Rivelli Anna Rita, James Richard A, Munns Rana, Condon A G Tony
Department of Plant Production, University of Basilicata, Potenza, Italy.
CSIRO Plant Industry, GPO Box 1600, ACT 2601, Australia.
Funct Plant Biol. 2002 Aug;29(9):1065-1074. doi: 10.1071/PP01154.
Four wheat genotypes with contrasting degrees of Na exclusion were selected to see if low Na uptake had an adverse effect on water relations or growth rates during exposure to saline conditions. Plants were grown in supported hydroponics with and without 150 mM NaCl, and sampled for measurements of water relations, biomass, stomatal conductance, and ion accumulation. After 4 weeks exposure to salt, biomass was reduced in all genotypes to a similar extent (about 50%), with the effect of salinity on relative growth rate confined largely to the first week. There was little difference between genotypes in the effect of salinity on water relations, as indicated by their relative water content and estimated turgor. Osmotic adjustment occurred in all genotypes, with one of the low-Na genotypes having the greatest adjustment. In the low-Na genotypes, osmotic adjustment depended on higher K and high organic solute accumulation. Stomatal conductance of all genotypes was reduced by saline conditions, but the reduction was greater in the low-Na genotypes. These genotypes also showed a larger fall in the value of carbon isotope discrimination measured in expanding leaves, indicating a greater transpiration efficiency when exposed to saline conditions. Chlorophyll fluorescence measurements failed to indicate damage to photochemical pathways in either high- or low-Na genotypes. These data indicate that selecting lines with low Na accumulation for the purpose of improving salt tolerance is unlikely to introduce limitations for osmotic adjustment.
选择了四种钠排斥程度不同的小麦基因型，以研究在盐胁迫条件下，低钠吸收是否会对水分关系或生长速率产生不利影响。将植株种植在有或没有150 mM NaCl的支持水培系统中，并取样测量水分关系、生物量、气孔导度和离子积累。在盐胁迫4周后，所有基因型的生物量均有相似程度的降低（约50%），盐度对相对生长速率的影响主要局限于第一周。从相对含水量和估算膨压来看，盐度对水分关系的影响在基因型之间差异不大。所有基因型均发生渗透调节，其中一种低钠基因型的调节作用最大。在低钠基因型中，渗透调节依赖于较高的钾和高有机溶质积累。盐胁迫降低了所有基因型的气孔导度，但低钠基因型的降低幅度更大。这些基因型在展开叶中测得的碳同位素分辨率值下降幅度也更大，表明在盐胁迫条件下蒸腾效率更高。叶绿素荧光测量结果未显示高钠或低钠基因型的光化学途径受到损害。这些数据表明，为提高耐盐性而选择低钠积累的品系不太可能对渗透调节产生限制。
