Rooting of azalea cuttings of Otto and Terra Nova cultivars treated with auxin and boron

Abstract Azalea (Rhododendron simsii Planch.) is an ornamental plant native to China, propagated commercially by cuttings and cultivated in Brazil due to the beauty of its flowers. However, it presents rooting difficulties, which can lead to a reduction in the commercial production of these seedlings. Thus, the application of plant regulators is necessary to achieve rooting success as well as of nutrients that are involved in biochemical and physiological plant processes. This work aimed to evaluate the rooting performance of Otto and Terra Nova azalea herbaceous cuttings treated with indolebutyric acid (IBA) and boron. The experiments were conducted at a private property specialized in the production of potted azalea, located in Holambra County, São Paulo State, Brazil, and the evaluations were carried out at the Plant Seed Laboratory of the Crop Production Department, São Paulo State University (Unesp), School of Agricultural and Veterinarian Sciences, Jaboticabal. The experimental design for each experiment with each cultivar was completely randomized. The treatments were arranged in a 4x4 factorial scheme (IBA concentrations x boron concentrations) with four replications and 10 cuttings per replication. The evaluation was performed six weeks after experiment beginning. Auxin and boron did not influence rooting percentage of cuttings of both cultivars. However, Otto cultivar presented a better-quality root system when cuttings were treated with 2,000 mg L−1 IBA in the absence of boron. Resumo A azaleia (Rhododendron simsii Planch.) é uma planta ornamental originária da China, propagada comercialmente por estacas e muito cultivada no Brasil devido à beleza de suas flores. No entanto, apresenta dificuldades no enraizamento, o que pode provocar uma redução na produção comercial dessas mudas. Dessa forma, é necessária a aplicação de fitorreguladores para alcançar o sucesso do enraizamento, bem como a utilização de nutrientes que estejam envolvidos nos processos bioquímicos e fisiológicos das plantas. O objetivo do trabalho foi avaliar a influência do ácido indolbutírico (AIB) e do boro no enraizamento de estacas herbáceas das cultivares de azaleia Otto e Terra Nova. Os experimentos foram realizados em uma propriedade particular especializada na produção de azaleias em vasos, localizada em Holambra/SP, e as avaliações foram realizadas no Laboratório de Sementes e Plantas Hortícolas do Departamento de Produção Vegetal, da Faculdade de Ciências Agrárias e Vete