Substâncias húmicas na morfofisiologia e crescimento de schizolobium parahyba var. parahyba (Vell.) Blake

Abstract

Despite the prevalence of species of the genus Eucalyptus, the forest sector has directed investments for researches with native species such as Schizolobium parahyba (Vell.) Blake var. parahyba popularly known as guapuruvu. For a good development of seedlings, water and nutrients are needed, to improve the substrate, one can use compounds such as humic substances.The objective of this research was to analyze the main differences between the two varieties of the species Schizolobium parahyba (Vell.) Blake, var. amazonicum and parahyba, as well as to analyze the use of the humic substance in the initial development of Schizolobium parahyba (Vell.) Blake var. parahyba. The species Schizolobium parahyba (Vell.) Blake, var. amazonicum is popularly known as paricá and has a natural Brazilian Amazonian distribution, as well as in Peru and Colombia, its wood is used for various purposes, mainly for the manufacture of veneers and plywood. Schizolobium parahyba (Vell.) Blake, var. Parahyba is known as Guapuruvu, occurring from Bahia to Rio Grande do Sul, its wood is mainly used for the manufacture of doors and toys. The main differences between the two varieties are: places of occurrence, size of seeds and leaves. The use of humic substances in seedlings production is based on humic acids, fulvic acids and humin, which can influence root and leaf development, improving the development of seedlings. The experiment was conducted in the forest nursery of the Federal University of Tocantins. Ten treatments were used, divided into two humic substances (substrate immersion and foliar) and five doses (0, 5, 7.5, 10, 12.5). The following variables were evaluated: seed height (H), neck diameter (DC), number of leaves (NF), number of leaflets (NFO), stem dry mass (MSC), leaf dry mass (MSA), dry mass of the root (MSR), total dry mass (MST), chlorophyll A (CLA), chlorophyll B (CLB), total chlorophyll (CLT), chlorophyll A and B ratio (A), stomatal conductance (gs), transpiration (E), specific leaf area (AFE), total leaf area (AFT), leaf area index (IAF), development quality index (IQD). The use of humic substances interfered in the development of seedlings of Schizolobium parahyba (Vell.) Blake var. parahyba, with the best responses being 12.5 ml L-1 for immersion and 7.5 ml L-1 foliar. In all parameters analyzed in relation to seedling quality, the treatments obtained higher values, thus affirming that the use of SH can improve the morphological and physiological patterns of the seedlings.