Evaluation And Genetic Improvement Of Cold Tolerance At Seedling Stage Of Perennial Rice

Perennial rice is a new type of rice which bred by using the asexual propagation characteristics of Oryza longistaminata in recent years,could reduce the input and simplify the rice production.Low temperature is one of the main factors that affected the overwinter of perennial rice.Searching for cold-tolerance germplasm resources and improving cold tolerance of perennial rice,can improve the regional adaptability of perennial rice and expand its planting range.Lijiang is a typical high-altitude rice area with cold weather due to an average altitude of 2400 m,has abundant cold-tolerant rice resources.Exploring the cold tolerant rice resources from Lijiang,has great practical significance on the breeding of perennial rice with high cold tolerance.In this study,five perennial rice varieties(lines)from our team and 14 rice lines from Lijiang were selected to identify the cold tolerance,and then selecting high cold tolerance rice lines.We improved the cold tolerance of perennial rice by using the high cold tolerance rice lines.The main results of this study are as follows.There were significant differences among the cold tolerance of perennial rice at seedling stage under different variety,temperature and duration of low temperature.The cold tolerance of different rice variety showed as PR23(45.83%)> PR25(51.33%)>PR101(56.33%)> PR107(63.33%)> PR24(78.42%),the cold tolerance of different rice stubble showed as PR23(45.20%)> PR25(50.73%)> PR24(56.82%)> PR101(66.31%)> PR107(76.88%);The seedling dead rate of perennial rice under different temperature showed as 0℃(91.53)> 4℃(44.87)> 8℃(41.15);The seedling dead rate of perennial rice under different duration of low temperature showed as 96 h(100.00%)> 72 h(56.33%)> 48 h(48.20%)> 24 h(31.67%).The seedling dead rate of rice stubble showed as 9 d(80.72%)> 6 d(60.19%)> 3 d(36.64%).2.Rice variety,temperature and duration of low temperature were all significantly affected the cold tolerance of the 19 rice lines at seedling stage.The cold tolerance of different rice lines showed as Ligeng15(0.75%)= Ligeng11(2.00%)= Ligeng9(2.58%)> Ligeng14(7.50%)= Lijiang Xintuan Heigu(8.92%)> Lijiang Xiaobaigu(10.25%)= Yongning Xiaobaigu(10.92%)= Li geng 3(11.25%)> Yongning Dabaigu(13.58%)> Heixuan 5(21.58%)= Ligeng2(23.58%)> Lijiang Maxiangu(29.25%)>Chengguan Xiaohonghegu(33.92%)> PR23(45.83%)> PR25(51.33%)> PR101(56.33%)> Wahuigu(59.50%)> PR107(63.33%)> PR24(78.42%).The seedling dead rate of rice lines under different temperature showed as 4℃(51.77)> 6℃(20.39)> 8℃(11.62);The seedling dead rate of rice lines under different duration of low temperature showed as 96 h(51.77%)> 72 h(29.68%)> 48 h(21.18%)> 24 h(9.12%).In this study,we selected 3 rice varities with high cold tolerance(Grade 1)and 6 rice varities with cold tolerance(Grade 3).3.We improved the cold tolerance of perennial rice by using these 3 rice lines with high cold tolerance,and three combinations of perennial rice with high cold tolerance were obtained,as Ligeng15/Perennial rice 23,Ligeng15/Perennial rice 24,and Li geng15/Perennial rice 25.