Establishment Of An Evaluation System Of Cut Chrysanthemum Gray Mold Resistance And Prevention Technology

Chrysanthemum is a traditional famous flower in china,and is one of the four major cut flowers in the world.It has the advantages of rich and diverse flower types and high ornamental value.In recent years,gray mold disease is prone to occur during the storage and transportation of cut chrysanthemums,which seriously affects the quality of cut flowers and causes great economic losses.The key to solve this problem is to screen and cultivate excellent cut chrysanthemum varieties resistant to gray mold disease.Meanwhile,it is important to strengthen the prevention and control management of gray mold in the field.At present,there are few reports on the screening of cut chrysanthemum varieties resistant to gray mold and development of related prevention and control technologies.In this study,the pathogenic strains of gray mold were isolat from cut chrysanthemum ‘Yuuka’,and their biological characteristics were clarified;37 cut chrysanthemum varieties were evaluated for gray mold disease resistance at the seedling stage.effects of fungicide on the prevention and control of postharvest gray mold of cut chrysanthemum investigatedwas.The main results are as follows:1.The pathogenic bacteria of gray mold disease was isolated from cut chrysanthemum‘Yuuka’ by tissue block cultivation.Morphological observation and 18 SrDNA-ITS amplification and a phylogenetic analysis were conducted,together with Koch’s rule,the pathogen was determined to be Botrytis cinerea.2.The biological characteristics of this strain were explored,and it was found that the most suitable carbon source for Botrytis cinerea was soluble starch,and the most suitable nitrogen source was ammonium chloride.Both PDA and PSM were suitable for mycelial growth,and a small amount of sclerotia might be produced in the later stage.It is difficult to produce spores.The optimum pH is 5-6.The hyphae could grow at 5℃ and stop growing at 35℃,and the optimum growth temperature is 20-25℃,the optimum temperature for spore germination is 20-25℃.Compared with water,using potato dextrose water as the nutrient phase is more conducive to spore germination;light time has no effect on mycelial growth.3.The gray mold resistance of 37 cut chrysanthemum varieties was identified,including 7 moderately resistant varieties,14 moderately susceptible varieties,and 16 susceptible varieties.The representative varieties of the moderately resistant varieties is‘Qinhuai Ranxia’ and the moderately susceptible varieties ‘Jinzhao’ and the susceptible variety ‘Qinhuai Tea’.4.The bacteriostatic effects of ten broad-spectrum fungicides on gray mold were tested on plate bacteriostasis,and four fungicides,i.e.,iprodione,thiophanate-methyl,difenomethacin,and polyoxin with good bacteriostatic effects were screened out,and field trials were conducted as well.The prevention and control test found that these four fungicides can effectively inhibit the occurrence of gray mold,of which difenoconazole has the best effect on the prevention and control of postharvest gray mold when fungicides were at the same concentration.5.A real-time fluorescent quantitative PCR reaction system was develop to detect the occurrence of gray mold on cut chrysanthemum,a pair of primers BC-F and BC-R specific for gray mold(Botrytis cinereal)pathogens of cut chrysanthemum were successfully developed,which could discriminate Botrytis cinereal from the 9 species of pathogens occurred on chrysanthemum,such as sclerotinia sclerotiorum,black spot disease(Alternaria spp).,fusarium wilt(Fusarium oxysporum),and stem rot.This method could detect the DNA of Botrytis cinerea at the lowest concentration of 1 pg/μl.