Study On The Relationship Between Endogenous Hormone And It's Cold Resistance Of Kernel Apricot In Blossom And Fruit Period

Kernel apricot is an important kernel tree, which has been widely planted in many areas of northern China. A lot of large scale production bases has been established. However, as a result of its susceptibility to cold damage, the fruit yield decreased to nearly 30%～40% for the reason of flower and young fruits injured by the frost. Three wide planted kernel apricot cultivars Longwangmao, Youyi, and Baiyubian as research objects, this paper studied on the relationship between dynamic change of endogenous hormone and it's cold resistance of reproductive organs of kernel apricot in blossom and fruit period. Moreover the effects of exogenous abscisic acid on enhancing the kernel apricot resistance ability to frost be investigated. The main results are as follows:(1) A simple and rapid reversed phase high performance liquid chromatography method has been achieved for the determination of eight hormones in reproductive organs of kernel apricot for the first time, which include adenine, zeatin, gibberllin3, indole-3-acetic acid, 6-benzylaminopurine, colchicine, abscisic acid and indole-3-butyric acid. These ingredients were separated on a diamonsil (C18 column 150mm×4.6mm, 5μm), the mobile phase was composed of methanol/0.075% acetic acid (45/55; v/v). The detection was performed at a flow rate of 0.7mL/min, and detected at 254nm within 30min. Eight hormones were successfully separated from each other and their recoveries were in the range of 95.41%～103.48%.(2) In the development process from dormancy to bloom, the content of endogenous ABA of the reproductive organs had a curve just like a'M'. The content of endogenous GA3 of the reproductive organs had a curve just like a converse'V', which increased slowly at first and then went down quickly. The content of endogenous IAA in dormancy kept at a relatively high level and then dropped, but after blooming it increased again, and had a peak from then on. At the stage of dormancy and bloom buds swelling endogenous 6-BA kept at a low level, it increased rapidly at the stage of flower revealing, then decreased sharply again at early flowering stage.(3) The content of endogenous ZT kept at a stable high level at dormancy stage, then it decreased at all times. The content of endogenous IBA had a similar change trend with IAA. The content of endogenous adenine had a similar change trend with ZT. The content of endogenous colchicine kept at a low level at the stage of dormancy and bloom buds swelling, after flower revealing it increased quickly and had the biggest peak at early flowering stage, then it dropped sharply again.(4) The blossom and fruit period of kernel apricot was the dehardening period of cold resistance, from dormancy to bloom the cold resistance decreased. During dehardening period, the content of endogenous ABA, GA3, IAA, ZT and IBA were positively correlated with cold resistance under natural temperature. But the content of endogenous 6-BA, adenine and colchicines of reproductive organs were no correlation with cold resistance under natural temperature.(5) To spraying ABA could enhance the content of endogenous ABA and inhibit endogenous GA3, accordingly the rate of ABA/GA3 increased. Exogenous ABA could also enhance the activities of SOD and POD, the content of soluble sugar and soluble protein. It reduced the content of MDA, the membrane permeability, the electrolyte-leakage ratio and the lethal temperature of 50%. Then membrane structure Integrity was protected, that resulted in the enhancement of cold resistance of kernel apricot.