干旱区不同地理种群骆驼刺元素组成及表面结构特征的对比研究

碳(C)、氮(N)、磷(P)元素在植物各器官中的组成,及植物表面结构差异是其对外界环境适应性的重要表征。以干旱区3个地理种群骆驼刺(塔里木盆地策勒种群,吐鄯托盆地托克逊种群,准噶尔盆地阜康种群)为研究对象,通过对植株各器官C,N,P元素组成的测定及表面形貌观测,对其在不同环境中的适应特性进行了比较研究。结果表明:(1)同一种群的骆驼刺,C元素在各器官中的分配没有显著规律;N元素在叶片中含量最高,茎中最低;策勒种群和阜康种群的P含量,叶片中最高,茎与刺中差异不显著;但托克逊种群茎中P含量显著高于其他部位。(2)3个地理种群的骆驼刺叶中元素组成相比,策勒种群C,N含量均最高,托克逊种群C,N含量最低;3个种群叶片的P含量,C∶N,C∶P,N∶P值均没有显著差异。刺中元素含量相比,C含量没有显著差异;N含量阜康种群策勒种群托克逊种群。茎中元素含量相比,N含量差异不显著,但托克逊种群茎中P含量为其他两个种群的2倍,可能与托克逊土壤中高浓度的全N,速效N,速效P有关。(3)托克逊种群表皮极厚,蜡质非常致密,各器官气孔密度均高于其他两个种群;策勒种群比阜康种群叶表皮增厚,蜡质致密,但叶片气孔密度却减小;策勒种群和阜康种群茎与刺的气孔密度差异不显著。研究表明,策勒种群骆驼刺最适应当地环境条件:其叶片具有最高的C,N含量,且表面结构没有明显的干旱胁迫特征。托克逊种群表现出明显的干旱适应特征:其表皮增厚,蜡质致密,气孔密度增大,叶片C,N含量最低。虽然托克逊种群茎中P含量显著高于其他地理种群,但3个地理种群骆驼刺叶片中C∶N,C∶P,N∶P比值保持恒定,C∶N=30.6±4.3,C∶P=357.4±49.9,N∶P=12.0±2.4,说明骆驼刺能够保持较高内稳性,这也可能是其在新疆各地广泛生存的重要原因。

Elemental compositions and surface structures of Alhagi sparsifolia Shap. in different geographical populations in arid zone

The compositions of carbon, nitrogen, phosphorus and different surface structures in different organs of plants are important factors in their adaptability to the external environment. In this study, plants of Alhagi sparsifolia Shap. of the Cele population in the Tarim Basin, the Toksun population in the Tuotuo Basin, and the Fukang population in the Junggar Basin, were studied. The C, N, and P concentrations in the organs of A. sparsifolia were measured and the surface morphology was observed. A comparative study of these adaptive characteristics in different environments was conducted. The results showed that:(1) There was no significant distribution of C in the same population of A. sparsifolia, N content was highest in leaves and lowest in stems, P content was highest in leaves in the Cele and Fukang populations, there was no significant difference between stems and thorns, and P content in stems of the Toksun population was significantly higher than other organs. (2) Compared with the elemental compositions in the leaves of the three geographical populations, the C and N contents were highest in the Cele population and lowest in Toksun population, and the P content, C:N, C:P, and N:P mass ratios in leaves were similar among the three populations. In the thorns, there was no significant difference in the C content among the three geographical populations, and the N content was greatest in the Fukang population > Cele population > Toksun population. In the stems, there was no significant difference in N content among the three geographical populations, but the content of P in the stems of the Toksun population plants was twice that of the other two populations; this was probably related to the high concentrations of total N, available N, and available P in the Toksun soils. (3) Plants in the Toksun population had a very thick epidermis with very dense waxes, and the stomatal density of each organ was higher than that of the other two populations. Plants of the Cele population had thicker epidermis and wax than those of the Fukang population, but stomatal density was reduced; stomatal density in stems and thorns of the Cele and Fukang populations were not significantly different. Studies have shown that the Cele population of A. sparsifolia was the most suitable for local environmental conditions-the leaves had the highest C and N contents, and the surface structure showed no obvious characteristics of drought stress. Plants of the Toksun population showed characteristics of drought adaptation-the epidermis was thickened, the wax was dense, the stomatal density increased, and the leaves had the lowest content of C and N. Although the content of P in stems of plants of the Toksun population was significantly higher than that of other geographical populations, the ratios of C:N, C:P, and N:P in the leaves of the three populations remained constant:C:N=30.6 ±4.3, C:P=357.4 ±49.9, N:P=12.0 ±2.4, indicating that A. sparsifolia maintains high homeostasis. This may also be an important reason why it can survive in the entire area of Xinjiang Province.