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草业学报 ›› 2021, Vol. 30 ›› Issue (1): 197-207.DOI: 10.11686/cyxb2020057

• 研究论文 • 上一篇    下一篇

裸果木幼苗根系形态和生理特征对水分胁迫的响应

黄海霞1,*(), 杨琦琦2, 崔鹏1, 陆刚1, 韩国君3   

  1. 1.甘肃农业大学林学院,甘肃 兰州 730070
    2.甘肃林业职业技术学院,甘肃 天水 741020
    3.甘肃农业大学资源与环境学院,甘肃 兰州 730070
  • 收稿日期:2020-02-19 修回日期:2020-05-14 出版日期:2021-01-20 发布日期:2021-01-08
  • 通讯作者: 黄海霞
  • 作者简介:黄海霞(1974-),女,甘肃民勤人,副教授,博士。E-mail: 1057821914@qq.com
  • 基金资助:
    甘肃农业大学学科建设专项基金(GSAU-XKJS-2018-110);国家自然科学基金项目(3196061)

Changes in morphological and physiological characteristics of Gymnocarposprzewalskii roots in response to water stress

Hai-xia HUANG1,*(), Qi-qi YANG2, Peng CUI1, Gang LU1, Guo-jun HAN3   

  1. 1.College of Forestry,Gansu Agricultural University,Lanzhou 730070,China
    2.Gansu Vocational and Technical College of Forestry,Tianshui 741020,China
    3.College of Resources and Environment,Gansu Agricultural University,Lanzhou 730070,China
  • Received:2020-02-19 Revised:2020-05-14 Online:2021-01-20 Published:2021-01-08
  • Contact: Hai-xia HUANG

摘要:

裸果木起源于地中海,为亚洲中部荒漠区分布的第三纪孑遗植物种,对研究旱生植物演化过程具有重要价值。本研究以一年生裸果木实生苗为对象,于2018年开展盆栽试验,设置4个水分处理,包括对照和轻度、中度、重度水分胁迫,土壤含水量分别控制在田间持水量的45%~50%、30%~35%、15%~20%和5%~10%,通过称重法控制水分,每个处理10个重复,测定分析根系形态和生理指标对干旱胁迫的响应规律。结果表明,水分胁迫使裸果木幼苗根长和根表面积显著减小;重度水分胁迫下根系生物量显著降低;中度和重度水分胁迫促使根冠比显著增大,细根比根长和比表面积增大,束缚水含量/自由水含量(Va/Vs)显著增大;水分胁迫导致根系活力显著下降。土壤水分含量降低时,根系脯氨酸含量先减小后显著增大,而可溶性糖和可溶性蛋白含量变化与之相反。在水分胁迫下,根系丙二醛(MDA)、过氧化氢(H2O2)和超氧阴离子(O2-)含量均显著升高,根系细胞膜系统受到了明显伤害,超氧化物歧化酶(SOD)活性显著上升,过氧化物酶(POD)活性明显降低,过氧化氢酶(CAT)活性显著增强。总之,干旱胁迫下,裸果木幼苗形态上通过增大根冠比、细根比根长和比表面积来提高水分吸收效率;生理上通过降低代谢强度,减少水分消耗;主动积累有机溶质,降低细胞渗透势;增强SOD和CAT酶活性,减轻细胞膜伤害。

关键词: 水分胁迫, 裸果木, 根系, 形态特征, 生理特性

Abstract:

Gymnocarpos przewalskii originates from the Tethys Sea, and is a Tertiary relic of the desert area in central Asia. This species is very important for research on xerophyte evolution. Using 1-year-old seedlings of G. przewalskii as the experimental materials, we evaluated the responses of root morphological and physiological characteristics to drought stress in a pot experiment. Four water treatments were established, comprising a gradient corresponding to a control and light, moderate, and severe water stress (soil water content controlled at 45%-50%, 30%-35%, 15%-20%, and 5%-10% of field capacity, respectively). The different soil water contents were maintained by regular weighing and re-watering pots to target weights. There were 10 replicates of each treatment. The seedlings were cultivated in pots in 2018 under these conditions, and the responses of the roots were analyzed. It was found that with increasing severity of drought stress, root length and root surface area significantly decreased. The root biomass decreased markedly under severe drought stress. Moderate and severe drought stress caused significant increases in the shoot:root ratio, specific root length, and specific root surface area of fine roots, and increased the ratio of bound water to free water. Drought stress led to a significant decrease in root vitality. As the soil water content decreased, proline content in roots initially decreased then markedly increased, while the soluble sugar and soluble protein content showed the reverse trend. Under drought stress, the concentrations of malondialdehyde, hydrogen peroxide, and the superoxide anion significantly increased, indicative of damage to the root membrane system. Root superoxide dismutase (SOD) activity markedly increased, peroxidase activity significantly decreased, and catalase (CAT) activity significantly increased under drought stress. In short, under drought stress, roots of G. przewalskii seedlings showed several morphological changes to increase their water-absorption efficiency, i.e., the shoot∶root ratio, specific root length, and specific root surface area of fine roots all increased. The physiological changes in response to drought stress were a decrease in metabolism to reduce water consumption, active accumulation of organic solutes to decrease cell osmotic potential, and increases in SOD and CAT activity to reduce cell membrane damage.

Key words: water stress, Gymnocarpos przewalskii, root system, morphological characteristics, physiological characteristics