College of Life Science, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin of Xinjiang Production & Construction Corps, Alar, People's Republic of China.
Plant Biol (Stuttg). 2020 May;22(3):366-375. doi: 10.1111/plb.13078. Epub 2020 Jan 5.
Euphrates poplar (Populus euphratica Oliv.) has heteromorphic leaves including strip, lanceolate, ovate, and broad-ovate leaves from base to top in the mature canopy. To clarify how diameter at breast height (DBH) and tree height affect the functional characteristics of all kinds of heteromorphic leaves, we measured the morphological anatomical structure and physiological indices of five crown heteromorphic leaves of P. euphratica at 2, 4, 6, 8, 10, and 12 m from the same site. We also analysed the relationships between morphological structures and physiological characteristics of heteromorphic leaves and DBH and the height of heteromorphic leaves. The results showed that the number of abnormalities regarding blade width, leaf area, leaf thickness, leaf mass per area, cuticle layer thickness, palisade tissue thickness, and palisade tissue/sponge tissue ratio increased with size order and sampling height gradient. Net photosynthetic rate, transpiration rate, stomatal conductance, instantaneous water use efficiency, stable delta carbon isotope ratio, proline and malondialdehyde (MDA) content increased with DBH and sampling height. By contrast, blade length, leaf shape index, and intercellular CO2 concentration decreased with the increase in path order and sampling height gradient. Although MDA content and leaf sponge thickness were not correlated with DBH or sampling height, other morphological structure and physiological parameters were significantly correlated with these variables. In addition, correlations were found among leaf morphology, anatomical structure, and physiological index parameters indicating that they changed with path order and tree height gradient. The differences in the morphology, anatomic structure and physiological characteristics of the heteromorphic leaves ofP. euphratica are related to ontogenesis stage and coronal position.
胡杨（Populus euphratica Oliv.）具有异形叶，成熟树冠的叶片从上到下依次为条形、披针形、卵形和宽卵形。为了阐明胸径（DBH）和树高如何影响各种异形叶的功能特征，我们在同一地点测量了 5 种树冠异形叶的形态解剖结构和生理指标，包括 2、4、6、8、10 和 12 m 处的异形叶。我们还分析了异形叶的形态结构和生理特性与 DBH 和异形叶高度的关系。结果表明，叶片宽度、叶面积、叶厚、叶面积比、角质层厚度、栅栏组织厚度和栅栏组织/海绵组织比等叶片异常数量随着尺寸顺序和采样高度梯度的增加而增加。净光合速率、蒸腾速率、气孔导度、瞬时水分利用效率、稳定的δ碳同位素比、脯氨酸和丙二醛（MDA）含量随着 DBH 和采样高度的增加而增加。相比之下，叶片长度、叶形指数和胞间 CO2 浓度随着路径顺序和采样高度梯度的增加而降低。尽管 MDA 含量和叶片海绵厚度与 DBH 或采样高度无关，但其他形态结构和生理参数与这些变量显著相关。此外，还发现叶片形态、解剖结构和生理指标参数之间存在相关性，表明它们随路径顺序和树冠高度梯度而变化。胡杨异形叶的形态、解剖结构和生理特性的差异与个体发育阶段和冠层位置有关。
