银杏实生树与嫁接树光合特性的比较

 对银杏实生树与嫁接树的光合特性及日变化进行了比较研究。结果表明：实生苗嫁接树和二次嫁接树的最大净光合速率、光饱和点和日光合产物积累量均显著高于实生树，这与嫁接提早银杏结果密切相关。嫁接后光合能力的提高与其比叶面积低，单位面积氮含量高有关；但其光合氮利用效率显著低于实生树。实生树与嫁接树光合速率和气孔导度日变化均呈“双峰”型。光合速率的“午休”与强光、高温和低湿度有关，实生树“午休”的原因主要是非气孔限制，两种嫁接树主要是气孔限制。

Comparative on the Photosynthetic Characteristics of Grafted and Seeded Ginkgo biloba L.

The photosynthetic and physiological characteristics, and diurnal variation of photosynthesis in leaves of grafted and seeded Ginkgo biloba were studied. The results showed that: 1) Maximum net photosynthetic rate(Pn), the light compensation point and the diurnal photosynthetic production yield of the grafted and double-grafted Ginkgo biloba were significantly higher than those of Ginkgo biloba seedling, which contributed to their prematurity and great yield. 2) The higher photosynthetic capacity of the grafted and double-grafted Ginkgo biloba was associated with their lower specific leaf area and higher leaf nitrogen per unit leaf area; However, their photosynthetic nitrogen-use efficiency was lower than that of Ginkgo biloba seedling. 3) The diurnal variation of Pn and stomatal conductance were ‘two-peaked’ curves. The rapid reduction of Pn at midday was due to high light, high temperature and low relative humidity, the main cause of which in Ginkgo biloba seedling was due to stomatal restriction factors, whereas, which was due to non stomatal restriction factors in grafted and double-grafted Ginkgo biloba.