样品预处理方法对海岸典型沙生植物非结构性碳水化合物含量测定的影响

Influence of sample pretreating methods on determination of non-structural carbohydrate contents in typical coastal psammophytes

关键词:  沙生植物, 非结构性碳水化合物, 去皮或未去皮, 过筛目数, 苯酚-浓硫酸法, 平潭岛

Key words:  psammophyte, non-structural carbohydrate, peeled or not peeled, mesh size, phenol-sulfuric acid method, Pingtan Island

摘要:

量化植物非结构性碳水化合物(non-structural carbohydrate, NSC)含量对研究其生长和适应策略具有重要意义,但其预处理方法多样,导致不同研究结果之间的可比性较差。该研究以华南海岸典型沙生植物木麻黄、老鼠艻、海马齿和厚藤为例,采用苯酚-浓硫酸法,分析是否去皮和过筛目数大小对其NSC及组分含量测定的影响。结果表明:(1)不同龄级木麻黄样品去皮后提取的NSC、可溶性糖和淀粉含量均出现下降趋势,与对照相比,幼龄林和中龄林样品可溶性糖含量下降达到显著水平(P<0.05),而淀粉含量差异不显著,成龄林样品NSC及其组分含量差异均不显著。龄级越小,去皮预处理对树木NSC及其组分提取影响越大,尤其以可溶性糖影响最为明显,建议乔木处理时统一保留树皮。(2)不同沙生植物枝(茎)样品提取的NSC及其组分含量随过筛目数增大总体呈增加趋势,且木麻黄和老鼠艻枝(茎)过筛100目相对18目提取的NSC含量均达到显著水平(P<0.05),而叶(同化枝)样品除老鼠艻外均变化不显著。(3)沙生植物器官机械组织含量越高,不同过筛目数提取的NSC及其组分含量差异越大,综合考虑样品获取难度及NSC含量的测定精度,建议所有沙生植物枝叶样品均过100目筛。

Abstract:

Quantification of non-structural carbohydrate(NSC)contents of plants is of great significance to the exploration of their growth and adaptive strategies. However, various pretreating methods often lead to the poor comparability among different results. In this paper, four typical psammophytes on the coast of South China including Casuarina equisetifolia, Spinifex littoreus, Ipomoea pes-caprae and Sesuvium portulacastrum were studied, and the effects of pretreating methods on the determination of non-structural carbohydrate contents of plants by phenol-concentrated sulfuric acid method were analyzed, including the existence of the peel and mesh size. The results were as follows:(1)When peeled, NSC, soluble sugar and starch contents of the Casuarina equisetifolia samples all had a decreasing trend compared with the control group, especially significant in the soluble sugar contents of the young-aged forest and the middle-aged forest(P<0.05), but had no difference in both starch contents and all component contents in adult ones. The younger the age of samples, the greater the effect of peeling pretreatment on NSC and its component contents in trees, especially affected on soluble sugar, so we suggest to preserve tree bark when samples are processed.(2)The contents of NSC and its components of different psammophytes's branches(stem)all raised with the increase of mesh size, and there were significant differences(P<0.05)in the Casuarina equisetifolia's and Spinifex littoreus's branches(stem)samples which passed through the 100 and 18 mesh sieve. Except for Spinifex littoreus, all psammophytes' leaves(assimilating branches)samples did not change much under different mush sizes and had no significant difference.(3)The higher the content of mechanical tissue in the samples, the more significant difference in the content of NSC and its components extracted by different mesh sizes. Considering the difficulty in obtaining samples and the accuracy of the determination of NSC content, we suggest that all branches and leaves of psammophytes should be processed by 100 mesh sieve. The conclusion of this study can guide the sample processing methods of related research in the coast of South China, standardize experimental methods and improve the comparability among different studies.