Cooling Effects and Humidification Potentials in Relation to Stomatal Features in Some Shade Plants
ABDULRAHAMAN, A. A.; OLAYINKA, B. U.; HARUNA, M.; YUSSUF, B. T.; ADEREMI, M. O.; KOLAWOLE, O. S.; OMOLOKUN, K. T.; ALUKO, T. A.; OLADELE, F. A.

Abstract
Thirty shade trees namely Lonchocarpus cyanenscens, Albizia lebbeck, Blidelia ferruginea, Prosobis africana, Burkea africana, Lophira lanceolata, Ficus elastica, Ficus trichopoda, Annona senegalensis, Citrus aurantifolia, Gliricidia sepium, Dioclea reflexa, Gmelina arborea, Acacia auriculiformis, Anacardium occidentale, Vitellaria paradoxa, Parkia biglobosa, Citrus paradisi, Citrus reticulata, Citrus limon, Citrus sinensis, Terminalia catappa, Tectonia grandis, Delonix regia, Mangifera indica, Thevetia neriifolia, Plumeria alba, Blighia sapida, Azadirachta indica, and Daniela olivieri were studied to determine their canopy characteristics in relationship to stomatal features possessed and the rate at which they transpire. The canopy characteristics vary in all species with D. oliveri, T. catappa and L. cyanenscens, etc has the widest canopy while P. alba and C. limon has the narrowest canopy. Density of leaves (LD) is highest in T. neriifolia and D. regia, and it is lowest in P. alba, B. sapida, T. grandis, T. nerifolia. The tree height is tallest in L. cyanenscens followed by A. auriculiformis , G. arborea and D. oliveri . In each species, leaves were taken and observed anatomically to reveal stomatal features and rate of transpiration; for instance, T. catappa, A. auriculiformis and others that possessed amphistomatic leaves with heterogeneous stomatal complex types (SCTS) transpired faster than species such as T. grandis, A. senegalensis, A. occidentale etc with hypostomatic leaves and homogeneous SCTS. Stomata in the studied species were all more than 15µm with A. auriculiformis, having larger size (73.75µm) while D. regia possessed the smaller size (47µm). T. catappa has the highest stomatal density of 91.00mm2 while D. regia has the lowest stomatal density of 8.25mm2. Coolness provided by the shade trees is evidence in the temperature under the trees and in the open space; temperature is higher in the open than under the trees in all the 30 species studied. Based on the canopy characteristics and stomatal features possessed by each of these shade plants as well as their rate of transpiration, species such as T. catappa, A. indica, A. lebbeck, F. trichopoda, L. cyanenscens, D. regia, D. oliveri, and A. auriculiformis are the most preferable shade plant.

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