低氧胁迫对苹果砧木幼苗生长与生理特性的影响

Growth and Physiological Characteristics of Apple Rootstock Seedlings under Hypoxia Stress

以苹果砧木‘平邑甜茶’(Malushupehensis Rehd.)和‘变叶海棠’(Malustoringoides Rehd.)为材料,采用营养液培养的方法,研究了低氧胁迫对苹果砧木幼苗生长和生理特性的影响。结果表明:低氧胁迫下苹果砧木幼苗新叶数减少,根系和最长新根长度下降,叶片中叶绿素a(Chla)、总叶绿素(Chl)和类胡萝卜素(Car)含量降低,并引起不同色素间比例的改变;根系活力先升后降并在胁迫中后期低于对照;根、叶中超氧阴离子(O2■)产生速率和过氧化氢(H2O2)含量持续增加,丙二醛(MDA)含量上升,膜透性增大,且根系变化幅度大于叶片;低氧耐性较强的‘平邑甜茶’除根系活力外其余指标变化幅度均小于耐性较弱的‘变叶海棠’。说明低氧胁迫影响了苹果砧木幼苗的根系活力和叶片光合色素水平,抑制了植株的生长,导致其体内活性氧自由基(ROS)过量积累,加重膜脂质过氧化作用,从而使植株受到伤害,且这种影响存在基因型和组织差异,根系和低氧耐性较弱的砧木受到的伤害较重。

With two apple rootstock seedlings, Malus hupehensis Rehd. and Malus toringoides Rehd. , the effects of hypoxia stress on growth and physiological characteristics were studied with the nutrient solution culture. The results showed that hypoxia stress decreased the number of new leaves, length of root and maximum length of new root of apple rootstock,and decreased the contents of chlorophyll a （Chl a） ,total chlorophyll （Chl） and carotenoid （Car） ,which leaded to the changes of ratio between different pigments. Hypoxia stress made the root activity of apple rootstock seedlings increasing first and then decreasing,but less than control since media-later period of the stress. Comparing to the control,the generation rate of superoxide radical （O2·^-） and the content of hydrogen peroxide （H2O2） increased gradually in apple rootstock seedlings under hypoxia stress,which caused more malonaldehyde （MDA） and higher membrane permeability, and these changes in roots were more than that in leaves. Except root activity, the changes of all indicators of M. hupehensis were less than that of M. toringoides. Therefore, hypoxia stress affected the root activity and the level of photosynthetic pigments of apple rootstock seedlings, and inhibited the growth of these plants. It also caused the excessive accumulation of reactive oxygen species （ROS）,which leading to more serious membrane-lipid peroxidation, and damaging the plants. These effects of hypoxia stress on the plants were different from genotype and organ. The damages to roots and hypoxia-sensitive rootstocks were serious than leaves and more hypoxia-tolerance rootstock.