Free Proline in Barley, Pearlmillet and Chickpea Grown under Soil Salinity Stress

With a view to assess the effectiveness of free proline accumulation in leaves as a criterion of selection for salinity resistant plants, a number of varieties of three different crops, barley (Hordeum vulgare), pearlmillet (Rennisetum typhoides) and chickpea (Cicer arietimm) were evaluated for yieldand salt resistance at varying or standardised levels of soil salinity in 90-cm deep microplots, which simulate a field profile reasonably well. When only 2–3 varieties from resistant, semi-tolerant ad sensitive classes within each crop were considered, it appeared that salt resistance might insomecasesbe positively related to free proline accumulation and in other cases, negatively correlated. If data on all the varieties within a crop were taken into account, any such correlation vanished. But with regard to pearlmilet hybrids (i.e. excluding synthetic lines) a significant negative correlation was detected between free proline accumulation and yield level at a given salinity level. Free proline in leaf was, even in this case, not related to salinity resistance as measured by relative reduction of genotypes dues to salinity stress. The conclusion is that salinity resistance was a complex trait, and generalisation over different varieties of a crop might not be possible.