risk assessment of boron due to the long term reuse of treated effluent in irrigation in different soil textures in the gaza strip , Although boron is an important element for the growth of the plant, the border between being adequate or toxic for crops is very narrow, especially in citrus, where boron concentration should not exceed 0.5 mg/l in irrigation water , boron، mg، concentration، soil، treated، kg، wastewater، lemon، irrigation، water