Seleção de progênies via germinação de sementes de Mimosa caesalpiniifolia B. sob estresse salino.

Abstract

Mimosa caesalpiniifolia Benth., known as sabiá, is a native forest specie of Caatinga belonging to the Fabaceae family. Species that develop in arid and semi-arid regions, such as sabiá, usually encounter adverse conditions for germination and emergence, such as high soil salinity and water deficit. Thus, the objective of this work was to verify whether it is possible to select progenies of M. caesalpiniifolia that are tolerant to the stress caused by doses of saline solutions in the early stages of development. Seeds were collected from 16 matrices located in different states (PE, PI, CE, RN), four per state. The experiment was carried out in the forest seed analysis laboratory at the Federal Rural University of Pernambuco (UFRPE). To simulate saline stress, NaCl solutions were used, with osmotic potentials of 0.0; -0.2; -0.4; -0.6; -0.8; -1 MPa. Percentage and germination speed index, length and dry mass of shoots and roots and percentage of abnormal seedlings were evaluated. The experimental design was completely randomized with four replications of 32 seeds for each potential. After carrying out the evaluations, the maximum dose of pre-established tolerance was reapplied in four replications of 25 seeds from each provenance to identify the genetic divergence in terms of tolerance to saline stress. For the germination percentage, the values were adjusted to the quadratic regression model and for the germination speed index, the data were adjusted to the decreasing linear regression model, reducing as the osmotic concentration increased. Salinity reduced the germination and vigor of M. caesalpiniifolia seeds, decreasing the characters evaluated at the lowest osmotic potentials. The germination test with sabiá seeds proved to be effective for determining tolerance to salt levels (NaCl), the species M. caesalpiniifolia tolerates low osmotic concentrations of sodium chloride and the critical level selected was -0.4 MPa. Through the Mulamba and Mock index, it was possible to select the P1-CE, P2-PI, P3-RN, P1-PE and P1-PI progenies in early stages of development that showed tolerance to salinity levels for the production of seedlings.