Morpho-anatomical and physiological adaptations to high altitude in some Aveneae grasses from Neelum Valley, Western Himalayan Kashmir

• DOI: 10.1007/s11738-016-2114-x
• Publication Date: 2016-03-14T02:15:40Z
• Authors: Khawaja Shafique ...; Mansoor Hameed; Sana Fatima; Muhammad Ashraf; Farooq Ahmad; Mehwish Naseer; Noreen Akhtar
• Keywords: Trichome; Specific leaf area; Pith; Petiole (insect anatomy)

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.