Efeito da salinidade induzida no desenvolvimento e crescimento inicial de Carnaúba(Copernicia prunifera(Miller) H.E.Moore): suporte e estratégias de restauração em áreas salinizadas

Abstract

Actually, several regions of earth face serious soil problems because of salinisation. A major part of these cases occurs in regions with an accentuated water deficiency and shallow soils. The damage caused by salinity may become even more critical by inadequate handling and insufficient draining. High soil salt concentration has been one of the factors with major influence on reduced growth rates and productivity in cultivated plants. The Carnauba (Copernicia prunifera (Miller) H.E.Moore) is able to produce under conditions of low precipitation and is an option for income of great importance for the population of the Brazilian semi-arid regions. In our study, we tried to assess the effect of salinity on growth and initial development of Carnauba plantlets destined at supporting restoration of areas of permanent conservation (APPs) that were deforested or suffer from salinisation as well as to promote extractivism as a source of income in this region. In the experiment, we applied a 5x1 factorial arrangement. The assay made use of 4 repetitions with 15 plantlets each in a random distribution. Salinities of 0, 25. 50, 75 and 100 mol.m-³ NaCl, corresponding to conductivities of 2.0, 4.6, 7.1, 9.6 and 12 dS.m-1, respectively, were evaluated in relation to the indexes of initial growth of Carnauba plantlets. The following variables were studied: leaf length (Cra); leaf width (Lra); root length (CRp), fresh weight (PMF); dry weight (PMS); aerial part – root ratio (PAR) and survival rate (TS). Salinity differentially affected each variable studied, with TS suffering a major impact. As to the salinities applied, plantlets demonstrated best results at 25 and 50 mol.m-³ NaCl, better even at 25 mol.m-³; here, the development of leaf width was best. Elevated salinities of 100 mol.m-³ or higher put at risk development and possibly survival of this plant, that thus turns out to be a glycophyte;production and/or replanting are not recommended for areas with these levels of soil salinity.