The Physiological Integration Of Light In Commelina Benghalensis L.

Clonal plant belongs to a very large and special group in the plant kingdom, which has a greater advantage over non-clonal plants in surviving, growth, reproduction and use of resources. Commelina benghalensis L. is a kind of annual herbaceous plants of C. benghalensis L., depending on its stolon for the asexual reproduction, which belongs to a kind of typical clonal plants. Light is the key factor affecting plant survival, growth and reproduction, while physiological integration clonal plants is an important feature in clonal plants. In this study, C. benghalensis L. was treated with shading and cutting off stolons, to determine the biomass of each type of mother ramet and duaghter ramet, water content, relative conductivity, free proline content, soluble sugar content, MDA content, antioxidant enzyme (SOD, POD, CAT) activities, chlorophyll content, chlorophyll fluorescence parameters, photosynthetic rate in leaves, to reveal the physiology integration of C. benghalensis L. under the heterogeneous light environment. The result were as follows:(1) It was found that physiological integration did exist in C. benghalensis L. under the stress of light, and the direction of integration was two-way:the integrated strength from duaghter ramet to mother ramet in leaves was 10.03%, and that from mother ramet to duaghter ramet was 6.64%. Integrated strength from duaghter ramet to mother ramet in stems was 11.9%, and that from mother ramet to duaghter ramet was 7.9%. The integrated strength of soluble sugar from duaghter ramet to mother ramet in leaves was 9.1%, and that from mother ramet to duaghter ramet was 6.6%.(2) Under adequate sunlight, the leaf and stem biomass of C. benghalensis L was almost the same, that was, the leaf and stem of C. benghalensis L. were distributed the same resources. When duaghter ramet was shaded, the mother ramet had larger dry weight of flowers than mother ramet and duaghter ramet all non-shaded. The results indicated that the mother ramet was allocated more resources when duaghter ramet in shade stress and the mother ramet under sufficient sunlight, which meant that the nutrition environment of daughter ramet could affect the resource distribution of the whole plant. It was concluded that the integration could allocate resources reasonablly, so as to promote the phenotype of clonal plants to accommodate the different habitats.(3) When the plant was shaded, the chlorophyll content and light energy conversion efficiency reduced, which resulted in the decrease of leaf soluble sugar content and dry matter accumulation. Furthermore, the SOD activity went up and CAT activity decreased in leaves of duaghter ramet, while the POD activity went up in mother ramet.The reduction of CAT activities could be regarded H2O2 as a stress signal to activate other antioxidant defense system. After shading, the MDA content, proline content and relative conductivity in leaves also increased, which meant the membrane system was damaged to some extent.(4) When the mother ramet or duaghter ramet of C. benghalensis L. was shaded, the MDA and proline content in shaded leaves were higher than the control, but less than that in the whole shading plant. So, with the physiological integration, the clonal ramets could reduce the degree of oxidative damage in cell membrane, and improve the adaptation to light stress by increasing the proline content.(5) After the duaghter ramets with cutting stolons was shaded, the leaf SPAD value, Fv/ Fm value and water content in leaves were significantly lower than the shaded ramets with connected stolons, which proved that physiological integration could reduce the stress on duaghter ramets, and also delay its aging process.