Effect of foliar spray of nano urea and novel organic liquid nutrient on growth performance of kharif rice (Oryza sativa L.) under Southern Gujarat conditions

Introduction

Rice (Oryza sativa L.) is one of the most important cereal crops worldwide and serves as the staple food for nearly half of the global population. In India, rice is the principal food crop, contributing significantly to national food and nutritional security. However, sustaining rice productivity has become increasingly challenging due to rising input costs, declining resource-use efficiency, and the adverse impacts of climate change. Therefore, the adoption of sustainable nutrient management strategies is essential to enhance productivity while minimizing environmental degradation. Nitrogen (N) is the most important nutrient for the growth, development, and productivity of rice. It is an essential component of chlorophyll, amino acids, proteins, enzymes, and nucleic acids, thereby playing a pivotal role in photosynthesis, tillering, biomass accumulation, and grain development. Despite its importance, the nitrogen use efficiency (NUE) of conventional nitrogen fertilizers in rice remains low because of substantial losses through ammonia volatilization, leaching, denitrification, and surface runoff. Consequently, excessive application of nitrogen fertilizers not only increases production costs but also contributes to soil degradation, environmental pollution, and greenhouse gas emissions. Improving NUE has therefore become a key objective for achieving sustainable rice production. Recent advances in nanotechnology have led to the development of nano-fertilizers as an innovative approach to improving nutrient-use efficiency. Nano urea, developed by the Indian Farmers Fertiliser Cooperative Limited (IFFCO), is a liquid nano-fertilizer designed to enhance nitrogen absorption and utilization through foliar application.

Its higher nutrient-use efficiency offers the potential to reduce the requirement for conventional nitrogen fertilizers without compromising crop growth and productivity. Likewise, the novel organic liquid nutrient (NOL), developed by Navsari Agricultural University from fermented banana pseudostem sap, represents an eco-friendly nutrient source rich in essential plant nutrients and bioactive compounds. Besides supplying nutrients, it has the potential to improve crop growth, physiological performance, and soil health through sustainable nutrient recycling. Although several studies have demonstrated the beneficial effects of nano urea and organic nutrient sources individually, information on their combined application under reduced nitrogen levels in rice is limited, particularly under the agro-climatic conditions of Southern Gujarat. Understanding the interactive effects of these nutrient management strategies is essential for developing efficient and environmentally sustainable fertilizer recommendations. Therefore, the present investigation was undertaken to evaluate the effects of different nitrogen levels, foliar application of nano urea and novel organic liquid nutrient, and spray schedules on the growth performance of rice (Oryza sativa L.) under the agroclimatic conditions of Southern Gujarat.

