Studies on the effect of nano-nitrogenous fertilizer on growth of rice crop (Oryza sativa L.)

Introduction

Rice (Oryza sativa L.) is the primary food source for more than half of the world's population and plays a vital role in global food security. In India, it is one of the most important cereal crops with respect to cultivated area, total production, and productivity. Globally, rice is cultivated over nearly 162 million hectares with an annual production of about 503 million tonnes and an average productivity of around 4.67 t ha⁻¹. In Southeast Asia, the average productivity is approximately 4.41 t ha⁻¹ (FAOSTAT, 2020) [6] . In India, rice contributes significantly to total food grain and cereal production. The crop occupies about 44 million hectares with production exceeding 120 million tonnes, while productivity ranges around 2.8 t ha⁻¹. During 2022-23, the country's rice production was estimated at nearly 125 million tonnes. (Annonymous 2022-23). An average productivity of 2.6 t/ha (NRRI, 2020). It is thus no surprise that India had the highest export volume of rice worldwide, at 21.5 million metric tons as 2022-23 (APEDA, Ministry of commerce and industry, Govt. of India). Agriculture in Uttar Pradesh is highly diversified due to its wide agro-climatic variability, which supports the cultivation of several crops. Among food grains, rice is one of the most important crops in the state. Uttar Pradesh is the second largest rice-producing state in India after West Bengal. Rice is cultivated over about 5.8 million hectares in the state with an annual production of nearly 15.27 million tonnes, contributing around 12% to the total rice production of the country. (Economic Survey 2022-23). Rice serves as the staple food for nearly half of the global population and provides a major share of daily calorie and protein intake, especially in developing countries. Rice grains mainly consist of carbohydrates in the form of starch, along with moderate amounts of protein, moisture, and small quantities of fat. Because of its nutritional importance and widespread consumption, improving rice productivity remains essential for ensuring food security (Sangeetha and Baskar). Fertilizers play a vital role in enhancing crop growth and productivity. Since the introduction of high-yielding fertilizer-responsive varieties during the Green Revolution, fertilizer consumption in Indian agriculture has increased considerably.

