A greenhouse experiment was conducted to investigate the effects of NaCl-induced stress on emergence and early growth of six citrus rootstock cultivars, namely Rangpur lime (Citrus limonia Osbeck), rough lemon(Citrus jambhiri Lush.), Volkamer lemon (Citrus volkameriana Pasquale), sour orange (Citrus aurantium L.), Swingle citrumelo and citrumelo 4475 (Citrus paradisi Macf. x Poncirus trifoliata (L.) Raf). Seeds of the six rootstocks were sown in a peat-based substrate in a factorial design and irrigated during two months with a nutrient solution containing NaCl at 0 (control), 20 and 40 m M concentrations. The results have shown significant effects of salinity on emergence speed and growth of seedlings by the end of the experimental period, but no effect on final emergence rate. Significant differences were found notably among the cultivars studied suggesting a high tolerance of Rangpur lime and Swingle citrumelo and a low tolerance sour orange and rough lemon. In addition, a considerable accumulation of chloride ions was observed in plant tissue with increasing salinity, which was significantly correlated with final seedling height, biomass reduction and time to 50% emergence. Based on correlation coefficients, shoot chloride concentrations were better linkedtothese parameters than root chloride concentrations and proved to be a more reliable tool for ranking salt tolerance of citrus rootstocks at early growth stages.
