Growth and morphological responses of Handroanthus impetiginosus (Mart. ex DC.) Mattos seedlings to nitrogen fertilization

Abstract

The use of native tree species for restoration of degraded areas is often hindered by the lack of information about the nutritional requirements of seedlings at the nursery stage. Therefore, this study aimed to evaluate the growth and morphological responses of Handroanthus impetiginosus seedlings to mineral nitrogen fertilization. The experiment was carried out from July to October 2013 in a seedling nursery under 50% shade cloth. Seeds were germinated for 15 days in low density polystyrene trays and then transplanted into 0.9-L polyethylene plastic bags. A complete randomized block design was used, with four replications and four plants per experimental unit. Treatments consisted of five nitrogen levels (0, 50, 150, 300 and 450 mg N dm-3), using ammonium sulfate as the nitrogen source. Two months after transplanting, the following variables were assessed: leaf chlorophyll content; leaf area; specific leaf area; leaf area ratio; root, stem, leaf and total dry mass; shoot dry mass/root dry mass ratio; shoot height/shoot dry mass ratio; and Dickson quality index. Mineral nitrogen fertilization improved seedling growth by promoting higher results of the leaf chlorophyll content, leaf area and shoot dry mass production. Thus, fertilized seedlings significantly expanded their leaves and invested more in shoot growth, improving their hardiness and quality. The nitrogen level of 240 mg dm-3 was considered to be the most effective for production of H. impetiginosus seedlings.

Crescimento e qualidade de mudas de Citharexylum myrianthum em resposta à fertilização nitrogenada

“…A resposta ao N foi maior para a matéria seca da parte aérea (maior coeficiente angular da regressão) que para raiz. Leite et al (2017) observaram que com o aumento da fertilização nitrogenada em mudas de Handroanthus impetiginosus, a planta investiu maior potencial de crescimento da parte aérea comparada com o sistema radicular, resultando em uma maior produção de folhas. Na fase inicial da produção de mudas é aplicada maior quantidade de nitrogênio, com o objetivo de aumentar a área foliar e, consequentemente, proporcionar maior atividade fotossintética (Silveira e Higashi 2003), o que resulta em maior incremento de matéria seca da parte aérea.…”