Condições de cultivo da planta matriz, uso da injúria e auxina no enraizamento de miniestacas de Caryocar brasiliense

Abstract

The pequi tree (Caryocar brasiliense Camb.), a species native to the Brazilian cerrado, presents its economic, sociocultural and ecological importance. Its propagation is limited both via the seminal route, due to seed dormancy, and vegetative. The aim was to evaluate the impact of the cultivation environment of the mother plant and the moment of injury on the rooting process of mini-cuttings, in addition to the potential for regrowth, production and rooting of C. brasiliense. Mother plants were grown in full sun, under a screen and in a greenhouse, while mini-cuttings were injured at 0, 7 and 14 days, post-cutting. Also, it was evaluated the effect of three pruning heights (5, 10 and 15 cm from the stem) and four mini-cutting collection times (80, 130, 150 and 240 days) on the behavior of the mini-stumps, in addition to topping, basal injury and IBA concentrations (0, 250, 500, 1,000 and 2,000 mg.L-¹). They were evaluated the rooting and morphoanatomy, physiology and biochemistry of the matrices and mini-cuttings, in addition to the ontogenesis of the adventitious root. The mother plants grown in greenhouses presented cuttings with greater rooting, accumulation of dry mass, concentrations of sugars and starch, in addition to adventitious roots formed mainly from the vascular cambium, phloem and cortex. Rooting showed the highest positive correlations with the levels of indole-acetic acid (IAA), jasmonic acid (JA) and peroxidase (POD), while with abscisic acid (ABA) and cytokinins (CYT) were negative. The mini-stumps, with greater pruning height, survived longer and produced mini-cuttings with greater vigor. The shoot apex and IBA did not influence the rooting rate, but higher concentrations of IBA provide better quality adventitious roots. The topping height of 15 cm in the mini-stump, associated with the removal of the apical bud and the absence of injury, optimize the C. brasiliense cutting process, resulting in 70.6% rooting and better quality of the adventitious roots. The adoption of these strategies in clonal mini-gardens could increase the efficiency of vegetative propagation of C. brasiliense, enabling its application in environmental recovery programs, commercial plantings and genetic conservation of the species.