Arthrocnemum macrostachyum : a potential case for agriculture using above seawater salinity

Abstract

Arthrocnemum macrostachyum L. is a stem-succulent perennial in the family Chenopodiaceae and is widely distributed in the tidal marshes of Pakistan. Seeds were collected from a coastal salt marsh situated on the Arabian Sea coast at Sands Pit, Karachi, Pakistan. Results indicated that seeds are highly salt tolerant and 3% seeds germinated at 1000 mM NaCl. Germination was significantly higher at 15 - 25 degreesC thermoperiod at 600 and 800 mM NaCl. The osmotica, proline and betaine, did not relieve salinity-induced dormancy. Plant growth regulators, gibberellic acid and kinetins significantly alleviated the salinity-induced germination inhibition over different salinity ranges and to different degrees, When the seeds were transferred to distilled water after 20 days exposure to salinity, most recovered in 24 h with recovery percentages at highest salinity varied from 72 to 86% at various thermoperiods. Shoot biomass was highest at 400 mM NaCl, while at salinities of 600 mM or higher it was inhibited. There was little increase in succulence and it decreased at high salinity, while root succulence peaked at 400 mM NaCl. The ash contents of plant were about 60% in all salinity treatments. Na+ and Cl- concentrations increased 10-fold in the highest salinity treatment. Our results indicate that A. macrostachyum has a high degree of salt tolerance and could accumulate a large amount of Na+ and Cl- ions. It could be used as food crop through seawater irrigation.