GIBBERELLIC-ACID, TEMPERATURE, LIGHT, STRATIFICATION, AND SALINITY AFFECT GERMINATION OF PENSTEMON-PARRYI SEED

Treatment of desert beardtongue (Penstemon parryi Gray) seed with 500 ppm (1.44 mM) GA3 for 24 hours greatly enhanced germination. The optimum temperature range for seed germination was 15 to 20C in light and darkness. However, light significantly reduced seed germination when the temperature was below or above the optimum range. Stratification of seed at 5C was less effective than GA3 treatment in inducing seed germination. Imbibition of seed in 2000 ppm (34.2 mM) and 4000 ppm (68.4 mM) NaCl reduced the percentage of germination by 30% and 80%, respectively. Chemical name used: gibberellic acid (GA3).