Study on the Common Characteristics of High-Yielding Population of Mechanical Direct-Seeding Indica Hybrid Rice
[Objective]This study aimed to clarify the common characteristics of high-yielding popula-tions of mechanical direct-seeding indica hybrid rice and to construct a standardized identification method and index system for these varieties.[Method]Eleven indica hybrid rice varieties were used as test materials to study the effects of mechanical direct seeding on population quality and yield.The com-mon characteristics of high-yield populations and their relationship with yield were discussed.[Result]Compared to medium-and low-yielding varieties,the two-year average yield of high-yielding varieties increased by 2.77%to 9.63%and 11.19%to 18.31%,respectively.The above-ground dry matter accu-mulation of high-yield type varieties at the jointing,full-heading,and maturity stages significantly in-creased by 27.78%to 58.62%,15.38%to 32.35%,and 18.23%to 34.32%,respectively.The harvest in-dex significantly increased by 24.25%to 34.84%.The high-efficiency leaf area index at the full-heading stage significantly increased by 37.92%to 85.43%.The lengths of the top three leaves were longer(34.17-42.17 cm for the flag leaf,46.23-50.30 cm for the second leaf from the top,and 55.17-59.23 cm for the third leaf from the top).The second(1.67-1.93 cm)and third leaves from the top(1.40-1.53 cm)were wider.The internode lengths of N1,N2,and N3(from the base to the first,second,and third internodes)decreased by 12.06%to 47.34%,14.02%to 15.85%,and 1.97%to 14.21%,respectively,while those of N4 and N5(from the base to the fourth and fifth internodes)increased by 6.86%to 9.95%and 6.68%to 7.86%,respectively.Correlation analysis showed that under mechanical direct seeding con-ditions,above-ground dry matter quality,leaf area index(LAI),flag leaf length and width,the length and width of the second and third leaves from the top,and leaf angle(angle between the stem and the straight part of the leaf blade)were closely related to rice yield and its components.In particular,the cor-relation between the high-efficiency leaf area index,second leaf width,flag leaf length,and yield at the full-heading stage reached a very significant level,with correlation coefficients ranging from 0.910 to 0.927.[Conclusion]It was indicated that increasing the high-efficiency leaf area index(6.04-7.19)at the full-heading stage and paying attention to the synergistic increase of the flag leaf length(34.17-42.17 cm)and the width of the second leaf(1.67-1.93 cm)are the common laws for achieving high yields in mechanical direct-seeding indica hybrid rice.
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