However, excessive and imbalanced use of fertilizers, particularly nitrogenous fertilizers such as urea, has created several challenges including low nutrient use efficiency, micronutrient deficiencies, groundwater contamination, and eutrophication of water bodies. In cereals, the recommended N:P:K ratio is generally 4:2:1, but the current imbalance in fertilizer application has widened considerably due to the overuse of nitrogen fertilizers. Most rice-growing soils are deficient in nitrogen, and only a limited amount of the crop's nitrogen requirement is fulfilled through biological nitrogen fixation by cyanobacteria and other diazotrophic microorganisms (Hashem). Therefore, application of nitrogen fertilizer becomes essential to meet the nutrient requirement of the rice crop. However, the efficiency of applied nitrogen in rice largely depends on the source, method and rate of application, as well as crop and nutrient management practices. (Wang et al., 2011) [19] . Prilled urea (PU) is commonly used as a nitrogen source in rice cultivation, but its nitrogen use efficiency is relatively low, generally ranging between 30-45%. Major nitrogen losses occur through denitrification, ammonia volatilization, and leaching, which reduce the effective utilization of applied nitrogen by the crop (Hakeem et al., 2011) [8] . Therefore, the development of slow-release fertilizers is necessary to regulate nitrification and ensure a continuous supply of nitrogen throughout the crop growth period. Nitrogen is an essential nutrient for all crops and is particularly important in cereal crops due to its major role in plant growth, development, and grain production (Sahrawat, 2000) [18] . Currently, nitrogen fertilizer is used to produce food for half of the world's population (Ladha et al., 2005) [11] . Among all essential nutrients, nitrogen plays the most significant role in rice growth and productivity. Adequate nitrogen availability during tillering, panicle initiation, and grain filling stages is essential for proper crop development and higher grain yield. In puddled rice ecosystems, nearly 60% of the applied nitrogen may be lost through different pathways, resulting in poor nitrogen use efficiency. With the expansion of high-yielding rice varieties, nitrogen fertilizer application has increased substantially in many countries. Rice cultivation alone accounts for a considerable share of global nitrogen fertilizer consumption. However, excessive and imbalanced use of nitrogen fertilizers often leads to nutrient losses through leaching, runoff, volatilization, and other processes, causing groundwater contamination and eutrophication of water bodies. Due to these losses, nitrogen use efficiency in rice cultivation in India remains quite low, generally around 20-25% (Pramanick et al., 2020) [16] . Such low N use-efficiency also creates a big concern for the Indian economy. Currently, about INR 79600 Cr subsidies have beengiven by GOI accounting for about INR 900 per bag subsidy for urea (Business Standard, 2021). So, if the use-efficiency of N-fertilizer has been increased through better agronomy then it would have been very beneficial forthe overall economics of the nation. Nanotechnology offers the potential to develop fertilizers with desired chemical compositions that can improve nutrient use efficiency, enhance crop productivity, and reduce environmental pollution. Therefore, nanotechnology can play an important role in balanced nutrient management and sustainable agriculture. Nano-fertilizers also have wideranging applications in agriculture and food processing systems (Kim et al., 2018) [9] . Nano-fertilizers have great potential to improve fertilizer use efficiency because they are required in smaller quantities and are generally more efficient than conventional fertilizers. Most nano-fertilizers are applied through foliar spray for better nutrient absorption. Several studies have also indicated that nanourea can partially replace conventional granular urea, with the potential to substitute nearly 50% of its requirement (Kumar et al., 2020) [10] Studies have reported that supplying 50% nitrogen through conventional fertilizers and the remaining 50% through nano-N foliar spray, along with a single spray of nano-Zn and nano-Cu, significantly improved the yield of wheat, maize, and barley. However, information on the use of nano-N fertilizers in transplanted rice is still limited. Nano fertilizer feeds the agricultural plant in a regulated and progressive manner. In contrast to chemical fertilizer fast and spontaneous release of nutrients (Singh, 2020) [10] . Nano-fertilizers can enhance nutrient use efficiency, minimize soil toxicity, and reduce the adverse effects associated with excessive fertilizer application and frequent use, thereby lowering production costs. Due to their small particle size and larger surface area, nano-fertilizers are easily absorbed and translocated within plants, which promotes photosynthesis, increases dry matter accumulation, and ultimately improves crop yield (Pandey, 2018) [15] . Nanotechnology has emerged as an efficient and innovative tool in modern agricultural research. Due to their extremely small size (1-100 nm) and large surface area, nanoparticles exhibit rapid action and improved efficiency, making them increasingly popular in agriculture. Nano urea particles are much smaller than conventional urea granules, which facilitates quick absorption and utilization by plants. Foliar application of IFFCO Nano Urea at 2-4 ml per litre during critical growth stages has been found beneficial for crop growth and development. Nano-fertilizers enable precise nutrient application, helping to reduce fertilizer consumption, application costs, and environmental pollution while improving nutrient use efficiency. Their efficient absorption and translocation within plant tissues contribute to enhanced crop productivity and better economic returns. Nano urea particles can easily pass through stomata and plasmodesmata, allowing rapid movement within the plant system and active participation in metabolic processes. (Dutta et al., 2021) [5] .

