| Hybrid rice varieties provided by our research group were used as tested varieties,and Yliangyou9918 and Zhunliangyou608 were used as control varieties.The growth period,the flexural resistance in the main crop,the grain yield in the main crop,the grain quality in the main crop,the ratoon rate(final value),the grain yield in the ratoon crop,and the grain quality in the ratoon crop were taken as indicators.The random block design was used and three repetitions were made.In 2017—2019,the varieties suitable for ratooning were screened in Changsha,Hunan.The yield in the two crops and the yield components in the two crops were correlatively analyzed.The ratoon rate and the yield traits in the two crops were correlatively analyzed;On this basis,Liangyou389 was used as the test variety,Nliangyou002,YLiangyou9918 and Zhunliangyou608 were used as the control varieties,The growth period,ratoon rate in different periods,yield and yield components in two crops,and total dry weight,LAI,SPAD value of flag leaf,photosynthetic rate of the flag leaf,SOD activity of the flag leaf,MDA content of the flag leaf,root TTC deoxidizing ability in several important periods in the growth process of two crops were investigated,and the mechanism of high grain yield of Liangyou389 in the ratoon crop was studied in 2019.The main results were as follows:1.The experiment results of three years showed that when Liangyou389 and Wangliangyou889 were used to ratoon(remaining pile height:30cm),the growth period in the main crop of them were not more than 140d.Their flowering stage in the ratoon crop were before the September 20th,and their mature stage in the ratoon crop were in late October.The flexural resistance of them were higher than that of the control varieties.The grain yield in the main crop of them were higher than that of the control varieties.The ratoon rate(final value)of them were higher than that of the control varieties.The grain yield in the ratoon crop of them were higher than that of the control varieties.The grain quality in the ratoon crop of Liangyou 389 was awarded second grade that was consistent with the control varieties.The grain quality in the ratoon crop of Wangliangyou889 was awarded third grade.Therefore,Liangyou389 and Wangliangyou889 were suitable for ratooning in the region of Changsha.2.The correlation analysis showed that the grain yield of the main crop had a extremely significant positive correlation with the filled grains rate of the main crop and 1000-grain weight of the main crop,a significant positive correlation with the effective panicles of the main crop,and a non significant positive correlation with the spikelets per panicle of the main crop.The grain yield of the ratoon crop had a extremely significant positive correlation with the effective panicles of the ratoon crop,the filled grains rate of the ratoon crop and the 1000-grain weight of the ratoon crop,and a non significant positive correlation with the spikelets per panicle of the ratoon crop.The ratoon rate(final value)had a non significant positive correlation with the spikelets per panicle of the main crop,the filled grains rate of the main crop and the 1000-grain weight of the main crop,a non significant negative correlation with the grain yield of the main crop,and a extremely significant negative correlation with the effective panicles of the main crop.The ratoon rate(final value)had a significant positive correlation with the effective panicles of the ratoon crop,a extremely significant positive correlation with the grain yield of the ratoon crop,a non significant positive correlation with the 1000-grain weight of the ratoon crop,a extremely significant positive correlation with the filled grains rate of the ratoon crop,and a non significant negative correlation with the spikelets per panicle of the ratoon crop.Therefore,it was important to improve the filled grains rate and 1000-grain weight of the two crops and increase the effective panicles of the ratoon crop for increasing the ratoon rate and the grain yield of ratoon rice in the whole year.3.The grain quality in the main crop of the tested varieties didn’t meet the grain quality rating standard,which mainly dued to the lower head rice rate and higher chalkiness.Therefore,it was an important way to develop ratoon rice by breeding ratoon rice varieties with high grain yield,high grain quality and high temperature resistence in the main crop.4.According to the three-year grain quality results,the milled rice rate in the ratoon crop was 20.6%higher than that in the main crop,and the chalky rice rate and chalkiness in the ratoon crop were 24.0%and 18.1%lower than those in the main crop.Therefore,the grain milling quality and the appearance quality in the ratoon crop were better than those in the main crop.5.It was concluded that the reason for the high grain yield of Liangyou389 in the ratoon crop is:in Changsha,the growth period of Liangyou389 was in line with the requirements of ratoon rice,and the ratoon crop avoided the harm of "cold dew wind";the strong lodging resistance of Liangyou389 not only guaranteed the high yield of the main crop,but also laid a solid foundation for the high grain yield in the ratoon crop;the LAI of the late growth stage of Liangyou389 was higher,the flag leaf of the main crop was in life in the late growth stage of the main crop,the senescence of flag leaf in the main crop was slow,the stress tolerance of flag leaf in the main crop was strong,the root activity decreased slowly in the late growth stage of the main crop,the total dry weight of the main crop was high and the distribution was reasonable,which could provide nutrients for the growth and development of the ratoon buds.At the same time,Liangyou389 had a high ratoon rate(final value),a large number of effective panicles in the ratoon crop,a large green leaf area in the late growth stage of the ratoon crop,and a high level of LAI.In the late growth stage of the ratoon crop,the flag leaf did not show premature senescence and slow aging.In the mature stage of the ratoon crop,the crop growth rate,the total dry weight and the harvest index were all high,and the four yield components of the ratoon crop were coordinated. |
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