CAN PHYTOHORMONES STIMULATE INITIAL GROWTH OF BRAZILIAN SAVANNA TREES?

Resumo

The initial growth of Cerrado tree species is slow, what impairs large scale seedling production for planting. The effect of plant hormones is well known for crop species, in this study we aimed to test the effect of two commercial biostimulants on the initial growth of six native tree species widely distributed and abundant in Cerrado. We applied nine treatments using foliar spray: T₀ - control (water); commercial Progibb^í® (gibberellic acid) T₁ - 0,8 mL.L^-1; T₂ - 1,6 mL.L^-1; T₃ - 2,4 mL.L^-1 and T₄ - 3,2 mL.L^-1; commercial Stimulate^í® (gibberellic acid, cytokinin and auxin): T₅ - 6,0 mL.L^-1; T₆ - 8,0 mL.L^-1; T₇ - 12,0 mL.L^-1; T₈ - 18,0 mL.L^-1 and T₉ - 24,0 mL.L^-1. We measured plant height and diameter every other week and recorded root and shoot biomass and leaf area after 111 growing days. No treatment significantly increased plants' initial growth, which may only happen after higher and/or repeated use of these two biostimulants, especially Progibb^í® for Anacardium humile and Jacaranda cuspidifolia and Stimulate^í® for Hymenaea stignocarpa and Copaifera langsdorfii.