Abstract:

With a potting experiment, morphological parameters and five physiological indicators including malondialdehyde(MDA), catalase(CAT), chlorophyll(Chl), proline(Pro), and leaf water content(LWC) of the 4-year-old Pinus densiflora var. zhangwuensis and P. sylvestris var. mongolica were measured in different soil moisture gradient. The results showed that: P. densiflora var. zhangwuensis had significantly heavier total dry weight, dry weight of root, dry weight of stem and greater ratio of root and stem, had significantly smaller single needle area, and had slightly more thick needle than P. sylvestris var. mongolica. In different water gradient, P. densiflora var. zhangwuensis had lower MDA contents, and higher CAT and Pro contents than P. sylvestris var. mongolica. In mild drought area(40%FMC), MDA, CAT and Pro contents of P. sylvestris var. mongolica had a ascending trend in comparison with those in control area(100%FMC), and the three physiological indicators had a further increase in moderate drought area(30%FMC) and reached to the maximum in serious drought area(20%FMC). By contrast in mild drought area these three physiological indicators in leaves of P. densiflora var. zhangwuensis were lower than those in control area, and began to increase in moderate drought area, especially the CAT content was significantly higher than that in control area, and they also reached to the maximum in serious drought area. The above results determinated that P. densiflora var. zhangwuensis showed stress symptoms at a lower soil moisture, and it could endure and adapt to drought stress by improving protective enzyme activity(CAT) and increasing osmotic substance(Pro). At different moisture gradient, both Chl and LWC of P. densiflora var. zhangwuensis were more than those of P. sylvestris var. mongolica, and these two indicators in the same species had the same changing trend, which was : CK> mild drought area> moderate drought area> serious drought area.

Key words: sandy soil, Pinus densiflora var. zhangwuensis, P. sylvestris var. mongolica, drought resistance, physiological characteristics