Materials and Methods

The current study, entitled "Effect of Foliar Spray of Nano Urea and Novel Organic Liquid Nutrient on Growth Performance of Kharif Rice (Oryza sativa L.) under Southern Gujarat Conditions," was conducted during the kharif seasons of 2023 and 2024 at the Main Rice Research Station, Navsari Agricultural University, Navsari, Gujarat. The study aimed to evaluate the effects of different nitrogen levels, foliar application of nano urea and novel organic liquid nutrient, and spray schedules on the growth parameters of kharif rice. The experiment was laid out in a Factorial Randomized Block Design (FRBD) comprising three factors: nitrogen levels [N₁: 50% recommended dose of nitrogen (RDN) and N₂: 75% RDN], foliar spray treatments [U₁: nano urea @ 2 ml L⁻¹, U₂: nano urea @ 4 ml L⁻¹, U₃: nano urea @ 6 ml L⁻¹, U₄: novel organic liquid nutrient @ 1%, and U₅: novel organic liquid nutrient @ 2%], and spray schedules [S₁: one spray at 30 DAT and S₂: two sprays at 30 and 45 DAT]. In addition, a control treatment receiving 100% recommended dose of fertilizers (RDF) was maintained outside the factorial design. The experimental soil was classified under the order, Inceptisol with a clayey texture, slightly alkaline reaction, medium available nitrogen and phosphorus, high available potassium, adequate micronutrient status, and normal electrical conductivity. A brief perusal of the weekly meteorological data recorded during the crop growth period revealed that the maximum temperature ranged from 28.3 to 36.1 °C and 29.6 to 35.7 °C, while the minimum temperature varied from 18.1 to 28.1 °C and 15.8 to 27.5 °C during 2023 and 2024, respectively. The morning relative humidity ranged from 75 to 97% in 2023 and 69 to 99% in 2024, whereas the evening relative humidity varied from 31 to 94% and 34 to 92%, respectively. Bright sunshine hours ranged from 0.3 to 9.3 h day⁻¹ during 2023 and 0.4 to 8.9 h day⁻¹ during 2024. Similarly, evapotranspiration varied from 0.9 to 5.6 mm day⁻¹ in 2023 and 0.3 to 6.1 mm day⁻¹ in 2024. Rainfall was distributed from the second week of June to the last week of September, with an additional rainfall event during the last week of November in 2023, whereas in 2024 rainfall continued from the second week of June until the last week of October. A total of 56 and 72 rainy days were recorded during the crop growth periods of 2023 and 2024, respectively. Plant height was recorded at 60 and 90 DAT and at harvest from five randomly selected and tagged plants in each net plot by measuring the distance from the base of the plant to the tip of the last fully expanded leaf using a wooden metre scale. The mean plant height was expressed in centimetres (cm). The total number of tillers was recorded at 60 DAT from two randomly selected one-metre row lengths in each net plot. The observations were averaged and multiplied by a factor of five to express the total number of tillers per square metre (m⁻²). Effective tillers were recorded at 75 DAT by counting the panicle-bearing tillers from the same observation units and expressed as number m⁻². Leaf area was measured at 90 DAT using five randomly selected plants from each treatment. Fresh green leaves were immediately passed through a leaf area meter (Model LI-300, LI-COR Inc., Nebraska, USA), and the mean leaf area was expressed as cm² plant⁻¹. The leaf area index (LAI) was calculated as the ratio of total leaf area to the corresponding ground area occupied by the crop, following the method proposed by Watson (1952). Dry matter accumulation was recorded at 60 and 90 DAT and at harvest. Five plants from each net plot were uprooted, sun-dried, and subsequently ovendried at 60±1 °C until a constant weight was attained. The dry weight was recorded and expressed as g plant⁻¹ by dividing the total dry weight by the number of sampled plants.

Results and Discussion

Plant height

The results on the effect of different treatments on plant height of rice at 60 DAT, 90 DAT and at harvest are presented in Table 1. Plant height was significantly influenced by nitrogen levels and foliar nutrient application at 60 DAT during both the years as well as in the pooled analysis. At 90 DAT, nitrogen levels and foliar nutrient application exerted a significant effect only in the pooled analysis. At harvest, nitrogen levels significantly affected plant height during 2023 and in the pooled analysis, whereas foliar nutrient application remained significant during both the years as well as in the pooled analysis. The spray schedule had a significant effect only in the pooled analysis. The interaction effects among nitrogen levels, foliar nutrient treatments and spray schedules were non-significant at all stages of crop growth. Among the nitrogen levels, application of 75% RDN (N₂) recorded significantly taller plants at 60 DAT, 90 DAT and at harvest than 50% RDN (N₁). Among the foliar nutrient treatments, nano urea @ 6 ml L⁻¹ (U₃) produced significantly taller plants, followed by nano urea @ 4 ml L⁻¹ (U₂), whereas the lowest plant height was recorded with the application of 1% novel organic liquid nutrient (U₄). The two-spray schedule (S₂) also recorded significantly greater plant height than the single-spray schedule (S₁) in the pooled analysis. The increase in plant height under 75% RDN coupled with foliar application of nano urea might be attributed to the adequate and sustained supply of nitrogen, which enhanced chlorophyll synthesis, photosynthetic activity, cell division and cell elongation, thereby promoting vigorous vegetative growth. Similar findings have also been reported by Kowsalya et al. (2023) [2] in rice.

