling injury and crop yield reduction ratio,the insurance reasonable premium rates for rice in the booting and flowering stages are 1.5%~2.3% and 4.8%~6.9%,respectively.Based on accumulated temperature and growth length,the potential planting area was basically satisfied the thermal condition of rice production.Meanwhile,we should take into account the chilling injury risk when rice expanding.Chilling injury caused increase the loss of output and production damaged,however,chilling injury insurance was an important strategy to reduct disaster and transfer the risk.In the future,the study on rice expansion in Northeast China should not only consider the risk of total thermal resources and chilling damage,but also consider the multiple constraints of water resources,cultivated land,and environmental capacity in the further research.