Vol. 2, Issue 3 (2017)
Stomatal studies in some afforestation tree species
Author(s): Saralabai Viswanathan Chathlingathe, Sakthivel Vellaikkannu, Magadevan Subramani
Abstract: Trees form an important stabilizing agent in the forest and Savanna Ecosystem by protecting the soil against radiation and erosion. They conserve soil water by encouraging percolation and discouraging surface run off. They also play an important role in the water cycle as more than 98% of water absorbed by plants is lost to the atmosphere through stomatal, cuticular and lenticular transpirations. Over the years, exploitation of trees for domestic, agricultural and industrial purposes has been indiscriminate, thus resulting in deforestation, a progressive process of forest removal, which also causes climate change. Frequency of each stomatal complex type was determined as percentage occurrence in a total of 120 fields of view at 40 objective lens. Stomatal index was determined based on the number of stomata plus number of epidermal cells per square millimeter multiplied by 100. From both upper and lower surfaces, presence or absence of stomata was noted to determine the leaf type whether it is epistomatic, hypostomatic or amphistomatic. The index of similarity between the abaxial and adaxial surfaces of the leaf was determined as the number of stomatal complex types common to both surfaces. Stomatal complex types are heterogeneous in all the four species studied. The heterogeneity varies from species to species. Four types in Eucalptus globulus, four types in Polyalthia longifolia, three types in Ficus benghalensis and three types in Ficus religiosa. The heterogeneity of the stomatal complex types is noteworthy. It is believed to be a factor in stomatal conductance. Those species with most heterogeneous stomata transpired more than others which are not. For instance, E. torelliana and P. longifolia which have four types each transpired at higher rate than E. camaldulensis and P. pendula with three types respectively. Moreover, the number of subsidiary cells having direct contact with the guard cells is relevant in determining the rate of transpiration. Presence of trichomes in this species may also be a factor of its lower transpiration rate than E. Torelliana.