Resistance to water flow, hydraulic conductivity and leaf nutrient concentration among Theobroma cacao L. grafts. In: Agrotrópica v. 29 p. 5-12, 2017.

Abstract

Theobroma cacao L. is a perennial species of worldwide economic importance. In Brazil, in the last 25 year there was a decrease in the production of dried cacao beans caused by biotic and abiotic factors, especially cacao witches’ broom disease. This malady is considered one of the most important diseases of cacao due to the enormous economic damage it causes to the crop. Installed in the Cacao Region of South Bahia, Brazil, for over two decades, cacao production decreased about 75%. Aiming to minimize the damage caused by this pathogen, production of seedlings with genetic tolerance/resistance is the most efficient and economical alternative to control the disease. Especially grafting resistant genotypes onto rootstocks is of wide use in the field. However, there are no studies specifically addressing the effect(s) of the interaction between scion and rootstock in cacao. The objective of this study was to verify and determine the interactions between scion and rootstock of cacao clones using resistance to water flow and leaf mineral concentration as diagnostic parameters. The evaluated seedlings were cleft grafted individuals. The clones used were CCN51, Eucalipto, UP and their respective combinations and three rooted stocks, with four replications. After grafting, the plants were grown in 5.0 L pots in a greenhouse and maintained under a drip automatic irrigation system. The experimental design was completely randomized. It was evaluated resistance to water flow and leaf mineral concentrations three months after grafting. The results showed a significant difference within and between grafted plants and control plants for resistance to water flow and concentration of minerals at the leaf level, suggesting that the grafting process changes these parameters, as a function of the genotype used. It was found that CCN51 showed to be an adequate rootstock.