Foliar urea and nano urea applications: impacts on growth, chlorophyll content, yield attributes and economics of wheat (Triticum aestivum L.)

Introduction

Wheat (Triticum aestivum L.) is an important cereal crop belongs to family "Poaceae" and genus "Triticum". It is the world's most important cereal crop, accounting for 30% of all cereal food produced globally. It occupies around 220.7 million hectares of area across the world with the annual production of 783.43 million tones with the productivity of 3.55 metric tons per hectare (USDA, 2023). It has been under cultivation in the Indian subcontinent from pre-historic times and is an integral part of country's economy and food security. Wheat accounts for almost 55% of all carbohydrates and 20% of all dietary calories consumed globally (Graur and Breiman, 1995). Wheat is grown in India on 31.23 million hectares and produces of 112.92 million ton with national average productivity of 3615 kg ha -1 during 2023-24 (IIWBR, Karnal, 2023-24). Nitrogen is the universal deficient macro nutrient in Indian soil (Dey and Sekhon 2016). Wheat is highly responsive to nitrogen fertilization and is sensitive to insufficient nitrogen. Macro nutrients like N, P and K in sufficient quantity throughout the growing season are essential for optimum plant growth (Haque et al., 2001) [3] . Nitrogen is a fundamental component of protein and an essential part of the chlorophyll molecule, which is crucial for photosynthesis. Consequently, the nitrogen supply determines the amount of protein, chlorophyll, and protoplasm available, which ultimately influences leaf area and cell size. When a plant has an adequate supply of nitrogen, it grows at an optimal rate and its leaves remain a healthy dark green. In contrast, a nitrogen deficiency leads to light green leaves, reduced tillering, and low protein synthesis, all of which reduce the crop's growth and yield.

Materials and Methods

The field experiment entitled "Response of foliar application of urea and nano urea on growth, yield and quality of wheat under irrigated condition" was conducted at Post Graduate Institute Farm, MPKV, Rahuri during rabi 2023-24. The experiment consists of 12 treatments viz., T1: Absolute control; T2: General recommended dose of fertilizers (120:60:40 N:P2O5:K2O Kg ha -1 + 10 t ha -1 of FYM); T3: 75% RDN through soil + foliar spray of nano urea @ 0.2%; T4: 75% RDN through soil + foliar spray of urea @ 2%; T5; 75% RDN through soil + foliar spray of nano urea @ 0.4%; T6: 75% RDN through soil + foliar spray of urea @ 4%; T7: 75% RDN through soil + foliar spray of nano urea @ 0.6%; T8: 75% RDN through soil + foliar spray of urea @ 6%; and T9: 50% RDN through soil + foliar spray of nano urea @ 0.4%; T10: 50% RDN through soil + foliar spray of urea @ 4%; T11: 50% RDN through soil + foliar spray of nano urea @ 0.6%; T12: 50% RDN through soil + foliar spray of urea @ 6%. Potassium and Phosphorus will be applied through MoP and single super phosphate; P2O5 and K2O applied as per the recommended dose of fertilizer for wheat except T1. The experiment was laid out in randomized block design (RBD) with three replications. Line sowing of wheat seeds was done on flat beds at spacing of 20 cm between rows. The soil was clay loam in texture, low in available nitrogen (191.6 kg ha -1 ), medium in available phosphorus (18.3 kg ha -1 ) and high in potassium (436.6 kg ha -1 ). The mean available nitrogen, phosphorus and potassium content in soil after harvest of wheat crop were 210.5, 45.4 and 418.2 kg ha -1 respectively. The soil was slightly alkaline in reaction (pH 8.16) with medium in organic carbon content (0.57%). The pH is measured by Potentiometry and electrical conductivity measured by Conductometry method. The organic carbon estimated by Wet oxidation method Walkey and Black (Nelson and Sommer, 1982) [6] . The available Nitrogen, Phosphorus and potassium measured by Alkaline permanganate method (Subbiah and Asija, 1956) [9] , Olsen method 0.5 M NaHCO3 (Watanabe and Olsen, 1965) [14] and Flame photometry method (Jackson, 1973) [5] respectively. The recommended dose of fertilizer (120:60:40 N:P2O5:K2O kg ha -1 + 10 t ha -1 of FYM) was applied 60:40 kg ha -1 P2O5:K2O as a basal through SSP and MOP in treatment T2 to T12. N applied as per treatments. Thereafter, foliar application of urea and nano urea was done at 20 and 35 days after sowing, respectively.

