Study On The Flower Bud Differentiation And The Change Of Endogenous Hormones In Chestnut

Chestnut(Castanea mollissima BI.) is an important kernel tree in our country.The cultivation of chestnut has a long history and the chestnut has been widely planted in many areas of northern China.Chestnut production of our country was 800,000 tons in 2004, accounting for 71.7% of world total production. For a long time, although the chestnut cultivation technology in China has accumulated rich experience, but its output remains low. Overall, male flower of chestnut is excessive, but the female flower is insufficient, the proportion of female to male flowers usually reach to 1:2000 to 1:3000, which has became a major constraining factor for chestnut production.Therefore,the research on the flower bud differentiation and selection a technology of controlling flower bud differentiation are crucial.The different differentiation flower buds of three wide planted chestnut cultivars"Taishanyihao","Shifeng", and"Dahongpao"as research objects,this paper studied the relationship between endogenous hormone(ZT,GA3,IAA and ABA) and the flower bud differentiation by the paraffin cut method and the the high performance liquid chromatography in order to revealing and reasonablely adopting related technology to control the flower bud differentiation.The main results are as follows:1. The crucial differentiation stages of flower bud of chestnut on northern slope of Qinling Mountains were the pre-winter and post-winter younger shoot differentiation stage.The progress of the female flower bud differentiation can be divided into pre-winter inflorescence primordium differentiation stage(September 15th to November 15th), dormancy(November 15th to next January 15th), post-winter inflorescence primordium differentiation stage(February 1th to March 1th), flower clusters bract primordium differentiation stage and flower cluster primordium differentiation stage(March 1th to early April).Pre-winter and post-winter inflorescence primordium differentiation stage make a great impact on flower bud differentiation. 2. In the progress of the flower bud differentiation, the content of ZT had a curve with two peaks.ZT content kept a steady upward after mid-September, and then reached the first peak at mid-November,after that ZT content decreased rapidly and dropped to the lowest level during the dormancy. ZT content rapidly increased after dormancy and reached the second peak at mid-January(next year).The ZT content kept a steady upward in the differentiation stage of pre-winter inflorescence primordium.3. In the progress of the flower bud differentiation, the content of GA3 just like a'M'.GA3 content gradually increased after mid-September and reached the first peak at pre-winter inflorescence primordium differentiation stage,after that GA3 content decreased rapidly and dropped to lower level during the dormancy. After dormancy,the content of GA3 rapidly increased and reached the second peak at post-winter inflorescence primordium differentiation stage.4. In the progress of the flower bud differentiation, the trend of IAA content was upward.The content of IAA gradually increased after mid-September and reached the max in the flower cluster primordium differentiation stage.5. In the progress of the flower bud differentiation, the content of ABA increased at first and then decreased slowly.ABA content increased rapidly after mid-September and reached the max at pre-winter inflorescence primordium differentiation stage.After this stage, ABA content decreased to a stable low level and maintained this level to flower cluster primordium differentiation stage.