平潭岛海岸三种典型沙生植物非结构性碳水化合物含量特征研究

非结构性碳水化合物(non-structural carbonhydrate,NSC)作为光合作用的主要产物,其含量多少可反映植物整体的碳收支平衡关系及对外界环境胁迫的适应策略。该研究采用改进的苯酚-浓硫酸法对福建省平潭岛海岸处于生长旺盛期的3种典型沙生植物木麻黄、单叶蔓荆和老鼠艻茎叶的NSC及其组分含量进行测定。结果表明:(1)单叶蔓荆叶片、茎干可溶性糖含量均最大,分别为(137.83±3.75)、(90.74±2.65)mg·g~(-1),老鼠艻叶片、茎干淀粉含量均最大,分别为(105.41±2.49)、(120.48±7.67) mg·g~(-1),二者茎叶NSC含量均大于木麻黄,且全部达到显著水平(P0.05)。(2)沙堆表面老鼠艻叶片NSC及组分含量从雏形、发育到稳定阶段变化不明显,但茎干NSC及组分含量在雏形阶段沙堆表面显著大于其他两个演替阶段(P0.05),且依次呈现下降趋势。(3)从幼龄林、中龄林到成龄林阶段,木麻黄NSC含量呈现先上升后下降趋势,其中成龄林叶片可溶性糖、淀粉和NSC含量、茎干可溶性糖和NSC含量均显著低于其他两个生长阶段(P0.05)。(4)不同沙生植物对环境胁迫的适应策略各异,海岸沙丘表面植被恢复应充分考虑物种特性及其更新。

Variations of non-structural carbohydrate contents in three typical psammophytes in the coast of Pingtan Island

As the dominant products of photosynthesis, non-structural carbohydrate(NSC)contents can be used to indicate the carbon balance of plants and their adaptation strategies under environmental stresses. Three typical psammophytes at the fast growing stage, including Casuarina equisetifolia, Vitex trifolia var. simplicifolia, Spinifex littoreus in the coast area of Pingtan Island, Fujian Province, were selected and their NSC contents in leaf and stem were determined by an improved phenol-sulphuric acid method. The results were as follows:(1)Soluble sugar contents were the largest in both leaf and stem of Vitex trifolia var. simplicifolia,(137.83 ± 3.75)and(90.74 ± 2.65)mg·g^-1 respectively, while starch contents were the largest in both leaf and stem of Spinifex littoreus,(105.41 ± 2.49)and(120.48 ± 7.67)mg·g^-1, respectively, and NSC contents in above two species were all significantly larger than those in Casuarina equisetifolia(P<0.05).(2)The NSC and its components contents in leaf of Spinifex littoreus on the coppice dunes from rudimental period, developmental period to stabilized period showed no obvious trends, while decreasing trends were observed in its stem along the succession gradients, in which NSC and its component contents of S. littoreus on the coppice dunes in rudimental period were significantly larger than those in other two succession stages(P<0.05)and showed a decreasing trend.(3)From the young-aged, middle-aged to old-aged growth period, the NSC and its component contents in leaf and stem of Casuarina equisetifolia firstly demonstrated an increasing trend, then followed by a decreasing trend. The soluble sugar, starch and NSC contents in the leaf, soluble sugar and NSC in the stem of old-aged C. equisetifolia all suggested more significant lower contents than them in other two growth periods(P<0.05).(4)Species specific characteristics and its regeneration should be fully considered in the vegetation reestablishment in coastal sand dune ecosystems, due to the different adaptation strategies of species under various environmental stresses.