Materials and Methods

The field experiment was conducted during the Rabi season of 2025 at Agronomy Research farm of Rama University, Kanpur Uttar Pradesh. The soil of the experimental field was sandy clay loam in texture, neutral in reaction (pH 7.2), which is common in the district's alluvial soils. The soil was low in available nitrogen (246.60 kg ha⁻¹) as determined by the alkaline permanganate method (Subbiah and Asija). The available phosphorus content was medium (14.5 kg ha⁻¹), estimated by Olsen's method (Olsen et al., 1954). The soil was found medium to moderately high in available potassium (294.40 kg ha⁻¹), determined through the flame photometric method (Metson) at 0-15 cm soil depth prior to the initiation of the experiment. These fertility levels are generally representative of the Indo-Gangetic alluvial soils of the district. The research was carried out in randomized block design with three replications. The nine treatment T1-Control

Result and Discussion

A. Growth Parameter 1. Plant population Data presented in Table 1 revealed that there is no significant influence of traditional and nano forms of fertilizers on the initial and final plant population. Thus, the plant population was almost unvaried in all the plots.

Plant height was recorded at different growth stages of the crop is presented in Table 2. At 30 DAT, plant height did not differ significantly among treatments as nano fertilizer spraying had not been applied. At 60 DAT, the maximum plant height (68.8 cm) was recorded in T6 (T 2 + Nano N spray at 30 & 45 DAT), which was statistically at par with T 4 (67.32 cm) and T 9 (65.82 cm), while the minimum plant height (41.92 cm) was observed in T 1 [Control (100% P & K)]. Similar trends were observed at 90 DAT and at harvest, where T 6 recorded the highest plant height and remained at par with T 4 and T 9 , whereas T 1 showed the lowest plant height. These results were quite similar to the results of Marimuthu and Surendra (2015) [13] and Benzon et al. (2015) [3]

The data pertaining to leaf area at different growth stages was registered and was presented in Table 3. At 30 DAT, leaf area did not differ significantly among treatments, though the maximum leaf area (490.7 cm²) was recorded in T 3 (75% N RDN + 100% P & K). At 60 DAT, T 6 (T 2 + Nano N spray at 30 & 45 DAT) recorded the highest leaf area (1026 cm²), which was at par with T 4 and T 9 , while T 1 (Control -100% P & K) showed the minimum leaf area. Similar trends were observed at 90 DAT and at harvest, where T 6 recorded maximum leaf area and remained statistically at par with T 4 and T 9 , whereas T 1 recorded the lowest leaf area. These results were quite similar to the results of Dhoke et al. (2013) [4] and Mahmoodzadeh et al. (2013) [12] .

The data pertaining to number of tillers m -2 as influenced by the application of traditional and nano forms of fertilizers is presented in Table 4. At 30 DAT, no significant difference in number of tillers m⁻² was observed among treatments, though T 3 (75% N RDN + 100% P & K) recorded the maximum tillers (290). At 60 DAT, the highest number of tillers m⁻² (453) was recorded in T 6 (T 2 + Nano N spray at 30 & 45 DAT), which was at par with T 4 (444) and T 9 (432), while the minimum tillers (273) were observed in T 1 (Control -100% P & K). Similar trends were observed at 90 DAT and at harvest, where T 6 recorded maximum tillers and remained statistically at par with T 4 and T 9 , whereas T 1 recorded the minimum number of tillers. These results were quite similar to the results of Armin et al.

Dry matter accumulation increased progressively with crop growth. At 30 DAT, treatments showed no significant difference, though T 3 (75% N RDN + 100% P & K) recorded higher dry matter accumulation (3015 kg ha⁻¹). At 60 and 90 DAT, T 6 (T 2 + Nano N spray at 30 & 45 DAT) recorded maximum dry matter accumulation and remained at par with T 4 and T 9 , while T 1 (Control -100% P & K) recorded the minimum values. At harvest, the highest dry matter accumulation (14982 kg ha⁻¹) was observed in T 9 (T 3 + Nano N spray at 30 & 45 DAT), which was at par with T 8 , whereas T 1 recorded the lowest dry matter accumulation (7722 kg ha⁻¹).These results were quite similar to the results of Hafeez et al. (2015) [7] and Rathnayaka et al. (2018) [17] . Table 5: Influence of nano nitrogen on dry matter production (kg ha-1) of rice

