Effect of seasonal variability on the physiological performance of selected cocoa (Theobroma cacao L) clones in Nigeria

Eleven cocoa clones namely AMAZ 15, ICS 95, IMC 47, MAN 15, PA 150, SCA 9, SPEC 54, UF 67, F3 AMAZON, N 38 and TC 2were hand pollinated and the seeds were raised for 6 months before being transplanted to the field at 6 months. Survival count of the clones was taken for 36 months starting from the first month of establishment. Data on the gas exchange characteristics of cocoa clones started when cocoa were 12 months and continued for the next 2 wet and 2 dry seasons. Majority of cocoa clones showed higher values of stomatal conductance, stomatal transpiration, photosynthetic rates, relative water content, cuticular transpiration and stomata density during wet season while eight of the eleven cocoa clones had higher water use efficiency performance in dry season. The regression analysis also showed a linear, positive and significant relationship between stomatal transpiration and stomatal density of all cocoa clones. The results showed significant differences in the abilities of cocoa clones to cope with water stress while majority of cocoa clones performances significantly differed between dry and wet seasons.