The Studies On The Different Light Stress On Two Species Ground Covers

Glechoma longituba (Nakai). Rupr. and Duchesnea indica not only have brilliant leaf color, but also growth rapidly and have strong mulching ability. They are excellent ground covers, but at present their application on landscaping in china is less. This study regards Glechoma longituba (Nakai). Rupr. and Duchesnea indica as to research objects. By different light stress treatment (0,30%,50%,70% of full sunlight), study on four aspects: growth, physiological index, photosynthesis characteristics and blade anatomy structure, comprehensive study on shade tolerance of two species ground covers.1. The effects of light stress on two species ground covers growth is significant, as stress degree increased, the length of Glechoma longituba stem node, the height of Duchesnea indica and the areas of two species ground covers increase. As the results of the test shows, on 50% shading treatment Glechoma longituba growth best, on 70% shading treatment Duchesnea indica growth best.2. The effects of light stress on the two species ground covers physiological index is different. The content of chlorophyll and carotenoid are great influenced. As stress degree increased, the content increased, they are positive correlated; As stress degree increased , leaf water content and membrane permeability increased, the difference from different light stress treatment is extremely significant; The proline content of Glechoma longituba is no significant difference, but the praline of Duchesnea indica difference is significant(P<0.05); The difference of Glechoma longituba protein content is extremely significant(P<0.01), the protein content of Duchesnea indica difference is significant(P<0.05).3. From different light stress treatment, study on photosynthetic indexes change in a day and light response curve, diurnal variation of photosynthesis curve of two species ground covers is single peak curve, there is no midday depression of photosynthesis, as stress degree increased the transpiration rate is decreased, diurnal variation of intercellular CO₂ concentration and diurnal variation of photosynthesis has opposite trend; From light response curve, we know two species ground covers have low light compensation point and low light saturation point, they are more shade tolerance ground covers.4. Through blade paraffin section of two species ground covers, the observation of leaf anatomical structure, light stress can effect leaf anatomical structure of Glechoma longituba and Duchesnea indica. Two species plant blade is consist of epidermis, mesophyll tissue and vein. As stress degree increased, leaf thickness is beveloided, cell arrangement is loose, there are some epidermis cell fractured. From observation, there is differentiation of palisade tissue and spongy tissue in Glechoma longituba, but there is no differentiation of palisade tissue and spongy tissue in Duchesnea indica, there is only one line cell to epidermis, but there are more veins in Duchesnea indica.