Cutting propagation of blueberry in seasons of the year with indolebutyric acid and bottom heat

O objetivo deste trabalho foi avaliar os efeitos da aplicação de concentrações do ácido indolbutírico (AIB) e do aquecimento do substrato sobre o enraizamento de estacas caulinares das cultivares de mirtilo Bluebelle, Bluegem e Powderblue, nas quatro estações do ano. Utilizou-se o delineamento experimental inteiramente casualizado, com arranjo fatorial 4x5x2 (estações x concentrações de AIB x com e sem aquecimento do substrato), com 4 repetições e 20 estacas como unidade experimental. Foram avaliadas as percentagens de estacas enraizadas, mortas, vivas e com calo, e o número e o comprimento médio de raízes. As maiores percentagens de enraizamento foram 57,1% na 'Bluegem', no verão, 30% na 'Bluebelle', na primavera, com aquecimento, e 63% na 'Powderblue', no verão, com aquecimento. O AIB na concentração de 2.000 mg L-1 aumentou o enraizamento de estacas das cultivares Bluegem e Powderblue. O aquecimento do substrato melhora o enraizamento das estacas coletadas no outono e no inverno, em todas as cultivares e, também, das estacas coletadas no verão e na primavera, na cultivar Bluebelle. The objective of this work was to evaluate the effects of the application of concentrations of indolebutyric acid (IBA) and of bottom heat on rooting of stem cuttings of the blueberry cultivars Bluebelle, Bluegem, and Powderblue in the four seasons of the year. A completely randomized design was used, with a 4x5x2 factorial arrangement (seasons x concentrations of IBA x with and without heat), with 4 replicates and 20 stem cuttings as an experimental unit. The percentage of rooted cuttings, dead, alive and with callus, and the number and average length of the roots were evaluated. The highest rooting percentages were 57.1% for 'Bluegem' in summer, 30% for 'Bluebelle' in spring, with heating, and 63% for 'Powderblue' in summer with heating. IBA at the concentration of 2,000 mg L-1 increased the rooting of cuttings of the cultivars Bluegem and 'Powderblue'. Bottom heat increases the rooting of the cuttings harvested during autumn and winter in all cultivars, and also the cuttings harvested during summer and spring in the Bluebelle cultivar.