Two field experiments were carried out during two summer seasons of 2013 and 2014 years at the Experimental Farm of Kaha Station, Qalubia Governorate to study the effect of using three irrigation intervals (7, 15 or 21 day) and five treatments of water absorbent substrates as adding to soil before transplanting ,i.e. (without substrates (control), SAP at 15 kg/fed., SAP at 20 kg/fed., compost at 5 t/fed. and compost at 10t/fed.) on sweet  pepper plants c.v. Mohanad and the effect of that on growth, yield, physical and chemical characters of sweet  pepper fruits. The results indicated that, the highest values of all vegetative growth parameters, yield and yield components were registered by the treatment of 7 days or 15 day irrigation intervals. Concerning of using water absorbent substrates, it was found that, pepper plants grown in the soil fertilized at 10 t/fed. or treated with super absorbent polymer (SAP) 20 kg/fed., respectively gave the highest values of vegetative growth parameters, yield and yield components.It is obvious that the plants fertilized at 10 t/fed. and irrigated every 7 days gave the highest values of fruit length, fruit diameter, fresh fruit weight and total yield. While, plants treated with SAP at 20 kg/fed. and irrigated every 15 day gave the highest values of fruit diameter and fresh fruit weight, but the differences did not reach to significance level for fruit length and early yield in both growing seasons. On the other hand, compost at 10 t/fed., compost at 5 t/fed. and SAP at 20 kg/fed. with irrigation every 21 day were the best treatments for yield and yield components of pepper plants.
Generally, it can recommend by using compost at 5 t/fed., or super absorbent polymer (SAP) at 20 kg/fed. with irrigation every 15 days and this mean that increased the irrigation period without any injury or statistical effect on the fruit crop to obtain high pepper fruit yield  with height quality and height net income to the growers.