Screening And Physiological Response Mechanism Of Ground-cover Chrysanthemum Against Fusarium Wilt Disease Varieties

In this experiment,16 kinds of ground-cover chrysanthemum were used as experimental materials.First,the pathogen of Fusarium wilt,Fusarium oxysporum(FO.)and Fusarium solani(FS.),were inoculated and cultured.The resistance to Fusarium Wilt of ground-cover chrysanthemum was determined by the wounding inoculation of detached leaves,and the varieties with different resistance were identified.In order to study the condition of Fusarium wilt,the Fusarium was inoculated with the wound root soaking method.The inoculation density and the root soaking time of two Fusarium species were screened,and the relationship between the infection concentration,the time of Fusarium and the occrance of Fusarium Wilt in ground-cover chrysanthemum was investigated.Five kinds of ground cover chrysanthemum were selected as experimental varieties,and their pathogeny and their physiological and biochemical responses were studied.The main conclusions are as follows:Firstly,there were significant differences in resistance of FO.and FS.wilts in 16 kinds of ground-cover chrysanthemum.According to the wounding inoculation of detached leaves,the results of FO.Resistance are as follows:’Zihe changduan xin’ and ’Qiaofen’ge’ belonged to disease-resistant varieties;’Ruhe’,’Zixia’ and ’Pudifen’ belonged to medium resistant varieties;’Xianhong’,’Huoyan’,’Linglong’,’59 Ju’,’Lianghuangzao’ and ’Fenzhuangrong’ were all susceptible varieties;’Zijiao’,’Bailong 45’,’Fen’,’Zirongqiu’ and ’11Z1’ were high susceptible varieties,which leaves had a high death rate.The results of FS.Resistance are as follows:’Qiaofenge’,’Zihe changduan xin’ and ’Zixia’ were disease-resistant varieties;’Xianhong’,’Ruhe’ and ’59 Ju’ were medium resistant varieties;’Huoyan’,’Linglong’,’Lianghuangzao’ and ’Pudifen’ were susceptible varieties;’Zijiao’,’Bailong 45’,’Fen’,’Zirongqiu’,’11Z1’ and ’Fenzhuangrong’ were high susceptible varieties.In summary,the selected varieties with strong resistance to chrysanthemum wilt were ’Qiaofen’ge’,’Ruhe’ and ’Zihe changduan xin’,which should be emphasized and popularized.Secondly,the inoculation density and root soaking time of Fusarium species significantly affected the disease index of ground-cover chrysanthemum wilt.When the concentration of FO.and FS.spore suspension was 2.5×107/m1,the disease index of the infected ground-cover chrysanthemum was the fastest.When the FO.and FS.infection time was 30 min,the disease index of ’Ruhe’ and ’Huoyan’ increased relatively rapidly.The infection concentration and time of Fusarium were closely related to the incidence of Fusarium wilt.Thus,the optimum inoculation concentration of two Fusarium species was 2.5×107/ml,and the best time of root soaking was 30min.Thirdly,changes in chlorophyll,malondialdehyde,proline,soluble protein content,superoxide dismutase,peroxidase,and catalase activity in the leaves of the ground chrysanthemum were closely related to the disease resistance of wilt.Research shows,the physiological indexes of ground-cover chrysanthemum were closely related to the resistance of chrysanthemum wilt.After being infected by chrysanthemum wilt,the content of chlorophyll(Ch1)increased first and then decreased with the aggravation of the disease,and the relative content of Ch1 in the resistant varieties was high.The content of malondialdehyde(MDA)increased first and then decreased with the time of the disease.The content of MDA in the susceptible varieties was significantly higher than that of the resistant varieties,and the content of the MDA was negatively correlated with the resistance of chrysanthemum.After inoculation of Fusarium,the content of proline(Pro)in resistant varieties increased rapidly,indicating that the higher the content of Pro,the stronger the resistance of ground bed chrysanthemum.The content of soluble protein(SP)increased first and then decreased with the increase of the time of the disease,and as long as the content of SP in the resistant varieties increased faster,the total content was higher than that of the susceptible varieties.The activity of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)in the leaves of ground bed chrysanthemum increased and then decreased with the increase of the time of disease.The activity of SOD,POD and CAT enzyme in the resistant varieties had a higher activity rise speed and enzymatic activity.Through the comprehensive resistance evaluation of various physiological indexes,the resistance of 5 species of ground-cover chrysanthemum to FO.from strong to weak was’Qiaofenge’>’Ruhe’>’Flame’>’Xianhong’>’Linglong’,and the resistance of FS.from strong to weak was’Qiaofen’ge’>’Ruhe’>’ Xianhong’>’Flame’>’Linglong’.