Abstract:

This paper employed several research techniques, including micronucleus technology, TBA reaction method, conductivity meter method, NBT reduction and guaiacol method, to investigate changes in physiological parameters related to chromosome damage of Pinus massoniana under lead stress and analyzed the correlations between the traits. The results showed that: 1) Different concentration leads significantly affected micronucleus rate of P. massoniana compared with the untreated control by t test. 2) With increasing concentration of lead, micronucleus rate, MDA, cell injury, SOD and POD activities gradually increased. The treatment with 2 000 mg·L^-1 lead, brought about the highest MDA content, cell injury, SOD and POD activities, and over the concentration of lead, MDA content, cell injury, SOD and POD activities began to decline with gradually increasing lead concentration, suggesting that the antioxidant enzyme systems had limited capacity in protecting the plants from Pb²⁺ toxicity. 3) Regression analyses showed that correlation between lead concentrations and the micronucleus rate fitted a Cubic model; correlations between micronucleus rate and degree of damage, between micronucleus rate and MDA, between MDA and the degree of damage, between MDA and POD took a S model; and MDA and SOD, SOD and POD regressions with an Inverse model best predicted changes in each other.The relationships were significantly or very significantly correlated.

Key words: Pinus massoniana, seedlings, lead stress, micronucleus rate, physiological index, regression analysis