YIELD AND QUALITY OF TUNIS GRASS AS AFFECTED BY PLANT HEIGHT AT CUTTING AND N FERTILIZER

The present investigation was conducted at Giza Experimental Agricultural Research Station (ARC) to study the effect of plant heights at cutting as well as the rates of N fertilizer on forage yield and quality of the new forage species; Tunis grass (Sorghum virgatum Hack.). The experimental design was split plot with three replications. The study included three plant heights of cutting i.e. 60, 90 and 120 cm and three rates of N (20, 30 and 40 kg N/cut/fad. with control treatment (zero N). The trial was conducted in two successive years; 2005 and 2006. Results showed that cutting the plant at the height of 120 cm and fertilized with 40 kg N/cut/fad. caused significant increases in the accumulated fresh and dry forage yields and chemical constituents i.e. fiber, ash and cell wall contents (neutral detergent fiber (NDF) and acid detergent fiber (ADF), while cutting the plant at the height of 60 cm and fertilized with 40 kg N/cut/fad. caused significant increases in protein content, total digestible nutrient (TDN) and digestible crude protein (DCP); and also toxic chemical component i.e. Hydrocyanic acid (HCNμg/100g).