基于生长期和累积生长度日的龙眼果树催花法

Growth-Stage and Cumulative Growing Degree-Days Based Longan Tree Flowering Induction

龙眼树开花少和座果效益低是全球范围内热带水果生产最突出的共性问题之一。龙眼(Dimocarpus longan)是主要的热带名特优水果,危及龙眼产业生存的主要原因在于冬季早春气候变暖,不能满足花芽分化所需要的低温,龙眼树无法扬花。本研究目的是利用龙眼树的生长期和累积生长度日(cumulative growing degreedays,CGDD)进行适时花器官生长诱导以及检验催花肥氯酸钾(KCl O3)的催花效率。试验起始于2012年夏季,地处热带海南岛北部,试验地土壤为酸性沙质红壤(p H5.43±0.49),龙眼树品种是国内主栽品种‘石硖’。修剪矮化后,在新梢生长起始时开始计算CGDD值,依据龙眼生长期季节性累积CGDD值进行催花处理。结果表明:CGDD为1 650℃时可使用多效唑(PP333)诱导中止梢枝营养生长,CGDD为1 850℃时可使用复合型细胞分裂素GA3使龙眼营养生长集中向花器官生长转化;CGDD值为2 150℃时龙眼花开始萌芽,CGDD为2 850℃时开花;依据生长期CGDD进行的催花处理(每株根施0.60 kg KCl O3,加少量叶营养肥KH2PO4)显著地促进了龙眼树生理光合作用和花芽分化(p<0.05)。本研究开发了基于生长期CGDD的综合使用催花肥-植物生长调节剂-叶营养素的催花配套技术,为在冬季气候变暖环境条件下有效地诱导龙眼树开花和座果提供定量信息,有助于龙眼生产的可持续性发展。

Longan（Dimocorpus longan）, a major tropical fruit crop, unreliable flowering and fruit-bearing due to increased temperatures in the winter are the common concerns in tropical fruit production in the world today. As longan trees need relatively low-temperatures to meet its chilling requirements, high winter temperatures inhibit its flower bud formation and differentiation. Our objectives were to assess the efficiency of cumulative growing degree- days（CGDD）in guiding longan tree flower induction procedures using chemical applications（oxidant KClO3）and to examine the correlations of longan tree physiological aspects. The field experiment was started in the summer of 2012, using popular cultivar（cv. ＇Shixia＇）trees grown in an orchard situated in the north of tropical Hainan Island. The soil was a sandy, acidic red soil（pH5.43±0.49）. The experimental treatments for longan flower induction were applied based on the seasonal CGDD values. At CGDD 1 650 ℃ plant top growth could be inhibited using growth regulator PPm. At CGDD 1 850 ℃ plant growth could be transformed into flower organ growth using plant growth regulator GA3. The results showed that longan tree flower budding occurred at CGDD 2 150 ℃ and full blooming showed up at CGDD 2 850 ℃. The relatively low rate （0.60 kg KClO3 per tree） plus leaf nutrient KH2PO4 applications at flower organ growth stage resulted in significantly higher flowering induction and higher leaf photosynthesis and carbonxylation efficiency compared to the control（p〈0.05）. The growth--stage and CGDD-based method was innovative for longan tree flower induction. The results had the implication in longan tree flowering regulation, which could be helpful for promoting sustainable tropical fruit production under winter warning climate conditions.