Screening And Evaluation Of Rice Germplasm Resources With High Nitrogen Efficiency And Low Nitrogen Tolerance

With the increasing population and the gradual deterioration of the ecosystem,food security has become a hot topic in recent years.The stable and high yield of grain crops is an important breeding goal for breeders.Rice is one of the most important food crops.Ensuring the sustainable high yield of rice is the key to ensure food security.In rice breeding,researchers are committed to improving rice yield.Among them,the application of nitrogen fertilizer is a common means of increasing production.Nitrogen is an important mineral element affecting plant growth and development,too little application of nitrogen fertilizer will lead to the decline of rice yield;excessive application of nitrogen fertilizer will waste resources and pollute the environment.By breeding and popularizing nitrogen efficient and low nitrogen tolerant rice varieties and reducing the amount of nitrogen fertilizer,the pollution of nitrogen fertilizer to the environment can be effectively reduced.In this experiment,144 rice germplasm resources collected by rice genetics and Breeding Laboratory of Northeast Agricultural University were used as experimental materials.Field experiments were carried out in Acheng rice experimental practice base of Northeast Agricultural University.Three nitrogen levels of no nitrogen(0 kg/hm~2),low nitrogen(50 kg/hm~2)and normal nitrogen(150 kg/hm~2)were set to determine the yield characters of 144 rice germplasm resources,and the effects of different nitrogen levels on rice yield characters were analyzed,In order to provide a theoretical basis for the breeding of nitrogen efficient rice varieties and low nitrogen tolerant rice varieties,the screening of nitrogen efficient germplasm resources and low nitrogen tolerant germplasm resources were carried out.The research conclusions are as follows:(1)When the application rate of nitrogen fertilizer was 0-150kg/hm~2,increasing the amount of nitrogen fertilizer significantly increased plant height,single plant yield,effective panicles,grains per panicle and panicle length of rice.Compared with no nitrogen application(0 kg/hm~2),applying50-150kg nitrogen fertilizer per hectare will significantly increase the average plant height of rice by 7.64-17.51cm,the average single plant yield by 6.59-12.51g/plant,the average number of effective panicles by 2.45-5.13,the average number of grains per panicle by 1.94-8.01,and the average length of panicles by 0.06-1.24cm.(2)Compared with the normal nitrogen application rate(150 kg/hm~2),reducing nitrogen application(50 kg/hm~2)will reduce the average plant height of rice by 9.8cm,the average yield per plant of rice by 5.92g/plant,the number of effective panicles of rice by 2.65,the number of grains per panicle of rice by 6.07,and the length of panicles of rice by 1.18cm.(3)Based on the yield and its components,30 rice varieties with high nitrogen efficiency and4 rice varieties with low nitrogen tolerance were selected,which provided a theoretical reference for rice breeding with high yield and high efficiency and low nitrogen tolerance.