Mini-Nut Propagation Technique of Kola (Cola nitida, (Vent.) Schott and Endl.): Prospects for Germination and Propagation of Kola Plantlets in the Pre-Nursery

Abstract

Limitations against propagation of Cola nitida include pronounced dormancy of between 1 and 8 months after sowing (MAS) leading to uneven germination and seedling growth. This experiment was conducted in a screenhouse, Federal University of Agriculture Abeokuta, Nigeria, to evaluate the effects of mini-nut and nut-color on germination and seedling growth of C. nitida nuts. The experiment was in a completely randomized design replicated 3 times. Treatments comprised two factors: nut/seed-colored biotype (white, pink, and red) and mini-nut (embryonic portion of cotyledon) [excised embryonic portion cotyledon (EEPC), 25% embryonic portion cotyledon (EPC), 50% EPC, 75% EPC, and 100% EPC (whole nut/seed)], giving 15 treatment combinations sown in plastic cups of 50 cl filled with sawdust. Germination percentage and morphological growth of plantlets (plant height (cm), number of leaves, dry matter yield (g/plant)) were monitored; data subjected to analysis of variance and mean comparisons done (p ≤ 0.05). As early as 4 WAS, the EEPC and 25% EPC had 67.78% and 54.44% germination, respectively. Within the same period, 51.33%, 48.00%, and 31.33%, respectively, of white-, pink-, and red-colored seeds germinated. At 6 WAS, the white-, pink-, and red-colored seeds had mean germination of 80.67%, 92.00%, and 72.67%, respectively. At 12 WAS, germination was observed to complete with the pink-, red-, and white-colored nuts having 97.33%, 92.61%, and 91.33%, respectively. Within the same period, the mini-nut sizes had between 92.22% and 95.56% germination. Combining the two factors, 50% EPC, 25% EPC, and EEPC of white-nut biotype germinated earliest with 50.00–76.67% at 4 WAS and 73.33–80.00% at 5 WAS. The EEPC of pink-colored biotype attained 100% at 6 WAS, while other treatments were between 56.67% and 93.33%. Thus, while earliness in germination pattern follows the order: EEPC > 25% EPC > 50% EPC > 75% EPC > whole nut, the plantlet morphological growth followed a reverse order. With mini-nut technique therefore, timely and even germination of kola nuts were obtained and 50%EPC would be recommended for conventional propagation while EEPC would require nutrient amendment for improved growth.