Comparative agricultural studies on the cropping system

本项目对泰国不同种植系统进行生理生态学研究，旨在根据其系统和相关小气候，确定不同气象条件和作物生产方式下各系统的特征。调查了清迈、孔庆、邦艾、甘榜盛、罗永和合艾等单作或间作果树、芒果、龙眼、红毛丹、酸橙、榴莲等的地区和果园。利用冠层或裸地温湿度记录仪分别测量了各果园的小气候，并在雨季和旱季以单叶为单位估算了光合作用活性。结果表明，单作和间作果园的平均温度和最高温度均低于裸地，而最低温度无显著差异。果园保持高湿度；平均和最大相对湿度高于裸地。如上所述，室内小气候取决于种植制度的类型及其组合。单叶饱和点光强旱季为800 ~ 1000 μmol m-2s-l，丰季为800 ~ 1400 μmol m-2s-l。无论旱季还是雨季，不同象限和位置叶片的光合活性均无差异。它们在低饱和度pct下的CERs在3.5 ~ 10之间。旱季为L μmol m-2s-l，雨季为5.5 ~ 17.81 μmol m-2s-l；除红毛丹外，本次调查中使用的所有红毛丹树均表现出上述趋势。无论何种果树，CER与气孔导度均呈高度正相关，空气湿度可能是影响热带果树气孔开度的重要因素，在任何季节都会影响CER。

This project was made on physio-ecological research for various crcppmg systems in Thailand ainimg to determine the characteristic of each system under different meteorological condition and crop production methods on the basis of their systems and related microclimate. The following regions and orchards under either mono cropping or intercropping system incorporated with fruit trees, mango, longan, rambutan, lime, durian, and so forth, were surveyed : Chiang Mai, Khon Kaen, Bang Yai, Kampheng Saen, Rayong and Hat Yai. The microclimate of each orchard was successively measured by temperature and humidity data logger employed on canopy or bare field, and the photosynthesis activity was also estimated based on individual leaf at rainy- and dry-season. As results, the average and maximum temperatures in orchard irrespective of mono- or intercropping were lower than a bare field, while minimum temperature did not differ from each. High humidity was maintained in case of orchards ; the average and maximum relative humidities were left higher than a bare field As mentioned above, an interior microclimate, depends upon the type of cropping system and its combination.The light intensity at a saturation point of individual leaf was 800-1000 μmol m-2s-l during dry season, and 800-1400 μmol m-2s-l during rany season. No difference in photosynthesis activity among leaves at different quadrant and position was found regardless of dry- or rainy season. Their CERs at a light saturation pcdnt were, at range of 3.5 to l0.l μmol m-2s-l during dry season, and 5.5 to 17.81 μmol m-2s-l during rainy season ; all firot trees used in this survey showed the tendency above with one exception of rambutan. There was high positive correlation between CER and stomatal conductance irrespedive of kind offruit trees, and it is likdy that air moisture can sway the CER of tropical fruit trees as an important factor affecting the stomatal aperture during any season.