Studies On The Physiological Property Of Leaves Of Tea For Cr, As, Cd And Pb Compound Pollution

In this study, two years old Pingyangtezao tea and Mingshan 131 tea were chosed as the research subject,which had been training in lab with a series of potted incubation experiments through the orthogonal test were analyzed,soil applicating of different concentration levels of Cr(NO3)3·9H2O, As2O3, Cd(NO3)2·4H2O and Pb(CH3COO)2·3H2O was carried out to determine the Cr, As, Cd, Pb compound pollution on physiological characteristics of two varieties of tea. The results showed that:(1) Effects of compound pollution of Cr,As,Cd and Pb on the amount of growth in young sprouts of tea.Within the limits of the concentration for the compound pollution, there was a significant effect on the tea shoot growth(length and weight) for two varieties.Compared with their spring shoots length, they were all lower than the control treatment except treatment 1, treatment 2 and treatment 4 of spring shoots in length.For the weight, in addition to treatment 1 higher than the control, the rest were lower than the control treatment. It is suggested that two varieties of tea shoot growth were inhibited by the combined pollution. Mingshan 131 tea plant had stronger inhibition than Pingyangtazao,which showed that with the process of pollution stress,tea plant was damaged even severely.(2) Effects of compound pollution of Cr,As,Cd and Pb on photosynthetic physiology of tea leaves.In this study, two varieties of tea leaves of chlorophyll a, b and total chlorophyll content were lower than the control, both of them have reached a significant level, and the overall decline of Mingshan 131 chlorophyll content was especially more than Pingyangtezao.Range analysis showed that chlorophyll a, b and total chlorophyll content of Mingshan 131 had the same trend, both decreases with increase in concentration of Cr, As, Cd, Pb and Cr, As were the greatest impact indicators.For Pingyangtezao,Cr could affect chlorophyll a and total chlorophyll content increased then decreased with different concentration of Cr, in the concentration of 100 mg/kg there was a maximum value.It showed that there were a definite stimulating effect about chlorophyll a and total chlorophyll content by the soil concentrations of 50mg/kg and 100mg/kg of Cr.While decline on which by As, Cd, Pb. They all showed that their synthesis of chlorophyll was inhibited and Mingshan 131 was more seriously.Compared with the control, the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr) of two varieties leaves were decreased, indicating that photosynthesishave also been inhibited. Range analysis shows that, there was the most pronounced on Gs, Tr of two species' leaf by Cr.while on the Pingyangtezao As had the greatest impact early in the Pn, Pb had the greatest impact early in the Pn on Mingshan 131.Analysis of variance showed that Cr and As had highly significant influence on Pn, Gs, Ci, Tr of Pingyangtezao(P<0.01), indicating Pingyangtezao tea plants were more sensitive to the pollution of Cr and As.Cr had highly significant influence on Pn, Gs, Ci, Tr of Mingshan 131 (P<0.01), indicating Mingshan 131 tea plants were more sensitive to the pollution of Cr than As.(3) Effects of compound pollution of Cr,As,Cd and Pb on hardiness physiology of tea leaves.By the combined pollution, the two tea varieties' SOD, POD, CAT activity, proline, MDA, the relative conductivity of content showed an increasing trend, all the treatments were significantly higher than the control.The increase in enzyme activities showed that tea had some tolerance on the Cr, As, Cd, Pb combined pollution in the range of concentration.The increase in proline and MDA showed that combined pollution had toxic effect in these two kinds of tea leaves.The increase in antioxidant enzyme activities could not avoid the role of membrane lipid peroxidation.Range analysis showed that, for Pingyangtezao, there was the most pronounced on the SOD, POD, CAT activity, proline content of the relative conductivity of two species' leaf by Cr and the greatest impact on the MDA content by As.For Mingshan 131, Cr were the largest effect factor on the six indexes. Analysis of variance showed that Cr had highly significant influence on the six indexes of the two varieties(P<0.01). Multiple regression analysis showed that, for Pingyangtezao, effects of compound pollution of Cr, As, Cd and Pb on the synthesis about enzyme activities, proline, malonaldehyde and relative electric conductivity were synergistic separately,mainly affected by Cr and As. For Mingshan 131,effects of Cr, As, Cd and Pb on the SOD,POD, proline, malonaldehyde and relative electric conductivity were synergistic separately,effects of Cr,As and Pb on CAT were synergistic, but Cd were antagonistic effects on it.The synthesis about enzyme activitiesmainly affected by Cr, but the synthesis about proline,malonaldehyde and relative electric conductivity mainly affected by Cr and As.The order to the concentration of Cr, As, Pb, Cd was Pb>Cr>As>Cd. The concentration of Pb was the highest, but it had the lowest effect on physiological property of tea. The concentration of As was lower, but it was the key factor. The concentration of Cd was much higher than the soil environmental quality standards in the critical value of the soil, but it also had a little effect on physiological property of tea. In general, tea was not only impacted by adding the element of Cr, As, Pb, Cd, but also by the impact of coexisting elements, its impact was more complex, depending on the concentration of elements in combination. The strongest antagonistic or synergistic effect was most by a certain point on the coexistence of elements. Therefore, the impact of compound pollution on the tea was a combined effect.There are common and difference between the physiological response of the combined pollution for the genetic characteristics of different varieties.These results show that Pingyangtezao has stronger tolerance than Mingshan 131 for the compound pollution.