Morphological responses of cocoa seedlings to moisture availability in South-West Nigeria

Cocoa clones SCA 6, SCA 9, NA 32, ICS 96, N 38, PA 7 and PA 150 were either self or cross pollinated to form six cocoa genotypes namely: SCA 9 * SCA 12, NA 32 * NA 32, ICS 95 * ICS 95, N 38 * N 38, PA 7 * PA 150 and SCA 12 * SCA 9. The selection of the parent cocoa clones were based on their reported varied genotypic performances and traits to water stress conditions. The seeds of the six cocoa genotypes were pre-germinated for two weeks before their seedlings were transplanted into 4kg topsoil inside each of the plastic pots in a greenhouse where they were examined for their responses to three different watering regimes at 25, 50 and 100 percent field capacities for 30 weeks using Completely Randomised Design (CRD). Data were collected on the physico-chemical properties of the experimental soil, the plant height, stem diameter, number of leaves, leaf area, fresh root weight, dry root weight, root length, root percentage moisture contents well as well as the leaf contents for N, P, K, Ca, Mg and Fe nutrients. While the height, stem diameter, number of leaves, leaf area, root fresh weight and root dry weight were significantly higher at 100% field capacity (fc) than 25% fc, the root length of seedlings placed under 100% fc were significantly shorter than those under 25% fc for all the cocoa genotypes. The leaf N, P, Ca and Fe contents showed higher concentrations at lower fc while K and Mg contents increased at higher water regimes. The results showed genotypic differences in the morphological and nutritional performances of the cocoa seedlings.