Postharvest Benzothiadiazole Treatment Promotes Wound-healing Of ’zaosu’ And ’huangguan’ Pears

Decay is an important cause of postharvest loss of pears.All rot-causing pathogens can invade through the wound on the surface of the fruits.Therefore,it is necessary to take measures to reduce wounds on the surface of pears.In this paper,two pear cultivar,’Zaosu’and’Huangguan’,were used as test materials.After artificial wounded,the fruit were treated with benzothiadiazole（BTH）at 100mg/L for 10min,then stored in normal darkness condition（20-25^oC,RH 75-85%）.The effects of BTH treatment were studied on wounding-healing of fruit,as well as the changes of enzyme activities and products content related in phenylpropanoid,active oxygen and energy metabolism.The results showed as below:1.BTH treatment significantly reduced the decay incidence of’Zaosu’and’Huangguan’fruit inoculated with Penicillium expansum,which were 48.4%and33.3%lower than the control on the 4th in wound-healing.The treatment decreased the weight loss of wounded fruit to a certain extent,however,there was no significant difference compared with the control.The decay incidence indicated that BTH treatment promoted wound-healing of harvested pears,’Zaosu’pears performed better.2.The treatment significantly promoted the accumulation of suberin polyaliphatic（SPP）,suberin polyphenolic（SPA）and lignin at wounded sites of pears.After 4th in wounding-healing,the amount of SPP and SPA accumulation of’Zaosu’and’Huangguan’pears was significantly higher than the controls.The accumulation of lignin of treated fruit was also significantly higher in the mid and late wound-healing than the control.In addition,the treatment also significantly increased L*,and reduced a*and b*values at wounded sites of’Zaosu’pears.3.The treatment inhibited the excessive accumulation of O₂^-.and H₂O₂ at wounded sites,increased the activity of superoxide dismutase（SOD）,catalase（CAT）and peroxidase（POD）,and enhanced the polyphenol oxidase（PPO）of the’Huangguan’pears.On the 4th day after wounded,SOD activity of treated pears was significantly different from the control.POD activity of’Huangguan’and’Zaosu’pears peaked on the 2nd and 4th of wound-healing,and significant higher than the control.4.The treatment significant increased the activity of phenylalanine ammonia-lyase（PAL）,cinnamate-4-hydroxylase（C4H）,and 4-coumaryl-CoA（4CL）at wounded sites of pears,and enhanced the cinnamyl alcohol dehydrogenase（CAD）of’Zaosu’pears.On the 6th day of wounded,PAL activity of’Zaosu’pears reached the peak,and on the 4th day of wounded,4CL activity of two cultivar reached the peak.Meanwhile,the treatment promoted the accumulation of total phenols,flavonoids,and lignin at wounded sites of pears,’Zaosu’pears had higher accumulation than’Huangguan’pears.5.The treatment increased the content of ATP,ADP,AMP and level of energy charge at wounded sites of pears.BTH also inhibited the respiratory rate and ethylene release of’Zaosu’pears.On the 6th day of wounded,the maximum difference was found between the treatment and the control.There was no difference on respiration rate between two cultivar,however,’Zaosu’pears had higher the amount of ethylene released.It is suggested that post-harvest treatment with BTH significantly promotes the wound-healing of pear fruit,which is related with promoting the metabolism of phenylpropanol,eliciting antioxidant enzyme activities and increasing energy levels.’Zaosu’pears performs better with BTH treatment.