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在田间条件下研究了铁观音品种叶片的光合作用特性。结果表明：铁观音叶片的净光合速率（Ｐｎ）比毛蟹、肉桂、本山、黄、福鼎大白茶等品种低；展叶后５～１０ｄ，Ｐｎ开始转为正值，３０～９０ｄ的叶龄叶片的Ｐｎ维持在较高的水平上，９０ｄ左右达到最大值，而后缓慢下降；同一成熟新梢上，中间的叶片Ｐｎ高，顶部与基部低；同一植株上，上部叶片Ｐｎ最高，下部叶片其次，中部最低。铁观音叶片Ｐｎ年变化呈双峰曲线型，第一高峰出现在３月，第二高峰在６月（最高）和８月，５～８月Ｐｎ均维持较高水平。不同季节、不同天气、不同叶龄叶片Ｐｎ的日变化也不同：在春季和秋季的晴天都是双峰曲线型，一天中１０时和１４时最高，低谷在１２时左右，有明显的“午休”现象；秋季多云天“午休”现象不明显，阴雨天Ｐｎ较低，且只有一个高峰；随着叶龄增大，Ｐｎ的日变化逐渐趋缓。
The photosynthetic characteristics of leaves of Tie Guan Yin were studied under field conditions. The results showed that the net photosynthetic rate (Pn) of Tieguanyin was lower than that of Crab, Cinnamon, Bonsan, Huangpi and Fuding Dabai Tea. Pn began to change to positive value 5 to 10 days after leaf unfolding, In the same mature shoots, the middle leaves Pn high, the top and the bottom of the lower; the same plant, the upper leaves Pn the highest, the lower leaves Second, the lowest in the middle. The annual variation of Pn in Tieguanyin was bimodal curve, with the first peak appearing in March and the second peak in June (the highest) and in August and the May to August Pn all maintained a high level. The diurnal variations of Pn in different seasons, weather and leaf ages were also different: the bimodal curves were in the sunny days in spring and autumn, with the highest at 10 o’clock and 14 o’clock in the day and the trough was around 12 o’clock with obvious “ The phenomenon of ”midday break" was not obvious on cloudy days in autumn, Pn was low on rainy days, and there was only one peak. With the increase of leaf age, the diurnal variation of Pn gradually decreased.