Study On Combination Ability,Heterosis And Starch Properties Of Nucleus-Cytoplasmic Hybrid Wheat

At present,the utilization of heterosis is an important way to improve yield and quality in wheat.The development of Nucleus-cytoplasmic male sterile lines（CMS）has quickly promoted the utilization of heterosis and provided a broad prospect for crossing breeding in wheat.However,some studies have shown that there are problems such as limited male sterility resources、unstable recovery and adverse cytoplasmic effects in the CMS breeding process of wheat.Given this,two sets of stable genetic wheat CMS with four different cytoplasmic were used as the female and four restorer lines were used as the male to make up the cross combination.Yet,it was unclear that combining ability among parents and heterosis of hybrids F₁.On the one hand,the study showed combining ability and heritability analysis by investigating the agronomic traits,grain physical traits and quality traits of hybrid F₁,and screened out two restorers with higher combining ability for heterosis analysis,on the other hand,by exploring the differences in starch composition and physicochemical properties of hybrids F₁with different nucleus-cytoplasmic background to provide a theoretical basis for selection of hybrid combinations and CMS germplasm resources innovation in wheat.The main results were as follows:1.The GCA of different traits or different parents of the same trait existed great differences.Compared to XC-1236,the GCA value of AK58 was higher in agronomic traits and grain physical traits,while there was no significant difference in the GCA value of quality traits;among different restorer lines,the biggest GCA value of agronomic character was R5174,the biggest GCA value of grain physical character was R2726,and the biggest GCA value of quality character was R113;the combination of XC-1236 and R5174 showed higher SCA effect on agronomic traits and grain physical traits,and the combination of AK58 and R113 showed higher SCA effect on quality traits;grain physical traits of population heritability were greater than agronomic traits and quality traits,length of uppermost internode were mainly inherited by non-additive effects,starch was mainly inherited by additive and non-additive effects,the rest traits were mainly inherited by additive effects.2.There were significant differences in phenotypic traits of hybrid F1 except for flag leaf width、spike number per plant、spikelet number、cricularity and water content,the variations coefficient of different traits varied from 1.43%to 32.72%;the heterosis of different traits was prevalent in hybrids F₁,the average mid-parent heterosis ranged from-3.85%to 14.88%,the minimum positive rate was 31.25%,while the average over-parent heterosis ranged from-14.79%to 7.97%,and the maximum positive rate was 81.25%;the correlation analysis showed that GCA was positively correlated with heterosis,while SCA was positively but not significantly correlated with heterosis.The Four principal factors were extracted by principal component analysis and cross combinations were divided into four groups by clustering analysis.The hybrid combination of AK58 and R2726 showed the excellent performance in phenotype traits,which was regarded as excellent hybrid combination of wheat CMS.3.The amylose content of hybrids F₁ that XC-1236 and R5174 was higher compared to other cross combinations,and the amylopectin content of F₁ hybrid line that AK58 and R2726 was used as female was higher.There were significant differences of other starch components except for amylose content between the different cytoplasmic of same cross combination;the quantity of starch granules of A type and B type was significantly different among different hybrids,while the volume difference of which was small;the viscosity traits of different hybrid combinations were significantly different,（Y）XC-1236×R2726combination had the highest peak viscosity、setdown value and good thermal stability,while（T）AK58×R5174 combination had the largest setback value and good cold stability.The thermal properties of starch proved that the hybrid combination of AK58 and R5174 had the highest enthalpy（△H）;the correlation analysis showed that not only starch composition was correlated with physicochemical properties,such as amylose was significantly positively correlated with pasting property,while amylopectin was significantly negatively correlated with them.But also,starch properties were significantly correlated with yield factors and grain traits,such as amylose was significantly negatively correlated with grain weight and grain shape,while amylopectin was significantly positively correlated with them.