References

1. Anonymous. Agricultural statistics at a glance 2020. Ministry of Agriculture and Farmers Welfare, Government of India; 2020.
2. Armin M, Akbari S, Mashhadi S. Effect of time and concentration of nano-Fe foliar application on yield and yield components of wheat. International Journal of Biosciences. 2014;4(9):69-75.
3. Benzon HRL, Rubenecia MRU, Ultra VU Jr, Lee SC. Nano-fertilizer affects the growth, development and chemical properties of rice. International Journal of Agronomy and Agricultural Research. 2015;7(1):105117.
4. Dhoke SK, Mahajan P, Kamble R, Khanna A. Effect of nanoparticles suspension on the growth of mung (Vigna radiata) seedlings by foliar spray method. Nanotechnology Development. 2013;3(1):e1-e1.
5. FAOSTAT. FAOSTAT database. Food and Agriculture Organization of the United Nations; 2020.
6. Hafeez A, Razzaq A, Mahmood T, Jhanzab HM. Potential of copper nanoparticles to increase growth and yield of wheat. Journal of Nanoscience with Advanced Technology. 2015;1(1):6-11.
7. Hakeem KR, Ahmad A, Iqbal M, Gucel S, Ozturk M. Nitrogen-efficient rice cultivars can reduce nitrate pollution. Environmental Science and Pollution Research. 2011;18(7):1184-1193.
8. Kim DY, Kadam A, Shinde S, Saratale RG, Patra J, Ghodake G. Recent developments in nanotechnology transforming the agricultural sector: a transition replete with opportunities. Journal of the Science of Food and Agriculture. 2018;98(3):849-864.
9. Kumar Y, Tiwari KN, Nayak RK, Rai A, Singh SP, Singh AN, Raliya R. Nanofertilizers for increasing nutrient use efficiency, yield and economic returns in important winter season crops of Uttar Pradesh. Indian Journal of Fertilisers. 2020;16(8):772-786.
10. Ladha JK, Pathak H, Krupnik TJ, Six J, van Kessel C. Efficiency of fertilizer nitrogen in cereal production: retrospects and prospects. Advances in Agronomy. 2005;87:85-156.
11. Mahmoodzadeh H, Aghili R, Nabavi M. Physiological effects of TiO₂ nanoparticles on wheat (Triticum aestivum). Technical Journal of Engineering and Applied Sciences. 2013;3(14):1365-1370.
12. Marimuthu S, Surendran U. Effect of nutrients and plant growth regulators on growth and yield of black gram in sandy loam soils of Cauvery new delta zone, India. Cogent Food and Agriculture. 2015;1(1):1010415.
13. Olsen SR, Cole CV, Watanabe FS, Dean LA. Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circular. 1954;939:19.
14. Pandey G. Challenges and future prospects of agrinanotechnology for sustainable agriculture in India. Environmental Technology and Innovation. 2018;11:299-307.
15. Pramanick B, Brahmachari K, Mahapatra BS, Ghosh A, Ghosh D, Kar S. Growth, yield and quality improvement of potato tubers through the application of seaweed sap derived from the marine alga Kappaphycus alvarezii. Journal of Applied Phycology. 2017;29:32533260.
16. Rathnayaka RMNN, Iqbal YB, Rifnas LM. Influence of urea and nano-nitrogen fertilizers on the growth and yield of rice (Oryza sativa L.) cultivar 'Bg 250'. International Journal of Research Publications. 2018;5(2):7-7.
17. Sahrawat KL. Macro-and micronutrients removed by upland and lowland rice cultivars in West Africa. Communications in Soil Science and Plant Analysis. 2000;31(5-6):717-723.
18. Wang X, Suo Y, Feng Y, Shohag MJI, Gao J, Zhang Q, Lin X. Recovery of 15N-labeled urea and soil nitrogen dynamics as affected by irrigation management and nitrogen application rate in a double rice cropping system. Plant and Soil. 2011;343(1):195-208.