Number of tillers/m²

The effects of nitrogen levels, foliar nutrient treatments and spray schedules on the number of total tillers m⁻² and effective tillers m⁻² during both the years and in the pooled analysis are presented in Table 2. The individual effects of nitrogen levels (N), foliar nutrient treatments (U) and spray schedules (S) were significant, whereas their interaction effects and the control vs. rest comparison were non-significant. Application of 75% RDN (N₂) recorded significantly higher number of total tillers m⁻² at 60 DAT and effective tillers m⁻² at 75 DAT than 50% RDN (N₁).

Among the foliar nutrient treatments, nano urea @ 6 ml L⁻¹ (U₃) recorded the highest total and effective tillers m⁻², followed by nano urea @ 4 ml L⁻¹ (U₂). The two-spray schedule (S₂; at 30 and 45 DAT) also recorded significantly higher total and effective tillers m⁻² than the single-spray schedule (S₁). The higher tiller production under 75% RDN and foliar application of nano urea @ 6 ml L⁻¹ may be attributed to improved nitrogen availability and utilization, which enhanced vegetative growth and tiller initiation. These findings are in close agreement with those reported by Lemraski et al. (2017) [3] and Namasharma et al. (2023) [4] in rice.

Leaf Area Index (LAI)

The effect of different treatments on leaf area index (LAI) at 90 DAT is presented in Table 2. The results revealed that nitrogen levels (N) and spray schedules (S) had no significant effect on LAI, whereas foliar nutrient treatments (U) significantly influenced LAI. The interaction effects among the treatments and the control vs. rest comparison were also found to be nonsignificant.

The results on the effect of different treatments on dry matter production (DMP) (g plant⁻¹) of rice at 60 DAT, 90 DAT and harvest are presented in Table 3. The individual effects of nitrogen levels (N) and foliar nutrient treatments (U) on DMP were significant at 60 DAT, 90 DAT and at harvest during both the years as well as in the pooled analysis. The effect of spray schedule (S) was significant at 60 DAT during 2023 and in the pooled analysis, whereas at 90 DAT, it was significant only in the pooled analysis. At harvest, the spray schedule had no significant effect. The interaction effects among nitrogen levels, foliar nutrient treatments and spray schedules, as well as the control vs. rest comparison, were non-significant at all stages. The present observation is in conformity with the findings reported by Pedireddy et al. (2024) [5] and Benzon et al. (2015) [1] in rice.

Conclusion

Among the nitrogen levels, application of 75% RDN (N₂) recorded significantly superior growth performance by producing taller plants, a higher number of total tillers m⁻² and effective tillers m⁻², greater leaf area index (LAI) and higher dry matter production than 50% RDN (N₁). Similarly, among the foliar nutrient treatments, nano urea @ 6 ml L⁻¹ (U₃) significantly enhanced plant height, total tillers m⁻², effective tillers m⁻², LAI and dry matter production over the other treatments. With respect to spray schedules, the two-spray schedule (S₂; at 30 and 45 DAT) recorded significantly better growth performance than the singlespray schedule (S₁). Overall, application of 75% RDN in combination with two foliar sprays of nano urea @ 6 ml L⁻¹ significantly enhanced the growth parameters of kharif rice. Therefore, the application of two foliar sprays of nano urea @ 6 ml L⁻¹ can reduce the soil-applied nitrogen requirement by 25% without compromising crop growth under the agro-climatic conditions of Southern Gujarat conditions.

Acknowledgement

Acknowledgement:The authors are grateful to the Honorable Vice Chancellor, Navsari Agricultural University, the Director of Research, the Registrar, and the Principal and Dean, N. M. College of Agriculture, for providing the research facilities, equipment, experimental inputs and necessary support for the successful conduct of the experiment.

References

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