Comparison Of Photosynthetic And Antioxidant Characteristics Of Different Resistant Rice Varieties Inoculated With Rice Blast Fungus

In order to investigate the changes in photosynthetic and antioxidant properties of rice varieties with different resistance to rice blast during the infection process after inoculation with rice blast fungus,this study used high resistance rice variety Jinongda 505,medium resistance rice variety Xinyu 40,medium sensitivity rice variety Jinongda 809,and high sensitivity rice variety Mongolian rice as experimental materials.The rice seedlings were artificially inoculated with rice blast fungus at the 4th leaf stage,and distilled water was sprayed as a control.One day after inoculation Measure the photosynthetic parameters,chlorophyll fluorescence parameters,carbon dioxide response curve,antioxidant enzyme activity,antioxidant related substance content,photosynthetic pigment content,and relative conductivity of leaves at 3,5,and 7 days,respectively.Analyze the changes in photosynthetic and antioxidant characteristics of different resistant rice varieties during the infection process after inoculation with rice blast fungus.The research results are as follows:（1） After inoculation of different resistant rice varieties with rice blast fungus,the disease incidence level of high resistant rice varieties was 0;The disease incidence level of medium resistant varieties is Level 1;The incidence level of moderately susceptible varieties is 5 levels;The incidence level of highly susceptible varieties is 9.（2） Compared with the control,the photosynthetic pigment content of different resistant rice varieties decreased after inoculation with rice blast fungus,and decreased with the increase of treatment time.The decrease in susceptible varieties was greater than that in resistant varieties;Pn,Gs,Tr,and AMC all decreased to varying degrees,decreasing with the increase of treatment time,while Ci showed an upward trend in the opposite direction,with the range of change showing as highly susceptible varieties>moderately susceptible varieties>moderately resistant varieties>highly resistant varieties.（3） Compared with the control,the Fm,Fv/Fm,Fv/Fo,Y （Ⅱ）,ΦPSII and q P showed a downward trend,and decreased with the increase of treatment time;Both Fo and NPQ showed an upward trend and increased with the increase of treatment time,with the variation range of highly susceptible varieties>moderately susceptible varieties>moderately resistant varieties>highly resistant varieties.（4） Compared with the control,the CSPn,CSP,Jmax,Vcmax,and TPU of leaves of different resistant rice varieties inoculated with rice blast fungus showed a downward trend,and decreased with the increase of treatment time;The CCP shows an upward trend,increasing with the increase of processing time;The range of variation was as follows:highly susceptible varieties>moderately susceptible varieties>moderately resistant varieties>highly resistant varieties.（5） Compared with the control,the activities of POD,SOD,and CAT in the leaves of different resistant rice varieties after inoculation with rice blast fungus significantly increased,and the activities of POD,SOD,and CAT increased first and then decreased.The activities of POD,SOD,and CAT in resistant rice varieties increased faster in the early stage,and were always higher than those of susceptible rice varieties,with a peak value appearing in 3-5 days;The activities of APX,PAL,and PPO increased significantly,and the activity and increase range of resistant varieties were higher than those of susceptible varieties.The early growth rate of resistant varieties was faster and the activity decreased after being high,while the susceptible varieties continued to rise slowly.（6） Compared with the control,the O₂^-production rate,H₂O₂ content,MDA content,and relative electrical conductivity of the leaves of different resistant rice varieties after inoculation with rice blast fungus significantly increased.The O₂^-production rate,H₂O₂ content,and MDA content of the leaves of resistant varieties decreased faster in the early stage,and then tended to be stable and gradually close to non-infected,while the susceptible varieties decreased slightly in the early stage and then increased significantly;The relative electrical conductivity of leaves increased with the increase of treatment time,with the variation range of highly susceptible varieties>moderately susceptible varieties>moderately resistant varieties>highly resistant varieties.