Maximum efficiency concentration of indole butyric acid in promoting the rooting of Japanese Flowering Cherry

Prunus serrulata is a species widely used in the ornamentation and its economic importance is mainly due to the time of its flowering. The objective was to assess the feasibility of cutting technique for propagating P. serrulata , using stem cuttings from current-year shoots, and to estimate the maximum efficiency concentration of auxin indole butyric acid (IBA), in the promotion of rooting. Collection of plant material took place in late spring. Cuttings were made with about 8±1cm length and two leaves reduced to 50% of its original surface. Twenty one IBA concentrations have been assessed (0, 250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000, 3250, 3500, 3750, 4000, 4250, 4500, 4750 e 5000mg L-1), applied in base of cuttings, which were placed in acclimatized greenhouse. After 60 days, there was a gradual increase in the rooting percentage compared to the increment of IBA to the approximate concentration of 2700mg L-1, with results higher than 80%. In addition, low efficiency concentrations of growth regulators have resulted in fewer roots per cutting, which could compromise the survivability of the seedlings under ambient conditions. Conversely, the decrease in the percentage of callus may be an indication that root formation in P. serrulata occurs directly, without requiring callus formation and its further de-differentiation and re-differentiation in roots. RESUMO: Prunus serrulata é uma espécie muito empregada na ornamentação e sua importância econômica deve-se principalmente à ocasião de sua floração. Objetivou-se avaliar a viabilidade da técnica de estaquia para a propagação de P. serrulata , utilizando-se estacas caulinares provenientes de brotações do ano, bem como estimar a concentração de máxima eficiência da auxina ácido indol butírico (AIB), na promoção do enraizamento. A coleta do material vegetativo ocorreu no final da primavera. As estacas foram confeccionadas com cerca de 8±1cm de comprimento e duas folhas reduzidas a 50% de sua superfície original. Foram avaliadas 21 concentrações de AIB (0, 250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000, 3250, 3500, 3750, 4000, 4250, 4500, 4750 e 5000mg L-1), aplicadas na base das estacas, as quais foram acondicionadas em casa de vegetação climatizada. Após 60 dias, verificou-se um aumento gradativo do percentual de enraizamento em relação ao incremento de AIB até a concentração aproximada de 2700mg L-1, com resultados superiores a 80%. Ademais, concentrações de ba