Balasimha, D.2014-06-022014-06-022007-02-08In: Tree crop physiology. Edited by M. R. Sethuraj and A. S. Raghavendra. Elsevier Science Publishers, Amsterdam 263-285http://hdl.handle.net/123456789/2167Among plantation crops, in cocoa (Theobroma cacao L.), the physiology is studied extensively. The vegetative and reproductive growth of cocoa is influenced by a complexity of environmental factors, particularly rainfall, temperature and wind. The plants are shade tolerant and are generally grown under shade of taller trees. The removal of shade does enhance the yields in initial years of productivity, but will result in deleterious effects in subsequent years. Cocoa is a very sensitive plantation crop to drought. Water stress affects the most important physiological determinants of yield - canopy architecture, photosynthetic production, and partitioning of assimilates between source and sink - are influenced by water stress. Regulation of stomatai closure high leaf elasticity, maintenance of leaf turgor, higher cuticular wax content and better metabolic activity under stress are among the drought tolerant attributes of some, cocoa accessions. The average annual yields in farmers fields are far below the potential yields. An integration of better agronomic practices to suit environmental factors, physiological determinants and genetical potential is required, to improve further the yields of cocoa.encocoaArticle