NaCl priming affects salt tolerance of onion (Allium cepa L.) seedlings

Abstract

Seeds of onion cultivars 'Valencia' and 'TEG-502' were primed for 3 days at 15 degrees C with a NaCl solution (EC: 18 dS m(-1)) to examine the response of the seedlings to salinity. Non-primed (NP) and primed (P) seeds were sown in plastic trays containing sphagnum peat and sand. The plastic trays were placed in a heated greenhouse and watered with NaCl solutions at different salinity levels (0.3, 4.5, 9.0 and 13.5 dS m(-1)) for a period of 4 weeks. The effects of NaCl priming on increasing salt tolerance in both onion cultivars were examined on the bases of total emergence rate, mean emergence time, tolerance ratio and tolerance index parameters. Total emergence rates decreased due to the increase in NaCl concentrations, in both onion cultivars. However, seedlings derived from P seeds were more tolerant to salinity than those of the NP ones. Moreover, it was concluded that cv. 'TEG-502' was more tolerant to salinity than cv. 'Valencia'.