Abstract
AbstractIn a pot experiment the responses of two alfalfa cultivars differing in salt tolerance were evaluated in terms of root nitrogen remobilization rates (RNRR) and their relationship with the ionic status of the plants. A split‐plot design with factorial treatments in three replications was used. Three levels of salinity stress with electrical conductivities (ECs) of 1.2, 7 and 12 ds m−1 were established in irrigation water by using tap water with and without NaCl. The average data taken from plant materials at three defoliations were used for statistical analysis. Each time, plant materials were harvested at the 10 % flowering stage and then 10 days later. From the results observed, it was found that alfalfa shoot growth is highly dependent on RNRR under salinity stress. However, the total N reserves within the roots do not appear to be a limiting factor. The high positive correlation coefficient between shoot K+/Na+ and RNRR (r = 0.77; P = 0.01) indicates that lower demands for N because of diminished metabolic activities within the shoot sink may have reduced the rates of root N utilization. Unlike in some other species, the shoot K+ concentration and contents of alfalfa plants were significantly reduced by increasing salt stress. However, a relatively suitable K+/Na+ ratio of 7.1 is maintained in the shoots at the second level of salinity, as lowering the rates of salt induced an increase in Na+ uptake (Na exclusion). The salt tolerance recognized in the Bami cultivar may be attributed to the 339 % increase in its selectivity rates of K+ over Na+ in ion transport from the soil to the shoots, as the shoot Na+ content did not increase with increasing salt levels.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call