干旱-复水对两种石斛属植物叶水势的影响

石斛属植物多附着在其他植物体或岩石上,水分获取困难,其特殊的水分利用策略是其生存和发展的重要保证。为弄清石斛属植物对干旱胁迫的适应能力和机制,该文选用3年生金钗石斛和铁皮石斛,通过盆栽控水进行干旱胁迫和复水处理,探讨在不同干旱历时和干旱后复水条件下两种石斛的叶水势变化情况。结果表明:随着干旱时间的延长,两种石斛叶水势均呈升高趋势;金钗石斛叶水势由充分供水时的(-1.04±0.02)MPa增加到干旱60 d时的(-0.86±0.03)MPa,铁皮石斛叶水势由(-1.04±0.02)MPa增加到(-0.87±0.03)MPa;两种石斛均表现出高水势延迟脱水的抗旱适应机制;干旱结束后复水,两种石斛的叶水势随着复水时间的增加均呈下降趋势;复水20 d时,金钗石斛和铁皮石斛叶水势分别为(-0.96±0.05)MPa和(-0.96±0.02)MPa,其叶水势均未恢复到干旱前充分供水时的水平;相关分析结果显示,两种石斛的土壤含水率和叶水势间相关关系显著(P<0.05)。由此认为,两种石斛属植物均表现出较强的干旱胁迫耐受能力和相对较差的胁迫后恢复能力。

Effects of drought-rewatering on leaf water potential of two Dendrobium plants

Dendrobium plants are attached to other plants or rocks, and water is difficult to obtain. Its special water use strategy is an important guarantee for its survival and development. In order to clarify the adaptability and mechanism of Dendrobium plants to drought stress, three-year-old D. nobile and D. officinale were selected, and the drought stress and rewatering treatment were carried out by potted water control, and leaf water potential changes of the two Dendrobium species were studied under different drought durations and rewatering conditons. The results were as follows: With the prolongation of drought time, the leaf water potential of the two Dendrobium species were increased; The leaf water potential of D. nobile increased from(-1.04±0.02)MPa at the time of full water supply to(-0.86±0.03)MPa at 60 d of drought, and the leaf water potential of D. officinale increased from(-1.04±0.02)MPa to(-0.87±0.03)MPa; The two Dendrobium species showed the drought-tolerant adaptation mechanism of high-water potential delayed dehydration; Rewatering after the end of drought, the leaf water potential of the two Dendrobium species showed a downward trend with the increase of rewatering time; After rewatering for 20 d, the leaf water potentials of D. nobile and D. officinale were(-0.96±0.05)MPa and(-0.96±0.02)MPa, respectively, and did not return to the level of sufficient water supply before drought; Correlation analysis showed significant correlation between soil moisture content and leaf water potential(P<0.05). In summary, both Dendrobium plants showed strong drought stress tolerance ability and relatively poor post-stress recovery ability.