Ecology of water relations between mistletoe (Taxillus vesititus) and its host oak (Quercus floribunda)
2002
Garkoti, S.C. | Akoijam, S.B. | Singh, S.P. (Kumaun University, Nainital (India). Department of Botany)
The infestation of Quercus floribunda trees by Taxillus vestitus is common in Himalaya. Seasonal gas exchange and water relations of T. vestitus its host Q. floribunda were studied under natural field condition in Nainital, Indian Himalaya. Leaf water potential and leaf conductance were followed through the growing seasons on T. vestitus and infested Q. floribunda. Consistent with the reports elsewhere for other species of mistletoe, T.vestitus frequently transpire more rapidly than its host, and maintains more negative water potential. Predawn and midday water p potential for Q. floribunda are in the range of -0.9 bars and -5.9(Rainy seasons) to -12.3 (summer seasons) and -4.4 (Rainy season) to -20.5 (summer season) bars and -5.9 (rainy season) to -25.2 (Summer season) bars, respectively during predawn and midday. A gap in water potential between host and mistletoe occurred throughout the study period, which increased with the severity of moisture. During all seasons T.vestitus out transpired the host. It appears that the low water potential enables the mistletoe took have access to host water all the time and higher transpiration further enhances water uptake and hence possible intake of valuable elements for growth. Both the species studied showed stomatal control during the dry season, which seems to be determined by the increase of the evaporative demand.
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