Identification and evaluation of resistance to fusarium wilt of ginger varieties and screening of resistance indexes

【Objective】To screen ginger varieties resistant to fusarium wilt and establish disease resistance evaluation system,so as to provide theoretical reference for the research on disease-resistant variety breeding of ginger and theory of disease resistance mechanism.【Method】Five main ginger varieties in the main producing areas were selected,and the effects of fusarium wilt pathogen(Fusarium solani)infection on superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),phenylalaninammo-nialyase(PAL),chitinase(CHI),β-1,3-glucanase(GLU)enzyme activities,secondary antibacterial substances content,superoxide(O₂^-·),hydrogen peroxide(H₂O₂),and malondialdehyde(MDA)content of different ginger varieties were determined by indoor artificial inoculation method. The disease resistance of five ginger varieties at seedling stage was comprehensively evaluated by combining disease resistance coefficient,principal component analysis,cluster analysis,correlation analysis and membership function.【Result】The results showed that the disease index of Shandong ginger was the lowest(4.0),the incidence rate was the lowest(4%),and the disease cycle was the longest(24 d),showing strong disease resistance. The disease index of Luoping small yellow ginger was the highest(45.2),and the disease cycle was the shortest(7 d),showing weak disease resistance. Physiological indexes of different ginger varieties after inoculation showed different changes. Antioxidant enzyme(SOD,POD and CAT)activity,defensive enzyme(PAL,CHI and GLU)activity and secondary antibacterial substances(total phenols,flavonoids,lignin)content in Shandong ginger were higher than those of other varieties,and the O₂^-·,H₂O₂ and MDA content in Shandong ginger were lower than those of other varieties. Luoping small yellow ginger showed the opposite trend. Twelve individual physiological indexes were transformed into three independent comprehensive indexes by principal component analysis,and five ginger varieties were divided into three categories by cluster analysis. Taking comprehensive evaluation results of membership function into account,the order of disease resistance of five main varieties from strong to weak showed as: Shandong ginger>Fengtou ginger>Zhugen ginger>Guizhou yellow ginger>Luoping small yellow ginger. The ranking results were consistent with the results of artificial inoculation identification of disease resistance. Correlation analysis showed that SOD had an extremely significant positive correlation with flavonoids and comprehensive evaluation value of disease resistance(D value)(P<0.01).【Conclusion】Shandong ginger has the strongest disease resistance among the five ginger varieties,and Luoping small yellow ginger has the worst disease resistance. SOD and flavonoid can be used as the main reference indexes for the identification of ginger disease resistance.