Nano iron fertilization significantly increases tomato yield by increasing plants’ vegetable growth and photosynthetic efficiency

Abstract

Nano fertilization is a precision approach to sustain economically viable and environmentally compatible crop production. The objective of our study was to evaluate the effects of different sources and rates of iron (Fe) fertilization as an essential micronutrient on the growth, physiological processes, and yield of greenhouse-grown tomatoes (Solanum lycopersicum cv. Bigdena F1). A factorial experiment in randomized complete block design with four replications was conducted using three sources (Conventional, FeCl3.6H2O [Conv-Fe]; Chelated with 6% Fe [Che-Fe]; and Nano Fe2O3 [Nano-Fe], alpha, 99%, 30–50 nm) and rates of Fe (0, 50, and 100 mg/kg soil) during 2015 and 2016 growing seasons. Averaged across Fe rates, the Nano-Fe significantly increased plant height, leaf number and area, shoot and root fresh and dry weights, and Soil Plant Analysis Development (SPAD) readings. Nano-Fe at 100 mg/kg significantly increased plant height, leaf number and area, fresh and dry weights of shoot and roots, gas exchange parameters i.e., photosynthesis (Pn), stomatal conductance (gs) and transpiration (E) rates, total yield, and yield components of tomatoes in comparison to the other rates. While there were no significant simple and interactions of Fe on plant physiological processes, the Nano-Fe had the highest Pn with an associated decrease in E and an increase in gs. Nano-Fe, when applied at 100 mg/kg, produced the highest fruit diameter, fruit numbers/plant, total fruit weight/plant, mean fruit weight/plant, total fruit numbers/ha, and total fruit weight/ha, followed by Nano-Fe at 50 mg kg as compared with other Fe sources and rates. In conclusion, Nano-Fe fertilization is more effective than Conv-Fe and Che-Fe fertilizations across growing seasons to improve growth characteristics and metabolic processes of tomato plants, as Fe plays an important role in photosynthates accumulation and translocation. Nano-Fe increased tomato yield by 11% compared to Conv-Fe and Che-Fe fertilizers and will greatly improve farmers’ profitability.