干旱胁迫对日本荚蒾幼苗生理生化特性的影响

Effects of Drought Stress on the Physiological and Biochemical Characteristics of Viburnum japonicum Seedlings

为了探讨日本荚蒾(Viburnum japonicum)幼苗对干旱胁迫的适应能力和对策,采用盆栽控水方法,设置正常供水(CK)、轻度干旱(LS)、中度干旱(MS)和重度干旱(SS)4个水分梯度,测定了叶片相对含水量(RWC)、丙二醛(MDA)含量、可溶性蛋白含量、可溶性糖含量、保护酶(SOD、POD)活性、生物量分配等指标。结果表明,随着土壤含水量的减少,日本荚蒾幼苗叶片RWC逐渐降低,MDA含量逐渐升高,重度干旱下质膜损伤最为严重。正常供水、轻度、中度干旱下可溶性蛋白、可溶性糖含量,SOD、POD活性均随土壤含水量的减少逐渐上升,但重度干旱处理可溶性蛋白、可溶性糖含量在胁迫60d比中度干旱有多降低,SOD活性从胁迫30d起逐渐下降,POD活性在胁迫30、45d大幅升高,60d又显著(P<0.05)降低。总生物量积累随胁迫加重逐渐降低,根冠比、根生物量比则逐渐上升,轻度干旱处理叶生物量比有明显(P<0.05)上升。说明日本荚蒾幼苗对轻中度干旱条件有一定的抗逆性和适应性,但长期重度干旱下叶片失水严重,代谢紊乱,导致植物枯萎死亡。

Taking Viburnum japonicum as test material, this paper studied its adaptability and response to drought stress. Two-year-old seedlings were potted with four soil water levels： normal water supply （control,80% of the field moisture capacity）,mild water stress （LS,60V0 of the field moisture capacity）,moderate water stress （ MS,40% of the field moisture capacity） ,and severe water stress（ SS,20% of the field moisture capacity）. The physiological indexes were measured,including the relative water content （RWC）, content of malondialdehyde （MDA）, soluble protein content, soluble sugar content, superxide dismutase （SOD） ,peroxidase （POD） and biomass allocation. The results showed that with the increase of stress in- tensity and duration,RWC decreased and MDA increased, cytoplasmic membrane of seedlings were damaged seriously and finally died under SS. The soluble protein content,soluble sugar content,SOD,POD increased as the water content decreased under normal,LS and MS,while under SS for 60 days,the contents of soluble protein and soluble sugar were lower than MS. SOD began to decrease from 30 d,POD increased sharply in 30 d,45 d and dereased significantly in 60 d. The results also showed that total biomass production increased with soil drought stress, however the root to shoot ratio and root mass ratio demonstrated the opposite trend. Leaf mass ratio had a significant （P〈0.05） increase under LS. In general,V, japonicum seedlings under LS and MS were resistant and adaptive to drought, while in the later stage of SS,leaves dehydrated seriously and exhibited metabolic disorders and died finally.