| Fusarium Wilt is a kind of serious soil-borne diseases. To study the mechanismof watermelon resistance to fusarium wilt, the fusarium spore suspension andfusarium venom were used to treat three watermelon collections with differentresistance to Fusarium race1, leaf stomatal exchange parameters, leaf waterphysiological indicators and leaf protective enzyme activity changes after twotreatments were determined. The results were as followings:1.After irrigating watermelon root with Fusarium oxysporum spore suspensionand Fusarium oxysporum venom, Gs of watermelon leaves continued to decline,resulted in Pn, Tr and Ci decreased, indicating temporal stomatal limiting of leafphotosynthesis. With the time passing, Ci began to increase, while Pn continue todecline, suggesting non-stomatal limiting of the photosynthesis. Reduced Tr resultedin decreased leaf water potential and relative water content, as well as loweredabsorption and transportation of nutrients, thereby reduced the resistance ofwatermelon to Fusarium oxysporum infection.2.SOD, POD, CAT, PPO and PAL involved in active oxygen removal and thesynthesis of disease resistance material such as phenols, lignin and phytoalexins, andcan resist reactive oxygen and oxygen free radical damage to the cell membranesystem, thus enhance plant ability to resist diseases.Defensive enzymes is animportant biochemical mechanism of watermelon resistance to Fusarium wilt.3.Resistance of watermelon varieties to Fusarium oxysporum is significantlypositively correlated to leaf Pn, Tr and Gs, leaf water potential and relative watercontent, as well as protective enzyme activities.4.Compared with Fusarium spore suspension, Fusarium venom caused hostplants responses more quickly, but the Fusarium spore suspension did induced moredurable and stronger host plants damage and resistance responses in watermelon. |
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