Influence of PGPR, AM Fungi and Conventional Chemical Fertilizers Armament on Growth, Yield Quality, Nutrient’s translocations and Quercetin Content in Onion Crop Cultivated in Semi-Arid Region of India

The rhizosphere is the thin region of the soil that is directly affected by secretion from the roots and the microbes accompanying the soil, known as the root microbiome. The rhizosphere involving the pores of the soil includes many beneficial bacteria and other diverse microorganisms. The field experiment was conducted during the Kharif season at the Lasalgaon taluka of Nashik district farmers’ field, Maharashtra, India, to determine the influence of biofertilizers on onion. To study the effect of five combinations of biofertilizers compared with the recommended rate of chemical fertilizers on cash crop onion cv. Nashik Red. The treatments were control (100% RRF), Azotobacter + AM fungi, Azospirillum + AM fungi, Azotobacter + Azospirillum, Azotobacter + Azospirillum + AM fungi and Bio consortium (NPK) + Azospirillum + AM fungi. Height (64.24 ± 3.22 cm) and the number of leaves (13.58 ± 3.12) of the plant was maximum with the application of the consortium (NPK) + Azospirillum + AM fungi. The maximum leaf area (84.45 ± 2.44 cm2) was recorded in T6 and the minimum in T4 (82.45 ± 2.25). Different doses of onion plants inoculated with biofertilizers showed a significant increase in quality parameters such as neck thickness (1.12 ± 0.22cm), bulb diameter (14.45 ± 0.53cm), bulb size index (19.45 to ± 0.51 cm2), bulb weight (68.15 ± 2.27g), bulb length (6.21 to ± 1.48 cm), bulb scale (11.23 ± 1.23) was maximum in the consortium (NPK) + Azospirillum + AM fungi treated onion. Biofertilizers such as consortium treatments such as consortium (NPK) + Azospirillum + AM fungi resulted in a better morphological character, quality yield, TSS, starch, reduction sugar, quercetin contents among root colonization of mycorrhizae compared to the uninoculated control (100% RRF). The consortium (NPK) + Azospirillum + AM fungi and 100% RRF provided a maximum bulb length of 6.21 ± 1.48cm and 6.12 ± 1.59cm, respectively. The maximum number of scales per bulb (11.23 ± 1.23) was counted by the consortium (NPK) + Azospirillum + AM fungi. Plants treated with the consortium (NPK) + Azospirillum + AM fungi produced the maximum bulb weight (68.15 ± 2.27g) and the minimum (64.23 ± 2.39 g) in Azotobacter + Azospirillum. The maximum TSS (13.354 %) was noticed in T6 and the minimum in T3. The maximum percentage of starch (6.65%) and the highest percentage of reducing sugars (1.98%) were detected by Azotobacter + Azospirillum + AM fungi. Total pooled weight loss (%) up to 60 days was found to be minimal (11.87%) by Azotobacter + AM fungi followed by Azotobacter + Azospirillum (14.40%). The maximum colonization of mycorrhizae (79.9%) was recorded in the consortium (NPK) + Azospirillum + AM fungi and the minimum in the control (46.67%). It was therefore concluded that the combination of the consortium (NPK bioinoculum) + Azospirillum + AM fungi are improved for onion quality and productivity than the others in terms of sustainable production and environmental consideration.