園藝作物之光合成及光呼吸測定方法之研究

Studies on the Method of Estimating Rates of Photosynthesis and Photorespiration in Horticultural Crops

開放密閉二用系統，以Beckman 864-21-2-3 IRGA及十時平臺式記錄器，作絕對值式測定之設計、裝配及運作方法均曾論列。標定用氣體之配製、室外高空清潔空氣之引入及過濾，送風通氣系統利用測微毛管閥加入CO2之方法、裝有隔熱水槽的照明系統的照度射、及同化槽之空調等均經討論。因為所用之IRGA對水汽不起反應，系統內之溫度問題會予考慮。十個大豆系統及三個莧栽培種之毛光合成P_G，淨光合成P_N，光呼吸（PIB, R_ L），暗呼吸R_D，及二氧化碳補從點（CO2CP）行等均經測定。證明此項設備憑PIB及CO2CP來檢定C3及C4光合成頗為理想。與光合率有關的因子，及供試驗用切葉之採取與調製，也曾加以討論。

Design, construction and operation of an open-closed reversible system equiped with a Beckman 864-21-2-3 IRGA and a ten-inch strip chart recorder for absolute measurement are described. The preparation of standard gases, the introduction of outside clean air and its filtration, methods of adding CO2 to the gas handling system by a micrometric capillary valve, irradiance and illuminance of the lighting system equiped with a water tank as a heat barrier, and air conditioning of the leaf chamber are discussed. The IRGA used in the experiment is insensitive to H2O vapor. Thus the humidity problem in the system is discussed. Ten soybean lines and three Amaranthus cultivars were studied for their gross photosynthesis P(subscript G), net photosynthesis P(subscript N). post-illumination burst (PIB, R(subscript L)), dark respiration R(subscript D)Z and CO2 compensation point (CO2CP). The equipment is ideal for identification of C3 and C4 photosynthesis by their PIB and CO2CP nature. Factors affecting the photosynthetic rates and methods of preparing the detached leaf samples are discussed.