Alex. J. Agric. Res. 39 (3): 1994 ( pp: 159-170) YIELD RESPONSE OF FORAGE OATS (AVENA SATIVA L.) TO NITROGEN FERTILIZATION HARVESTED AT SUCCESSIVE STAGES OF MATURITY By Abdulaziz M. Assaeed Department of Plant Production, College of Agriculture, King Saud University P.O. Box 2460, Riyadh 11451, Saudi Arabia Received on: 27/6/1994 Accepted on: 14/11/1994 ABSTRACT Oats, Avena sativa L. has recently gained importance as a winter forage crop. However, few information exists on management practices of the crop in Saudi Arabia. A field study was conducted to evaluate yield response of forage oats, c.v. Cayuse, to nitrogen fertilization when harvested at different stages of maturity. The experiment was conducted at the Agricultural Research and Experiment Station. King Saud University, College of Agriculture, Dirab, located about 50 km south west Riyadh. Fresh yield. plant height number of leaves and leaf area per plant were measured at time of harvest. Percentage dry matter and leaf-stem ratio were also determined. Plant height, percentage dry matter and dry matter production increased significantly as time of harvest was delayed. Number of leaves per plant. leaf area per plant and leaf stem ratio decreased significantly as time of harvest was delayed. Increased in rate of nitrogen fertilization from nil to 150 kg/ha