Abstract

Phragmites karka (Retz.) Trin. ex Steud. is a pan-tropical, wetland, grass, and this study restricted water availability to P. karka by either low matric potential (water deficit) or low osmotic potential (salinity). Growth, water relations, mineral nutrition, and photosynthesis were compared when plants were irrigated at control (100% water holding capacity WHC), 300 mM NaCl (salinity, at 100% WHC), or water deficit (40% WHC) conditions. Leaf water potential and plant growth decreased substantially under salinity and water deficit. This led to stomatal closure and a decrease in gas exchange with the risk of oxidative injury. Under saline conditions, stress was mitigated by an increased dissipation of absorbed light energy by non-photochemical quenching. Water deficit conditions led to higher PS II quantum yield efficiency. Shoot Na⁺ toxicity was reduced by 10-fold higher Na⁺ sequestration in salt-treated roots, and enhanced proline and soluble carbohydrate accumulation in the leaf, compared to the control. Inorganic and organic substances maintained a higher soil-to-plant water gradient in salt-stressed plants compared to drought-stressed plants. P. karka survived in both forms of restricted water via growth plasticity, regulated osmotic and ionic homeostasis, and efficient gas exchange and PSII photochemistry.

摘要

Phragmites karka（Retz。）Trin。前Steud。是一个泛热带，湿地，草地，而这项研究的限制水供应到P. karka低基质势（缺水）或低渗透势（盐度）。在对照（100％持水量WHC），300 mM NaCl（盐度，100％WHC）或缺水（40％WHC）的条件下灌溉植物时，比较了植物的生长，水分关系，矿物质营养和光合作用。在盐度和水分亏缺的情况下，叶片水势和植物生长显着下降。这导致气孔关闭并减少气体交换并具有氧化损伤的风险。在盐水条件下，通过非光化学猝灭增加了吸收光能的耗散，从而缓解了压力。水分亏缺条件导致PS II量子产率更高。芽Na ⁺毒性降低了10倍以上Na ⁺与对照相比，盐处理过的根中的螯合，以及脯氨酸和可溶性碳水化合物在叶中的积累增加。与干旱胁迫的植物相比，盐胁迫植物的无机物和有机物保持较高的土壤-植物水梯度。卡尔卡卡氏菌通过生长可塑性，调节的渗透和离子稳态，有效的气体交换和PSII光化学作用，以两种受限水形式生存。