57个橡胶树优树无性系表型多样性分析及抗旱性综合评价OA

This study investigated 57 superior Hevea brasiliensis clones collected from first-generation rubber plantations in China.A total of 25 quantitative traits were measured,encompassing stem circumference,leaf morphological characteristics,and anatomical structure.The variation extent,genetic diversity indices,and inter-trait correlations were analyzed.Systematic cluster analysis and principal component-based evaluation were subsequently conducted using this comprehensive phenotypic dataset.The results revealed highly significant differences among the 57 clones for all 25 traits.The coefficient of variation(CV)ranged from 7.26％to 45.29％.The largest CV was observed for stem circumference at the seedling stage(first year),while the smallest was for the ratio of left vein width to leaf width.The phenotypic genetic diversity index ranged from 1.018 to 2.188,with leaf area showing the highest genetic diversity index and the left vein width/leaf width ratio exhibiting the lowest.Among the 25 traits,most showed highly significant or significant correlations with one another.Exceptions were the ratio of left vein width to leaf width,leaf vein number,midrib thickness,leaf vein angle,palisade to spongy tissue ratio,cell structural tightness ratio,and cell structural looseness ratio,which showed no significant correlation with most other traits.Notably,stem circumference was strongly positively correlated with leaf area,leaf length,and leaf thickness,with correlation coefficients all exceeding 0.8.Among leaf anatomical traits,indicators such as leaf thickness,cuticle thickness,palisade tissue thickness,spongy tissue thickness,and upper epidermis thickness exhibited highly significant or significant pairwise correlations,with the exception of palisade tissue thickness and spongy tissue thickness,which was not significantly correlated.Moreover,these anatomical traits were also significantly correlated with most leaf morphological traits.Systematic cluster analysis categorized the 57 clones into six distinct groups,with no apparent relationship to their geographic origins.Group Ⅰ contained 29 clones.Groups Ⅳ and Ⅴ exhibited desirable traits,such as larger stem circumference and leaf area,sparse vein distribution,and greater thickness across various leaf anatomical parameters.Based on cluster analysis and principal component comprehensive evaluation,six superior clones,with numbers 7,10,33,27,46,and 14,were identified as fast-growing and drought resistant.By the seventh year,all six clones attained a stem circumference exceeding 52 cm.Among them,clone 7 and 10 were triploids.This study highlights the phenotypic diversity present in scattered superior tree resources within China's rubber planting areas,providing valuable genetic materials for parental selection and targeted breeding in H.brasiliensis.