The Effect Of Hydrogen Cyanamide On Dormancy Release And Flower Organs Development Of Sweet Cherry In Warm Winter Region

Since 1980s, sweet cherry has been brought to and cultivated in Shanghai from Yiantai and Dalian time from time. However, it always performed unconformable symptoms, such as delayed bud break and flowering, abnormal flower organs, low fruit set, and so on. So far, none profitable orchard of sweet cherry has been built successfully in Shanghai. The lack of chilling during winter leading buds failed to release from dormancy probably is the main reason of this phenomenon. The effect of hydrogen cyanamide on dormancy release and flower growing of sweet cherry in Shanghai region was synthetically evaluated through the estimate of chilling and heat requirements, anatomical observation of flower buds progression, testing of the content change of protein and carbohydrate in shoots, using Summit and Hongdeng sweet cheery varieties and compared to the ones from normal economic garden in Taian of Shandong province. The object of this study was to provide some basis for economic cultivation of sweet cherry in Shanghai region. The essential results are follows:(1) The chilling requirement of Hongdeng sweet cherry was about 1200h by the artificial chilling treatment, which cannot or hardly be satisfied in Shanghai area because 1200h was always beyond the reach of the chilling accumulation of Hongdeng in the field of Shanghai calculated by 0-7.2℃model.(2) Hydrogen cyanamide advanced the dormancy release and bud break of sweet cherry in warm winter area, especially to Hongdeng cultivar which needs high chilling requirement. After the treatment of hydrogen cyanamide, the date of dormancy break and germination was brought forward 3-4 days in Summit, while sprout moved up 9 days in Hongdeng.(3) 6, 3 and 0 days before full bloom, the development of nucellus stagnated in the mother cell macrospore and macrospore stages and abortion ratios reached 13%, 15% and 45% respectively in Hongdeng sweet cherry cultivated in the field of Shanghai. However, its abortion ratio of microspore was only 4%.Moreover, 18-0 days before full bloom, the rate of ovule and embryo sac development of sweet cherry in shanghai nature area was slower than the ones of hydrogen cyanamide treatment and cultivated in Shandong area, while its rate of microspore was normal.(4)The contents of soluble protein and sorbitol were minimized in hydrogen cyanamide treatment and unsettled shoots, 36 days and 27 days before bloom separately; 54-36 days before full bloom, the content of glucose increased obviously in both the two treatments. After the treatment of hydrogen cyanamide, there was a distinct difference between the treatment and the control and the former was lower than the latter, from which it is clear that hydrogen cyanamide accelerated the translation and transportation of sorbitol.