Effect Of Ethephon And Paclobutrazol Treatment On Bermudagrass's Growth And Physiology

Bermudagrass was used as the experiment material. At four leaves stage, plant of bermudagrass were sprayed with 100mg/L 200mg/L and 300mg/L of ethephon, and 100mg/L, 200mg/L and 300mg/L of paclobutrazol and water (control) on the leaves respectively. The population structures of bermudagrass lawn before and after clipping were observed periodically. The plant height, stem height, root length and top unwrapped leaf length, plant nodes, tilling rate, leaf area were measured and analyzed after spraying the plant growth regulators. The electric conductivity, Chla+b content, fatty acid components and their content, soluble sugar content, proline content and fibre content of bermudagrass were determined. Morphological structure of the stem and leaf tiss were observed. The main results were as follow:1. Both the ethephon and paclobutrazol treatments optimized the population structure of bermudagrass lawn. The plant height got shorter and the tillering rate increased and the leaves got narrower and shorter. The later is better. But the lOOmg/L ethephon treatment showed contrary to the other treatments. The paclobutrazol treatments repressed the leaf length and stem height, but the 200mg/L and 300mg/L ethephon treatments repressed extension of regenerated leaves and promoted the stem growth and the lOOmg/L ethephon treatment promoted both extension of stem and leaf.2. The paclobutrazol treatments promoted extension of the main root and growth of the secondary root, the ethephon treatments resulted in more main roots and secondary roots growing on the surface of soil and restraining root growth.3. At the early stage after spraying plant the growth regulators, Chla+b content in the leaves was decreased. All the treatments inhibited the formation and development of the mesophyll cells and chloroplasts and the effect of paclobutrazol is stronger than that of ethephon.4. Both the ethephon and paclobutrazol treatments reduced the electric conductivity and proline content of bermudagrass, but the treatments with lower concentration showed lower electric conductivity and proline content.5.With cold treatment, both the ethephon and paclobutrazol treatments increased the soluble sugar content in the stem and leaves, but the paclobutrazol treatments also reduced the leaf nonsaturation fatty acid content, suggesting that the ethephon treatment had stoonger cold resietance than paclobutrazol.6. The effect of ethephon and paclobutrazol treatment on fibre content in bermudagrass stem and leaves was not obvious. The ethephon and paclobutrazol treatments repressed growth of the epidermal sclerenchyma cells. The paclobutrazol treatment promoted the vascular tissue growth, but effect of ethephon treatment is contrary. The ethephon treatment repressed the formation of the protective tissue and mechanical tissue of leaves, but the paclobutrazol's effect is contrary. So, the paclobutrazol treatments had better endurence to tread than the ethephon treatment on tissue structure.