Study On Shade Tolerance Of Ground-cover Chrysanthemum

Ground-cover chrysanthemum (Chrysanthemum morifolium), which is a branch of Compos itae and subordinate to Chrysanthemum, is herbaceous perennial plant. Ground-cover chrysanthemum has a compact plant type, rich colors in flowers, long flowering period and with a capacity of strong resistance, resistance to extensive management, and it could be used as an excellent ground-cover plant of flowers. In order to pick out the shade-tolerance cultivars of ground-cover chrysanthemum and to expand the range of applications of chrysanthemum and increase the understory plants species of flower, rich landscape level, a greenhouse experiment was conducted to investigate the morphological, physiological, and photosynthetic indices of ground-cover chrysanthemum under different shading treatments (transmittance of 25%,50%,85%,100%) of 17cultivars of ground-cover chrysanthemum and 1 Chrysanthemum indicum. Software of Spass20.0 and Excel were used to give a systematic analysis of the data of the indicators, results showed that:1. Shading treatments had produced a significantly effects on the plant height, crown width, stem diameter and internode length. With the increase of shading radio, the plant height increased, crown width decreased, stem diameter became smaller and the internode length became longer.2. After shading treatment, leaf thickness, leaf length, leaf width, leaf area were significantly different. With the increase of shading radio, leaf thickness became thicker, the leaf length, leaf width and leaf area increased significantly.3. The number of flowers and the number of branches of C. morifolium had suffered significant effects by the light conditions. With the increase of shading radio, the number of flowers and the number of branches decreased significantly, flower diameter increased somehow.4. After shading treatment, the specific leaf weight (SLW), fresh weight per unit area and water content per unit area of C. morifolium had changed greatly, and the trend was consistent. With the increase of shading radio, the specific leaf weight (SLW), fresh weight per unit area and water content per unit area decreased.5. The Chlorophyll content of leaves under shading treatments was significant higher than the Chlorophyll content in full light. The specific performance showed as follows, With the increase of shading radio, chlorophyll a, chlorophyll b, the total chlorophyll content (chlorophyll a+b), Carotenoid increased, while the radio of chlorophyll a to chlorophyll b (chlorophyll a/b) decreased.6. With the increase of shading radio, The photosynthetic light compensation point (LCP), photosynthetic light saturation point (LSP), maximum net photosynthetic rate and the dark respiration rate (Rd) decreased. After shading treatment, the diurnal variation of photosynthesis between different treatments exist significant difference, and the time of point of the curve delayed. The curve of diurnal variation of the net photosynthetic rate in full light of some cultivars were appeared as bimodal curve, however, after shading treatments, the curve turned to be a single peak curve.7. Through a comprehensive analysis and evaluation of the indicators of 18 cultivars of ground-cover chrysanthemum, results showed that, the shade-tolerance sequence of the 18 cultivars tested from strong to weak is in following order:C.’Chongbanwanhuang’, C.’Yuanguanzi’, C. ’Yurenzao’, C.’Xiaozi’, C.’Jinluyi’, C.’Maoxiangyu’, C. indicum, C.’Zaomihuang’, C.’0621’, C. ’Meihong’, C.’Chongbanzaohuang’, C.’Jinbuhuan’, C.’Guoqingcheng’, C.’Zaobailong’, C. ’Yurenmian’,C.’Xinwanhuang’, C’YY3’, C.’TY51’.8. By stepwise regression analysis, seven shade-tolerance identification indices, such as crown width, leaf width, fresh weight per unit area, The number of flowers a, flower diameter, photosynthetic light saturation point (LSP) and light compensation point (LCP) have been screened, what’s more, the stepwise regression equation for the ground-cover chrysanthemum shade-tolerance evaluation has been established as well.9. In summary, ground-cover chrysanthemum is a sun plant with shade tolerance. When under shade treatments, it will have changes on its morphology and physiology to adjust the new environment of low light. When the rate of light transmission is was only 25%, ground-cover chrysanthemum could grow up and flower normally, which still has some ornamental value.