The effect of plant growth promoting rhizobacteria on the water-yield relationship and carotenoid production of processing tomatoes

Abstract

Open field experiments were conducted to investigate the effects of plant growth promoting rhizobacteria (PGPR) biofertilizer on processing tomato, grown under three different irrigation regimes. The field effectiveness of rhizobacteria inoculation on total biomass, yield, water use efficiency (WUE), carotenoid, and ascorbic acid production was examined in 2015 and 2016. The experimental design used was randomized block and the number of replications was four for each treatment. There were three different irrigation regimes: rain-fed control (RF), deficit water supply (WS50), and optimum water supply (WS100), which was delivered by drip irrigation in accordance with daily evapotranspiration (ETc). The test was performed on the Uno Rosso F1 processing tomato hybrid. Red fruit were measured at harvest in August and high-performance liquid chromatography (HPLC) was used for analysis. We evaluated yield quantity and total carotenoids and their composition (lycopene and β-carotene) depending on water supplement in 2 years. The marketable yield varied between 14.7 t·ha–1 and 126.9 t·ha–1 depending on treatment. The average soluble solids content (SSC) of the treatments ranged from 3.0 to 8.4. The total carotenoid yields of the treatments ranged from 0.8 to 40.4 kg·ha–1 and the average lycopene yield of the treatments ranged from 0.6 to 34.1 kg·ha–1. The effect of PGPR treatment was clearly positive for harvested yield, but this effect only prevailed under irrigated conditions.