Seed germination of Melocactus zehntneri (Cactaceae) submitted to water and saline stress

Abstract

The seeds are subject to multiple stresses, such as water and salt stress, which limit imbibition and its chances of germination. Therefore, the aim of this study was to evaluate the germination behavior of seeds of Melocactus zehntneri (Britton & Rose) Luetzelb. (Cactaceae) when subjected to water and saline stress. From a completely randomized block experimental design, the water deficit was simulated with PEG6000 solutions at potentials: 0.0 (distilled water); -0.1; -0.3; -0.6 and -0.9 MPa, the same was done with NaCl for salt stress. Non-germinated seeds were washed and replaced to germinate in distilled water to assess recovery, and germinability (%) and t50 (days) were evaluated. Seeds subjected to water stress germinated up to the potential of -0.3MPa (82.0 ± 16.2%), without germination at -0.6 and -0.9 MPa. Under salt stress, the seeds germinated up to the potential of -0.6 MPa, with a reduction in germination as the NaCl concentration increased. When placed back in distilled water, the seeds that had been subjected to water stress germinated at –0.6 MPa and -0.9 MPa, but with a delay in germination (0.0 MPa: 5.96 ± 0.32 days; -0.3 MPa: 11.10 ± 0.76 days). Under salt stress, seeds submitted to -0.9 MPa germinated, demonstrating that NaCl did not cause damage (0% stress versus 39.0 ± 14.7% in recovery). Therefore, the seeds of the studied population of M. zehntneri are tolerant to water and salt stress.