Study on Weak Light Tolerance of 61 Watermelon Germplasm Resources at Seedling Stage

Shang Wenkai; Liu Yongpeng; Luo Hengbin; Ma Xiaojing; Han Yawei; Li Xiaohui; Wang Yong; Piao Fengzhi; Zhang Tao; Zhao Weixing

doi:10.14083/j.issn.1001-4942.2025.02.005

Abstract：In this study,61 watermelon germplasms were used as experimental materials,and two indoor LED light intensity treatments were set as 200 μmol·m-2·s-1(CK)and 60 μmol·m-2·s-1(weak light).Through detecting 13 seedling indicators of different watermelon germplasms,and using multiple analysis methods including correlation analysis,principal component analysis,membership function analysis and clus-ter analysis,their tolerance to weak light were comprehensively evaluated.The results indicated that under weak light stress,the variation coefficient of plant height,stem diameter,leaf width,leaf length,petiole length,aboveground and underground dry and fresh weights,and root indicators of seedlings of the 61 water-melon germplasms exceeded that of CK,and there were significant genetic differences between them.All the 13 indicators had varying degrees of correlation,which comprehensively affected the weak light tolerance of watermelon seedlings.By principal component analysis,the 13 indicators could be transformed into 4 inde-pendent comprehensive indicators with the cumulative contribution rate as 80.48％.After membership function analysis and cluster analysis,the 61 materials were divided into 4 categories according to the D value,among which,the Ⅰ category included 1 germplasm resource with extreme weak light tolerance,the Ⅱ category in-cluded 22 germplasm resources with weak light tolerance,the Ⅲ category included 7 germplasm resources with medium tolerance to weak light,and the Ⅳ category included 31 germplasm resources sensitive to weak light.The germplasm resources of HY-25,HY-90 and HY-81 were selected with higher tolerance to weak light.These results could provide references for screening identification indicators of weak light tolerance for water-melon and scientifically evaluating the weak light tolerance of watermelon germplasms.