Abstract
Experiments were conducted to evaluate the interactive effects of different nitrogen and irrigation levels in 2017 and 2018 (April–July) on greenhouse‐grown tomato considering irrigation water, growth, physiology and productivity parameters. A randomized block design with three replications and two factors, water (W 1 , 100% of the requirement; W 2 , 90%; W3, 70%) and nitrogen fertilizer (F 1 225 kg/ha, F 2 180 kg/ha), was established. The highest values of crop consumptive use (ET) were observed under the W 1 F 1 treatment during both seasons (266 and 226 mm during 2017 and 2018, respectively). The highest values of stem and root biomass were also observed under W 1 F 1 during both experimental seasons, followed by W 1 F 2 and W 2 F 1, without significant differences. Compared with W 1 F 1 , W 1 F 2 and W 2 F 1 had no significant difference, but other treatments decreased the photosynthesis rate and stomatal conductance significantly during both seasons. The highest irrigation level, W 1, increased fruit yield under both nitrogen levels (W 1 F 1 yielded 91 and 102 t ha −1 , followed by W 1 F 2, with 90 and 99 t ha −1 during 2017 and 2018, respectively). W 2 increased fruit yield under higher nitrogen levels (F 1 ) but decreased fruit yield under lower nitrogen levels (F 2 ). W 3 decreased yield drastically under both nitrogen levels. W 3 significantly decreased water use efficiency and irrigation water use efficiency. The highest partial factor productivity values of 23% and 22% were obtained under W 1 F 2 in 2017 and 2018, respectively, when compared with the control treatment. It was concluded that W 1 F 2 could be the best strategy for improving greenhouse‐grown tomato productivity.