Screening And Comprehensive Identification On Low Nitrogen Tolerance And Cold Tolerance Of Zhejiang Photosensitive Japonica Rice Cultivars

Rice (Oryza sativa L.) is one of the most important food in the world. The rice with high-yield, insect-resistant, high-quality, well adaptability is breeding workers’ goal. The environmental conditions such as fertilizer and the temperature effect on the normal growth and development of rice. Selection and utilization of low nitrogen and low temperature tolerant varieties of rice is a very significant work in high yield and quality breeding of rice. Combination of the use of laboratory and field test, fuzzy membership, function method and the principal component analysis methods,58 Zhejiang photosensitive japonica rice varieties was screening and comprehensive evaluation under low nitrogen and low cold stress during 2014-2015. Screening low nitrogen and cold tolerance varieties provide a reference to genetic research and new varieties cultivation. At the same time, in order to explore the methods of comprehensive evaluation of different indicators of rice stress treatment. The main results are as follows:1. In order to find out screening indexes and suitable identification method of low nitrogen resistant rice cultivars, and obtain low nitrogen tolerant photosensitive japonica rice cultivars for production, 58 photosensitive japonica rice cultivars in Zhejiang were treated under low nitrogen stress by the nutrient solution and field production. The results showed that low nitrogen stress had a significant impact on the morphological and yield indexes of different rice cultivars and the degrees of effect among the indexes and cultivars were significantly different. Based on the coefficients of variation of relative values of different indexes, total of 7 indexes including root tips, dry weight of shoot, dry weight of root, root to shoot ratio of dry weight, tiller number, panicle number and yield per plant were selected as indexes for screening and evaluation of the degree of low nitrogen tolerance of rice. And then we used fuzzy membership function, principal component analysis and cluster analysis identified Zhejing88, Zhejing59, Xianghu13 as low nitrogen resistant cultivars.2. In order to find out the suitable way to identification and comprehensive evaluation the cold tolerance of rice,16 Zhejiang photosensitive japonica rice cultivars were used to analysis the differences under different cold level treatment at bud stage and seedling stage in Light incubator. Results showed that the method for identifying cold tolerant rice cultivars at bud stage, seedling stage and booting stage is feasible and bud livability, seedling mortality and seed2setting rate of rice are reliable indexes for cold tolerance identification which are correlated with some physiological parameters in different rice cultivars under chilling treatment.The cold tolerance of rice cultivars at the three stages showed cultivar difference, according to the differences the fuzzy membership function analysis was conducted. And then we used cluster analysis and identified Jia58, Chunjiang063 as cold resistant cultivars, Jia33 as sensitive cultivars. These results provide reference for screen low cold tolerant rice cultivars, genetic studies on cold tolerance.