Morpho-anatomical and physiological adaptations to high altitude in some Aveneae grasses from Neelum Valley, Western Himalayan Kashmir
Morpho-anatomical and physiological adaptations to high altitude in some Aveneae grasses from Neelum Valley, Western Himalayan Kashmir
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DOI：
10.1007/s11738-016-2114-x
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发表时间：
2016-04-01
影响因子：
2.6
通讯作者：
Akhtar, Noreen
中科院分区：
文献类型：
--
作者：
Ahmad, Khawaja Shafique;Hameed, Mansoor;Akhtar, Noreen
从西喜马拉雅山脉 Neelum Valley 的低山（海拔 1100 米）和高地山脉（海拔 2300 米）采集了五种燕麦族草，以评估其对海拔变化的生理解剖学适应性。证实以下假设的证据：由于环境梯度的异质性，不同海拔的植物在结构（内部修饰）和功能上必定有所不同。所有草类对高海拔的总体反应是每株植物的总叶面积和干物质的生长迟缓。除Ca2+含量外，大部分离子和叶绿素含量在高海拔地区显着较低。解剖学的改变，如叶子厚度、维管束和髓部周围的密集硬化、后生木质部导管面积的减少、高柔毛（微毛和毛状体密度增加）在这些草应对海拔胁迫的高度耐受性中发挥了重要作用。叶子的机械强度对于防止恶劣气候下的损害和高海拔种群的整体生存至关重要，似乎取决于叶子背面和正面的硬化强度和密集的柔毛。高海拔草类因应对低温而增加叶子的整体厚度可能会保护叶肉等代谢活跃的组织。高密度的毛状体也可能参与阻止蒸腾水和内热。低海拔和高海拔草的不同反应与气温、降雨模式和养分有效性密切相关。
Five grasses of tribe Aveneae were collected from low (1100 m. a.s.l.) and highland (2300 m. a.s.l.) mountain range of Western Himalaya, Neelum Valley, to evaluate the physio-anatomical adaptations to altitudinal variability. An evidence to confirm the hypothesis that plants vegetating different altitudes must be different structurally (internal modifications) and functionally due to heterogeneity in environmental gradients. The general response of all grasses to high altitude was growth retardation in terms of total leaf area per plant and dry matter. With exception of Ca2+ content, most of the ionic and chlorophyll content were significantly low at high elevations. Anatomical alterations such as, leaf thickness, intensive sclerification around the vascular bundle and pith area, reduced metaxylem vessel area, high pubescence (increased microhair and trichome density) played an important role in high degree of tolerance of these grasses to cope with altitudinal stresses. The mechanical strength of leaf, which is critical for preventing damage under harsh climate and overall survival of high altitudinal populations, seems to be depended on intensity of sclerification and dense pubescence at abaxial and adaxial surfaces of the leaf. Increase in overall thickness of leaf in high altitude grasses in response to low temperature may protect metabolically active tissue like mesophyll. Also high density of trichomes may be involved in blocking transpiration water and internal heat. Differential response of low and high altitude grasses is highly related to air temperature, pattern of rainfall, and availability of nutrients.