BSTRACTTwo greenhouse experiments were carried out at Army Farm, at El-Amria region, Alexandria, Egypt, during the two seasons of 2016-2017 and 2017-2018, as an attempt to rationalize of irrigation water through studying the effect of three water regimes, three pruning systems and four potassium silicate rates on the dry mass accumulation in the various plant organs of sweet pepper. Results showed that application of the lower amount of irrigation water (30% depletion ratio) with repeat its addition achieved the highest significant mean values of roots, stems, leaves and whole plant dry mass at one, three and nine months after transplanting (MAT), as well as fruits dry mass after three and nine MFT, in the two seasons. Furthermore, the results indicated that un-pruned sweet pepper plants achieved significant higher mean values of roots, stems and whole plant dry mass, at three and nine MAT, in both seasons, as well as fruits dry mass at nine MAT only , in both seasons. The addition of, foliar application of potassium silicate up to 500 or 1000 mg l -1 , significantly, accumulated higher dry weight in roots, branches, leaves, fruits and whole plant of sweet pepper plants after one, three and nine MAT, compared with that unsprayed, in the two seasons. Likewise, sweet pepper plants that un-pruned or pruned up to 3 branches plant -1 and irrigated with the lower amount of irrigation water (30% depletion ratio) achieved the highest values of the dry mass of branches, leaves, fruits and whole plant at one, three and nine MAT compared with that pruned on two branches plant-1. However, the highest dry mass value of roots, branches, leaves, fruits and whole plant of pepper were obtained from the treatment combination included the lower amount of water (30 % water depletion ratio) and spray 1000 mg l -1 of potassium silicate, in both seasons, after one, three and nine MAT. Interactions between pruning systems and potassium silicate concentrations indicated that the highest values of the dry mass of roots, branches and whole plant of sweet pepper plants were achieved from treatment combinations containing un-pruned plants and sprayed the plants with 1000 mg l -1 of potassium silicate, in both seasons.