Growth, water relations and accumulation of organic and inorganic solutes in the halophyte Limonium latifolium cv. Avignon and its interspecific hybrid Limonium caspia x Limonium latifolium cv. Beltlaard during salt stress

Plants of two genotypes, Limonium latifolium cv. Avignon and its interspecific hybrid Limonium caspia x Limonium latifolium cv. Beltlaard: grown in a hydroponics culture were submitted to 140 mmol/L NaCl nutrient solution for 20 days (saline treatment). The physiological traits of salt tolerance that differ among these cultivars have been studied. Shoot growth parameters of Beltlaard plants showed that they were affected by salinity, inducing a significant reduction in shoot dry weight and leaf area with respect to the control treatment, while these parameters remained unchanged in Avignon. The behaviour of leaf water relations under saline stress was not different between both genotypes, which indicated that the osmotic effect was similar for both cultivars. At the end of the experiment the cultivars studied were able to achieve the same degree of osmotic adjustment. However, in L. Beltlaard the maintenance of turgor did not permit the maintenance of the growth rate. Leaf growth reductions in response to salinity were associated with higher tissue levels of Na+ and Cl- and changes in the contribution to leaf osmotic potential of K+ and NO3-. The rates of NaCl absorption by roots and the net transfer from roots to shoots was higher in Beltlaard than in Avignon; this fact suggests that the radical exclusion mechanisms are more operative in Avignon. In conclusion, although Avignon showed lower NaCl uptake rates, the growth reduction was more pronounced in Beltlaard because the accumulation of salt in the tissue generated toxicity and nutritional disturbances.