A study was carried out on a field scale during two successive growth seasons (2009/2010 and 2010/2011) on tomato plants irrigated with saline ground water (2.24 and 3.86 dS m^-1) using drip irrigation system, subjected to water stress (irrigation every 3, 4, and 5 days), and were grown under application of potassium fertilization (96, 120, and 144 kg K₂O/feddan) in newly reclaimed lands at the Agricultural Experiments and Research Center, Faculty of Agriculture, Minia University, El-Minia Governorate, Egypt. The current study aims to investigate the effects of irrigation water salinity and water stress on tomato growth, tomato yield, and tomato fruit quality under application of a salinity and water stress alleviated amendment (potassium fertilization) using drip irrigation system.  The obtained results of the current study showed that increasing irrigation water salinity level from 2.24 dS m^-1 to 3.86 dS m^-1 decreased tomato plant height, tomato shoots fresh weight, average tomato fruit weight, fresh tomato fruit yield, and tomato fruit dry weight, while, it increased tomato shoots dry weight, number of tomato fruits per plant, total soluble solids of tomato, and tomato fruits marketability (shelf life) in growth seasons. Increasing irrigation interval from 3 up to 5 days decreased tomato shoots fresh weight in both growth seasons, however, it increased tomato shoots dry weight, total soluble solids, and tomato fruits marketability in the two growth seasons. Increasing the potassium fertilization level from 96 up to 144 kg K₂O/feddan increased the tomato plant height, tomato shoots dry weight, average tomato fruit weight, total soluble solids of tomato, and tomato fruits marketability. Increasing the potassium fertilization level from 96 to 120 or 144 kg K₂O/feddan increased the tomato shoots fresh weight, number of tomato fruits per plant, fresh tomato fruit yield, and tomato fruit dry weight in the two growth seasons.  The increase in the tomato plant height, tomato shoots fresh weight, tomato shoots dry weight, number of tomato fruits per plant, average tomato fruit weight, fresh tomato fruit yield, total soluble solids of tomato, tomato fruits marketability, and tomato fruit dry weight implies that application of potassium fertilization to soil alleviated adverse effects of salinity stress and water stress on tomato growth, tomato yield, and tomato fruit quality. The results of the current research indicated that it can be recommended that to alleviate and manage adverse effects of salinity stress and water stress on tomato growth, tomato yield, and tomato fruit quality, good cultural practices management to be followed are: (1) irrigate tomato plants every 4 days, (2) apply appropriate and optimized requirements of potassium fertilization to soils (120 kg K₂O/feddan), and (3) use drip irrigation system as an irrigation management which might control soil salinity build-up and soil water content since it can keep a high soil water content and low salt concentration in the root zone.