A field experiment was performed using potato (Solanum tuberosum L.; cv. Cara) grown in a private farm at Meet Zonkor village, Talkha, Dakahlia Governorate, to test the influence of water quantities, compost and polymer on growth of potato plants and water relationships under drip irrigation method in 2016 and 2017 summer growing seasons. A strip-split plot design was used with irrigation water quantities (800 "draught stress", 1200 and 1600 m³/fed) and the last water quantity is considered as the common water management (control treatment) as main plots, compost (0 and 7.5 ton/fed) and polymer matrix composite (PMC) at the rates of (0, 10, 20, 30 kg/fed) as soil conditioners randomly distributed within sub and strip-plots, respectively. Each treatment was repeated three times.  Application of compost or polymer significantly affects the vegetative growth and its water relationships issues compared to control. The mutual interaction of irrigation with 1200 or 1600 m³/fed with compost soil amendments (7.5 ton/fed) and polymer (30 kg/fed) had significant effects on most vegetative growth features (plant height, dry weight and leaves area) of potato plants. Moreover, data showed that plant water relationships parameters (relative transpiration rate, RTR and leaf water deficient, LWD) were significantly affected with the highest levels of irrigation water quantity without application of soil conditioners (compost and polymer) in both seasons. Furthermore, including polymer dually with compost under the scarce of water irrigation led to better water use efficiency WUE.