To study the involvement of N in proline production and salinity tolerance, activity of GK, P5CS and proline oxidase was determined.It was observed that proline content increased under salt stress and further increased with N supplementation. Maximum increase in proline was recorded with 10 mM N in the absence of salt stress and with 20 mM N under salt stress compared to control (Fig. 3).Activity of GK and P5CS increased in salt stressed plants and also in N plus salt stress treatments. Nitrogen availability increased activities of GK and P5CS differently without salt stress or under salt stress. Application of 10 mM N increased activity of GK and P5CS by 135% and 105% in the absence of salt stress and by 106% and 81%under salt stress compared to control. Supplementation of 20 mMN in the absence of salt stress increased GK and P5CS activity by101% and 76%, whereas under salt stress it increased by 126% and 99%, respectively compared to control (Figs. 3 and 4). The proline degrading enzyme, proline oxidase decreased with the supplementation of N alone or with salt in comparison to control, accounting for the observed increased proline content. The activity of proline oxidase decreased by 62% with 10 mM N and by 32% with 20 mM in the absence of salt in comparison to control. In contrast, under salt stress, 10 mM N and 20 mM N decreased activity of proline oxidase by 34% and 63%, respectively compared to control.