短枝型苹果杂种后代早期鉴别及评价

Identification and evaluation of the progenies of spur-type apple(Malus domestica Borkh.)

[目的]快速有效地筛选和鉴定短枝型苹果种质资源。[方法]以新红星和宫崎短枝富士的正反交群体为试材,调查了658株3年生实生树的8项枝芽形态指标,然后进行相关性和主成分分析,并在其10年生时进一步开展类型确证。[结果]节间长度、枝条基部粗度和萌芽率的次数分布符合正态分布,枝条长度、平均成枝数、总芽数和尖削度的频数分布为偏态分布;采用概率分级法,设X±0.5346S两个分点,将6项指标均分成3级,其中关于萌芽率、枝条长度及枝条基部粗度的分级或可应用于枝芽形态特征的评价;相关分析表明,枝条形态特征指标间信息重叠,单一指标不能直接或准确地评价枝芽特性,为此运用因子分析,将影响枝条形态的指标综合成为5类因子,即枝条的长度因子(短枝率、枝条长度、尖削度)、空间密布因子(萌芽率和平均成枝数)、节长因子(节间长度)、节度因子(总芽数)和粗度因子(枝条基部粗度)。运用主成分分析对23个单株幼树期枝条的枝芽进行短枝型苹果形态指标的综合评价,后经成年期形态确认,发现这种评价能较好地区别短枝型与非短枝型植株,符合率为86.9%。[结论]采用概率分级的方法对苹果杂种后代枝条的萌芽率、枝条长度及枝条基部粗度进行评价;利用主成分分析筛选苹果杂种实生后代中短枝型种质,为苹果后代短枝型的选择和评价提供了一种新方法和新思路。

[Objective]Spur-type is one of the excellent agronomic traits in fruit trees,particularly in apple,peach,and Chinese date.The spur-type apple has been widely cultivated in apple industry in the world.However,there are only a few spur-type apples developed by hybridization breeding The aim of this study was to seek for rapid and effective identification of spur-type hybrid individuals from the progenies generated from the hybridization between spur type apple varieties to improve the breeding efficiency.[Methods]Eight characters including length of shoot(LS),length of internode(LI),total number of sprouts(TNS),mean number of shoots(MNS),percentage of spurs(PSU),shoot base thickness(SBT),percentage of sprouts(PSP),and conicity(CI)of 658 apple hybrid seedlings(generate from the reciprocal cross between Malus domestica‘Starkrimson’and M.domestica‘Miyazaki Spur’)were determined.The trees investigated were three-years old after budding on Malus×robusta(Carri?re)Rehder.Firstly,correlation analysis was used to clarify the correlation between the investigated morphological characters,correlation and principal component analysis of these characters were then performed to simplify the number of morphological evaluation indicators.The principal components of twenty-three fruit-bearing individual plants were calculated based on the eigenvalues and corresponding eigenvectors,and the threshold for determining the short shoot type was found.Phenotypic investigation was carried out on these individual seedlings of the trees to verify the determination results of principal component analysis when the trees were ten-years old after budding.[Results]The distributions of values of the LI,SBT and PSP conformed to the normal distribution,but those of the LS,TNS and MNS tended to be more likelyχ2 distribution,thus the values of normally distributed characters could be divided into three grades by(X-0.5246 S)and(X+0.5246 S).i.e.X±0.5246 S were set in the indexes of germination rate,branch length and branch base thickness to divide each index into three grades:low,medium and high,which could be applied to the analysis and evaluation of shoot morphological characters.The correlation coefficient matrix of the eight related branch morphological characters was calculated,and it was found that there was a certain correlation among all indexes,and it was not possible to accurately evaluate the characteristics of the branches by directly using the above single index.Therefore,multiple indexes should be used to comprehensively evaluate the hybrid offspring of spur type in apple.According to principal component analysis,the information constituted by the five factors of the eight morphological indexes of branches accounted for 89.16%of the total information,which basically reflected the main information of branches.These factors were defined as length factor,spatial density factor,node length factor,node length factor and thickness factor of branches respectively.The results also showed that the composite principal component score value of each individual plant could determine whether a seedling was spur-type or not.When the score value was positive,it was mostly spur-type in the field.And when it appeared negative value,it is mostly non-spur type in the field.The principal component analysis of shoots and buds of spur-type apple could be used to evaluate the morphological type of individual seedlings,with coincidence rate of 86.9%.[Conclusion]The PSP,LS and SBT of the branches of spur-type seedlings were evaluated by probability grading method in this study.The information overlapped between the eight morphological characteristics of the branches of apple seedlings,so the characteristics of the branches could not be evaluated directly or accurately by a single index.Therefore,by using factor analysis,the eight morphological indexes could be integrated into five factors,and then the individual plant types could be identified according to the scores of principal component analysis,with the coincidence rate of more than 85%.