龙眼荔枝大幅度减产的气象原因分析及对策

Analysis on the Meteorological Factors Causing Heavy Yield Decrease of Longan and Litchi and the Preventive Strategies

树体、花序受寒（冻）害和花期高温干旱，是导致１９９６年广西龙眼荔枝大幅度减产的主要气象原因。在辐射天气条件下，若最低气温＜０℃，地面最低温＜－２℃时，幼苗和嫩梢发生不同程度的霜害；最低气温≤－２℃、地面最低温≤－４℃时，分枝和幼树主干发生霜害；最低气温≤－４℃时，大分枝甚至主干被冻死。在平流天气条件下，若全冬（１２～３月）＜１２℃的有害积寒＞８０℃·ｄ、最强一次平流积寒＞４５℃·ｄ，花序和嫩梢易受寒害死亡。花期高温干旱，使授粉受精不良，是导致果实严重败育的主要原因。针对上述问题提出了相应对策。

Low temperature in inflorescencing time and hot dry weather in blossoming time are the critical factors caused heavy yield decrease of Longan ( Euphoria Longana Stead) and Litchi ( Litchi chinensis Sonn) in 1996. In the radiation weather in which the minimum air temperature (MAT) is below 0℃ and the minimum landsurface temperature (MLT) is below -2℃, the seedlings and young shoots of longan and litchi are injured to different degrees by freeze; and in the weather in which MAT is below -2℃ and MLT is -4℃, most stems of trees are frozen to death. In cold weather in which the accumulated harmful temperature (<12℃) (AHT) from December to next March is >80℃·d and one of the AHT is >45℃·d, inflorescences and young shoots are easily injured to death. During the blossoming period, hot dry weather caused poor pollination and fertilization and consequently resulted in fruits blasting. So, better cultivars popularization, strong production management and necessary counter measures, are the strategies to resolve the above problems.