Study On Yield Formation And Lodging Resistance Of Super Hybrid Rice Guiliangyou 2 With High Harvest Index

To clear yield formation characteristics and lodging resistance characteristics of high harvest index super hybrid rice,a field experiment was conducted in Yongan Town,Liuyang City,Hunan Province from 2018 to 2020.Two super hybrid rices,‘Guiliangyou 2’and‘Y-liangyou 1’were used in the experiment.The two were compared and analyzed in yield,dry matter production characteristics,temperature and light utilization characteristics,nitrogen absorption and utilization characteristics,lodging resistance and stem mechanical characteristics.The results showed that:(1)The average yield of Guiliangyou 2 and Y-liangyou 1 was 8.83t/hm~2 and 8.86t/hm~2,respectively,with no obvious difference.But the yield formation characteristics of the two were obviously different.Before heading,the solar radiation,apparent temperature use efficiency(TUE),apparent radiation use efficiency(RUE),crop growth rate(CGR)and dry matter accumulation of Guiliangyou 2 were 15.54%,12.82%,10.47%,14.39%and 7.38%lower than Y-liangyou 1,respectively.However,after heading,the opposite trend was observed.The solar radiation,apparent temperature use efficiency(TUE),apparent radiation use efficiency(RUE),crop growth rate(CGR)and dry matter accumulation of Guiliangyou2 were 11.79%,17.78%,18.48%,28.99%and 50.23%higher than those of Y-liangyou 1,respectively.The advantage of light and temperature resource utilization efficiency of Guiliangyou 2 after heading was related to the slow leaf senescence(i.e.,the leaf area index and leaf soluble protein content decreased slowly).The total dry matter accumulation of Guiliangyou 2 was 7.97%lower than that of Y-liangyou 1,but its harvest index(0.53)was10.42%higher that of Y-liangyou 1(0.48).(2)The plant height and fresh weight of Guiliangyou 2 were 5.43%and 20.39%lower than that of Y-liangyou 1,respectively,in 25 days after heading.It made the plant lodging index of Guiliangyou 2 25.93%lower than that of Y-liangyou1.The lower plant height of Guiliangyou 2 was related to the lower nitrogen content absorbed by the single plant before heading.The internode length,stem diameter,stem wall thickness and breaking moment of thee second internode at the base of Guiliangyou 2 were not significantly different,but the center of gravity height and bending moment of the single stem were 7.68%and 14.57%lower than that of Y-liangyou 1,which resulted in the single stem lodging index of Guiliangyou 2 was 19.82%lower than that of Y-liangyou 1.To sum up,compared with Y-liangyou 1,Guiliangyou 2,the high harvest index super hybrid rice,absorbed less nitrogen per plant before heading,which resulted in a lower plant height and center of gravity height,and thus stronger lodging resistance.However,due to the slow senescence of leaves after heading,the light and temperature resources use efficiency and dry matter accumulation were improved,and the higher harvest index could be obtained,which could compensate for the lower dry matter accumulation before heading and total dry matter accumulatio,thus obtained high grain yield.In conclusion,it is an effective way to breed super rice varieties with high harvest index for both high grain yield and strong lodging resistance.