不同海拔高度对星油藤叶片特性、植株生长及种子成分的影响

Leaf Traits, Plant Growth and Seed Chemicals of Plukenetia volubilis Cultivated Along an Altitude Gradient

为了探讨不同海拔高度上星油藤植株生长和产量构成的差异,在西双版纳雨季,对4个海拔梯度（560、900、1 200、1 490 m）上栽培的星油藤（Plukenetia volubilis）进行了叶片光合与解剖、植株生长与种子成分的观测。结果表明：不同海拔高度的星油藤叶片的最大净光合速率差异不显著;高海拔（≥1 200 m）叶片的气孔导度和呼吸速率值显著小于低海拔（〈1 200 m）,但水分利用效率较高。叶片上下表皮的气孔密度随海拔升高均显著减小,而叶片厚度和气孔大小的变化则不显著。单株的总生物量、果实生物量、地上部生物量、地下部生物量和叶面积指数均随海拔的升高而减小,比叶面积和比根长则随海拔的升高而增大。低海拔（560 m）星油藤具有较大的根茎叶非结构性碳水化合物（NSC）含量以及氮和NSC库,较高海拔（900~1490 m）植株则存在不同程度的碳源供应不足。不同海拔高度星油藤种子的NSC、脂肪酸、蛋白质和多酚含量差异不显著。试验结果表明,不同海拔高度星油藤生物量的差异主要由植株冠层碳源供应不足造成;雨季种子产量随海拔升高而降低,但种子的品质没有显著差异。

Leaf photosynthesis, anatomical structure, plant growth and seed chemical compositions in the rainy season were measured in Plukenetia volubilis cultivated along an altitude gradients（560, 900, 1 200 and 1 490 m）in Xishuangbanna, in order to unravel the differences of P. volubilis plant＇s growth and the yield component between different altitudes. The results showed that the maximum net photosynthetic rate had no difference between the four altitudes, while the stomatal conductance and respiratory rate were significantly lower, and water use efficiency were higher in high altitudes（≥1 200 m） than those in low altitudes（1 200 m）. With an increase of altitude, the stomatal density decreased significantly, while stomata size had no difference in both adaxial and abaxial leaves. The total biomass, fruit biomass, aboveground vegetative biomass, underground vegetative biomass and leaf area index of plants decreased, while the specific leaf area and specific root length increased with the increasing of elevation. In 560 m, non-structural carbohydrates（NSC） content, nitrogen pool and NSC pool in roots,stems and leaves were the highest, which indicated that the plants in high altitudes（ 900-1 490 m） showed the growth limitation due to carbon source deficiency. No significant differences were observed in the content of seed chemical compositions（NSC, fatty acids, protein and polyphenol） between the four elevations. It is concluded that biomass and yield difference of P. volubilis along an altitude gradient was mainly attributed to carbon source deficiency. Seed chemicals of P. volubilis are relatively stable in the rainy season.