Journal of Sustainable Development Vol. 17, Nos. 1 & 2 September, 2020 (Special Edition) 63 EFFECTS OF ORGANIC FERTILIZER ON COCOA HYBRID SEEDLINGS. OLAIYA, A. O AND LAWAL, O. I Plant Physiology and Crop Production Department, Federal University of Agriculture, Abeokuta, Nigeria. Email: olaiyaabideen@yahoo.com; olaiyaao@funaab.edu.ng ABSTRACT This study was conducted to determine the influence of organic fertilizer rate on cocoa hybrid seedlings in the nursery between May-July 2018 The experiment was a 4 × 3 factorial arrangement laid out in a completely randomized design replicated three times. The treatment were three of the newly released cocoa hybrid varieties in Nigeria, KASIMAWO PA/AMELONADO (T65/7×N38) TC1; PETA-1 (POUND7×PA150) TC2 and EFEH AMAZON/TRINITARIO (T65/7×T9) TC3 while poultry manure were tested at four levels (0, 1, 2 and 3) t/ha. Data collected on number of leaves, plant height, stem girth and leaf area were subjected to analysis of variance and means were separated using least significance difference at 5% probability level. Poultry manure application did not show any significant effect on (p<0.05) number of leaves irrespective of the rate or variety throughout the period of the experiment. There was significant difference observed on plant height with TC2 having significantly higher height of 26.9 cm at 12 weeks after planting, stem girth 8.11 cm and leaf area 167.6 cm 2 at one tones per hectare rates of organic manure application. The application of 1 t/ha poultry manure significantly improved the plant height, stem girth and leaf area at various periods under experimentation is hereby recommended. The TC2 variety outperformed the other two varieties under organic production condition in the nursery and is thus recommended for good seedling establishment or rootstock production. Keywords: Cacao, Varieties, Poultry Manure, Fertilizer rate, Growth. INTRODUCTION Cocoa (Theobroma cacao L.) is a small, wide- branching evergreen tree that is native to tropical rainforest areas. It thrives best in soils that are moist, nutrient rich, well-drained and aerated. Cocoa seedlings requires nutrients such as nitrogen, phosphorous, potassium, etc. and metabolites (proteins, lipids, carbohydrates) for their growth and development (Gockowski et al., 2004). Several authors worked on cocoa seedlings growth conditions in nursery. Ayanlaja (2002), worked on cocoa seedlings shading regimes while many researchers reported results on soil quality. The sowing of cocoa beans in pot was suggested as against direct sowing method (Akanbi et al., 2014). With the works of Snoeck et al. (2006), nutrient requirements for cocoa tree growth can be computed by Soil-Diagnostic Method. In this approach, soil quality and soil quantity is required to evaluate the real needs for cocoa trees. So in nursery, the seedling growth depends on the available nutrients containing in a specific soil volume in the pot. The production of cocoa in Nigeria has witnessed a downward trend since the early 1970s due to numerous factors like ageing trees, ageing farmers, wrong application of recommended agronomic techniques by farmers, effects of pests and diseases and deficiencies in macro and micro nutrients in the soils (Adejobi et al., 2011a). Previous studies have attributed this yield decline essentially to soil nutrients imbalance (Ojeniyi et al., 1981; Ayanlaja, 2002). One way of combating this problem is the use of fertilizer. However, African farmers use very little fertilizer (8kg/ha) compared to their counterparts in other parts of the agrarian world, hence, Africa’s soils are increasingly depleted of nutrients (IFDC, 2008/2009). This is particularly true with cocoa farms in Nigeria. Ogunlade et al. (2009) reported that more than 85% of cocoa farmers in Nigeria do not use fertilizers on cocoa. Reasons for this low usage of fertilizers vary from lack of farmers’ knowledge of the nutrients status of their soils to scarcity and high cost of fertilizers where available. The need to pay attention to soil fertilization is now almost as important as the control of capsids and black-pod disease in cocoa.