Germination and growth response of salt tolerant native grasses from ephemeral wetlands in inland Victoria

Summary of final report on the Australian Flora Foundation funded project:

Brown, A.J., Reddy, N., Cody, J. and James, E.A.
State Chemistry Laboratory, Agriculture Victoria
Royal Botanic Gardens Melbourne

Grant Details    Final Report

Germination and hydroponic growth trials were conducted on a number of native grass species to examine their growth characteristics and physiological responses to different levels of salinity. Germination, under a regime of 12 hours light and 12 hours dark at 25ºC, ranged from 0 19% to 0 54% for 17 and 164 after ripening days respectively. Particularly poor germination (< 5%) was found for Poa salacustris, Distichlis distichophylla and Puccinellia stricta var. perlaxa. Excluding light significantly increased germination in one of two populations of each of Agrostis adamsonii and the Puccinellia sp. and in all three populations of A. robusta but decreased germination in both populations of A. punicea. Of three populations tested under saline conditions, A. robusta and the Puccinellia sp. gave better germination than A. adamsonii but all gave poor results at 200 and 300 mMol salt. Salt treatment (100, 200 and 300 mMol NaCl), depressed growth in all tested species. At least 50% of the plants survived the seven week growth trials; the worst being a population of A. avenacea and both populations of A. punicea at the 200 and 300 mMol treatments. Overall growth was superior in A. adamsonii and A. robusta but a high degree of salt tolerance was also noted in a further population of A. avenacea and in the slow growing Puccinellia sp. Significant increases in root length were observed for some of these populations as salt concentration increased. Relative water content and osmotic potential deceased in leaf tissue with increasing salt for most populations, in conjunction with increased uptake of sodium and chloride. Some evidence of osmotic adjustment was seen for some populations but salt exudation onto upper leaf surfaces appears to be a major salt tolerance mechanism.