Efeito da calagem e da correção dos teores de Ca e Mg do solo sobre o crescimento de mudas de angelim-pedra (Dinizia excelsa Ducke), cedro (Cedrela odorata L.) e mogno (Swietenia macrophylla King)

Abstract

The production of quality seedlings, fundamental for the development of the species, is one of the most important stages in the cultivation of forest species. Therefore, it is necessary to acquire knowledge about the characteristics of the species during the nursery stage, especially regarding their nutritional requirements and their responses to substrate correction. Thus, the objective of this study was to evaluate the effect of liming with different types of limestone and of Ca and Mg deficiency correction, along with non-corrective sources of soil acidity, on the development of angelim-pedra (Dinizia excelsa), cedar (Cedrela odorata) and mahogany (Swietenia macrophylla) seedlings. This study was carried out in the FCA/UFAM greenhouse, using as a Yellow Latosol substrate. We tested three types of limestone and three Ca:Mg ratios (with non-corrective products of acidity). The treatments tested were: T0 - control, T1 - dolomitic limestone (3:1), T2 - magnesium limestone (9:1), T3 - calcitic limestone (15:1), T4 - Ca and Mg in 3:1 ratio; T5 - Ca and Mg in 9:1 ratio and T6 - Ca and Mg in 15:1 ratio. The experimental design was composed of randomized blocks with 5 repetitions, for a total of 35 plots. Each plot was formed by 3 seedlings, grown in citropotes, with a capacity of 3.2 kilograms of substrate. Corrective fertilizating was done in doses equivalent to 100, 250, 150 and 15 kg.ha-1, N, P2O5, K2O and S, respectively, and Chelamix, a source of B (0,5% ), Cu (0,2%), Fe (0,3%), Mn (0,2%), Mo (0,5%) and Zn (2,4%), disolved in water, was used as a source of micronutrients . The growth characteristics evaluated were height, diameter, dry weight of the shoot (ADM), dry weight of the root, total dry weight, root/shoot ratio and shoot nutrient content. The means were compared using a Scott-Knott test with a 5% probability. The angelim-pedra seedlings responded to the different limestone sources and to Ca and Mg addition, for all the assessed growth characteristics, except for the root/shoot ratio. The best results were obtained when the seedlings developed under a Ca:Mg ratio of 9:1, regardless of source. The cedar seedlings were more sensitive to the acidity of the growing substrate, responding only to the addition of magnesium limestone for all the evaluated growth characteristics, with the exception of height, which responded to the addition of calcitic limestone, and of the root/shoot ratio. The mahogany seedlings showed the effect of the different treatments only regarding height, with the limestone treated seedlings being the same to the seedlings treated with the 15:1 Ca and Mg ratio. However, the liming had a positive effect on the absorption of K, Ca and Mg by the seedling shoots, showing the importance of liming for obtaining quality seedlings. Overall, the three species under study showed the best results when cultivated using magnesium limestone as a corrective for acidity and as a source of Ca and Mg in the growing substrate.