Study On Flower Bud Differentiation Of Postharvest Shoots And Methods To Promote Flower Bud Differentiation Of Pear.Cv Guihua

In this study, nine-year-old trees of Pear cv.Guihua were taken as materials to study the following two aspects. (1) study on the flower bud differentiation process of postharvest shoots by means of paraffin method, (2) study the effects of different treatments (folia spraying with paclobutrazol, potassium nitrate or PBO and girdling) on the content of soluble proteins, carbohydrates and endogenous hormones in the leaves and the flower buds formation on postharvest shoots. The purpose of the study is to understand the law of the flower bud differentiation of postharvest shoots of Pear cv.Guihua and to find the best approach to promote flower bud differentiation of Pear cv.Guihua and provide a reference for the research of Pear cv.Guihua’s flower bud differentiation and high-yield cultivation. The results of the study indicated that:1. The process of flower buds differentiation of Pear cv.Guihua can be divided into undifferentiated stage, inflorescence differentiation, bud differentiation, differentiation calyx, petal differentiation phase, stamen differentiation and pistil differentiation. The beginning of morphological differentiation occurred in early September, the calyx formation period come in mid-October, the stamen formation appeared in early November and the pistil appeared in late November. The duration lasted about 100 days. The flower formation rate of buds on spurs was about 95% and started the period of bud morphological differentiation two and a half weeks earlier than the long shoots. The flower buds formed on the spurs were also the best in quality. Medium length and long shoots shared a similar rate of flower formation rate of 70%, but flower buds begin to differentiate later and buds quality is of general quality and easy to form a "degenerate flower bud".2. The soluble protein content in the leaves of postharvest shoots showed a trend of rising first and then decreasing during flower bud differentiation. The soluble sugar content was 1 to 2.5 times greater than the reducing sugar, but there was not significant different between the two. The content of starch did not change significantly from the undifferentiated stage to the calyx differentiation, but the rapid increase appeared after the beginning of petal differentiation stage. The maximum (29.75mg/g) appeared after the beginning of stigmas stage and then deceasing. The hormone content was in the order of ABA> IAA> ZR> GA3.The four kinds of hormones during flower bud differentiation showing a trend of " low-high-low "3. The leaf soluble protein, soluble sugar, reducing sugar and starch content increased if folia spraying with paclobutrazol, potassium nitrate or PBO or practicing girdling. Among which girdling significantly increased the soluble sugar, reducing sugar and starch content. Leaf soluble protein increased when folia spraying with paclobutrazol, PBO or potassium nitrate, bud girdling had little effect on the protein content. Four treatments increased the endogenous hormones in leaves (ABA, GA3, IAA and ZR), among which paclobutrazol significantly increased endogenous hormone content, PBO treatment had the least effects on the increasing of the four endogenous hormones.4. The number of flower bud of trees sprayed with paclobutrazol, potassium nitrate and PBO or girdling or control increased respectively. The treatments of spraying with PBO and paclobutrazol better effects.