The role of the duple interaction of Tricoderma hirazanum fungus and Azotobacter ssp bacteria with sulfur in the growth and yield of onions (Allium cepa L.) and some active compounds

Abstract

A field experiment was conducted on onion plants at the spring season of 2025 to study the duple interaction of three factors: the first factor was the fungus Tricoderma hirazanum at three levels (0, 2, and 4) kg.ha-¹the second factor was inoculation with Azotobacter ssp at two levels (non inoculation and inoculation); and the third factor was agricultural sulfur at three levels (0, 30, and 50 kg.ha^-1). A B.R.C.D. design was used. After 90 days of planting , the following indicators were measured: wet weight of the onion (g), protein content (mg.g-1), ascorbic acid (mg.kg^-1), Azotobacter ssp. 10⁷ CUf g⁻¹, and the duple interaction  treatment (T₄*B₁) inoculation with Tricoderma hirazanum 10⁻³ CUf g⁻¹ in the onion rhizosphere. Tricoderma hirazanum inoculation yielded 4 kg.ha⁻¹ + Azotobacter  ssp  inoculation .The highest significant increase was observed when the treatments reached 237.7 (g), 1.29 (mg.g^-1), 42.10 (mg.kg^-1), 4.10* 10⁷ CUf g^-1, and 71.71* CUf 10³ g^-1, compared to the control 168.7 (g), 0.83 (mg.g^-1), 24.67 (mg.kg^-1), 2.56* 10⁷ CUf g^-1, and 5.11* 10³ CUf g^-1, respectively. This experiment led to an increase in the productivity and quality of the onion crop and a reduction in environmental pollution resulting from the addition of mineral fertilizers.