| This experiment use half a year growed and potted seedlings of Lithocarpus polystachyus Rehd as experimental material. In order to explore the Cadmium stress environment of Lithocarpus polystachyus Rehd seedling growth, physiology, the effect of photosynthetic characteristics. This experiment adopts Single factor complete random block design, there are 6 cadmium concentration processing gradient in the experiment:the CK of 0 mg·L-1,50 mg·L-1,100 mg·L-1,150 mg·L-1,200 mg·L-1,250 mg·L-1. in total 6 months experiment period, the first 2 month is called "dealing time", which is dealing with the objects 6 times of watering 50ml Cadmium solution in every 10 days. Soil cadmium content is 0 mg·kg-1,7.5 mg·kg-1,15 mg·kg-1,22.5 mg·kg-1,30 mg·kg-1,37.5 mg·kg-1 after watering. Then in the next 4 months, continue to observe Lithocarpus polystachyus Rehd seedling growth status, measure its growth and photosynthetic indicator change in time. And then determine the physiological indexes after the experiment, also analyze all indicators by analysis of variance, multiple comparison, correlation and analysis of principal components. This article aims to analyze Lithocarpus polystachyus Rehd seedlings’resistance ability and the resistance mechanism when they are forced Cadmium stress, in order to provide theoretical basis of Lithocarpus polystachyus Rehd cultivation and domestication to the cadmium polluted area.The results shows:1. Cadmium stress has significant impact for Lithocarpus polystachyus Rehd seedlings’growth characteristics. Under Cadmium stress environment, various growth indexes are significantly affected:plant height growth, diameter growth, above ground biomass, but is weaker affected to Lithocarpus polystachyus Rehd seedlings’height growth.With the rising concentration of Cadmium stress, The change trend of Biological index of Lithocarpus polystachyus Rehd seedlings shows the same trend:rising firstly and then go downward. In 50 mg·L-1 Cadmium concentration stress environment, it had an actively effect on Lithocarpus polystachyus Rehd, but under the Cadmium environment of Cadmium concentrations greater than 50 mg·L-1 inhibits Lithocarpus polystachyus Rehd’s growth.2. Under different concentrations of Cadmium stress environment, Physiological index of Lithocarpus polystachyus Rehd seedlings shows different degree of influence:MDA conten, Cell membrane permeability, The content of soluble sugar, The content of soluble protein, CAT activity, POD activity, Chlorophyll a, Average net photosynthetic rate of light response curves had a very remarkable difference. Those indicators was strongly influenced by cadmium stress environment; And the SOD activity, Relative water content of leaves, Chlorophyll b, Total Chlorophyll didn’t have a very remarkable difference. Those indicators was weakly affected by cadmium stress environment.With the rising concentration of Cadmium stress, The change trend of Physiological index of Lithocarpus polystachyus Rehd seedlings was different: The content of soluble sugar, The content of soluble protein, CAT activity, POD activity, SOD activity perform a trend of rising firstly and then go downward. Chlorophyll a, Chlorophyll b, Total Chlorophyll perform a trend of rising firstly and then go downward and finally rising again. MDA conten, Cell membrane permeability, was increasing. Relative water content of leaves, Average net photosynthetic rate of light response curves, Light compensation point, Light saturation point, Dark respiration rate was decreased.3. About the comprehensive correlation analysis, Under Cadmium stress environment, the correlation of the each of Lithocarpus polystachyus Rehd seedlings’growth indicator is inseparable, the correlation of a part of physiological indexes and the growth indicator of Lithocarpus polystachyus Rehd seedling is inseparable, part of physiological index have their own correlation. The First principal components of Lithocarpus polystachyus Rehd’ seedling are mainly include The content of soluble sugar, The content of soluble protein, Root indexes, Biological indicators, Plant height, Diameter increment, CAT activity, POD activity, Average net photosynthetic rate. The Second principal components of Lithocarpus polystachyus Rehd’seedling are include Chlorophyll a, Chlorophyll b. The Third principal components of Lithocarpus polystachyus Rehd’ seedling are Relative water content of leaves, Total Chlorophyll. The Fourth principal components of Lithocarpus polystachyus Rehd’ seedling are MDA content, SOD activity, Cell membrane permeability.Comprehensive analysis concludes that Lithocarpus polystachyus Rehd has the ability to resistance the Cadmium stress in a certain degree. In the 50 mg·L-1 Cadmium concentration stress environment, seedlings of Lithocarpus polystachyus Rehd’s growth was promoted, growing well; And in the 250 mg·L-1 Cadmium concentration stress environment, although the growth and physiological functions of seedlings of Lithocarpus polystachyus Rehd are impaired but it can still survive. |
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