Physiological response of 5 ginger varieties to waterlogging stress and evaluation of their waterlogging tolerance

【Objective】 The effects of waterlogging stress on morphological changes and physiological indexes of ginger at seedling stage were investigated to provide a reference for the study of the waterlogging-tolerant mechanism and selection of waterlogging-tolerant ginger varieties.【Method】 Five main varieties in the main ginger producing areas were selected as experimental materials，including Shandong big ginger，Luoping small ginger，Guizhou small ginger，Zhugen ginger and Fengtou ginger，which were subjected to normal water treatment（CK）and flooding treatment（TR）.The growth indexes，physiological indexes and chlorophyll fluorescence parameters under different treatment conditions were measured，and the waterlogging tolerance of the 5 varieties at the seedling stage was comprehensively evaluated using the method of membership function.【Result】 Compared with CK，the plant height，stem diameter and root activity of all varieties decreased under waterlogging stress，with significant increases（P<0.05，the same below）of MDA and H₂O₂ in leaves.The activity of SOD and POD decreased in Zhugen ginger but increased in the other 4 varieties.The CAT activity exhibited an increasing trend in Shandong big ginger but a decreasing trend in the other 4 varieties.The PAL activity decreased in Zhugen ginger and Fengtou ginger，but increased in the other 3 varieties.After the flooding treatment，the 5 varieties displayed significantly decreased maximum photochemical efficiency（F_v/F_m）and photochemical quenching coefficient（qP）of Photosystem II（PSII），and significantly increased non-photochemical quenching coefficient（NPQ）.It was found that Shandong big ginger exhibited the best waterlogging tolerance，followed by the Guizhou small ginger，Luoping small ginger，Fengtou ginger and Zhugen ginger varieties.Moreover，it was noted that plant height and stem thickness were positively correlated with comprehensive evaluation value（D value）（P<0.01，the same below），while leaf MDA content was negatively correlated with D value.【Conclusion】Ginger resists oxidative damage by maintaining high root activity and improving its antioxidant capacity.Of the five varieties，Shandong big ginger exhibits the strongest waterlogging tolerance and Zhugen ginger shows the least waterlogging tolerance.Plant height，stem diameter and MDA content in leaves can be adopted as main reference indexes for screening waterlogging tolerant ginger varieties.