The presented study sought to determine the effect of sulfur, thiobacillus bacteria, and nano-zinc on biochemical and grain yield traits of maize (Zea mays L.) grown in calcareous soils. The experiment, laid out in a randomized complete block design with three factors and three replications, commenced in the spring of 2022 at the Ibn-Al-Bitar Vocational Preparatory School, Holy Kerbala Governorate, Iraq. The first factor comprised three doses of agricultural sulfur (0, 1500, and 3000 kg ha^-1), the second was two thiobacillus bacteria levels (control – no addition, and bacterium), and the third factor was the nano-zinc concentrations (0, 50, and 100 mg L^-1). The sulfur addition (3000 kg ha^-1) showed the highest grain yield (8.06 mg ha^-1) with percent of nitrogen (1.72%), phosphorus (0.53%), protein (10.79%), and sulfur (0.270%) in maize grains. The thiobacillus bacteria also exhibited the maximum 500-grain weight and grain yield (154.64 g and 7.52 mg ha^-1, respectively). For nano-zinc, the optimum level (100 mg L^-1) excelled in nitrogen (1.62%), phosphorus (0.41%), protein (10.79%), and sulfur (0.239%) in maize grains and 500-grain weight (155.53 g); however, nano-zinc (50 mg L^-1) outshone in grain yield (8.01 mg L^-1). The combine application of three factors also improved most biochemical traits of maize.

Keywords: Maize (Zea mays L.), agricultural sulfur, thiobacillus bacteria, nano-zinc, biochemical traits, grain yield

Key findings: Results showed sulfur’s highest level (3000 kg ha^-1) was superior in enhancing maize (Zea mays L.) grain yield and biochemical traits. The treatments with bacteria (thiobacillus) and nanozinc (100 mg L^-1) also excelled in all maize traits.