Studies on Water Stress in Kinnow As Influenced By Irrigation Schedules and Nitrogen Applications

In a split plot design, using open pan evaporation values of 100mm, 133 mm, 200 mm and no irrigation control plants, as main plots and three N treatments as sub plots, free proline and relative water content were measured in the kinnow leaves sampled from February and September growth flushes during 1981–82 and 1982–83. Two month old leaves were observed to contain maximum amount of free proline. However, the proline concentration sampled from five segments of a leaf did not show significant variation. A trend was noticed in the quantity of leaf free proline according to the degree of moisture stress. On rewatering the proline concentrations dropped to normal levels. Similarly, the relative leaf water content declined as the moisture stress developed. Nitrogen applications resulted in more proline accumulation in stressed plants, therefore indicating the necessity of increasing the frequency of irrigation where nitrogen is applied. But, relative leaf water content was not affected by N rates. These studies have indicated the possibility of using free proline and relative leaf water content as irrigation indices.