Effects of sodium chloride on seed germination and growth of two Chinese desert shrubs, Haloxylon ammodendron and H. persicum (Chenopodiaceae)

The effects of sodium chloride (NaCl), polyethylene glycol-6000, temperature and light on germination and the effects of NaCl on growth were investigated in two Chinese desert shrubs, Haloxylon ammodendron (C.A.Mey.) Bunge and H. persicum Bunge ex Boiss. et Buhse. Both species occur in non-saline sand dunes; H. ammodendron also occurs in saline land, although it is not dominant there. Percentage germination of H. ammodendron and H. persicum in –3.0 MPa (667 mmol kg –1 ) NaCl was 91 and 64%, respectively. Hydroponic culture of each species for c. 3 months with NaCl solutions of 0, 200, 400 and 600 mmol kg –1 showed that the survival of H. ammodendron was highest (82.3%) at 400 mmol kg –1 NaCl, while that of H. persicum decreased with increasing NaCl concentration and was low (11.1%) at 400 mmol kg –1 NaCl. Sodium concentration in shoot tissues of 99-day-old seedlings grown at 400 mmol kg–1 NaCl exceeded 1000 mmol kg –1 in both species, while Na concentration in non-transpiring young seedlings grown in 400 mmol kg –1 NaCl was 240 and 350 mmol kg –1 for H. ammodendron andH. persicum, respectively. The results indicate that both species have relatively low adaptability to salinity at the older seedling stage compared with that at the germination and young seedling stage, and that H. ammodendron shows higher adaptability to salinity at the older seedling stage than H. persicum. It was concluded that salinity adaptability in the later developmental stage of these species determines their distribution with respect to salinity.