Influence of nitrogen levels and inoculation of biofertilizers on yield and economics of wheat

Introduction

One of the most widely grown grains in the world is wheat (Triticum aestivum L.). It is the third most significant cereal in the world due to its plentiful end product manufacturing, nutritious diversity, and protein-to-carbohydrate ratio. In 2022, there were 221.84 million hectares of wheat cultivation worldwide, with a total production of 779.33 million metric tons and a yield per hectare of 3.51 metric tons. This is an increase in production of around 0.57 percent over the previous year. China leads the production scale for 2022, followed by the United States, Australia, Russia, India, the European Union, and so on (Global Market Analysis, FAS, USDA, 2023) [17] . Approximately 304.47 lakh hectares are planted with wheat in India (GOI, 2022) [7] . India produces about 111.32 million tons of wheat annually. Major wheat-producing states include Uttar Pradesh, Punjab, Haryana, Madhya Pradesh, and Rajasthan, with Uttar Pradesh ranking first in production. During 2022-23, Uttar Pradesh produced around 11.27 million tonnes of wheat. Wheat is traded more globally than all other crops put together. India's wheat is becoming more and more popular worldwide (APEDA, 2022) [1] . Nitrogen is one of the elements of the chlorophyll molecule that propels a crop's growth and output. Nitrogen is particularly important throughout the wheat crop's reproductive period, which subsequently exhibits noticeable fluctuations in grain output. Wheat protein content rises with nitrogen fertilization (Robinson et al., 1979) [16] , improving grain quality and vigor. According to Kelley (1995) [12] , applying nitrogen later in the season is more successful than applying it earlier.

In other words, applying nitrogen close to anthesis increases grain protein content more effectively than applying it earlier (Wuest and Cassman, 1992). Wheat grain yield is mainly determined by the number of kernels and their weight per unit area. Nitrogen plays a vital role in grain filling by promoting leaf area development and increasing dry matter accumulation through greater interception of solar radiation (Green, 1984) [8] . Grain weight is largely controlled by genetic factors, although environmental conditions during the grain-filling period can significantly influence its expression (Kausar et al., 1993) [10] . Biofertilizers are formulations of beneficial microorganisms that improve plant growth and soil fertility through nitrogen fixation, nutrient solubilization, growth hormone production, and disease suppression. They include bacteria, fungi, and cyanobacteria (AICRP, 2018) [2] . Among bacterial biofertilizers, Azotobacter and Azospirillum are highly effective in enhancing wheat growth and yield. Azotobacter is a free-living, nitrogen-fixing bacterium that contributes roughly 10-20 kg N ha⁻¹ per cropping season to the rhizosphere of a variety of crops, including wheat, maize, rice, sorghum, sugarcane, and cotton (Jadav et al., 1987). Apart from fixing nitrogen, it also produces a number of growth-promoting substances, including auxins, gibberellins, nicotinic acid, B vitamins, and biotin, which promote plant growth and root development (Rao, 1978). According to Narula and Gupta (1986) [14] , it also releases ammonia into the rhizosphere, which improves the availability and uptake of nutrients by plants. Azospirillum is a well-known rhizobacterium that fosters plant growth by forming an associative bond with plant roots. Through biological nitrogen fixation and phytohormone production, it improves crop growth in both field and greenhouse settings, leading to increased root growth and plant vigor.

Materials and Methods

The experiment was conducted during the Rabi season of 2022-23 at the Crop Research Farm, Department of Agronomy, Naini Agricultural Institute, SHUATS, Prayagraj, Uttar Pradesh, to evaluate the influence of different nitrogen levels and biofertilizer inoculation on the growth and yield of wheat. The experimental field had a sandy loam soil with a nearly neutral reaction (pH 7.8), low organic carbon (0.62%), available nitrogen (225 kg ha⁻¹), phosphorus (38.2 kg ha⁻¹), potassium (240.7 kg ha⁻¹), and zinc (2.32 mg kg⁻¹). The experiment was laid out in a Randomized Block Design (RBD) comprising 10 treatments and three replications. The treatments consisted of three nitrogen levels (100%, 75%, and 50% of the recommended dose) in combination with Azotobacter and/or Azospirillum seed inoculation. The treatment details were: T₁-100% N (150 kg ha⁻¹) + Azotobacter @ 20 g kg⁻¹ seed, T₂-100% N + Azospirillum @ 20 g kg⁻¹ seed, T₃-100% N + Azotobacter @ 10 g kg⁻¹ seed + Azospirillum @ 10 g kg⁻¹ seed, T₄-75% N (112.5 kg ha⁻¹) + Azotobacter @ 20 g kg⁻¹ seed, T₅-75% N + Azospirillum @ 20 g kg⁻¹ seed, T₆-75% N + Azotobacter @ 10 g kg⁻¹ seed + Azospirillum @ 10 g kg⁻¹ seed, T₇-50% N (75 kg ha⁻¹) + Azotobacter @ 20 g kg⁻¹ seed, T₈-50% N + Azospirillum @ 20 g kg⁻¹ seed, T₉-50% N + Azotobacter @ 20 g kg⁻¹ seed + Azospirillum @ 20 g kg⁻¹ seed, and T 10 :Control (RDF-150:60:40 kg/ha). Growth parameters such as plant height, number of tillers hill⁻¹, and plant dry weight, along with yield attributes including effective tillers hill⁻¹, grains spike⁻¹, grain yield, and straw yield, were recorded at harvest from randomly selected plants in each plot.

