Effect of storage, stratification, temperature and gibberellins on germination of dimorphic seeds of Suaeda salsa under saline conditions

Suaeda salsa, a leaf succulent annual herb in the family Chenopodiaceae, is a main halophytic species distributed widely in saline soils of north part of China with economic potentials as sources of oil, food, vegetable and fodder. It produces dimorphic seeds (brown and black seeds). The effect of storage, cold-wet stratification (4 degrees C for two days after water imbibition), treatment with gibberellins (GA(1) and GA(4)) and temperature regimes (5/15, 10/20, 15/25, 20/30, 25/35 degrees C) on germination of Suaeda salsa seeds under NaCl stress was investigated. After one year storage under room temperature, germination percentage of brown seeds decreased while that of black ones increased both in distilled water and in saline solution (300mM NaCl). Stratification and GA(4) treatments improved black seeds' germination, but showed little effect on brown seeds. However, treatment with GA(1) failed to promote seed germination of both kinds of seeds. Salinity, temperature and their interaction significantly affected the germination of both kinds of seeds. Brown seeds under all the conditions showed higher germination percentage than black seeds. Maximum germination percentage was noted in distilled water at 15/25 degrees C and 20/30 degrees C temperature regime for both kinds of seeds. The highest rate of germination was obtained in distilled water at 20/30 degrees C for brown seeds, and at 15/25 degrees C for black seeds. Possible mechanisms involved in germination of the dimorphic seeds and the ecological adaptation of the seeds to the natural habitat are discussed.