The Study On Physiological Characteristics And Leaf Color-emerging Of Two Leaf-colored Plants Under Lead Stress

Using five-year-old potted plants of Prunus cerasifera var atropurpurea, Prunus blireana'Meiren'as materials which artificial controlled the soil water to add lead. The soil lead contents were set as CK (no lead), 300,900,1500,2100mg/kg respectively. Leaf membrane lipid peroxidation, antioxidant enzyme activity, osmotic adjustment substance contents, pigment contents and leaf coloration changes under different soil lead contents of the two plants were studied in order to recover the vegetation and the color-leaf plant's cultivation and application in soil lead pollution areas.The results showed as follows: Prunus cerasifera var atropurpurea and Prunus blireana'Meiren'were both influenced in the soil polluted by lead. They displayed different symptoms with different soil lead contents after 30 days of lead treatment., 2 tree seeds were injured lightly in low lead contents of the soil.The colour of Prunus cerasifera var atropurpurea leaves were redder than CK in the 10 days at first and then restored under 300 mg/kg lead treatment. 2 tree seeds were injured seriously when more than 1500mg/kg lead content in the soil.With the increased of soil lead contents and the extended of treatment time, Leaf relative conductivity, MDA contents, oxygen free radical production rate, continued to rise; Antioxidant enzymes, proline and soluble sugar first increased and then decreased and the maximum value appeared around the 20th or 30th days after treatment. Soluble protein contents first decreased then increased and decreased at last. It is very possible that soluble sugar was the most important osmotic adjustment substance in Prunus cerasifera var atropurpurea and Prunus blireana'Meiren'when they were injured by lead. In both of the plants, Pb²⁺ contents in leaves were increased, but Ca²⁺,Mg²⁺, ,Fe³⁺contents were decreased.The pigments of the leaves(Anthocyanin, chlorophyll flavonoids and carotenoids) were decrease in both of trees with the increased of soil lead contents and the extended of treatment time. Correlation analysis showed that in the 2 plants, anthocyanin is main pigments determined the leaves color under lead stress, followed is flavonoids chlorophyll and carotenoids had less impact. With the increase of lead contents,"L*-value"increased obviously, but"a*-value"maintain a downward trend.It showed that after lead treatment, the leaf brightness values increased, and leaf color turn to yellow-green from deep purple.. The anthocyanin content in both of the trees was positive correlation with enzymes PAL and CHI and was extremely remarkable correlation with the soluble sugar content after lead treatment. The anthocyanin content was positive correlation with enzymes in Prunus cerasifera var atropurpurea but negative correlation in Prunus blireana'Meiren'.The value of L*,a*,b* changed obviously around the 20th days, so it is possible that the period of about the 20th after lead treatment was important for Prunus cerasifera var atropurpurea and Prunus blireana'Meiren'.to resist lead by themselves. The leaf color turned to green from deep purple when lead content over 900 mg/kg. Their ornamental value became lower. The changes of morphology and physiology were analysed comprehensively and we could summarize that Prunus cerasifera var atropurpurea had stronger lead-resistant ability than Prunus blireana'Meiren'.