BRASSINOLIDE APPLICATION TO LEPIDIUM-SATIVUM SEEDS AND THE EFFECTS ONSEEDLING GROWTH

Brassinosteroids have been reported to accelerate plant growth when ap plied to seeds. We examined the effects of seed treatment with brassin olide on early growth of Lepidium sativum (cress). Submicromolar and m icromolar concentrations of brassinolide inhibited root growth within 48 h after seed treatment. Germination of cress was not affected by br assinolide. The inhibition of cress root growth by brassinolide was ti me specific in terms of eliciting the response. Untreated germinated s eeds transferred to filter paper moistened with brassinolide solution did not exhibit the same level of root inhibition as treated seeds. Br assinolide (2 mu M) had no effect on ethylene levels, suggesting that at this concentration brassinolide is acting independently of ethylene to inhibit cress root elongation. Also, brassinolide had no effect on DNA synthesis within 24 h after seed treatment, but synthesis was red uced after 48 h. The results of this study illustrate a significant sp ecific effect on very early cress root growth by seed treatment with b rassinolide.