Phenotypic Variation and Early Selection of Half-sib Families of Pinus yunnanensis
Pinus yunnanensis is a unique native species to Southwest China,distributed in the southeastern margin of the Qinghai-Tibet Plateau,and its genetic degradation is a serious concern.To accelerate the breeding process and diversify the genetic resources,95 half-sib families of P.yunnanensis were evaluated and selected in the early stage based on the systematic analysis of nutritional growth traits(plant height,ground diameter,long crown diameter,short crown diameter,height under the branches,length of primary branches in the current year,and number of lateral branches in the current year)and reproductive growth traits(number of cones).The results indicated that:1)there were significant differences in nutritional growth traits among families of P.yunnanensis,indicating that it had rich genetic variation and selection potential.2)The coefficient of variation and heritability of phenotypic traits were 21.60％～86.07％and 0.75～0.78,respectively,indicating that the traits of P.yunnanensis had large variation,and they are strongly controlled by genetics.3)There is a strong correlation between phenotypic traits.By performing cluster analysis on the nutritional growth traits,the 95 families can be divided into three categories.4)By conducting a membership function analysis on the nutritional growth traits of P.yunnanensis,10 superior families were selected,and the genetic gain and actual gain of plant height were up to 19.63％and 25.17％,respectively,and ground diameter were up to 12.39％and 15.89％,respectively.There were abundant phenotypic variations among half-sib families of P.yunnanensis,and 10 superior families were selected based on vegetative growth traits.The results can provide material support and a theoretical basis for the breeding of improved varieties of P.yunnanensis.
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