果实膨大生长和吸水与气候变化之间的关系

Fruit Expansion Growth in Relation to Water-uptake under Climatic Changes

田间和遮雨生长棚下,甜橙和荔枝果实在台风雨期间出现突发性猛长现象,而受胁迫果实的反响更加强烈。发现在果实猛长同时,果实的呼吸强度也上升。这些现象与大气的水蒸汽压亏(VPD)的明显下跌有关。乙烯利溶液浸果试验证明,果实吸水的增多与乙烯利促进呼吸作用有关。果实的膨大生长主要依赖于水分的进入,果实的吸水包括被动和主动两种方式,呼吸为后者提供能量。果实的吸水也与其本身的生长潜势有关。

Citrus and litchi fruit diameters were measured regularly and atmospheric vapour pressure deficits (VPD) were monitored. It was found that fruit diameter increased ab-ruptly in response to the drop of VPD during typhoon rain period, even when potted test trees were grown under a plastic roof to avoid additional water supply through both the root system and fruit surface. Daily net growth of fruit diameter ( DNG) and VPD was negatively correlated, and fruits once subjected to water stress responded to the drop of VPD more sensitively than did nonstressed ones. Significant DNG increment demonstrated in typhoon weather was also found accompanied by an unconventional rise of fruit respiration. Laboratory immersion test with litchi fruit in ethrel solution showed enhanced respiration which was paralleled by an increase of fruit water-uptake. The suggested diversion of water stream into fruit due to severe depression of leaf transpiration under low VPD is a sort of water-uptake mechanism, which is passive in na-ture. The respriation rise of fruit in typhoon weather and its obvious link with intensified water-uptake suggest that an active water-uptake by fruit must also be involved and of importance in the studies of fruit growth mechanisms.