QUALIDADE DE MUDAS CLONAIS DE ERVA-MATE (Ilex paraguariensis A. St.- Hil.) COM USO DE ALUMÍNIO E CÁLCIO NO SUBSTRATO

Abstract

Yerba mate (Ilex paraguariensis A. St.-Hil.) is a native species from South America, where it grows in low fertility soils, tolerating both the natural lack of nutrients such as calcium (Ca2+) and the presence of toxic elements such as aluminum (Al3+ ). To rise the yerba population in natural environment, or to establish a yerba plantation, seedlings are needed, but little is known about their nutritional requirements, especially in terms of rooting substrate. In this study, we evaluated the growth, nutrition and quality of yerba mate seedlings in response to Al3+ and Ca2+ rates on the substrate, under green house conditions at Guarapuava, Paraná State, Brazil. In experiment 1, the substrate received Al rates (0; 0,36; 0,72; 1,44 e 2,88 g dm-³). In experiment 2, the interaction between Al3+ rates (0 and 0,36 g dm-³) and Ca2+ rates (0; 0,055; 0,11; e 0,22 g dm- ³) was studied. Seedlings were evaluated at 90, 150, 215 and 300 days after planting the cuttings (DAE), for morphological attributes (height, stem diameter, number of leaves) and SPAD index. At 90 and 300 DAE, we determined the consistency of the root ball, the weights of fresh matter (MF) and dry matter (MS) of roots (MFR, MSR), stem (MFC,MSC) and leaves (MFF, MSF). Based on these attributes, the Dickson Quality Index (IQD) was calculated, and the leaves were used to determine the leaf area and the leaf concentrations of nutrients and Al. In experiment 1, The growth of seedlings was influenced by the doses of Al3+ and by the time, the maximum values of diameter of the neck, plant height, number of leaves, leaf area, production of MSF and MSR were observed at 300 DAE were observed in the dose 1,44 g dm-³ of Al3+. In nutrient absorption, only Ca and K nutrients and Al content responded to treatments. The quality evaluated by the consistency of the root ball and IQD was satisfactory at the 1,44 g dm-3 dose of Al3+, and survival was not affected by the treatments. In another experiment, two doses of Al3+ (0 and 2.25 g dm-³) were evaluated, combined with doses of 0, 0.345, 0.690, and 1.38 g dm-³ of Ca2+, with evaluations equal to the first experiment. The highest values of neck diameter, plant height, number of leaves, production of MSF and MSR at 300 DAE were observed in the dose 1.38 g dm-³ of Ca2+ associated with 0 g dm-³ Al3+, already the leaf area achieved its greatest performance without the presence of Ca2+. In the levels of leaf nutrients, only Ca and S showed responses to treatments, for Ca the levels were reduced as a function of Al3+ doses, for S the result was the opposite. The quality of seedlings was influenced, the consistency of the root ball showed the maximum value in the dose 0 g dm-³ of Ca2+ associated with 2.25 g dm-³ Al3+, since the highest HEI was in the association between the maximum dose of Ca2+and Al3+ . It is concluded that there are positive effects on the development of seedlings with the presence of Al3+ and Ca2+ separately, but in association they tend to reduce the positive effects.