Adaptive strategies of reproduction in tropical fruit trees

为阐明热带水果生殖系统的适应性策略，对以下4个项目进行了研究；(1)开花季节，(2)与授粉和受精有关的花结构，(3)自交不亲和和无融合，(4)坐果潜力。泰国的气候条件，特别是降雨与季节性果实的生长周期密切相关，但在印度尼西亚，两者之间没有明确的关系，在适当的土壤水分控制下，通过施用生长调节剂，在商业果园中证明了人工调节反季节果实生产的诱导花。在泰国，氯酸盐的施用对龙眼开花有特殊的诱导作用，目前已在商业上用于淡季水果生产。详细研究了东南亚主要热带水果种的发育过程和花结构的特点。介绍了传粉和受精系统以及媒介昆虫的作用。结果表明，似乎存在许多花的结构和开花方式适合通过异花授粉形成种子的果种。自花授粉和异花授粉后，两种榴莲品种花柱花粉管行为均未发现明显的自交不亲和性，但需要更多品种的试验来进行推广。对山竹和山竹的无融合种子形成和果实发育进行了研究，并通过形态学观察揭示了山竹无融合的独特特征。旱季和雨季的变化通过土壤水分和光照条件影响局部果实的发育，本文以几种热带果树为研究对象，对其光合速率和同化物在果实位置上的分配进行了比较研究。光合速率因种而异，山竹发育缓慢与光合速率低有特殊关系。

To clarify the adaptative strategies of reproduction system in tropical fruits, the following four items were investigated ; (1) seasonality of flowering, (2) floral structure in relation to pollination and fertilization, (3) self-incompatibility and apomixis, and (4) fruit setting potential1. Climatic condition, especially rainfall in Thailand was closely related to growth cycle in seasonal fruiting species but no clear relationship between them was found in Indonesia Artificial regulation of flower induction for off-season fruit production was demonstrated in commercial orchard by application of growth-regulators under adequate soil moisture control. Chlorates application specifically induced flowering of longan fruits in Thailand, which is now commercially used for off-season fruit production.2. Developmental processes and unique features of floral structure in main tropical fruit species of Southeast Asia origin were investigated in detail. The system of pollination and fertilization and the role of vector insects were also described. It revealed that there seem to exist many fruit species whose floral structure and mode of flowering fit to form seeds by cross pollination.3. No clear self-incompatibility was found in two Durian cultivars in terms of pollen tube behavior in the styles after self- or cross pollination, but more cultivars should be tested to generalize. Apomictic seed formation and fruit development were surveyed with mangosteen and Lanceum(langsat and duke) and an elaborate morphological observation revealed the unique feature of apomixis in mangosteen.4. As alteration of dry and rain seasons influenced development of topical fruit through soil moisture and light condition, a comparative study of photosynthetic rate and assimilate assignment to fruiting position was conducted using several tropical fruit species. Photosynthetic rate varied with species and the slow development of mangosteen was specifically related to low photosynthesis.