Effect of various bioformulation, gibberellic acid and humic acid on growth and yield of onion

Introduction

Onion, scientifically known as Allium cepa L., is a bulbous biennial herb from the Alliaceae family, believed to have originated from Central Asia and the Mediterranean region; known as the "Queen of the kitchen. The total area under onion cultivation in India is 1914.18 thousand hectares, with a production of 312721.71 thousand tonnes and productivity is 16337 kg/ha in 2021-22. The major onion-producing states in India are Maharashtra, Madhya Pradesh, Karnataka, Gujarat, Rajasthan, Bihar, West Bengal, Andhra Pradesh, Tamil Nadu, Haryana, Uttar Pradesh. In Uttar Pradesh (2023-24), onions were sown in 196.7 thousand hectare area with production 4740.6 thousand tonnes and productivity is 24101 kg/ha. (National Horticulture Board). Inoculation with Azotobacter increases sporulation and mycorrhizal infection in onions due to growth-promoting substances produced by the bacteria, leading to enhanced plant growth, nitrogen and phosphorus uptake, ultimately improving crop productivity. Similarly, Azospirillum bacteria, through symbiosis with onion roots, fix atmospheric nitrogen, increasing nitrogen availability in the soil. Gibberellic acid (GA 3 ) is a plant growth regulator that influences onion growth by promoting stem elongation, increased internode length and cell division in leaves, stems, and bulbs. Its application during the vegetative stage leads to larger bulbs, while during bulb initiation, it increases the number of bulbs produced. Humic acid, an organic compound, enhances onion growth by improving soil structure, nutrient uptake, root growth and water retention. It also boosts beneficial microorganisms in the soil, leading to increased yield, larger bulb size and improved bulb quality in onion cultivation. Proper application of GA 3 and humic acid can contribute to the healthy growth and development of onions (Bhonde et al., 1997, and Dibute et al., 1993) [1,3] .

Methods and Materials

The present investigation was carried out at Department of Biological Science, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Prayagraj Uttar Pradesh. India.

Results and Discussion

Effect of Azotobacter, Azospirillum, GA3 and humic acid on growth and yield parameters Growth Parameters

The growth in height of onion plants recorded notable sensitivity to various treatments. The most remarkable plant height, measured at 60 days after planting (DAP), in T 10 is (51.56 cm) (GA 3 , Azotobacter, Azospirillum and Humic acid), which was at par with T 11 (RDF + Humic acid + Azotobacter + Azospirillum) (50.93 cm), while, the control plot (T 12 ) exhibited the smallest height at (43.17 cm). Similarly, at 90 DAP, the tallest plant stature (64.48 cm) was observed in T 10 , which was at par with T 11 (62.72 cm), whereas, the lowest height (53.13 cm) persisted in the control plot T 12 . Notably, the greatest plant height was consistently achieved in T 10 (RDF + GA 3 + Azotobacter + Azospirillum + Humic acid), contrasting with the lowest height observed in the control plot (T 12 ), both at the 60 and 90 DAP respectively. These factors collectively promote elongation of plant cells and expansion of the root system, resulting in enhanced plant height. These findings were also reported by Sajid et al. (2012) [8] and Mohammed and Ibraheem (2020) [7] .

The influence of various treatments on the leaf count per plant of onion plants displayed significant significance. Plant growth regulator that promotes cell elongation, which can lead to increased leaf formation. At 60 days after planting (DAP), the treatment T 10 , which encompassed GA 3 , Azotobacter, Azospirillum, and Humic acid, exhibited the highest leaf count per plant of (8.40). Which was at par with T 11 (8.20). In contrast, the control plot (T 12 ) recorded the lowest leaf count per plant of (7.18). Similarly, at 90 DAP, T 10 also achieved the highest leaf count per plant (11.43), while T 11 was at par with a count of (10.70). On the other hand, the lowest leaf count of 7.47 persisted in the control plot T 12 . This consistent trend was also reported by Singh et al. 2002 [9] . After 60 days after planting (DAP), the treatment designated as T 10 , which consisted of a combination of GA 3 , Azotobacter, Azospirillum and Humic acid, these stimulate cell division, elongation and overall leaf expansion, leading to an increase in leaf length. They obtain the most substantial leaf length recorded (46.16 cm). In contrast, the control plot labeled as (T 12 ) recorded the lowest leaf measurement of (40.70 cm) during the same period.

Similarly, at the 90-DAP, T 10 exhibited a remarkable maximum leaf length of (55.33 cm), while, T 12 demonstrated the lowest measurement of (46.50 cm) within the same timeframe. This consistent trend was also reported by Sajid et al. (2012) [8] and Kumar et al. (2017) [5] . The treatment T 10 , which included the application of GA [9] .

Yield parameters

The impact of different treatments on neck thickness exhibited significant variation. The highest neck thickness (2.22 cm) was observed in treatment T 10 (GA 3 , Azotobacter, Azospirillum and Humic acid), which was on par with T 11 (Humic acid, Azotobacter and Azospirillum) (2.21 cm). Conversely, the control plot T 12 recorded the lowest neck thickness (1.94 cm). These all combined applications stimulate cell elongation, division, and overall tissue expansion. These findings are consistent with the studies conducted by Banjare et al. (2015) [2] . The application of, GA 3 , Azotobacter, Azospirillum and Humic acid had a significant impact on bulb weight. These combined treatments stimulate cell growth, division, and nutrient storage, resulting in larger and heavier bulbs. The highest bulb weight (70.65 gm) was recorded in treatment T 10 (GA 3 , Azotobacter, Azospirillum and Humic acid), which was at par with T 11 (Humic acid, Azotobacter and Azospirillum) (70.16 gm). Conversely, the lowest bulb weight (57.36 gm) was observed in the control plot T 12 . These findings are consistent with the research conducted by Kumar et al. in 2019b [6] . The application of GA 3 , Azotobacter, Azospirillum and Humic acid had been shown to significantly influence both yield per plot and yield per hectare based on present study. The combined effects of GA 3 , Azotobacter, Azospirillum and Humic acid synergistically contribute to increased plant vigor, nutrient uptake, and overall productivity, ultimately leading to higher crop yield. The maximum yield per plot (16.10 kg) and per hectare (248.69 q) were recorded in T 10 , which were at par with the yield per plot (15.45 kg) and yield per hectare (237.97 q) in treatment T 11 . In contrast, the control plot T 12 exhibited the lowest yield per plot (12.36 kg) and yield per hectare (186.42 q). These findings align with the results reported by Waghmode et al. in 2010 [10] and Jamir et al. in 2013 [4] .

Conclusion

Based on the outcomes of this study, it can be deduced that the optimal approach to achieving a favorable crop growth, yield parameters, coupled with an impressive highest yield (248.69 q/ha) involves the application treatments. Specifically, the combined utilization of Azotobacter (5 kg), Azospirillum (5 kg), GA 3 (100 ppm) and humic acid (2 kg) has proven to be highly effective in enhancing crop productivity and economic benefits.

References

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