Selection Of Cold Tolerance Varieties In Jilin Province And Effect Of Nitrogen Fertilizer For Chilling Injury In Rice

Chilling injury is one of the major limiting factors for stable yield of rice in high latitudes.The growth and grain filling of rice were seriously affected by delaying chilling injury or critical chilling injury,which led to a decrease in yield and quality.High input of nitrogen fertilizer is one of the most important means of increasing rice yield.However,this measure aggravates the reduction of production when occurs at a low temperature during the critical period of growth and development of rice.Therefore,the rational use of nitrogen fertilizer plays a very important role in defense against low temperature stress and disaster mitigation.In this study,through the identification of cold tolerance rice varieties and the experiment of nitrogen fertilizer regulation,to propose the integrated defense measures combined with cold tolerance varieties and nitrogen applications.The results of cold tolerance identification of 203 rice varieties showed that there was a great difference in cold tolerance among the rice varieties.There were large chilling tolerance differences between different maturity stages or among different varieties in the same maturity stage in Jilin Province.According to the analysis,we finally selected 6 good cold tolerance varieties suitable for planting in low temperature area of Jilin Province,such as Songjing 16,Longjing 29,Songjing 15,Songjing 12,Yanjing 25 and Jiudao 12.Under cold water irrigation and normal conditions,there were significant differences in spikelet fertility and grain yield due to different nitrogen application or nitrogen application methods.The spikelet fertility and grain yield decreased with the increase of nitrogen application and the increase of nitrogen fertilizer input at the later stage of rice growth in the two cultivation conditions.The spikelet fertility and grain yield was significantly affected by combination of nitrogen application and nitrogen application under cold water irrigation.The spikelet fertility of treatment level combinations of nitrogen fertilizer 80kg/hm~2 combined with 90%before turn up the soil+10%striking root fertilizer(A3B4),nitrogen fertilizer 120kg/hm~2 combined with 90%before turn up the soil+10%striking root fertilizer(A2B4),and nitrogen fertilizer 80kg/hm~2 combined with 60%before turn up the soil+20%striking root fertilizer+20%input in July 5(A3B2)were significantly higher than that of other treatment level combinations.The grain yield of treatment level combination of A2B4 was significantly higher than that of other treatment level combinations except A3B4.Under normal condition,there were significant differences between deep water irrigation and shallow water irrigation on spikelet fertility and grain yield.The seed setting rate and yield of the treated level combinations,A2B4 and A3B4 were significantly higher than those of other treatment combinations in the two irrigation measures.The test of verification of the optimal treatment level combination showed that the spikelet fertility and grain yield at A2B4 was significantly higher than those of the other treatment level combinations.The demonstration results showed that optimal combination of A2B4 increasing the yield ranging 7.7-9.7%more than that of the control in four rice varieties under cold irrigation conditions.In summary,there was determined the best treatment level combination of nitrogen fertilizer 120kg/hm~2 combined with 90%before turn up the soil and 10%striking root fertilizer and deep water irrigation.The results show that cold tolerance Varieties Combined with suitable cultivation methods can effectively prevent chilling damage and reduce yield loss.