SEEDLING GROWTH OF TREE SPECIES UNDER DOSES OF HYDROGEL AND TWO LEVELS OF LUMINOSITY

• Published in: Revista árvore 2018-01, Vol.42 (1)
• Main Authors: Pontes Filho, Roberto Albuquerque, Gondim, Franklin Aragão, Costa, Mirian Cristina Gomes
• Format: Article
• Language: English
• Subjects: Condições semiáridas; Estratégia para reflorestamento; FORESTRY; Polímeros
• ISSN: 0100-6762; 1806-9088; 1806-9088
• DOI: 10.1590/1806-90882018000100012

ABSTRACT Hydrogels (polyacrylamide compounds) are recommended in agriculture and forestry as soil conditioners because they are able to absorb water and increase its stocks in the soil. The aim of this study was to determine the most suitable dose of hydrogel to establish seedlings of Enterolobium contortisilliquum (Vell.) Morong under two levels of luminosity. Seedlings of Enterolobium contortisilliquum (Vell.) Morong were planted in pots, following a design of subdivided plots, consisting of two levels of luminosity in the plots: full sun and 50% luminosity, and 10 doses of hydrogel in the sub-plots: 0.0, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 g L-1. Seventy-two days after the seedlings were transplanted to the pots, plant height and diameter were determined, together with the height to diameter ratio, root length and diameter, shoot and root dry weight, and the shoot to root ratio. The lowest ratios between height and stem diameter (8.50 and 8.68) occurred in the seedlings in full sun at the doses of 0 and 2 g hydrogel L-1 respectively. For shaded seedlings the lowest ratio (8.14) occurred at the dose of 3.0 g L-1, but with a lower coefficient of determination (R2 = 0.68). Shoot dry weight increased with the dose of 2 g L-1 in full sun, and 3.5 g L-1 under shaded conditions. The doses of hydrogel giving the best initial development in seedlings under evaluation were 2 g L-1 in full sun and 3.5 g L-1 in the shaded environment. Although a response by the species to the doses of hydrogel was found, the benefits of the polymer were not evident under the conditions of the present study. RESUMO Hidrogéis (compostos de poliacrilamida) têm sido recomendados na agricultura e na área florestal como condicionadores de solo, pois conseguem absorver água e aumentar seu estoque no solo. O objetivo deste estudo foi determinar a dose mais adequada de hidrogel para estabelecimento de mudas de Enterolobium contortisilliquum (Vell.) Morong em dois níveis de luminosidade. Mudas de Enterolobium contortisilliquum (Vell.) Morong foram plantadas em vasos, com delineamento em parcelas subdivididas, compreendendo dois níveis de luminosidade nas parcelas - pleno sol e 50% de luminosidade, e dez doses de hidrogel nas subparcelas: 0,0; 2,0; 2,5; 3,0; 3,5; 4,0; 4,5; 5,0; 5.5 and 6,0 g L-1. Aos 72 dias após o transplantio das mudas para os vasos, a altura e o diâmetro das plantas foram determinados, bem como a relação entre altura e diâmetro, comprimento e diâmetro das raízes