Analysis Of Characteristics And Combining Ability Of New Cytoplasm Male Sterile Lines In Rice(Oryza Sativa L.)

The key part of the breeding of new hybrid rice varieties is the breeding of elite sterile and restorer lines.To breed the elite indica-type three-line 007A?CMS?in rice,the mainter lines of F₆ generation,derived from the cross between Nandate B?an indica mainter line with large panicle?and Zhong 9B,were further treated with ⁶⁰Co in this study,and the excellent mutant strains were selected to successive backcross to Rongfeng A.After 15 generations about eight years,an elite three-line sterile line named 007A was obtained.A survey was conducted on fertility characteristics,outcrossing performance,rice quality,combining ability and so on.The results showed that:?1?Botanical characteristics:007A is of compact plant type,and the stem is thick.The plant height of 007A is 72.68 cm,which is about 10 cm higher than that of the control Rongfeng A;the color of leaf sheath,apex and stigma of 007A is purple,the length of flag leaf is 28.83cm,the width of flag leaf is 1.92cm,and the tillering ability is strong.The effective panicles per plant of 007A is 13-15,which is 2-3 more than Rongfeng A;The length of the spike was 19.95cm,a total of 271 grains per panicle;the broadcast duration of 007A was 75 days,7⁸ days longer than the control Rongfeng A,which is a moderate type;the 1000 grain weight was 22.8g.?2?Sterility:After many years of microscopic examination,the results showed that male sterility rate of 007A was 99.9%,dominating by typical abortion,with rare stained abortion.The bagging seed setting rate was 0%,and the rate of neck granules was about 7%lower than that of Rongfeng A.The flowering time of the 007A was concentrated,and the flowering duration lasts for about 7 days longer than that of Rongfeng A.The stigma exsertion rate of 007A was 83.7%higher than that of Rongfeng A by 9.7%,the bilateral exposure rate and unilateral exposure rate were44.9%and 38.8%;007A has good outcrossing characteristics,the outcrossing rate is63.6%,3.7%higher than Rongfeng A;007A has good flowering habits and strong stigma.?3?Rice Quality:The brown rice rate of 007A was 75.13%lover than Rongfeng A by 2.8%;the rate of milled rice was 64.43%,about 5%lower than Rongfeng A,the head rice rate was 42.69%,which was about 24%lower than Rongfeng A;the grain length is 7.86mm,about 1.6mm smaller than Rongfeng A,and the aspect ratio is 2.57,which is smaller than Rongfeng A.The chalkiness rate was 32.3%,which was about14%higher than that of Rongfeng A;The alkali consumption value was 2.08,which was a small difference from Rongfeng A.The gel consistency is 40.1mm higher than Rongfeng A;The amylose content is 13.87%smaller than Rongfeng A.?4?Combining ability:By crossing 007A and Rongfeng A with six indica rice restorer lines,the combining ability of agronomic and quality characters of two male sterile line combinations were analyzed.The results showed that the GCA values of plant height,panicle length,grain per panicle,total grain per panicle,seed setting rate,and yield of per plant for are all positive;the GCA values of growth period,effective panicles and 1000-grain weight are all negative.The results indicated that the combinations of 007A have less effective panicles,small grain weight,and short growing period,but high seed setting rate and huge yield potential.In terms of rice quality,the GCA values of milled rice rate,milled rice rate,chalkiness and gel consistency are all positive,while the GCA values of brown rice rate,alkali elimination value and amylose content are all negative.In all,although the combinations derived from 007A had lower brown rice rate,slightly smaller alkaline consumption value,and lower amylose content,but they had higher rice rate and whole polished rice is high,lower chalkiness,and the consistency of the gum is better.from the results,we concluded that the grain quality of combinations derived from007A is better than that of the combinations derived from Rongfeng A.?5?The correlation analysis of agronomic and quality trait:In terms of agronomic traits,the plant height was significantly negatively correlated with the growth period,and was significantly positively correlated with the panicle length,grain per panicle,total grain per panicle,and 1000-grain weight.Therefore,the relationship between other agronomic traits and plant height should be comprehensively coordinated so as to achieve the purpose of breeding superior CMS lines.In terms of grain quality,brown rice rate,milled rice rate and whole milled rice rate were significantly negatively correlated with chalkiness rate,which indicated that increasing brown rice rate,milled rice rate and whole milled rice rate had certain effects on reducing chalkiness grain rate.