干旱胁迫下柳枝稷在露天矿区土壤中的种子萌发和生长特性

将能源植物用作矿区生态修复物种，对矿区的经济发展和生态环境具有重要意义。以能源植物柳枝稷为研究对象，通过盆栽试验，分析其在对照、轻度、中度以及重度干旱胁迫下柳枝稷幼苗在矿区土壤基质和非矿区土壤基质下的生长特性，并结合不同干旱胁迫下矿区土壤基质中种子萌发特征，揭示柳枝稷对干旱胁迫的响应机制和对矿区土壤的生态适应性。试验结果表明：（1）柳枝稷种子发芽总数、发芽率、发芽势以及发芽指数在轻度胁迫下达到最大值，活力指数在对照组最高，而在重度胁迫下，各项指标均达到最小值；种苗各生长指标在轻度胁迫下最小，幼苗根长和鲜重在重度胁迫下最高，芽长和芽重在其余三组胁迫下相差不大。（2）干旱胁迫使两种土壤基质下的柳枝稷株高降低，枯叶率增加，在对照、轻度胁迫和重度胁迫下能够保持叶片水分含量和分蘖数稳定；矿区土壤基质中，柳枝稷根体积在轻度胁迫下最大，中度胁迫下根长最长，重度胁迫下根数最多；根冠比随着干旱胁迫的加剧表现出先减后增的趋势，在轻度胁迫下最小，在重度胁迫下最大。（3）与非矿区土壤基质相比，柳枝稷在矿区土壤基质下根冠比更大，其余生长指标均更小；随着干旱胁迫的加剧，柳枝稷在矿区土壤基质下的株高、枯叶率、叶片相对含水量以及分蘖数与非矿区土壤基质下变化趋势一致。综上，柳枝稷在矿区土壤下的生长特性比在非矿区土壤下表现更差；在轻度干旱胁迫下各项生理指标表现更好，在中度和重度干旱胁迫下虽然其生长发育受到限制，但能通过调整生物量配比确保自身存活。因此，柳枝稷在矿区土壤环境下具有一定的抗旱性和抗贫瘠性，将其作为矿区生态修复品种具有可行性。

Effect of drought stress on the seed germination and growth characteristics of switchgrass

Energy plant as one species for ecological restoration in mining areas is of great significance to the economic development and ecological environment of mining areas. Taking switchgrass, an energy plant, as the research object, through pot experiments, by analyzing the growth characteristics of seedlings in the soil matrix of the mining area and the non-mining area under the control, mild, moderate and severe drought stress, combining the seed germination characteristics in the soil matrix of the mining area, the response mechanism of switchgrass to drought stress and the ecological adaptability of the mining area soil were revealed. The test results showed that:(1) the total number of germinations, germination rate, germination potential and germination index of switchgrass seeds reached the maximum under mild stress, and the vitality index was the highest in the control group. Each index reached the minimum under severe stress. Each growth index of seedlings was minimal under mild stress, the root length and fresh weight of seedlings were the highest under severe stress, and the bud length and shoot weight were not much different under the other three groups of stress. (2) Drought stress reduced the plant height of switchgrass under the two soil substrates, and increased the rate of dead leaves. It could maintain the leaf relative water content and the number of tillers stable under the control, mild and severe stresses. In the soil matrix of the mining area, the root volume of switchgrass was the largest under mild stress, the longest root length under moderate stress, and the largest number of roots under severe stress. The root-shoot ratio showed a trend of first decrease and then increase with the intensification of drought stress, reaching the minimum value under mild stress and the maximum value under severe stress. (3) Compared with the soil substrate in the non-mining area, the root-to-shoot ratio of switchgrass under the soil substrate in the mining area was larger, and the other growth indicators were smaller. With the intensification of drought stress, the plant height, dead leaf rate, relative leaf water content and tiller number of switchgrass under the soil matrix in the mining area were consistent with those in the soil matrix in the non-mining area. In summary, the growth characteristics of switchgrass in mining soils were worse than those in non-mining soils. Physiological indicators performed better under mild drought stress, while the growth of switchgrass was restricted under moderate and severe drought stress. In arid and barren environments, switchgrass can ensure its own survival by adjusting the biomass ratio. Therefore, switchgrass had certain resistance to drought and barrenness and was feasible to use it as a variety of ecological restoration in the mining area.