Breeding And Resistance Evaluation Of Hybrid F1 Of Benihoppe × Resistant Varieties To Continuous Cropping Obstacle Of Strawberry

Continuous cropping obstacle not only affect the yield and quality of strawberry,but also seriously restrict the sustainable development of strawberry production.In this study,the strawberry hybrid F1 strain was obtained by conventional hybridization techniques with resistant varieties“Sweet Charlie”,“Flange”and susceptible variety“Benihoppe”as parents.Taking p-hydroxybenzoic acid,an autotoxic substance,and Fusarium oxysporum Schl.f.sp.fragariae as the selection pressure,the seedling emergence rate,growth development,root exudates and growth characteristics of the hybrid F1 population were determined by laboratory and field experiments,and then the resistance to continuous cropping obstacle was comprehensively evaluated.This study laid a foundation for the cultivation of new strawberry lines or varieties with the characteristics of high yield,excelent quality and resistance to continuous cropping obstacle,and provided new ideas or methods for the innovation and utilization of other crop germplasm resources with resistance to continuous cropping obstacle.The main results were as follows:1.The seed setting rates of“Benihoppe×Sweet Charlie”and“Benihoppe×Flange”were 47.1%and 54.5%,respectively,and the germination rates of hybrid F1 were 41.8%and 52.2%respectively with the emergence rates of 3.1%and 2.9%respectively.The seed setting rates of“Sweet Charlie×Benihoppe”and“Flange×Benihoppe”were 66.7%and35.0%,respectively,and the germination rates of hybrid F1 were 62.5%and 57.9%,respectively with the emergence rates were of 40.1%and 30.4%,respectively.There was no significant difference in seed setting rate and germination rate of hybrid F1 with“Benihoppe”as female and male parent,but the emergence rate of hybrid F1 was significantly higher than that of the latter.2.The optimum screening concentration of p-hydroxybenzoic acid,was 100 mg kg^-1DW.Both single treatment with p-hydroxybenzoic acid and its synergistic treatment with Fusarium oxysporum and p-hydroxybenzoic acid significantly inhibited the growth of leaves,plant height and leaf number of hybrid F1 lines.After treatment with p-hydroxybenzoic acid,the overall resistance of hybrid F1 was better than that of“Benihoppe”.After combined treatment,the resistance of“Sweet Charlie×Benihoppe”,“Flange×Benihoppe”F1 were significantly better than that of“Benihoppe×Flange”and“Benihoppe×Sweet Charlie”.3.Three kinds of autotoxic substances including p-hydroxybenzoic acid,benzoic acid and vanillic acid were detected in the root exudates of hybrid F1 with a resistance to continuous cropping obstacle,but without phthalic acid,ferulic acid and syringic acid.The relative content of vanillic acid was 0.0017⁰.0058 mg·g^-1,significantly higher than p-hydroxybenzoic acid and benzoic acid.The content of vanillic acid in root exudates of“Sweet Charlie×Benihoppe”and“Flange×Benihoppe”hybrid F1 with a resistance to continuous cropping obstacle was lower than that of their parents.The contents of threonine,serine and arginine in root exudates of hybrid F1 with a resistance to continuous cropping obstacle were all significantly lower than those of their parents,and the decreasesd by 1.33-10.71 mg·kg^-1,22.25-123.70 mg·kg^-1 and 12.23-69.34 mg·kg^-1,respectively.The contents of aspartic acid and glutamic acid which inhibited the mycelial growth of F.oxysporum Schl.f.sp.fragariae were significantly higher than those of their parents,and increase were 2.54-4.58 mg·kg^-1 and 1.19-0.93 mg·kg^-1,respectively.4.The field plant morphology of hybrid F1 with a resistance to continuous cropping obstacles was similar to that of their parents“Benihoppe”.The color of leaves was dark green with slightly leathery texture.Plant height is between the parents.Fruit color was orange,red or crimson.Among the three dominant lines selected for resistance to continuous cropping obstacle,“Sweet Charlie×Benihoppe”1-21,“Flange×Benihoppe”2-5,2-12 and yield per plant were higher than that of“Benihoppe”.The theoretical yield was up to 22.53 t·hm^-2、22.65 t·hm^-2、22.97 t·hm^-2 respectively.Fruit firmness was 0.64kg·cm^-2,0.80 kg·cm^-2 and 1.24 kg·cm^-2 respectively,which was higher by 0.20-0.80kg·cm^-2 than that of the parent“Benihoppe”.Among them,the content of soluble solids was 15.4%in“Flange×Benihoppe”2-12,and was significantly higher than that of parents.