Analysis Of Character Variation Of Regional Test Varieties And Breeding Parents In Rapeseed

The rapeseed cultivation in China relies on labour power too much,and the degree of mechanization is seriously insufficient.Farmers lack economic benefits in growing rapeseed,which leads to their lack of enthusiasm in growing rapeseed.The purposes of this research are(1)Comparing the variations of 25 traits and the correlations between yield and other 24 traits in the winter rape regional trial under low and high density in China to screen out the main trait parameters closely related to yield in different densities and regions.(2)Carrying out variation analysis,multivariate correlation analysis and cluster analysis of 24 trait parameters of 41 breeding parents to identify the maximum and minimum variation traits of breeding parents and the trait parameters with correlations and similar varieties.(3)Preparing diallel crosses for 10 backbone parents and analyzing their combining ability to screen out varieties with higher general combining ability and special combining ability.The main results obtained are as follows:1.Variations of traits and correlations between yield and traits of regional varieties:(1)Under low-density planting conditions,the character with maximum coefficient of variation was the content of erucic acid in the lower reaches of the Yangtze River with CV=6.06 and the characters with minimum coefficient of variation were the whole growth period in Huanghuai area and middle reaches of the Yangtze River with CV=0.01.Under the condition of high density planting,the character with maximum coefficient of variation was virus disease rate in the middle reaches of the Yangtze River with CV=6.06,and the characters with minimum coefficient of variation were drought tolerance,waterlogging in Huanghuai area and the whole growth period in the lower reaches of the Yangtze River with CV=0.01.(2)In different regions,the characters that had the most impact on yield per unit area as followed: in Huanghuai area,upper reaches of Yangtze River and lower reaches of Yangtze River were yield per plant;in early maturity area were frost damage index and sclerotinia sclerotiorum disease index;in the middle reaches of Yangtze River were yield per plant and number of pods per plant.(3)The traits with the greatest impact on yield at the both of low and high planting densities were the whole growth period in the national planting area.(4)The traits with the greatest impact on yield in different densities and regions were as flowed:in the low density of Huanghuai area was plant height and in the high density of Huanghuai area was sclerotinia sclerotiorum disease rate;in the low density of early maturity area was the whole growth period and in the high density of early maturity area was yield per plant;in the low density of upper reaches of Yangtze River was virus disease rate and in the high density of upper reaches of Yangtze River was yield per plant;in the low density of middle reaches of Yangtze River was frost damage rate and in the high density of middle reaches of Yangtze River was sclerotinia sclerotiorum disease index;in the low density of lower reaches of Yangtze River was silique number on main inflorescence and in the high density of lower reaches of Yangtze River was lodging resistance.2.Character variation analysis,multivariate correlation analysis and cluster analysis of breeding parents:(1)The characters with maximum coefficient of variation include the bending strength of stem and the number of total pods in maturity stage,e.g.QXDpurple was the most resistant variety,and Zhong502 had the largest number of pods.(2)The correlation between the length of pod at the later flowering stage and the length of pod at maturity stage was the greatest(r=0.84).(3)Varieties YC4、GQ4、Q8C、78066、R8Q10、D602、Q92588、QXDFu、CAT、XDgao showed similarity in main phenotype traits.3.Combining ability analysis of 10 backbone parents’ characters :(1)The parental varieties with maximum positive GCA or maximum negative GCA of each character were as followed: the parental variety with maximum positive GCA or maximum negative GCA of plant height were YC466 and 5005A;the parental variety with maximum positive GCA or maximum negative GCA of stem base diameter were H21 Aor D699;the parental variety with maximum positive GCA or maximum negative GCA of effective branch number were SG77 and D699;the parental variety with maximum positive GCA or maximum negative GCA of length of pod were H21 and YC466;the parental variety with maximum positive GCA or maximum negative GCA of seed numbers per pod were QXD and 5005A;the parental variety with maximum positive GCA or maximum negative GCA of number of pods were SG77 and D699.(2)The parental variety of the height GCA of plant height was the male parent QXD and the cross combination of the height SCA of plant height was Sap yellow × SG77.The results obtained in this paper had a certain reference value for defining the selection sequence of rape breeding parameters under high density and selection and breeding the rapeseed parents with plant types suitable for mechanized planting and harvest.