PJB-2018-1713
Salinity tolerance threshold of berseem clover (Trifolium alexandrinum) at different growth stages
Seyed Abdolreza Kazemeini, Hadi Pirasteh-Anosheh, Abdolrasol Basirat and Nudrat Aisha Akram
Abstract
The most crops are sensitive to salt stress, however, this sensitivity is varied among different growth stages. Therefore, in this study salt stress tolerance threshold at different growth stages was examined in berseem clover (Trifolium alexandrinum L.). The treatments included five saline irrigation levels: 0.62 (tap water as control), 3, 6, 9 and 12 dS m-1 and three growth stages at which salinity was applied: 2-leaf, 6-leaf and flowering. Growth parameters, ions accumulation and oxidative damage of berseem clover plants were evaluated. The results showed that salinity stress caused a significant reduction in plant shoot and root dry weights, root length, height, and potassium (shoot and root) concentration, but the impact of salinity varied from stage to stage. On the other hand, tissue sodium concentration and antioxidant enzymes activities were found to be enhanced due to salt stress. Higher levels of salinity had more negative effects on growth parameters and biochemical attributes. Salt stress imposed at the early growth stage had more severe effect on plant growth than that applied at the later growth stages. In view of salt tolerance threshold analysis worked out as 50% reduction based on Van-Genuchtan and Hoffman equation of berseem clover were 6.54, 7.99 and 10.00 dS m-1 at 2-leaf, 6-leaf and flowering, respectively. However, when salt stress was imposed at the 2-leaf stage, plants were able to recover in terms of ion accumulation and antioxidant enzymes, and they were as good as the non-stressed plants. Overall, it was revealed that berseem clover is a sensitive plant at early growth stage, but is relatively tolerant at the later growth stages.
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