Influence Of Plant Growth Regulating Substances On Biological Features Of Flowering In Apricot

Early flowering Armeniaca vulgaris, frequently inflicts its floral organs and young fruits to cold damage because of the lower climate, which of itself leads to large amount of flowers and fruitlets drop and reduce the yield and quality. In production practices, people regard flowering delay as an effective method to avoid the adverse early-spring weather, such as frost, coldness and so on. Besides environmental factors, GA3is the most important endogenous factor to regulate flowering induction, and GA3is one of the most effective approaches to control artificially flowering induction, which has become a focus in domestic and international research of flowering induction in recent years. Moreover, certain mass concentrations of GA3can make fruit trees get rid of spring chill or decrease its damage by putting off flowering phrase. Therefore, we made paraffin section and detected the endogenous contents of polyamines (including PUT, SPM and SPD) with Chuanzhihong, Yinxiangbai and Kuerletuoyong apricot buds sprayed with GA3of different mass concentration (25mg/L,50mg/L,75mg/L and100mg/L).In addition,there is high occurrence rate of hercogamy in apricot. Therefore, it is difficult to gain high yield and good quality in apricot industry, if orchard workers only depend on open pollination of apricot. Now people often collocate pollenizers or conduct artificial supplementary pollination. In order to enhance the efficiency, some substances are applied that can facilitate pollen germination and pollen tube growth, such as boric acid, sucrose and plant growth regulators. However, there is blindness in two aspects of types and concentration of plant growth regulators. In this study the pollen number per anther pollen germination rate and pollen tube growth of ten apricot cultivars including seven fresh apricot varieties、two almond apricot varieties and one apricot-plum hybrid were tested in solid culture medium of15%sucrose and1%agar and0.03%boric acid, and the percentage of full-grown flowers were investigated. And on that basis, effects of different plant growth regulators on pollen germination and pollen tube growth in three apricot cultivars (Shajinhong, Jintaiyang and Huanghongyike) were studied. Moreover, certain mass concentration of GA3can make fruit trees get rid of spring chill or decrease its damage by putting off flowering phrase. Therefore, we also made paraffin section and detected the endogenous contents of polyamines (including PUT, SPM and SPD) with Chuanzhihong, Yinxiangbai and Kuerletuoyong apricot buds sprayed with GA3of different mass concentration (25mg/L,50mg/L,75mg/L and100mg/L). We hope to provide scientific basis for properly using types and concentrations of plant growth regulators and selecting pollenizers in apricot cultivation.The main results are as follows:1. There were extremely significant differences in the pollen number per anther、pollen germination rate、pollen tube growth and the percentage of full-grown flowers of various apricot cultivars. And the pollen number per anther and the percentage of full-grown flowers significantly differed from each other because of different fruit types (Fresh, Almond and Apricot-plum hybrid).The pollen number per anther significantly correlated with pollen tube growth(r=0.417, p<0.05), but there was no significant correlation between pollen germination rate and the percentage of full-grown flowers;The correlation between pollen germination rate and pollen tube growth was extremely significant(r=0.691, p<0.01),and the correlation between pollen germination rate and percentage of full-grown flowers was negative but not significant.Further investigation on the pollination value of different peaches was performed based on cluster analysis. The apricot cultivars with larger pollen number and longer pollen tube which were suitable for pollenizers included Chuanzhihong, Shajinhong, Jintaiyang and Huanna; the apricot cultivars with lower pollen number, shorter pollen tube and higher percentage of full-grown flowers which ought to need pollenizers included Konglongdan, Weidi, Suiliansihao.2. According to different kinds and concentrations of plant growth regulators, there were significant difference in pollen germination and tube growth in apricot; in the same conditions using plant growth regulators effects and effect intensity of pollen germination and tube growth varied because of various apricot cultivars. This study found several relatively appropriate mass or molar concentrations of some plant growth regulators to pollen germination and tube growth in apricot, respectively:Shajinhong:0.025mmol/L of SPM; Jintaiyang:0.05mmol/L of SPD and0.25mmol/L of PUT; Huanghongyike:20mg/L of GA3.3. The influence of GA3on flowering of apricot varied because of different concentrations of GA3or different apricot varieties.50mg/L,75mg/L and100mg/L of GA3 could remarkably reduce the contents of endogenous PUT, SPM, SPD in Chuanzhihong,Yinxiangbai and Kuelertuoyong apricot flower buds.When the concentration of GA3was25mg/L, there was not such effect.75mg/L and100mg/L of GA3could inhibit the morphodifferentiation of Chuanzhihong and Yinxiangbai apricot flower buds.When the the concentrations of GA3were25mg/L and50mg/L, GA3could not PUT off the periods of Chuanzhihong and Yinxiangbai apricot flower bud differentiation.Treated with the four concentrations of GA3used in this study, there were not marked changes of Kuerletuoyong apricot flower buds.Comparing with the controlled experiment,25mg/L of GA3could not significantly postpone florescence of Chuanzhihong and Yinxiangbai apricot. When the concentrations of GA3were50mg/L,75mg/L and100mg/L, there was a florescence delay of2-8days, but GA3could not lengthen the florescence. GA3could not delay the florescence of Kuerletuoyong apricot. The downside was that there were strong side effects of GA3on Yinxiangbai apricot, such as reduction of flower number, weakness of growth potential of long fruit branches. To sum up,75mg/L of GA3is suitable for Chuanzhihong apricot.