A Study On The Effects Of The Girdling On Promoting Flower Bud Formation Of The Hybrid Progenies In Pear

The two ground hybrid progenies F1 of Yuluxiang×hongsucui and Yuluxiang×mantianhong that have grown for three years were used as the materials to explore the effects of girdling on the flower bud formation and some physiological changes by girdling. In order to provide reference for shortening the juvenile phase of pear, the relationship between these physiological changes and flower bud differentiation was discussed. The effect of the girdling were monitored for two years to explore the continuous effects on promoting flower bud formation of the hybrid progenies F1 in pear.The main results were as follows:1.The effects of the girdling on the flower of the hybrid progenies in pearThe effects of girdling on the accumulation of dry matter in leaf, the percentage of flowering plant, the flower number of each tree, the juvenile phase and the juvenile span of the hybrid progenies F1 were investigated. The results showed that girdling can increase the dry matter content of the hybrid progenies F1 leaves. The leaf dry matter content in Yuluxiang×mantianhong were significantly higher than that in the control on June 19 and July 22, but in Yuluxiang×hongsucui were almost equivalent to that in the control. The percentage of flowering plant and the flower number of each tree were both increased significantly by girdling. The girdling could shorten the juvenile phase, but could not significantly affect the juvenile span.2. The effects of the girdling on the physiological and biochemical indexes of the hybrid progenies in pearThe soluble sugar, starch and nitrogen, phosphorus and potassium of the two pear hybrid progenies F1 leaf were measured The results suggested that a few days after girdling, the contents of soluble sugar and starch were higher than the control and there was a significant or extremely significant difference. But the contents of nitrogen, phosphorus and potassium were lower than the control. At an early stage of girdling, the period during which the carbohydrate accumulation increased and the nitrogen contents reduced obviously correspond to the period during which the physiological differentiation of pear flower bud emerged. Thereby it could be indicated that girdling can block the transportation corridor of the photosynthetic products. The increasing sugar and starch laid a foundation for the flower bud formation.3. The persistent effect of the girdling on the flower of the hybrid progenies in pearIn 2014, the four years old trees that have been girdled in 2013 were girdled again by the same approach, and marked it as H2. Nongirdling were kept as controls. One line of leaves that were girdled in 2013 but not girdled in 2014 were added and marked as H1 to investigate the effects of girdling on the concentrations of carbohydrates, N, P and K in leaves. The results showed that at the beginning of girdling, the soluble sugar and starch concentrations in leaves of girdled trees were higher than the control(CK). It also showed that girdling in the appropriate time could increase the contents of the sugar and the starch, which provided sufficient nutrients to the flower primordium and influenced flower bud formation. The concentrations of N、P、K in leaves showed that these three indexed in the H1 were higher than that in the H2 and the control and their contents in the H2 and the control changed alternately.4. The effects of the girdling on the flower formation rate by three consecutive years’ investigationAccording to the investigation of the flower from 2013-2015, the main results were as follows: very few number of 3 years of pear hybrid progenies F1 passed the juvenile phase. In 2014, the percentages of flowering of the control(CK) of four years old hybrid progenies F1 plants were improved slightly, but the flowering percentages of those girdled plants were increased significantly. In 2015, the number of inflorescence of H2 were signigicantly greater than that of the H1. The result showed that girdling in early May, which is just a period of the pear flower bud physiological differentiation, helped the offspring of pear hybrids changed from vegetative growth to reproductive growth, promoted the flower bud formation and shortened the juvenile phase.