Preharvest BTH Treatment Induces Resistance In Fruit Of Muskmelon

Two muskmelons cultivars(cvs . Yindi and Huanghe-mi)was utilized as experimental objects in this paper.The possibility of preharvest BTH treatment that induced resistance was investigated in muskmelons,and the physiological mechanism was studied in this paper.The results indicated as below:1.The total latent infection rate and infection rate of two major fungi(Alternaria alternata and Fusarium sp)was reduced effectively with preharvest BTH treatment . The latent infection rate decreased with increasing of spraying times.Results showed that the four times of treatment by BTH is the best.In addition,disease incidence and lesion area of muskmelon inoculated with T.roseum could be controlled effectively by preharvest BTH treatment in the period of storing.2.Treatment of preharvest BTH enhanced activity of peroxidase(POD),poly-phenoloxidase(PPO),phenylalanine ammonia-lyase(PAL),4-coumarate:CoA Ligase(4CL),β-1,3-glucanase(GLU)and chitinase(CHT)in muskmelon,it also resulted in an increase of content of total phenolic,flavanoid,hydroxyproline-rich glycoprotein(HRGP)and lignin.Above-mentioned activity of defense enzyme and content of resistance—disease substances gradually increased along with BTH treatment times.In addition,treatment of preharvest BTH increased significantly production of H2O2 and activity of CAT and better effect was obtained by more times of BTH treatment.3.The preformed antifungal compounds was increased in melon's peel after treatment with BTH.It was found that compounds were increased with increasing of spraying times through TLC and bioassay identification.4.The array of cell became tighter and thickness of cell wall increased by preharvest treatment with BTH.Karyotheca and nucleus were kept comparative integrity in the cell treated with BTH.5.Preharvest BTH treatment was not obvious effect for firmess and the soluble...