Variation among Eucalyptus Species for Morphological, Physiological and Biochemical Traits under Simulated salt stress conditions

Abstract

The investigation was conducted on five-month-old seedlings of Eucalyptus camaldulensis, E. pellita, E. tereticornis and E. citriodora in earthen pots. Four levels of NaCl concentration i.e., 0, 40, 80 and 120 mM were applied through irrigation to these Eucalyptus species arranged in completely randomized design (CRD) in three replications. Significant differences among the species were found for morphological (plant height, collar diameter, root length and total plant length), physiological (relative water content, electrolyte leakage, chlorophyll and carotenoid content) and biochemical (proline, sugar and reducing sugar content) parameters. E. camaldulensis registered the highest average values (height 160.07 cm and collar diameter 10.65 mm) for morphological traits whereas the lowest average values (height 100.04 cm and collar diameter 6.82 mm) were in case of E. citriodora. Increase in salinity level ultimately led to significant decrease in all the traits indicating a reverse trend between these traits and salinity treatments. Significant reduction in total chlorophyll, carotenoids and relative water content was observed with increase in salinity level. Electrolytes leakage increased as the salinity increased indicating the damage caused by salt stress. Salinity stress raised the content of osmoprotectants such as proline, total soluble sugar and reducing sugar. E. camaldulensis was the most tolerant species which performed better than other species even at the highest salinity level and the salinity tolerance of species varied as E. camaldulensis > E. pellita > E. tereticornis > E. citriodora. These findings indicate more research into morphological, physiological and biochemical understanding of Eucalyptus species for salt tolerance mechanism.