干旱胁迫对梨属4个重要种幼苗膜脂过氧化和抗氧化酶活性的影响

以梨属Pyrus的杜梨P.betulaefolia，砂梨P.pyrifolia，川梨P.pashia和滇梨P.Pseudopashia等4个种1年生实生苗为材料，进行人工干旱处理，研究土壤干旱胁迫对梨属4个重要种幼苗膜脂过氧化和抗氧化酶活性的影响。结果表明：随着水分胁迫的加重，4个种幼苗叶片中的丙二醛质量摩尔浓度呈现先降低后升高的趋势；膜伤害度以砂梨最大，重度胁迫时为35．91％，滇梨和川梨分别为10．72％和10．34％，杜梨为8．00％；叶片中超氧化物歧化酶（SOD）活性，砂梨呈降低趋势，而其他3个种均先升高后降低。4个种的过氧化物酶（POD）活性和过氧化氢酶（CAT）活性一直降低。轻度干旱胁迫期，保护酶活性具有明显的适应性反应；随着干旱胁迫程度的加剧，梨属4个种叶片中SOD，POD和CAT活性变化幅度不同，说明4个种在清除活性氧以避免自由基对机体的伤害能力不同，其中杜梨最强，滇梨、川梨次之，砂梨最弱。

Soil drought stress on membrane-lipid peroxidation and antioxidant enzymes in pear rootstock

In order to breed drought-tolerant cultivars of pear, the effect of drought stress on membrane permeability and antioxidant enzyme systems the four one-year-old Pyrus （pear） species of （P. betulaefolia, P. pyrifolia, P. pashia, and P. pseudopashia） grown in pot, were studied in the Karst Fruit Tree Research Insititute of Guizhou University, from 2003 to 2005. Four treatments were set, including the control： the soil relative water content（SRWC） is（65.0±5.0）%, light stress： the SRWC is（50.0±5.0）%, moderate stress： the SRWC is （40.0±5.0）%, severe stress： the SRWC is （32.5±5.0）%, with three replication. Results showed that malondialdehyde（MDA） content significantly deereased（P 〈 0.01） with light stress for P. pyrifolia, but significantly increased （P 〈 0.01 ） with moderate and severe stress for all species. With severe drought stress, damage to the membrane structure of P. pyrifolia was greater than the other three species. Damage for P. pyrifolia was 35.91%, while P. pseudopashia was 10.72%, P. pashia was 10.34% and P. betulaefolia was 8.00%. Superoxide dismutase（SOD） activities of P. pyrifolia decreased, while the other three species first increased with light stress and then decreased with moderate and severe stress. Peroxidase （POD） and catalase（CAT） activities decreased for the four species. With drought stress and elimination of oxygen free radicals, the four Pyrus species avoided injury in the following order： P. pyrifolia 〉 P. pseudopashia 〉 P. pashia 〉 P. betulaefolia.