Effects of Brassinolide on Mesocotyl, Coleoptile and Leaf Growth in Rice Seedlings

Abstract

The effect of brassinolide at 10–9M to 10–5M on the growth of rice seedlings was examined in darkness and under the light. After treatment in darkness for one week, 10–7M and 10–5M brassinolide strongly stimulated mesocotyl and coleoptile elongation in all rice cultivars. The treatment with 10–5M brassinolide also induced the formation of the MC-type seedling, which consisted of only mesocotyl and coleoptile, the leaves being enclosed by the coleoptile. Under the light (120 μmol m–2 s–1, 14 h/day), brassinolide stimulated the leaf sheath elongation and increased the number of leaves. Brassinolide at 10–5M stimulated the elongation of the second leaf sheath, but inhibited that of the third leaf sheath.

Keywords

• Brassinolide
• Coleoptile
• Leaf sheath
• Mesocotyl1
• Rice.