Effects Of Different Plant Growth Regulators On Parthenocarpy Of 'Dangshansu' And 'Starkrimson' Pear

Pear is a cross-pollinated plant.The pollination tree or flowering period artificial pollination is needed to achieve the purpose of high quality and high yield.But extreme weather conditions such as low temperature,storm and frost affect fruit setting and yield of pear tree.In this study,‘Dangshansu'and‘Starkrimson'pear were used as materials.The effects of different combinations of plant growth regulators on parthenocarpy of two varieties were studied in order to improve fruit setting rate,fruit quality and seedless pear production to provide the basis.The main results are as follows:1.Effects of different plant growth regulators on parthenocarpy of‘Dangshansu'pear.The fruit setting rate of mixed plant growth regulators treatment group was significantly higher than that of the control group.Gibberellic acid(GA₄₊₇)50 mg/L mixed paclobutrazol?PAC?1.47 mg/L had the highest fruit setting rate and when GA₄₊₇+7 50 mg/L mixed abscisic acid?ABA?100 mg/L was followed by the second.Seeds of artificially pollinated fruits mature and sepals fall off.In treatment group,parthenocarpy formed seedless fruit and sepals did not fall off.The single fruit weight of the treatment group was significantly lower than that of artificial pollination and the fruit stalk was significantly longer than that of artificial pollination.The content of soluble solids treated with GA₄₊₇+7 50 mg/L was not significantly different from that of artificial pollination.The content of soluble solids in fruit could be increased by mixed treatment.The content of soluble solids in mixed ABA 50 mg/L treatment was the highest,followed by mixed PAC 1.47 mg/L treatment.Both were higher than artificial pollination and GA₄₊₇+7 50 mg/L.With the concentration of ABA and PAC increasing,the content of soluble solids decreased.The treatment of GA₄₊₇+7 and its mixed ABA decreased the titratable acid content of fruit.2.Effects of different plant growth regulators on parthenocarpy of‘Starkrimson'pear.The fruit setting rate of fruit treated with melatonin?MT?23.228 mg/L mixed cytokinin?CPPU?for 20 mg/L was the highest,followed by mixed cytokinin?6-BA?100 mg/L,Both were significantly higher than that of artificial pollination.The fruit setting rate of GA₄₊₇+7 5mg/L mixed ABA 100 mg/L was lower than that of artificial pollination.In artificial pollination,mature seeds and sepals could be shed,handling parthenocarpy without seeds,MT 23.228 mg/L treatment could exfoliate sepals,and the other treatments could not exfoliate sepal fleshy.The fruit weight of fruit treated with GA₄₊₇+7 5 mg/L was the smallest.MT and GA₄₊₇+ABA treatment group ranked second together,but there was no significant difference between the other treatments.Compared with artificial pollination,the fruit stalk increased in each treatment group,and GA₄₊₇+7 5 mg/L+ABA 100 mg/L was the highest in treatment group.The maximum fruit shape index of MT 23.228 mg/L+GA₄₊₇+7 5 mg/L treatment was significantly longer than that of artificial pollination.The content of soluble solids in MT23.228 mg/L+6-BA 100 mg/L was the lowest and GA₄₊₇+7 5mg/L soluble solids content was the highest.The firmness of MT 23.228 mg/L+6-BA 100mg/L was significantly higher than that of other treatments.The titratable acid content of MT 23.228 mg/L+CPPU 20 mg/L treatment was significantly lower than that of other treatments.Treatment can increase edible rate of fruit,and it is significantly higher than artificial pollinationthat that is a control treatment.The edible rate of MT 23.228 mg/L+GA₄₊₇+7 5mg/L was higher than that of other treatments.