铁观音茶树的光合特性

PhotosyntheticCharacteristicofTieguanyingTeaPlant

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。

ThephotosyntheticcharacteristicofTieguanyincultivarteaplantleavesunderfieldconditionwasstudied.Theresultswereasfollows:NetphotosyntheticrateofTieguanyinwaslowerthanthatofMaoxie,Rougui,Benshan,HuangdanandFudingDabaicha.Thenetphotosyntheticrate(Pn)changedfromnegativeleveltopositivelevelattheleafageof510d.Attheageof3090d theleafPnofTieguanyincultivarmaintainedatahighlevelandreachedthehighestpointat90 dorso,andthenbegantofallslowlylateron.ThePnwashigherforleavesinmiddlepositionthanintopandbasicpositionsonthesamematureteashoot.Inthesameteaplant,Pnofupperleaveswerethebiggest,thenextwasthatoflowerleavesandthemiddleleaveswerethelowest.ThecurveofannualvariationofTieguanyinleavesphotosynthesisshowedtwopeaks,thefirstinMarchandthesecondinJune(thehighestlevel)andAugust,thePnkeptahighlevelfromMaytoAugust.ThediurnalvariationofPnshoweddifferentcharacteristicindifferentseasons,underdifferentweatherconditionsanddifferentleafages.Underfineweathercondition,thecurveofdiurnalvariationofPninspring(March)andinautumn(Septem