EFFECT OF IRRIGATION INTERVAL AND PHOSPHORUS FERTILIZATION RATE ON FABA BEAN (Vicia faba l.) YIELD, YIELD COMPONENTS AND SOME CROP-WATER RELATIONSHIPS

A field experiment was conducted during 2012/13 and 2013/14 winter seasons at Sids Agric. Res. Station, Beni-Swief Governorate, Egypt. These trials aiming at investigating the effect of irrigation intervals, i.e. 14, 21 and 28 days and phosphorus fertilization rates of 7.5, 15 and 30 kg P₂O₅ fed^-1 and interaction on seed yield components, seed and straw yields and some crop-water relations of faba bean crop (Giza–843 hybrid). The adopted treatments were assessed in a split-plot design with four replicates. The most important results could be summarized as follows:-
 *Seed & straw yield and yield components e.g. plant height, pods N^o plant^-1, seeds N^o pod^-1 and 100-seed weight were significantly influenced due to the adopted  irrigation and P- rate treatments and interaction as well in 2012/13 and 2013/14. Higher values of seed yield and the abovementioned yield components resulted from irrigating at 21 days interval, whereas plant height and straw yield were positively responded with 14 days interval. The 30 kg P₂O₅ fed^-1 rate resulted in higher values of seed & straw yields and yield components e.g. pods N^o plant^-1, seeds N^o pod^-1 and 100-seed weight and plant height as well. Interaction of irrigating at 21days interval and 30 kg P₂O₅ fed^-1 rate exhibited higher values of the abovementioned variables, except plant height where the highest values were noticed with irrigating at 14 days interval as interacted with 30 kg P₂O₅ fed^-1 rate.
* The highest Water consumptive use (Cu) values were attained due to irrigating at 14 days interval, whereas Water Productivity and Water Use Efficiency were the highest as irrigation was practiced at 21 days interval. The highest figures of Cu, WP and WUE were achieved with supplying P fertilizer at the highest rate (30 kg P₂O₅ fed^-1). Irrigating at 14 days interval as interacted with 30 kg P₂O₅ fed^-1 rate exerted the highest Cu values, whereas interaction of irrigation at 21 days interval and 30 kg P₂O₅ fed^-1rate exhibited the highest WP and WUE values.  
 * Under the conditions of the present experiment and to conserve the limited irrigation water resources, as an important national issue, it is advisable to irrigate faba bean crop at 21 days interval and supplying P-fertilizer at 30 kg P₂O₅ fed^-1 rate in order to obtain reasonable values of seed yield, water productivity and water saving as well.