Comparative Salt Tolerance Study of Some Acacia Species at Seed Germination Stage

TL;DR

This study compares the seed germination responses of six Acacia species under varying salt stress levels, identifying species with high salt tolerance suitable for reforestation in saline soils.

Contribution

It provides a comparative analysis of salt tolerance during seed germination among Acacia species, highlighting A. raddiana as highly tolerant for salt-affected areas.

Findings

A. raddiana showed the highest germination percentage under salt stress.

Germination inhibition was reversible after transferring seeds to water.

Salt tolerance varied significantly among species, especially at moderate salt levels.

Abstract

Objective: The purpose of this study was to assess and compare the seed germination response of six Acacia species under different NaCl concentrations in order to explore opportunities for selection and breeding salt tolerant genotypes. Methodology: Germination of seeds was evaluated under salt stresses using 5 treatment levels: 0, 100, 200, 300 and 400 mM of NaCl. Corrected germination rate (GC), germination rate index (GRI) and mean germination time (MGT) were recorded during 10 days. Results: The results indicated that germination was significantly reduced in all species with the increase in NaCl concentrations. However, significant interspecific variation for salt tolerance was observed. The greatest variability in tolerance was observed at moderate salt stress (200 mM of NaCl) and the decrease in germination appeared to be more accentuated in A. cyanophylla and A. cyclops. Although, A. raddiana, remains the most interesting, it preserved the highest percentage (GC = 80%) and velocity of germination in all species studied in this study, even in the high salt levels. This species exhibited a particular adaptability to salt environment, at least at this stage in the life cycle and could be recommended for plantation establishment in salt affected areas. On the other hand, when ungerminated seeds were transferred from NaCl treatments to distilled water, they recovered largely their germination without a lag period and with high speed. This indicated that the germination inhibition was related to a reversible osmotic stress that induced dormancy rather than specific ion toxicity. Conclusion: This ability to germinate after exposure to higher concentrations of NaCl suggests that studied species, especially the most tolerant could be able to germinate under the salt affected soils and could be utilized for the rehabilitation of damaged arid zones.