田间茶树净光合速率及其生态生理因子的日变化

以铁观音茶树品种为试验材料，研究了茶树净光合速率（ Ｐｎ）及其生态生理因子的日变化．结果表明，不同季节、不同天气和不同叶龄叶片 Ｐｎ 的日变化不同．在春季和秋季的晴天 Ｐｎ 的日变化曲线都是双峰曲线型，一天中１１：００（春季）或１０：００（秋季）和１４：００ 最高，有明显的“午休”现象；秋季多云天“午休”现象不明显，阴天 Ｐｎ 较低，且只有 １ 个高峰；不同叶龄的 Ｐｎ 变化趋势相似， ３０ 天叶龄的叶片 Ｐｎ 大于老叶和嫩叶．茶树叶片光合能力变化受生态生理因子的影响，特别是主导因子的影响．经主成分和通径分析表明，光合有效辐射、叶温和气温是茶园生态系统的主导因子．生理因子中气孔导度对 Ｐｎ 的影响最大

Diurnal variations of net photosynthetic rate and its eco-physiological factorsof tea in the field

Tieguanyin, a tea cultivar, was used to study diurnal variations of net photosynthetic rate (Pn) and its eco physiological factors. The results were as follows. Diurnal variations of Pn varied in different seasons and weather and at different leaf ages. The curve of diurnal variation of Pn in spring (March) and in autumn (September) had two peaks in fine weather. The first peak appeared at 11 am (spring) or 10:00 am (autumn) and the second peak appeared at 14:00 pm which caused an obvious phenomenon of “midday depression”, but not so remarkable in cloudy days in autumn. In overcast days, however there was only a single peak with a low level of Pn. Pn at different leaf ages trended the similar diurnal variations and Pn in thirty day old leaves was higher than that in young or old leaves. The fluctuation of Pn was mainly affected by eco physiological factors, especally the dominant factors. According to path and principal component analysis, photosynthetic active radiation, leaf temperature and air temperature were the dominant factors in the field ecosystem. Stomatal conductance was the dominant physiological factor.