Results and Discussion

The results obtained from the present investigation as well as relevant discussion have been summarized under following heads: [15] , Dhaker et al. (2022), Rawate et al. (2022) [8] and Ojha et al. (2023) [7] .

Plant Population

Total Chlorophyll Content (SPAD) production is the relative process of effective utilization of the resources in better crop production environment. When wheat crop is subjected with foliar application of urea and nano urea, it results into higher total chlorophyll content because there was sufficient availability of nutrient to the wheat crop that results in increase in photosynthetic activities.

The current experiment's results are consistent with those published by Surve and Bhosale (2015) [10] , Wagan et al. (2002) [13] , Vikas et al. (2019), Yadav et al. (2021) [15] , Rawate et al.

(2022) [8] and Ojha et al. (2023) [7] . The data in respect of yield contributing characters of wheat as influenced by different treatments during rabi season of 2023-2024 are presented in table 3. Among yield contributing characters, significantly higher length of ear (9.16 cm), number of spikelets ear -1 (16.40), number of grains ear -1 (44.56), weight of grains ear -1 (1.66 g) and test weight (40.93 g) were obtained with application of general recommended dose of fertilizers (120:60:40 N: P2O5: K2O Kg ha -1 + 10 t ha -1 of FYM). The next best treatment was application of 75% RDN through soil + foliar spray of urea @ 6% recorded yield attributes viz., length of ear (8.76 cm), number of spikelets ear -1 (15.12), number of grains ear -1 (43.02), weight of grains ear -1 (1.61 g) and test weight (40.63 g) followed by application of 75% RDN through soil + foliar spray of urea @ 4% produced length of ear (8.51 cm), number of spikelets ear -1 (15.01), number of grains ear -1 (41.87), weight of grains ear -1 (1.58 g) and test weight (40.37 g). These results are similar with the results reported by Vikas et al.

Yield Contributing Characters

(2019), Yadav et al. (2021) [15] , Surve and Bhosale (2015) [10] ,

Wagan et al. (2002) [13] , Rawate et al. (2022) [8] and Ojha et al.

(2023) [7] . The mean grain and straw yield of wheat (34.4 and 44.7 q ha -1 , respectively) were obtained during investigation.

Economic studies

In the present investigation, significantly higher gross monetary returns (₹ 113955 ha -1 ) net monetary returns (₹ 64801 ha -1 ) and B: C (2.32) was obtained with application of general recommended dose of fertilizers (120:60:40 N: P2O5: K2O kg ha - 1 + 10 t ha -1 of FYM) as compared to other treatments. It was at par with application of 75% RDN through soil + foliar spray of urea @ 6% with gross monetary returns (₹ 112482 ha -¹), net monetary returns (₹ 62806 ha -1 ) and B: C (2.26) as well as application of 75% RDN through soil + foliar spray of urea @ 4% with gross monetary returns (₹ 110328 ha -1 ), net monetary returns (₹ 60721 ha -¹) and B: C (2.22). While the application of absolute control gives minimum gross returns (₹ 60730 ha -1 ), net monetary returns (₹ 33435 ha -1 ) and application of 50% RDN through soil + foliar spray of nano urea @ 0.4% gives minimum B: C (1.54). These results are in collaboration with findings of Wagan et al.

(2002) [13] , Vikas et al. (2019), Yadav et al. (2021) [15] , Dhaker et al. (2022), Rawate et al. (2022) [8] and Ojha et al. (2023) [7] .

Conclusion

The application of the general recommended dose of fertilizers (GRDF) at 120:60:40 kg N:P2O5:K2O per hectare with 10 tons of farmyard manure (FYM) per hectare, was found to be the most beneficial for the wheat crop. This treatment resulted in the highest significant values for plant population, chlorophyll content, yield contributing characters and economic returns compared to all other treatments. However, treatments involving 75% of the recommended nitrogen dose applied to the soil, combined with a 4% or 6% foliar spray of urea at the crown root initiation (CRI) and tillering stages, performed on par with the GRDF treatment. This indicates a potential to save 25% of the nitrogen fertilizer for the wheat crop while achieving comparable results

Acknowledgement

AcknowledgementWe are very thankful to the Post Graduate Institute, MPKV, Rahuri for providing all facilities and research grants to carry out this experimental work and authors cited in references for providing necessary literature material.

References

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