[Eco-physiological responses of Picea mongolica ecotypes to drought stress].

The seedlings of different Picea mongolica ecotypes were treated with drought stress, and their height growth, MDA, proline, and chlorophyll content were investigated. The results showed that the height growth was obviously reduced by drought stress. With sufficient water supply, the height growth of f. viridis W. D. Xu f. nov Picea mongolica was rapid and obviously better than that of f. purpurea W. D. Xu f. nov Picea mongolica, but was obviously reduced by intense drought stress. Furthermore, drought stress shortened the annual growth period of Picea mongolica, and made its terminal bud formation more than one month earlier increased in both needles and roots, but was higher in needle than in root. The MDA content was higher in Picea mongolica than in f. viridis W. D. Xu f. nov Piburcea mongolica, and the proline content in needles was increased with increasing drought stress, but in roots, the proline content was higher in f. viridis W. D. Xu f. nov Picea mongolica than in f. purpurea W. D. Xu f. nov Picea mongolica and f. rubra W. D. Xu f. nov Picea mongolica. The latter 2 forms showed a similar trend in chlorophyll content. Their chlorophyll a, chlorophyll b and total chlorophyll contents increased at the beginning of drought treatment, and then decreased with increasing drought stress. The chlorophyll content of f. viridis W. D. Xu f. nov Picea mongolica decreased with drought stress. The ratio of chlorophyll a/b decreased from maximum to minimum in f. viridis W. D. Xu f. nov Picea mongolica, but decreased in a relative small extent in f. purpurea W. D. Xu f. nov. It's proved that f. purpurea W. D. Xu f. nov Picea mongolica had a larger drought-resistance capacity than f. viridis W. D. Xu f. nov, and f. rubra W. D. Xu f. nov was a typical transitional ecotype from f. purpurea W. D. Xu f. nov to f. viridis W. D. Xu f. nov.