EFFECTS OF WATERING REGIME AND MYCORRHIZAL INOCULATION ON WATER USE, GROWTH AND DEVELOPMENT OF SEEDLINGS OF FIVE VARIETIES OF COCOA (Theobroma cacao L.)

Abstract

An experiment was conducted in the screen house of the Department of Crop, Soil and Pest Management, Federal University of Technology, Akure to evaluate the effects of watering regimes and Arbuscular Mycorrhizal Fungi (AMF) inoculation on water use, growth and development of five elite cocoa varieties. Treatments were 5 x 3 x 2 factorial scheme consisting of cocoa varieties (T65/7 x N38, T65/7 x T57/22, T82/27 x T12/11, PA150 x T60/887 and T82/27 x T16/17), watering regimes (4-, 8- and 14-day watering intervals with 1 litre of water applied per plant), and with or without AMF inoculation. The treatments were applied to five-month old cocoa seedlings. The experiments were laid out in a Completely Randomized Design with three replications. Data were collected on the growth parameters of cocoa seedlings for 11 months commencing from 2 weeks after treatment application (WATA). The period of the experiment was from June 2013 to April 2014. Treatment effects were significant (P< 0.05) on some of the measured growth variables of cocoa seedlings, including seedling water use, plant height, stem girth, plant biomass and number of leaves and branches. These variables were enhanced by the 4- and 8-day watering intervals and with or without mycorrhizal inoculation compared with 14-day watering intervals. Variety T82/27xT12/11 that was watered at 4- and 8-day intervals was consistently taller in height, had enhanced biomass and produced higher number of leaves and branches compared with those watered at 14-day intervals. Although, there were no consistent pattern in the amount of water used by the cocoa varieties, variety PA150xT60/887 in general appeared to have consumed more water and had wider stem girth. The interaction effects of watering regime and variety enhanced the growth parameters of varieties T82/27xT12/11 and PA150xT60/887 cocoa seedlings