Germination and growth of Secale montanum Guss. in the presence of sodium chloride

Abstract

The salt tolerance of Secale montanum varied at different growth stages. Tolerance during germination was high, with NaCl of more than 340 mol m-3 necessary to reduce germination by 50%. Seedling emergence was more sensitive to NaCl with a 50% reduction occurring at approximately 300 mol m-3. Up to 200 mol m-3aC1, all emerged seedlings reached the first leaf stage, although shoot dry weight of emerged seedlings at 200 mol m-3 NaCl was reduced to 64% of that of seedlings under non-saline conditions. During later plant growth, shoot growth (dry weight) had a salt tolerance threshold of 20 mol m-3 NaCl (electrical conductivity, ECw, of 2.7 mS cm-1). Subsequent yield decline up to approximately 100 mol m-3 NaCl (ECw, = 10.8 mS cm-1) was 6.7% of non-saline yield per mS cm-1 increase in ECw. At higher NaCl concentrations a more reciprocal form of yield decline occurred. Considerable plantto- plant variation for shoot dry weight existed in the presence of NaCl, indicating scope for selection to increase the tolerance of S. montanum. Osmotic adjustment was aided by a reduction in tissue water content under increasing NaCl and by the accumulation of sodium and chloride. Sodium was mainly accumulated in the roots, although the roots increased their selectivity for potassium over sodium. Chloride was mainly accumulated in the shoots. S. montanum could be classed as moderately salt tolerant, a tolerance similar to such pasture grasses as Lolium perenne, Phalaris aquatica and Festuca arundinacea.