油茶砧木根系形态特征及其对嫁接苗抗旱性的影响OA

This study aimed to explore the root morphological characteristics of Camellia oleifera rootstocks and their correlations with the drought resistance of grafted seedlings,thereby providing a theoretical reference for seedling cultivation manage-ment and drought-resistant rootstock breeding of C.oleifera.Seven C.oleifera varieties,namely Xianglin 1(XL1),Xiang-lin 27(XL27),Xianglin 97(XL97),Xianglin 331(XL331),Guoyou 15(GY15),Dezi 1(DZ1),and C.oleifera Germplasm 1(ZZ1,Guangxi Daqingguo),were selected as rootstocks,and grafted with the common C.oleifera clone Xianglin 210(XL210).The root morphological characteristics of the rootstocks were determined.Meanwhile,changes in leaf photosynthetic parameters and chlorophyll fluorescence parameters of the grafted seedlings were analyzed under simula-ted drought stress.Furthermore,comprehensive evaluation of rootstock drought resistance was conducted by combining principal component analysis(PCA)and cluster analysis.The results showed that there were significant differences in root morphological indices among different C.oleifera rootstock types.Among these rootstocks,XL331 had the highest number of root tips,reaching(1427.66±70.91)units,while ZZ1 exhibited the maximum root surface area and root volume,which were(150.44±7.58)cm2 and(9.47±0.77)cm3,respectively.Drought stress significantly altered the photosynthetic char-acteristics and chlorophyll fluorescence parameters of C.oleifera grafted seedlings.After drought stress treatment,ZZ1 showed the highest net photosynthetic rate,with a value of(4.80±0.01)μmol·m-2·s-1,whereas XL331 presented the optimal maximum photochemical efficiency of PSⅡand potential activity of PSⅡ,which were 0.65±0.07 and 2.13±0.59,respectively.Principal component analysis indicated that the graft combinations of XL331/XL210,ZZ1/XL210,GY15/XL210,and XL27/XL210 had relatively high comprehensive evaluation values of drought resistance,while XL97/XL210 and DZ1/XL210 had moderate values.Correlation analysis revealed that root length of roots with diameter(D)≤0.50 mm,total root length,and number of root tips were significantly and positively correlated with drought resistance metrics,which could be used as important indices for screening drought-resistant rootstocks.In conclusion,XL331 and ZZ1 had high com-prehensive evaluation values of root morphology,and their corresponding grafted seedlings exhibited strong drought resist-ance,making them ideal candidate materials for breeding drought-resistant C.oleifera rootstocks.