Abstract

High irradiance of a habitat in arid areas is usually associated with high temperature and dry air, which can cause water deficiency in plants. The Tulip tree (Liriodendron tulipifera) is a light-loving mesophytic species. This study showed that L. tulipifera forms shade or sun leaves depending on the light conditions. Some xeromorphic features were found in leaves of the trees in illuminated habitats. These sun leaves are smaller, denser, and thicker, with smaller epidermal cells and a thick cuticle; the spongy parenchyma consists of a larger number of rows of small cells; the cells of the columnar parenchyma are larger than the shade leaves. The sun leaf contains more total chlorophyll (by 20–30%), and the guard cells of the stomata of the sun leaf contain chloroplasts. The increased concentration of chlorophyll probably maintains the energy balance in the conditions of inhibited photosynthesis under high illumination and temperature. Decreased sizes of the sun leaf and epidermis cells, thickening of the cuticle and cell wall of epidermal cells, sunken stomata, compact mesophyll with small intercellular spaces, and multirow spongy parenchyma protect from overheating and passive loss of water and can be considered as xeromorphic features. Large numerous stomata and vascular bundles contribute to effective cooling of the surface by transpiration at high temperatures under sufficient water supply. Thus, the leaves of L. tulipifera have an ecological plasticity in relation to illumination and temperature, which contributed to the acclimation of the species to the habitat conditions in arid climates.

中文翻译：

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中亚干旱气候下鹅掌Li叶片的叶形特征

摘要

干旱地区栖息地的高辐照度通常与高温和干燥的空气有关，这可能导致植物缺水。郁金香树（Liriodendron tulipifera）是一种喜光的中生物种。这项研究表明，L。tulipifera根据光线条件形成阴影或太阳叶。在光照充足的栖息地的树木叶子中发现了一些干透性特征。这些太阳叶更小，更密，更厚，表皮细胞更小，表皮更厚；海绵薄壁组织由更多行的小细胞组成；柱状薄壁组织的细胞大于阴影叶片。太阳叶含有更多的总叶绿素（增加20％至30％），并且太阳叶气孔的保卫细胞含有叶绿体。在高光照和高温下，在抑制光合作用的条件下，叶绿素浓度的增加可能会维持能量平衡。太阳叶和表皮细胞的大小减小，表皮细胞的表皮和细胞壁增厚，下陷的气孔，紧凑的叶肉，细胞间空间小，多排海绵薄壁组织可防止过热和水的被动损失，可以认为是干性特征。大量的气孔和维管束有助于在足够的供水条件下通过高温蒸腾作用有效地冷却表面。因此，郁金香L. tulipifera在光照和温度方面具有生态可塑性，这有助于该物种适应干旱气候下的栖息地条件。