Effect of nano-urea application on yield and economics of kharif maize (Zea mays L.).

Introduction

Maize scientifically known as Zea mays L., belongs to the Gramineae family (2n=20) and the tribe maydeae, maize is often referred to as a "miracle crop" and the "queen of grains" due to its remarkable productivity holds third position among cereals in India, following wheat and rice. The term "corn" signifies its role in sustaining life, providing essential nutrients for both humans and animals globally. Maize cultivation occurs year-round in all seasons and is practiced worldwide. Its nutritional composition is notable, with approximately 72% starch, 10% protein, 8.5% fiber, 4.8% oil, 3.0% sugar, and 1.7% ash (Elamin and Elagib, 2001) [4] . Maize is an exhaustible crop that demands high nutrition for their growth and development. The productivity of crop depends on nutrient management system. Inorganic fertilizers are most widely used all over world as it gives higher yield and end result is also much appreciable. Efficient use of nitrogen is important for maize production as it increases yield and maximizes economic return and minimizes NO 3 leaching to ground. Nitrogen (N) occupies a conspicuous place in plant metabolic system. Nitrogen being a major part of plants, and it is an essential constituent of protein and chlorophyll present in many major portions of the plant body.Urea is the most extensively used commercial nitrogen fertilizer for enhancing crop output. Urea accounts for around 82% of overall fertilizer usage in India and approximately 55% of total nitrogen fertilizer consumption worldwide. Plants use around 30-40% of the nitrogen from urea. The remainder is lost owing to rapid chemical alteration as a result of leaching, volatilization, denitrification, and run off, resulting in low usage efficiency and also adding to environmental degradation and entering aquatic systems and leading to eutrophication (Navya et al., 2022) [10] . Whereas nano urea has high nitrogen use efficiency and also it is environment friendly. This fertilizer is popularly known as "smart fertilizer" because it cuts down the emission of nitrous oxide which is the prime pollutant of soil and air and also helps in reduction of global warming. These properties make it a promising alternative over conventional urea. (Kannoj et al., 2022) [5] . What makes nano urea effective is its tiny size that provides greater surface to mass ratio and hence helps in its targeted delivery of nutrients. In order to improve the nitrogen-use efficiency by crops, several strategies have been suggested in the past few decades. Nanotechnology denotes to study of particles on the atomic scale for their use and control (Khaveh et al., 2015) [6] . Nanotechnology focuses on creating new compounds by modifying the material. These "nano fertilizers" have high surface area, sorption capacity, and controlled-release kinetics to targeted sites making them an efficient distribution system (Kumar et al., 2021 a ) [7] . The greatest alternative to urea fertilizer presently is liquid nano urea. One bottle of nano urea (500 ml) equals one bag of urea (45 kg), which is about 10% less expensive than a bag of regular urea. It has the potential to reduce urea fertilizer imports. One liquid nano urea particle is 30 nanometer in diameter and has 10,000 times the surface area to volume size of regular granular urea (Sahu et al., 2022) [12] . Urea raises soil pH by hydrolysis, resulting in large ammonia volatilization losses. Many fertilizer companies in India developed nanotechnology-based Nano Urea (Liquid) fertilizer to address the imbalanced and excessive use of conventional pilled urea (Arya et al., 2022) [1] . Present day's nano fertilizers are emerging as an alternative to conventional fertilizers (Veronica et al., 2014) [15] . Nanotechnology is one possibility for reaching these aims in a long-term and precise manner, and scientists are now researching nano particles for use in plant science and agriculture. In various plants, a range of inorganic, organic, and composite nano materials have been researched to identify their potential effect on plant growth, development, and production.The effect of nano particles on plants is highly reliant on both their intrinsic properties (size, shape, surface area, surface charge, and so on) and their extrinsic nano biointeractions. (Kumar et al., 2021 b ) [8] . In order to solve higher fertilizer requirement during crop growth, and to address environmental issues and also taking economic aspects under consideration, the use of nitrogen nano fertilizer is essential (Sharma et al., 2022) [14] .

