Comparison of Three Variants of Substrate Preparation Used in the Propagation of Cocoa Standards/Comparacion de tres variantes de preparacion del sustrato empleado en la propagacion de patrones de cacao

This research was conducted to compare three variants of substrate preparation used in mass propagation of cocoa (Theobroma cacao L.) in nursery conditions. Three treatments were studied: T1-manual mixing with shovel, T2-mechanized mixing with motorized cultivator and T3-mechanized with mixer. Evaluations were made of the physical-chemical characteristics of the substrate, compaction, cotyledon height, number of leaves per plant, stem diameter, plant height at 20, 40 and 60 days, fresh weight of the plant and root and root length. The results showed that there are no statistically significant differences between the treatments, i.e. the method of preparation of the substrate does not have a direct incidence on the agronomic response of the plant, in the conditions and period investigated. The physical-chemical analysis of the mixed substrates showed, in all three cases, a sandy loam texture with an apparent density ranging from 1,17 to 1,19 g/[cm.sup.3], as well as an organic matter content ranging from 1,9 to 3,2 %. The average pH was 5.9. No statistically significant differences were found between the treatments in terms of effects on the vegetative development of the plant throughout the development cycle evaluated. The economic analysis showed that it is more profitable to use mechanized technology if it is used in mass propagation centers, since the productivity of the machines is three (T2) and four times (T3) more than the manual variant.