Abstract
Abstract The influence of two managements on yield and quality of plagiotropic mini-cuttings of four cacao clones was evaluated. The design was completely randomized in a 4 x 2 factorial scheme with 4 clones x 2 mother plant management (apical pruning and bending), with 10 replicates and one plant as experimental unit. Seedlings used were propagated by rooting of semi-woody cuttings of plagiotropic branches and at seven months of age, two seedlings of each clone were transplanted to 12 L pots filled with organomineral substrate. After transplantation, the apex of one of the plants was cut based on the count of the first six leaves from the apex. For bending, stems were folded and horizontally fixed. The first collection of mini-cuttings was performed 30 days after transplantation and the others during the following seven months. The yield of mini-cuttings was estimated during collections and part was used for rooting and quality evaluation of seedlings. After 90 days, 10 mini-cuttings of each clone were evaluated for quality using the Dickson quality index (DQI). Another 10 rooted mini-cuttings were transplanted to 1.5 L polyethylene bags and kept in greenhouse for another 120 days until final quality evaluation at 210 days. Data were submitted to analysis of variance and Tukey test at 5% probability. Shapiro-Wilk normality test and Pearson correlation analysis were performed. bending was more efficient in the average production of mini-cuttings especially for BN 34 clone. The Dickson quality index was correlated with root dry mass, at both 90 and 210 days, and the bending technique was responsible for the best DQI. Variable height was not adequate to estimate the quality of cocoa seedlings.
Highlights
The production of cocoa seedlings in quantity and quality has been an important support factor for the cacao activity in the state of Bahia, which is distributed in more than 50 municipalities and accounts for more than 50% of the production of dried cacao almonds in Brazil (SODRÉ et al, 2017)
The results indicate that this precocity appears in vegetative propagation and that this clone is more efficient in modifying the apical dominance of the plant, promoting the growth of lateral buds and improving the yield of mini-cuttings
The management of mother plants was more efficient than the apical pruning in the average production of cacao mini-cuttings, especially for the BN 34 clone
Summary
The production of cocoa seedlings in quantity and quality has been an important support factor for the cacao activity in the state of Bahia, which is distributed in more than 50 municipalities and accounts for more than 50% of the production of dried cacao almonds in Brazil (SODRÉ et al, 2017).Cutting is the propagation method frequently used for cacao, mini-cutting is a recent technique that has been successfully used in order to maximize the process of clonal propagation of some forest species such as Eucalyptus (ALMEIDA et al, 2007), Toona ciliata (SILVA et al, 2012; SOUZA et al, 2014) and the propagation of some fruit trees, Annona muricata L. (FIGUEIREIDO et al, 2013), Passiflora edulis (CARVALHO et al, 2007), and Theobroma cacao (SODRÉ and CORÁ, 2007).The use of mini-cutting as a tool for plant propagation was intensified in Brazil in the 1990s for the genus Eucalyptus and placed Brazil among the most efficient producing countries (ALFENAS et al, 2004, ASSIS, 2014). The growing concern with the yield and quality of cocoa seedlings has led to the adoption of managements for commercial production and changes in the production system, such as the use of clonal gardens in nurseries and potted mother plants (SODRÉ, 2013), always aiming greater uniformity of the material to be worked. The bending of stems of juvenile mother plants in order to fix them in a horizontal position, and the apical pruning that consists of the decapitation of the plant apex stand out In both situations, the break of apical dominance provides alterations in the hormonal balance, mainly between auxin and cytokinin, which in turn change the apical dominance of the plant, promoting the growth of lateral buds (TAIZ and ZEIGER, 2017)
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