Fertigation under different irrigation and nitrogen levels modulates the growth, physiology, nitrogen and fruit productivity of greenhouse tomato

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 W1F1 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 W1F1 during both experimental seasons, followed by W1F2 and W2F1, without significant differences. Compared with W1F1, W1F2 and W2F1 had no significant difference, but other treatments decreased the photosynthesis rate and stomatal conductance significantly during both seasons. The highest irrigation level, W-1,W- increased fruit yield under both nitrogen levels (W1F1 yielded 91 and 102 t ha(-1), followed by W1F2, 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 W1F2 in 2017 and 2018, respectively, when compared with the control treatment. It was concluded that W1F2 could be the best strategy for improving greenhouse-grown tomato productivity.