This investigation aims to evaluate the effect of water stress and foliar application of two different antitranspirants on growth, yield, quality and water use efficiency of Jerusalem artichoke grown a calcareous soil using drip irrigation system. For this purpose, two field experiments were carried out at soil salinity lab. Res., Agricultural Research Center, Alexandria Governorate, Egypt during the summer seasons of 2017 and 2018 using the split plot design. Jerusalem artichoke plants were irrigated by 100, 75 or 50% of water requirements (ET C ). The antitranspirants included glycine betaine (200 mg/l), potassium silicate (5 cm 3 /l) and their combination i.e. potassium silicate (P.S) x glycine betain(G.B) in comparison with spraying distilled water as control treatment. The gained results revealed that increasing irrigation water levels from 50% up to 100% significantly (P<0.05) increase, majority of plant vegetative growth characters Jerusalem artichoke tubers yield/feddan, its component parameters and tubers′ quality during both seasons. Foliar application of antitranspirant treatments; increased irrigation efficiency and potassium silicate was more effective than glycine betaine, in particular, upon irrigation with 50% ET C treatment. In general, spraying Jerusalem artichoke plants with potassium silicate; gave rise to the best results for plant height, No. of main stem/plant and plant fresh weight/plant with 100% ET C during both seasons. The dry matter percentage was not affected significantly (P>0.05) by the two independent variables. In addition, potassium silicate at 100% ETc; brought about the highest value for tuber yield in both seasons. Jerusalem artichoke plants irrigated with 75% of water requirements gave insignificant decrease in number of tubers/plant, tuber fresh weight and tuber yield than the treatment received 100% of water requirements. The interaction between irrigation tested levels and foliar application treatments was highly effective on tuber yield character in both seasons. The highest average values for tuber yield/feddan were recorded due to the treatments of water level of 75%ETc with spraying potassium silicate at 5cm 3 / l., while the lowest mean values were achieved due to apply at 50 % irrigation level compare with control treatment. Also, the interaction between irrigation levels foliar glycine betaine, potassium silicate, and G.B. x P.S. had a significant (P<0.05) effect on K of tuber content during both seasons. The compositional elements N, P and carbohydrate content in tubers were not significantly affected by this interaction during the two seasons except inulin content during the first season only. The best results were recorded due to apply water irrigation level of 100% ET C and 75%ET C with spraying of potassium silicate at 5cm 3 /l. Crop water use efficiency (CWUE) was doubled in the case of 50% ET C compared with consumptive 100% ET C. The water use efficiency increased as the irrigation level reduced.

Two field experiments were carried out on Jerusalem artichoke crop during two successive seasons of 2016 and