WHEAT GROWTH AS INFLUENCED BY THE INTERACTION OF DRAINAGE WATER AND NITROGEN-FERTILIZATION

Bread wheat is grown under irrigation in Saudi Arabia. Since water resources are limited, any additional agricultural development must make use of sources of water that are less than ideal, for example, saline drainage water. A two year field study was conducted to compare the effects of irrigating bread wheat with normal water, with a 1:1 mixture of normal water and drainage water, and with drainage water alone, at three levels of nitrogen fertilizer use. The mean electrical conductivity of the irrigation water was 2.6, 8.6 and 14.6 ds m-1, respectively, in the two seasons of the study. Irrigation with drainage water decreased yield and yield components but increased the protein content of the grain of the two wheat cultivars studied. Drainage water depressed straw yields more than it depressed the yield of grain. Nitrogen application increased yield and yield components in all the irrigation treatments, partially overcoming the adverse effects of the use of saline drainage water.