Comparative agricultural studies on the cropping system

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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.