Materials and Methods

The field experiment was conducted during the Kharif season of 2023 at the Agronomic Farm, Agronomy Section, College of Agriculture, Dhule, M.S. (India) during Kharif 2023. The Post Graduate Research Farm is located in Northern Maharashtra's Agro-climatic Zone-6, often known as the scarcity zone. It is located at 20.4 ºN latitude and 74 ºE longitude. The elevation is 258 meters above mean sea level. Climatologically, this area falls in the sub-tropical region at the North. The rainfall is mostly received in 34 to 40 rainy days in a year. The total rainfall of 1041.8 mm was received in 47 days during the experimentation, which was 87.25 per cent of annual rainfall. The experiment had eleven treatment and three replications was set up in a randomized block design. The Eleven treatments included T 1 -Absolute control (no fertilizer), T 2 -Water spray at 20,40 and 60 DAS,T 3 -100% N through urea,T 4 -75% N through urea + 25% N through two foliar sprays of nano urea at 20 and 40 DAS,T 5 -75% N through urea+ 25% N through three foliar sprays of nano urea at 20, 40 and 60 DAS,T 6 -50% N through urea+ 50% N through two foliar sprays of nano urea at 20 and 40 DAS,T 7 -50% N through urea+ 50% N through three foliar sprays of nano urea at 20,40 and 60 DAS,T 8 -75% N through urea+ 25% N through three foliar sprays of 2% urea at 20,40 and 60 DAS, T 9 -50% N through urea+ 50% N through three foliar sprays of 2% urea at 20,40 and 60 DAS,T 10 -75% N through urea+ 25% N through three foliar sprays of 2 ml/ L nano urea at 20,40 and 60 DAS,T 11 -50% N through urea+ 50% N through three foliar sprays of 4 ml/ L nano urea at 20,40 and 60 DAS. Whereas recommended dose of Phosphorous and Potassium is common to all treatment except T 1 . The recommended dose of fertilizer in the form of urea, SSP and MOP were applied as per treatment with recommended of fertilizer dose of 120:60:40 N: P 2 O 5: K 2 O kg ha -1 . The IFFCO nano urea (4% W/V) liquid was used for foliar spray. The crop of hybrid variety NK-6045 was sown at spacing 75 cm x 20 cm. 75% N through urea + 25% N through two foliar sprays of nano urea at 20 and 40 DAS. T5 75% N through urea+ 25% N through three foliar sprays of nano urea at 20, 40 and 60 DAS. T6 50% N through urea+ 50% N through two foliar sprays of nano urea at 20 and 40 DAS. T7 50% N through urea+ 50% N through three foliar sprays of nano urea at 20, 40 and 60 DAS. T8 75% N through urea+ 25% N through three foliar sprays of 2% urea at 20, 40 and 60 DAS. T9 50% N through urea+ 50% N through three foliar sprays of 2% urea at 20, 40 and 60 DAS. T10 75% N through urea+ 25% N through three foliar sprays of 2 ml/ L nano urea at 20, 40 and 60 DAS. T11 50% N through urea+ 50% N through three foliar sprays of 4 ml/ L nano urea at 20, 40 and 60 DAS. Note: 1. 500 ml bottle of liquid nano urea is equivalent to 50 kg urea bag. 2. For T2 no top dressing with urea is done. 3. 10 tonne ha -1 FYM is common to T2 to T11.

