Effects of salt stress on some morphological and physiological traits of Iranian turnip accessions (Brassica rapa L.)

In order to investigate effects of salt stress on some morphological and physiological traits of Iranian turnips accessions, a greenhouse experimental was carried out as a factorial with a completely randomized design in three replications. The first factor was the salinityof water at four levels (0, 60, 120 and 180 mM NaCl) and the second factor was the accessions of Iranian turnip at 15 levels. Results showed that salt stress reduced the fresh and dry weights of shoot (63, 33) and root tuber (86%), chlorophylls a and b (52 and 37.5%), potassium ion of leaf and tuber root (33.2 and 31.2%) and increased the sodium content of leaf and root tuber (84 and 90.3 percent. Results of interaction of salinity and accession showed that Mashhad, Yazd and Birjand accessions had the greatest reduction in proline (71, 64.5 and 61.6%); while, accessions from Mehriz and Kermanshah had the smallest decrease in chlorophyll a (22 and 32.3%) at 180 mM salinity compared to control. Chlorophyll a and b levels were positively correlated with fresh weight (0.8**, 0.72**) and dry weight of shoots (0.43**, 0.68**). Proline had a positive and negative correlation with sodium and potassium of leaf (0.43*, -0.42*), respectively. Root potassium and sodium had negative significant correlation. Results showed accessions of Iranian turnip exhibit different responses to salt stress and potassium and sodium ions can be used as a selection index for accessions of salt-tolerant turnip.