Aplicação de ácido jasmônico na rustificação em mudas de ipê roxo e guajuvira

Abstract

Lignin is an indispensable biomolecule for many biological processes of plants. It is one of the most important is to contribute to stem verticality and to ensure the transport of water and minerals. Thus, the search for modulatory ways of lignin biosynthesis is important especially with the application of growth regulators. This research was conducted with Handroanthus impetiginosus seedlings and American patagonula subjected to concentrations of acid jasmonic (0,5 μmol L-1, 1 μmol L-1 e 1,5 μmol L-1). The experiment was conducted as a completely randomized design in the nursery and in a randomized block in the field, with four treatments and five replications. The quantification of lignin was performed by the Van Soest method. In the field, measurements included seedling height, diameter, and number of leaves to evaluate seedling quality. In addition, I calculated the ratio of height to stem diameter, the ratio of above ground dry biomass to weight of the dry roots and Dickson quality index (DQI). Data analysis and graphs from the analysis of variance were performed with Statistics, considering a confidence level of 5%. After the imposition of treatments seedlings of H. impetiginosus externalized the smallest increment in height and the ratio between height and diameter for the three doses of AJ, compared to the control. There was an increase in the Dickson quality index, in lignin concentration in the above ground tissues and root in seedlings that received 1 μmol L-1 and 1,5 μmol L-1. For P. americana seedlings, the doses of 1 μmol L-1 and 1,5 μmol L-1 resulted in increased growth of stem diameter. There was a reduction of the ratio of height to diameter for all tested AJ concentrations. DQI and lignin percentage of the above ground tissues increased as a result of application of 1 μmol L-1 de AJ. In the field, the percentage of seedling survival of H. impetiginosus and P. americana was 100% 90 days after planting. H. impetiginosus seedlings showed increased stem diameter with application of 1,5 μmol L-1. P. americana seedlings resulted in small values for H/D as a result of application of 1 μmol L-1 and 1,5 μmol L-1 of AJ. The results indicated that jasmonic acid may be an effective way of promoting seedling rustification in order to improve the initial seedling performance of H. impetiginosus and P. americana seedlings after planting