SUBSTRATE pH MANAGEMENT STRATEGIES IN THE PRODUCTION OF YERBA MATE SEEDLINGS (Ilex paraguariensis A. St.-Hil.)

Abstract

One of the most important properties of a substrate is pH, which must be controlled to maintain levels between 5.3 and 6.5, and thus allow the production of good-quality seedlings. The objectives of this work were to evaluate strategies to maintain pH of pine bark compost-based substrate (SCCP) in the appropriate range and to verify its effect on the quality of seedlings of yerba mate (Ilex paraguariensis A. St.-Hil.). Six treatments were evaluated: T1= SCCP with corrected pH and application of dolomitic solution (SD) during cultivation; T2= SCCP with uncorrected pH and application of SD during cultivation; T3= SCCP with corrected pH and application of calcium nitrate (NC) during cultivation; T4= SCCP with uncorrected pH and application of NC during cultivation; T5= SCCP with corrected pH; and T6= SCCP with uncorrected pH. At the end of the trial, the aerial (MSA) and root dry mass (MSR), stem length and diameter, mineral elements in the leaf, electrical conductivity and pH of the substrate were measured. T1, T3 and T5 recorded pH values within the appropriate range until the end of the trial. T2 and T4 had a low initial pH (4.13), and only T2 recorded a final pH within the desirable range (5.34). The morphological variables of the seedlings in T6 had the lowest values. MSA was higher in T1 and T5, coinciding with the higher leaf Ca and Mg content. Correcting the pH of the SCCP with dolomite before use and applying SD to the SCCP with uncorrected pH during cultivation were effective strategies for the production of good-quality yerba mate seedlings.