The topography of the experimental field was uniformly levelled and well drained. The soil of experimental field was clayey in nature. Composite soil sample was collected and analysed for physical and chemical properties. The data of soil analysis revealed that the soil was clay in texture, low in available nitrogen, medium in available phosphorus and very high in available potassium content and moderately alkaline in reaction. The soil was free from any kind of salinity or sodicity hazards. Growth parameters like plant height (cm), number of functional leaves plant -1 , dry matter plant -1 (g), is recorded at 30 DAS, 45 DAS, 60 DAS, 75 DAS and at harvest from five selected plants from each net plot. Days to 50 per cent tasselling, days to 50 per cent silking, days to physiological maturity is recorded from net plot at tasselling, at silking, at physiological maturity, respectively in each plot. The number of cobs per plant -1 , length of cob without husk (cm), girth of cob without husk (cm), cob weight with husk (g), cob weight without husk (g), number of grains cob -1 , number of grains rows cob -1 , grain weight cob -1 (g) and seed index (100 grain weight) (g) observational plant was counted and mean was worked out by using five plants from each net plot. For grain yield (q ha -1 ), after harvest cobs were sun dried, and grains removed with the help of hand maize sheller. Grain weight per net plot was recorded and calculated as grain yield per hectare. For stover yield (q ha -1 ) harvested plant ware sun dried till they showed constant weight. The weight of stover per net plot was recorded and calculated as stover yield per hectare. The data collected and analysis of data was carried out by "Analysis of Variance method" by Panse and Sukhatme, 1967 [11] . When the treatment differences were significant standard error (S.E.±) and critical difference (C.D.) were calculated at 5% probability level and when the treatment differences were not significant, only standard error was worked out.

Results and Discussion

Growth Studies

Data in a respect of plant height (cm), number of functional leaves plant -1 , dry matter plant -1 (g) of maize as influenced by various treatments at different growth stages were analyzed statistically and presented in Table 2. The results indicated that growth attributes evaluated in study were significantly influenced by all the treatments over control (no fertilizer). The higher plant height (cm), number of functional leaves plant -1 , dry matter plant -1 (g) of maize was significantly influenced due to different treatment and various stages of crop, except 30 DAS. The observations regarding the growth viz., plant height (cm), number of functional leaves plant -1 , dry matter plant -1 (g) were significantly influenced by different nano-urea application treatments and days to 50 per cent tasselling, days to 50 per cent silking and days to physiological maturity shows non-significant results. The growth of maize crop in terms of growth attributes viz., plant height, number of functional leaves plant -1 , and total dry matter plant -1 was maximum with treatment application of 100% nitrogen (N) through urea (T 3 ) with the corresponding values were 190.36 cm, 8.82 and 203.63 g at harvest but it was at par with treatment application of 75% N through urea + 25% N through three foliar sprays of nano urea at 20,40 and 60 DAS (T 5 ) with corresponding values 177.25 cm, 8.25, 199.80 g, respectively and treatment 75% N through urea + 25% N through two foliar spray of nano urea at 20 and 40 DAS (T 4 ) with corresponding values 175.85 cm, 7.95, 194.71 g, respectively. However, substantial reduction in growth characters was observed in treatment absolute control (no fertilizers) (T 1 ). The maximum plant height in treatment T 3 may be due to balanced supply of NPK which help in various nutrients and translocation of better and more availability of more nitrogen for early establishment of photosynthetic apparatus such as enzymes, pigments and other compounds needed for photosynthesis and other beneficial effects of nitrogen in cell elongation and cell division in meristematic activity as well as internodal expansion. Nano-fertilizers are very effective tool for precise nutrient management in precision agriculture with matching the crop growth stage for nutrient and may provide nutrient throughout the crop growth stage period. Nano urea increases the efficiency of nutrient uptake and utilization and releases nitrogen in a regulated way, minimizing losses from volatilization and leaching. Nano-urea can improve a number of physiological functions in plants, including enzyme activity, photosynthesis, and nutrient uptake. The findings were analogous to those obtained by Chavan et al., (2023) [3] , Meena et al., (2023) [9] , Bhukya et al., (2024) [2] . [3] , Meena et al., (2023) [9] , Bhukya et al., (2024) [2] . Nano urea can enhance the uptake and utilization of nutrients, including nitrogen, by plants. Improved nutrient availability and utilization can lead to increased biomass and ultimately contribute to higher plant dry weight. Nano urea has been reported to positively influence various physiological processes in plants, such as photosynthesis, enzymatic activities, and nutrient metabolism. These enhancements can promote plant growth and biomass accumulation, resulting in increased plant dry weight. The findings were analogous to those obtained by Chavan et al., (2023) [3] , Meena et al., (2023) [9] , Bhukya et al., (2024) [2] .

