ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 66 Number 2
Responses of seedlings of two varieties of Theobroma cacao to wind
Responses of two varieties of 150-day-old Theobroma cacao seedlings to wind varied with variety, wind speed, sequential cycles of calm followed by windy days, and response parameters. In both varieties, Catongo and Catongo/Sial, wind speeds of 3.0 and 6.0 m s-1 caused abscission of leaves, tearing, marginal and interveinal browning, bruising of leaf tips, as well as curling and necrosis of leaves, with most injury induced by the highest wind speed. Stomata of both varieties were more widely open on windy than on calm days, and generally were wider at wind velocities of 1.5 and 3.0 m s-1 than at 6.0 m s-1. Wind altered transpiration, with the rate of both varieties declining as the wind speed was increased, apparently in response to a lower leaf-to-air vapor pressure gradient associated with the cooling effect of wind on the leaves. Wind also induced dehydration of shoots of both varieties. Such dehydration was not correlated with transpiration rates, presumably because wind caused extensive injury to the leaf epidermis, therby accelerating shoot dehydration.
Keywords: Cacao; Theobroma cacao; Wind; Leaf injury; Water relations