Preliminary establishment of a system for evaluating and characterizing drought resistance in watermelon seedling

CHENG Juanjuan; YUAN Gaopeng; HE Ying; WANG Huilin; ZHU Yingchun

doi:10.16861/j.cnki.zggc.2025.0292

Abstract：In order to establish a drought tolerance identification and evaluation system of watermelon seedling,and pro-vide a simple and rapid screening method of drought-tolerant material,five watermelon varieties named Xinong No.8,Tianguan No.2,Xinyou No.2,Zhongxinghong No.1,and Zhongnong Meiguan No.2 were used as test materials,and a pot experiment was set up with two treatments of drought stress(natural drought for 7 d)and normal watering to deter-mine the growth indexes of watermelon and physiological indicators,using the method of the affiliation function,princi-pal component analysis and other methods,to analyze the differences in the response of watermelon varieties to drought stress,and to screen out the key drought indicators of watermelon seedling stage.The results showed that the growth and physiological indexes of watermelon varieties changed of different degrees after drought treatment,and the height,root length,aboveground and belowground dry mass of watermelon seedling decreased to different degrees as a result of drought stress;at the same time,the proline and malondialdehyde content of watermelon seedling leaves increased signifi-cantly,and the catalase activity was enhanced,whereas the soluble protein content and the relative conductivity increased;the chlorophyll content of watermelon varieties was increased by drought treatment.Through the affiliation function meth-od,principal component analysis and other methods,it was concluded that the aboveground dry mass,root length and malondialdehyde content changed significantly after drought stress,therefore,these three indexes were selected as the in-dexes for the identification of watermelon seedling drought tolerance,and the regression equation was finally established:Y=0.870+0.260 RL+0.218 SDW-0.426 MDA.Drought tolerance was identified according to the magnitude of Y value.Y-value≥0.70 are drought-resistant materials,0.35＜Y-value＜0.70 are intermediate drought-resistant materials,and 0＜Y-val-ue≤0.35 are drought-sensitive materials.The research results have laid a foundation for the screening of drought-resistant resources at the seedling stage of watermelon and the breeding of drought-tolerant variety.