The University of Arizona, Department of Plant Sciences, Tucson, Arizona 85721 USA.
Am J Bot. 2003 Oct;90(10):1416-24. doi: 10.3732/ajb.90.10.1416.
Optimal growth of euhalophytes requires moderate concentrations of salt and, in dicotyledons, is associated with succulence and accumulation of Na(+) in plant tissues. However, reports of salt-stimulated growth in monocotyledons are rare. Relative growth rate (RGR), biomass accumulation, and water content were studied in Sporobolus virginicus (Poaceae), a C(4) chloridoid grass, grown hydroponically with different concentrations of NaCl. Cation concentrations were determined by atomic absorption spectrophotometry. Optimal growth occurred at 100-150 mmol/L NaCl and was not dependent on nitrogen levels or accompanied by accumulation of Na(+) in leaves. Biomass accumulation and RGR in plants grown at 450 mmol/L NaCl were greater than in plants grown at 5 mmol/L. The Na : K ratios were lower in leaves than in roots, indicating discrimination in Na(+) and K(+) transport. Secretion of Na(+) increased from 166.5 to 336.7 mmol · g(-1) dry biomass · d(-1) as the NaCl concentration of the nutrient solution increased from 125 mmol/L to 450 mmol/L. Water concentrations of leaves and shoots were significantly greater in plants grown at optimal levels of salinity than in plants grown at lower or higher salinities. These results demonstrate salt-stimulated growth in a monocotyledon.
盐生植物的最佳生长需要适度的盐浓度，并且在双子叶植物中，与多汁性和植物组织中钠离子的积累有关。然而，单子叶植物中盐刺激生长的报道却很少。本研究采用水培法，用不同浓度的 NaCl 培养 C4 氯草属植物须芒草（黍科），研究其相对生长率（RGR）、生物量积累和含水量。采用原子吸收分光光度法测定阳离子浓度。最佳生长发生在 100-150mmol/L NaCl 下，且不依赖于氮水平，也不会导致叶片中钠离子的积累。在 450mmol/L NaCl 下生长的植物的生物量积累和 RGR 大于在 5mmol/L NaCl 下生长的植物。叶片中的 Na∶K 比值低于根，表明在 Na(+)和 K(+)运输中存在选择性。随着营养液中 NaCl 浓度从 125mmol/L 增加到 450mmol/L，Na(+)的分泌从 166.5mmol·g(-1)干生物量·d(-1)增加到 336.7mmol·g(-1)干生物量·d(-1)。在最佳盐度水平下生长的植物的叶片和茎的水浓度明显大于在低盐度或高盐度下生长的植物。这些结果表明，单子叶植物中存在盐刺激生长现象。
