EFFECTS OF BRASSINOLIDE ON GROWTH AND CHILLING RESISTANCE OF MAIZE SEEDLINGS

Maize seedlings were cultured in plastic pots containing pearlite or on filter paper and treated with brassinolide (BR)in the dark or in the light. The results showed that at 10(0) ppm BR promoted the elongation of coleoptiles and mesocotyls but retarded the growth of leaves and roots, whether in the dark or in the light. The mesocotyls of etiolated seedlings showed either twining or transverse geotropism when treated by higher concentrations of BR. At 10(-3)-10(-1) ppm, BR improved the greening of etiolated leaves at different temperatures, especially at lower temperature in light. BR also promoted the growth recovery of maize seedlings following chilling treatment. The physiological effect of BR seems to be that of both auxin and cytokinin, and BR as a steroid may act on biological membrane systems.