Seed germination and radicle growth of a halophyte, Kalidium caspicum (Chenopodiaceae)

Effects of temperature, light, NaCl and polyethylene glycol (PEG)-6000 on seed germination and radicle growth in a halophytic shrub, Kalidium caspicum (L.) Ung.-Sternb. were investigated. When seeds were incubated in deionized water at constant temperatures between 10 and 30 degrees C, the percentage germination in the dark exceeded 75%; light suppressed seed germination at alternating temperatures. Incubating seeds with a hypersaline solution of NaCl for 30 d had no adverse effect on their germinability. The percentage germination of seeds incubated with a -0.8 MPa NaCl solution was 73, 80 and 54% at 10, 20 and 30 degrees C, respectively, but all radicles died before their length exceeded 5 mm. In contrast, when seeds were incubated with a -0.8 MPa PEG solution at 20 degrees C, 68% of seeds germinated, and 95% of the emerging radicles survived beyond 5 mm. The high sensitivity of small radicles of this species to salinity indicated that salt must be removed from the soil surface for seedling establishment. (C) 2000 Annals of Botany Company.