SCREENING OF DURUM-WHEAT GERMPLASM FOR NA-22 UPTAKE UNDER LOW AND MODERATE SALINITY

A series of experiments were conducted in this study to assess variati on for Na-22 uptake in durum wheat genotypes grown at low and moderate salt concentration, and verify the usefulness of this character as an index of intra-specific variability for Na accumulation. Wide variati on, much larger than previously reported for this taxon, was found amo ng genotypes for Na-22 uptake at 1 mol m(-3) NaCl. However, the charac ter did not seem able to discriminate among entries at higher NaCl con centrations (25 and 50 mol m(-3)). No relationships were found between Na-22 concentration in low-salt-grown seedlings and sodium acccumulat ion at higher salinity levels. Moreover, a correlation was found in so me cases between high Na-22 uptake at low NaCl concentration (presumab ly a detrimental attribute) and high K accumulation at higher salinity (a supposedly beneficial feature). The tests suggested that Na-22 upt ake into low-salt-grown seedlings is not necessarily closely correlate d with Na leaf concentration at higher salinity. These results clearly limit the value of assessing Na-22 uptake at low external NaCl concen tration, and the possible use of Na-22 as a within-species selection c riterion remains uncertain.