EFFECTS OF TEMPERATURE AND OSMOTIC POTENTIAL ON GERMINATION OF SUNFLOWER AND SAFFLOWER AND ON HORMONE-TREATED SUNFLOWER SEEDS

Abstract

The influence of three temperatures and solutions of different osmotic potentials obtained with NaCl and/or polyethylene glycol 6000 was tested on the germination of sunflower (Helianthus annuus L.) and safflower (Carthamus tinctorius L.) seeds. The effects of two hormones at two concentrations on the germination of osmotically stressed sunflower seeds were also investigated. Seeds of the Record cultivar of sunflower were more salt-tolerant than Chernianka-66. Furthermore, Record germinated better at 20 °C than at 10° or 30 °C, while Chernianka-66 showed higher germination at 20° and 30 °C and was most sensitive to salinity at 10 °C. Seeds from Ute safflower exhibited more salt tolerance than did Local 3151, especially at the lower NaCl-induced osmotic potentials. The two safflower cultivars germinated better at 10° and 20 °C than at 30 °C. Seed germination of both crops was restricted more with polyethylene glycol 6000 than with NaCl, presumably due to the greater water stress caused by the former osmotic substrate. Germination of Record in NaCl substrate was inhibited at 50 ppm α-naphthalene acetic acid (NAA). NAA at 50 ppm decreased the germination of cv. Chernianka-66, whereas 3-indole butyric acid (IBA) at 10 ppm enhanced its germination. In general, germination of both sunflower cultivars was stimulated more by IBA than NAA. Furthermore, seeds treated with 10 ppm concentration gave better response than those treated with 50 ppm, possibly due to toxic effects.