Diurnal Fluctuations in Relative Water Content, Nitrate Reductase and Proline Content in Water‐stressed and Non‐stressed Wheat

Diurnal variations in relative water content (RWC), nitrate reductase (NR) and proline content (PC) were studied at 3 h intervals during a 24 h cycle in the flag leaf of wheat ( Triticum vulgare , v. Kalyansona) grown under stressed and non‐stressed conditions. RWC was lower in stressed plants than in non‐stressed ones throughout the 24 h period. Although it was lowest at 12 h, it recovered by 15 h. Non‐stressed plants maintained higher NR activity compared to those under stress. The enzyme activity during night was about the same as during day time in both types of plants. Compared to non‐stressed plants, stressed ones had lower NO 3 − content. Proline accumulation occurred under stress conditions and had a maximum at 12–15 h. Non‐stressed plants exhibited higher PC during night than day time. Changes in temperature and relative humidity were noted during the period and their influence on RWC, NR and proline was discussed.