Breeding Of Three-line Indica Hybrid Rice With Low Cadmium Accumulation In Brown Rice By Different Panicle Types

With the development of industry and agriculture and the improvement of people’s living standards,the heavy metal pollution in staple brown rice production has attracted more and more attention,especially the accumulation of cadmium in grains.Panicle type is an important character of rice plant type and yield.It is very important to select Indica Hybrid Rice with low cadmium accumulation in brown rice by studying cadmium accumulation in hybrid rice with Different Panicle Types in order to ensure food hygiene and safety.In this study,42 hybrid rice combinations were bred by using NCII genetic design of 7 *6 in Three-line Indica Hybrid Rice Parents with different panicle types.By investigating the main agronomic trais and some leaf shapes of these hybrid rice combinations and their parents,the combining ability effect of cadmium accumulation in grains and the correlation between cadmium content in grains and different trais were determined and analyzed,and the regularity of cadmium content in grains of these materials with different panicle types was analyzed.The main results are as follows:1.There were only two panicle types in parents,curve panicle and erect panicle,and three panicle types in hybrid combinations,curve panicle,semi-erect panicle and erect panicle.Most of the phenotypic values of main agronomic traits were higher in curve panicle type than in erect panicle type,but the grain number per panicle and grain density were opposite.In crosses,most of the traits of semi-erect panicle type were intermediate type.2.The Cd content in grains of different materials was significantly different.In the parents,the Cd content of the maintainer and restorer lines of erect panicle type was significantly higher than that of the corresponding curve panicle parents,respectively.The Cd content of erect panicle type was lower than that of curve panicle type and semi-erect panicle type.The results of heterosis analysis showed that the heterosis of Cd content in different panicle type hybrids was mainly positive.The heterosis of low Cd content in grain was in the order of erect panicle type,semi-erect panicle type and curve panicle type.3.The combining ability analysis showed that the general combining ability of the cadmium content of the parents was significant.The GCA of male sterile line F62 A was the best,which was-10.74,and that of restorer line R3203 was-22.01.The erect panicle type parents were easier to produce the hybrid rice combinations with lower cadmium content.The special combining ability analysis showed that the semi erect panicle type was easier to get the hybrids with lower cadmium content.4.Genetic variance analysis of Cd content in rice showed that GCA variance accounted for 77.01% of the total variance.The additive effect of GCA gene played a dominant role in Cd content of the first generation of hybrid rice,which indicated that parental improvement had a better effect in early generation selection.5.Correlation analysis showed that the Cd content of hybrid rice was positively correlated with that of sterile line,and the Cd content of erect panicle type hybrids was positively correlated with that of erect panicle sterile line.The correlation analysis between Cd content and different agronomic traits of hybrid rice showed that Cd content of hybrid rice was negatively correlated with seed setting rate and flag leaf width,but not significantly correlated with other traits.6.Three good combinations with low cadmium content in brown rice and high grain yield were screened out: semi-erect panicle type combination F62A/R3203,F62A/R534 and curved panicle type combination F61A/R3203.