| The study of different concentrations of Pb stress ecotypes of Toona sinensis seedlings growth characteristics of, mainly by pot experiment to explore the distribution and accumulation regularity conditions of Toona sinensis growth characteristics, physiological and biochemical characteristics of Toona sinensis in different organs of lead stress, and to analyze the effect of Toona sinensis resistance to lead the main factor. The results are as follows:Lead stress on its growth has made a significant impact. Low concentration lead to the increase of leaf length and leaf area, leaf color changes and wrinkling phenomenon was not obvious; in high concentrations of lead conditions significantly inhibited leaf length and leaf area, leaf age spots and wrinkles increased. Low concentration promote the longitudinal growth of Toona sinensis rod, high concentration inhibited seedling stems of vertical development. Low concentration of lead in promoting stem lateral growth of Toona sinensis. Under the stress of different Pb concentration has a significant effect on the proportion between the roots and stems of Chinese Toona, increases in defoliation, with increasing concentration of lead, toon biological volume decreased significantly (P<0.01).With the increase of lead stress intensity, the content of soluble sugar increased significantly, and the content of soluble sugar increased by 34% in T4. And proline and soluble sugar content variation trend is consistent, toon of soluble protein in the lead stress intensity increased significantly (P< 0.05), along with the increase of concentration of lead, the Chinese toon SOD and POD activity change significantly (P<0.05), and the activities of pod and SOD in treatment concentrations more than 450 mg kg-1 reached the highest, then decreased rapidly. The activity of CAT increased significantly in Toona sinensis (P<0.05).The total chlorophyll content was significantly negatively correlated with the concentration of lead. The net photosynthetic rate of leaves increased with the increase of Pb concentration. With the increase of the lead stress intensity, the change of stomatal conductance, transpiration rate, intercellular CO2 concentration, net photosynthetic rate increased and then decreased. Low light intensity in the test range, net photosynthetic rate with par increases rapidly rising trend; and photosynthetic active radiation light intensity increased. Under high concentration of Pb stress, PN increased slightly trend, and gradually in a steady state.Under different intensity lead stress, the accumulation of lead in different organs was different. With the increase of concentration of lead stress, each organ accumulation leaves of Toona sinensis seedlings showed a significantly increased lead. The maximum accumulation of fine root, coarse root, on the part of the underground part of accumulation of lead content relatively little difference. Toona sinensis tolerance index values between the 0.61～1.07 has certain resistance characteristics of lead, toon enrichment coefficient and transfer coefficient are small (< 0.3), with lead stress improved strength decreases.Combined with principal component analysis to determine the effect of Toona sinensis seedlings lead tolerance index, indexes for 82.917%, the main factor of light photosynthetic rate of the contribution of the first principal component rate, relative conductivity, the content of soluble protein and the contribution of the second principal component rate for 15.955%, main factor with leaf area, the content of soluble sugar and other indicators, through the membership function to calculate the Toon lead tolerance index, it is concluded that CK, T1, T2, T3, T4, respectively for 0.6988,0.5036,0.3865 and 0.2915. Lead resistance among different treatments was:T1> CK> T2> T3>T4. |
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