N2fixation in faba bean grown under saline and non-saline conditions using a 15N-tracer technique

Abstract

A pot experiment was conducted to study the performance of faba bean and barley growing under saline conditions, in terms of dry matter yield, total N, and percentages and amount of N derived from the soil, fertilizer and atmosphere using a 15N isotope dilution method. Three saline treatments were employed: 1) plants were grown on saline soil and irrigated with saline water (SsWs); 2) plants were grown on saline soil and irrigated with non-saline water (SsWn); and 3) plants were grown on non-saline soil and irrigated with saline water (SnWs). Furthermore, a control treatment was employed by growing the plants on non-saline soil and irrigating them with non-saline water (SnWn). The different salinity treatments reduced plant growth and the reduction was more pronounced in faba bean than in barley. However, the relative growth reduction of plants grown only on saline soil, using non-saline water, did not exceed 50% of the control, whereas the reduction exceeded 50% when plants were grown under completely saline conditions. The percentage of N2fixed (%Ndfa) was not affected negatively by saline conditions.the results clearly demonstrated that the effect of salinity on faba bean was more evident on plant growth than on N2-fixing activity. Further studies are needed to obtain more salt-tolerant faba bean genotypes that possess a higher growth rate. This could simultaneously improve yield and N2fixation under severely saline conditions.