Germination studies in Horwoodia dicksoniae Turril

The use of native plants in urban landscape projects conserves natural plant diversity, imparts a natural appeal to the landscape, and requires less water and nutrients than do exotics. Desert annuals like Horwoodia dicksoniae Turril. have seeds with physiological dormancy. We studied the combined effects of dry heat (50°C) and GA₃ treatments on germination of Horwoodia dicksoniae. The results showed that the highest germination (88%) occurred when the seeds were subjected to a treatment combination consisting of exposure to dry heat (50°C) for 20 days followed by a treatment with 500 ppm GA₃ for 24 hrs. The next best treatment combination (86%) was the combination of 10 days dry heat (50°C) followed by a treatment with 1000 ppm GA₃ for 48 hours. This suggested that higher concentration of GA3 could compensate for shorter exposure period to dry heat.