Results and Discussion

Post-Harvest Observations on Yield Parameters

The data regarding yield attributes and yield of wheat are summarized in the table 1.

Number of effective tillers/hills

Treatment 3, which applied 100% N-150 kg/ha + Azotobacter 10 g + Azospirillum 10 g/kg seed, showed a significantly higher number of effective tillers/hill (6.03).Nonetheless, the treatment 1 which is 100% N-150 kg/ha + Azotobacter 20 g/kg seed, Treatment 5 which is 75%N -112.5 kg/ha + Azospirillum @ 20 g/kg seed were statistically equivalent to the 100%N -150kg/ha + Azotobacter @10 g + Azospirillum @10 g/kg seed) 100% N-150 kg/ha + Azotobacter 10 g/kg seed (T 3 ). More tillers were produced as a result of the improved early vegetative development in terms of larger leaf area, dry matter accumulation, and robust root systems, which in turn greatly boosted the number of effective tillers. Devi et al. (2011) [6] . found similar results. According to (Avivi and Feldman, 1982) [4] , an increase in the number of effective tillers per hectare following the application of biofertilizer may be attributed to the microorganisms' enhanced production of plant hormones or the roots' response to microbial colonization.

Number of grains/spikes

The largest number of grains/spike (50.06 t/ha) was observed with the application of 100% N-150 kg/ha + Azotobacter 10 g + Azospirillum 10 g/kg seed (Treatment 3). Nonetheless, the 50% N -75 kg/ha+ Azotobacter @10 g+Azospirillum@10 g/kg seed (T 9 ) were statistically equivalent to Treatment 03. Higher nitrogen dosages result in the formation of more spikelet, which causes a notable rise in the number of grains or spikes. Bhatta et al. (2020) [5] found similar results. Similar to this, an increase in grains or spikes may result from the simultaneous application of Azospirillum and Azotobacter bacteria, which fix nitrogen in the soil and aid in the synthesis of protein, carbohydrates, starch, and other assimilates by plants. Amit Kumar and Urmila (2018) [3] discovered similar results.

In treatment 3 with the application of 100% N -150kg/ha + Azotobacter 10 g + Azospirillum 10 g/kg seed was recorded significantly higher grain yield (4.96 t/ha) However, treatment 2 which is 100% N-150 kg/ha + Azospirillum 20 g/kg seed was statistically at par with the treatment 3. Grain output may have increased as a result of enhanced photosynthetic activity, increased vegetative growth, and improved yield qualities brought about by higher nitrogen application. According to Pandey et al. (2018) [15] , similar outcomes have been noted. According to Kaur et al. (2018) [11] , the improvement in yield characteristics and yield by biofertilizer may be due to the production of additional plant hormones (auxin, cytokinin, gibberellin, etc.) by the specific microbes or by the root in response to the microbial population.

Significantly higher straw yield (7.00 t/ha) was recorded in treatment 3 with the application of 100% N -150kg/ha + Azotobacter 10 g + Azospirillum 10 g/kg seed. However, treatment 6 with 75% N -112.5 kg/ha+ Azotobacter 10 g + Azospirillum 10 g/kg seed was statistically at par with the treatment 3. The application of biofertilizer enhanced wheat straw yields as well as growth and yield-attributing traits, according to Kaur et al. (2018) [11] . Higher plant height, the quantity of green leaves on each hill, and the production of dry matter all improved straw output, according to Bhatta et al. (2020) [5] . Thus, vegetative growth determines straw yield.

Test weight (g) Treatment 3 showed a higher test weight (40.03 g) when 100% N-150 kg/ha + Azotobacter @10 g + Azospirillum @10 g/kg seed was applied. Despite this, the treatments did not significantly differ from one another.

The treatment 3 which is application of 100% N-150 kg/ha + Azotobacter 10 g + Azospirillum 10 g/kg seed produced the highest harvest index (41.48%). Despite this, the treatments did not significantly differ from one another.

Economics Analysis

Table 2 displayed the information on cultivation costs, gross returns, net returns, and the B:C ratio as affected by various treatments.

When compared to other treatments, treatment Treatment 3, consisting of 100% N -150kg/ha + Azotobacter10 g + Azospirillum 10 g/kg seed resulted in the highest gross returns (₹109,120.00 ha⁻¹), net returns (₹71,770.00 ha⁻¹), and benefit-cost ratio (1.92) in wheat crop.

Conclusion

The results of the present investigation indicate that the 100% N 150kg/ha along with Azotobacter 10 g/kg seed and Azospirillum 10 g/kg (Treatment 3) was the most effective treatment, recording superior growth parameters, yield attributes, grain and straw yields, and economic returns. Hence, this treatment can be considered a viable option for improving wheat productivity and farm profitability under the prevailing conditions of the study.

References

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