Yield attributes and Yield

The yield attributes viz., number of cobs plant -1 , cob length without husk, cob girth without husk, grain weight cob -1 , number of grains cob-1 , cob weight with husk (g), cob weight without husk (g), number of grain rows cob -1 , seed index (100 grain weight) (g), grain yield (q ha -1 ) and stover yield (q ha -1 ) were differed significantly due to different treatments. The values of these yield attributes were maximum with application of 100% nitrogen (N) through urea (T 3 ). The corresponding values were number of cobs plant , cob weight with husk(g), cob weight without husk (g), length of cob without husk (cm), girth of cob without husk (cm), number of grain rows cob -1 , number of grains cob -1 , grain weight cob -1 (g), seed index (100 grain weight) (g), Grain yield (q ha -1 ) and stover yield (q ha -1 ) of maize as influenced due to different treatments

Tr.

No. Further, it was observed that the expression of these yield attributes ultimately reflected on higher grain yield (66.70 q ha -1 ) and stover yield (86.76 q ha -1 ) where application of 100% nitrogen (N) through urea (T 3 ) was done to maize crop which was at par with treatment application of 75% N through urea + 25% N through three foliar sprays of nano urea at 20,40 and 60 DAS (T 5 ) with grain yield (64.18 q ha -1 ) and stover yield (83.43 q ha -1 ) and treatment 75% N through urea + 25% N through two foliar spray of nano urea at 20 and 40 DAS (T 4 ) grain yield (63.13 q ha -1 ) and stover yield (82.76 q ha -1 ). The lowest grain yield (30.56 q ha -1 ) and stover yield (39.72 q ha -1 ) were observed in treatment absolute control (no fertilizers) (T 1 ). These are in accordance with those reported by Chavan et al., (2023) [3] , Meena et al., (2023) [9] , Bhukya et al., (2024) [2] . Nano urea enhance their solubility and improve nutrient availability. This increased nutrient uptake nitrogen, can contribute to improved plant growth, development and ultimately, higher maize yield. Nano urea has been reported to particularly enhance plant growth. Nutrient supply by the treatments and demand by the crop for nutrient wherever is balanced their source is well developed with proper increased photosynthesis that led to accumulation of carbohydrates and proteins in the sink (Samui et al., 2022) [13] . Increase in stover yield with higher dose of fertilization may be due to vigorous and luxuriant growth of maize. An improvement in stover yield with higher levels of nitrogen obtained may be attributed to higher meristematic activity and thus better growth of the plants, resulting ultimately in higher stover yield. The higher accumulation dry matter in plants might have improved the values of yield attributes at higher levels of nitrogen which resulted in higher stover yield. Increased stover yield was attributed due to enhanced morphological characters (Samui et al., 2022) [13] .

Cobs

Conclusion

Application of 100 per cent N through urea with 60 kg ha -1 P 2 O 5 and 40 kg ha -1 K 2 O or application of 75% N through urea + 25% N through three foliar sprays of nano urea at 20,40 and 60 DAS with 60 kg ha -1 P 2 O 5 and 40 kg ha -1 K 2 O or application of 75% N through urea + 25% N through two foliar spray of nano urea at 20 and 40 DAS with 60 kg ha -1 P 2 O 5 and 40 kg ha -1 K 2 O recorded higher values and found beneficial in terms of growth, yield contributing characters, yield in maize crop.

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