School of Agriculture, Food and Wine, Waite Campus, The University of Adelaide, PMB 1 Glen Osmond, South Australia 5064.
J Exp Bot. 2011 Mar;62(6):2189-203. doi: 10.1093/jxb/erq422. Epub 2011 Jan 27.
Soil salinity affects large areas of the world's cultivated land, causing significant reductions in crop yield. Despite the fact that most plants accumulate both sodium (Na(+)) and chloride (Cl(-)) ions in high concentrations in their shoot tissues when grown in saline soils, most research on salt tolerance in annual plants has focused on the toxic effects of Na(+) accumulation. It has previously been suggested that Cl(-) toxicity may also be an important cause of growth reduction in barley plants. Here, the extent to which specific ion toxicities of Na(+) and Cl(-) reduce the growth of barley grown in saline soils is shown under varying salinity treatments using four barley genotypes differing in their salt tolerance in solution and soil-based systems. High Na(+), Cl(-), and NaCl separately reduced the growth of barley, however, the reductions in growth and photosynthesis were greatest under NaCl stress and were mainly additive of the effects of Na(+) and Cl(-) stress. The results demonstrated that Na(+) and Cl(-) exclusion among barley genotypes are independent mechanisms and different genotypes expressed different combinations of the two mechanisms. High concentrations of Na(+) reduced K(+) and Ca(2+) uptake and reduced photosynthesis mainly by reducing stomatal conductance. By comparison, high Cl(-) concentration reduced photosynthetic capacity due to non-stomatal effects: there was chlorophyll degradation, and a reduction in the actual quantum yield of PSII electron transport which was associated with both photochemical quenching and the efficiency of excitation energy capture. The results also showed that there are fundamental differences in salinity responses between soil and solution culture, and that the importance of the different mechanisms of salt damage varies according to the system under which the plants were grown.
土壤盐度影响了世界上大面积的耕地，导致作物产量显著下降。尽管大多数植物在盐渍土壤中生长时，其地上组织会大量积累钠离子（Na(+)) 和氯离子（Cl(-))，但大多数关于一年生植物耐盐性的研究都集中在 Na(+) 积累的毒性效应上。先前有研究表明，Cl(-) 毒性也可能是大麦植株生长减少的一个重要原因。在这里，通过在不同盐度处理下使用在溶液和土壤系统中耐盐性不同的四个大麦基因型，展示了特定的 Na(+) 和 Cl(-) 离子毒性在盐渍土壤中生长的大麦生长的程度。高浓度的 Na(+)、Cl(-) 和 NaCl 分别降低了大麦的生长，但在 NaCl 胁迫下，生长和光合作用的降低最大，且主要是 Na(+) 和 Cl(-) 胁迫效应的累加。结果表明，大麦基因型之间的 Na(+) 和 Cl(-) 排斥是独立的机制，不同的基因型表现出两种机制的不同组合。高浓度的 Na(+) 降低了 K(+) 和 Ca(2+) 的吸收，并通过降低气孔导度主要降低了光合作用。相比之下，高 Cl(-) 浓度降低了光合能力，这是由于非气孔效应：叶绿素降解，以及 PSII 电子传递的实际量子产率降低，这与光化学猝灭和激发能捕获效率有关。结果还表明，土壤和溶液培养之间的盐度响应存在根本差异，不同盐害机制的重要性根据植物生长的系统而有所不同。
