Screening of Japonica Rice Germplasms Suitable for Direct Sowing and Their Optimal Planting Density

WANG Fuhua; LI Rui; ZHANG Qifei; MA Mengjuan; FU Jing; YANG Wenbo; WANG Shengxuan; WANG Yuetao; BAI Tao; YIN Haiqing; WANG Ya

doi:10.15933/j.cnki.1004-3268.2023.12.004

Abstract：To identify rice germplasms suitable for direct sowing in Henan Province,two thousand japonica germplasm resources were used to directly sow,the traits including seedling emergence ability,initial heading date,plant height and yield,etc.,were analyzed,the germplasms suitable for direct sowing were preliminarily screened.The germplasms suitable for direct sowing were screened again by analyzing yield related traits,and then the germplasms suitable for direct sowing were further screened by analyzing initial heading date and yield related traits.Meanwhile,the effect of planting density[80 kg/ha(T1),100 kg/ha(T2),120 kg/ha(T3)and 140 kg/ha(T4)]on yield and its component was analyzed,and the optimal planting density and final rice germplasms suitable for direct sowing with high yield were determined.The results showed that 8(0.40%),85(4.25%),1762(88.10%),102(5.10%)and 43(2.15%)germplasms were graded into class 1,3,5,7 and 9 according to the seedling emergence ability(SEA)among two thousand japonica germplasms.Average grade of SEA was 5.09,and grades of SEA of germplasms from distinct geographical regions ranged from 4.82 to 5.46.The initial heading date delayed with the decrease of latitude of geographical regions where the germplasms derived.The initial heading dates of germplasms from Heilongjiang,Jilin,Inner Mongolia,Xinjiang and Ningxia were generally before August 15th,with average days from sowing to initial heading(DTSH)of 47.5 d,54.9 d,54.8 d,57.8 d and 59.7 d respectively;the initial heading dates of germplasms from Liaoning Province,Japan and Korea,Beijing City,as well as Hebei Province were generally between August 20th to August 25th,with average DTSH of 65.8 d,66.4 d,68.9 d and 68.1 d,respectively;the majority of germplasms(48.33%—79.04%)from Shandong,Henan,Jiangsu and Yunnan failed to head,while the initial heading dates of germplasms which could head generally after August 25th,with average DTSH of 72.0 d,78.2 d,77.8 d and 75.2 d,respectively.A total of 194 germplasms were preliminarily screened with SEA less than class 7,initial heading date between August 15th and September 4th,plant height below 115 cm,no lodging,blast,sheath blight diseases and high yield.Then,a total of 150 germplasms suitable for direct sowing were identified with setting rate more than 80% and high yield by investigation of yield related traits.Majority of 150 germplasms were graded into class 5 according to SEA,and 3(2.0%),135(90.0%)and 12(8.0%)germplasms were graded into class 3,5 and 7,respectively;initial heading dates of 150 germplasms ranged from August 24th to September 4th;116,11,7,7 and 9 germplasms were derived from Liaoning,Hebei,Shandong,Henan and Jiangsu,accounting for 77.3%,7.3%,4.7%,4.7% and 6.0%,respectively;the average yield of germplasms from Liaoning Province was the highest with 9286.5 kg/ha,and the average yields of germplasms from Hebei,Shandong,Henan and Jiangsu were 6390.0 kg/ha,7053.0 kg/ha,6432.0 kg/ha and 7054.5 kg/ha,respectively.Given the outstanding yield performances of germplasms from Lioaning Province among the above selected 150 germplasms,a total of 76 germplasms from Lioaning Province with plant height less than 110 cm,initial heading date between August 20th and August 30th,and high yield,were selected to study the optimum planting density.It showed that the number of basic seedlings and panicles significantly increased with the increase of plant density;the total spikelet numbers of T3 and T4 treatments significantly higher than those of T1 and T2 treatments;the yields of T1,T2,T3 and T4 treatments were 7621.20 kg/ha,7735.35 kg/ha,8003.25 kg/ha and 7961.10 kg/ha,respectively,the yields of T3 and T4 treatments were significantly higher than those of T1 and T2 treatments,and the yield of T3 treatment was the highest.Finally,a total of 14 germplasms suitable for direct sowing were screened under T3 treatment.Among them,the yields of 9 germplasms,including Liaoxing 13,Liaojing 9,Ying 9207,Danjing 12,Jindao105,Liaoxing15,Meifeng 1,Liaoyannuo 10 and Xiangfeng 00-93,were significantly higher than that of control(Zhenghan 10),with the corresponding increase rates of 17.72%,7.75%,6.61%,6.15%,3.46%,3.16%,1.87%,1.27% and 0.93%,respectively compared with the control.These germplasms could be used for japonica rice direct sowing tolerant breeding in Henan and its neighboring areas,and Liaoxing 13 with the highest yield of 11018.0 kg/ha could be directly applied to direct sowing in Henan Province.