Optimization of foliar Nano urea and media composition for improved growth in ornamental philodendron

Introduction

Philodendron (Philodendron scandens), commonly known as Heart Leaf Philodendron, is one of the most popular ornamental foliage plants worldwide, valued for its lush green leaves, aesthetic appeal, and adaptability to indoor and landscape cultivation. Foliage quality, plant height, leaf size, and overall vegetative vigor are key parameters determining the commercial value of Philodendron, making efficient nutrient management crucial for sustainable production. Nitrogen (N) is an essential macronutrient that plays a central role in plant growth, as it is a key component of amino acids, proteins, nucleic acids, and chlorophyll. Nitrogen availability directly influences cell division, elongation, and differentiation, which are critical for vegetative growth and photosynthetic efficiency (Mahmoud et al., 2020) [8] . Conventional nitrogen fertilizers, such as urea, are widely used; however, their low use efficiency, leaching losses, and environmental impact necessitate the exploration of alternative nitrogen sources. Nano-fertilizers, particularly nano urea, have emerged as a promising approach to improve nutrient use efficiency due to their ultra-small particle size (20-50 nm), high surface area, and enhanced solubility. These properties enable nano urea particles to penetrate leaf surfaces effectively, stimulate enzymatic activity, and promote physiological processes such as auxin production and carbohydrate mobilization, ultimately enhancing vegetative growth and plant quality (Sharma et al., 2022; Sai Kumar et al., 2022) [13,12] . In addition to nutrient management, the composition of potting media significantly affects plant growth by influencing aeration, water retention, nutrient availability, and microbial activity. Components such as cocopeat provide high water-holding capacity and porosity, while farmyard manure enriches the media with organic matter and essential nutrients, promoting root development and overall plant vigor (Abad et al., 2002; Nair and Bharathi, 2015) [1,10] . Considering the potential of nano urea and optimized media, the present study was designed to evaluate the effect of different levels of nano urea and potting media compositions on the growth and development of Philodendron. The study aimed to determine the optimal combination of foliar-applied nano urea and media composition to maximize vegetative growth and improve foliage quality in potted Philodendron plants.

Materials and Methods

The investigation was carried out during the Rabi season of 2021 at the Post Graduate Research Block, College of Horticulture, Mojerla. The experimental material consisted of heart-leaf philodendron (Philodendron scandens L.), an ornamental foliage plant belonging to the family Araceae. Uniform and healthy mid-stem cuttings measuring approximately 15 cm in length with four nodes were used for planting. The experiment was laid out in a Factorial Randomized Block Design (FRBD) comprising two factors, twenty-four treatment combinations, and three replications. Each replication consisted of ten plants, grown individually in polybags of 10 × 12 inches. The first factor included six nitrogen treatments, namely control (no spray), conventional urea @ 2 g L⁻¹, and nano urea applied as foliar spray at 0.5, 1.0, 1.5 and 2.0 ml L⁻¹. The second factor consisted of four potting media combinations, viz., red earth alone; red earth + cocopeat (1:1); red earth + cocopeat + farmyard manure (1:1:1); and red earth + cocopeat + farmyard manure (2:1:1). Potting media were prepared by thoroughly mixing red earth, cocopeat, and well-decomposed farmyard manure in the prescribed proportions. Polybags were filled with the respective media and placed in sunken beds (10 cm depth) to facilitate moisture conservation and protection from extreme temperature fluctuations. Stem cuttings were initially treated with a fungicidal solution containing carbendazim and mancozeb for ten minutes, followed by dipping in IBA at 1000 ppm for fifteen minutes. Treated cuttings were planted in polybags, ensuring that two nodes remained below and two nodes above the surface of the media. Light irrigation was provided immediately after planting.

Preparation and application of nutrient solutions

Nano urea solutions of 0.05, 0.10, 0.15, and 0.20 per cent were prepared by diluting 0.5, 1.0, 1.5, and 2.0 ml of nano urea, respectively, in one litre of distilled water. A 0.2 per cent conventional urea solution was prepared by dissolving 2 g of urea in one litre of water. The first foliar spray was applied at 35 days after planting, followed by subsequent sprays at 15-day intervals for a period of three months. In total, six foliar applications were carried out during the experiment. Plants were irrigated once every two days during December to February, while irrigation was provided on alternate days during March to May. Intercultural operations such as regular weeding and periodic loosening of the growing media were performed to maintain optimum growth conditions throughout the experimental period.

Results and discussion

Vegetative growth of Philodendron scandens, including plant height, number of leaves, leaf length, leaf width, and leaf area, was significantly influenced by nano urea levels, potting media composition, and their interaction across all observation stages (65, 95, and 125 DAP), except for leaf length, which showed non-significant variation. These growth parameters are critical indicators of plant vigour and aesthetic quality, particularly for ornamental foliage plants, as they directly influence photosynthetic capacity, resource allocation, and overall canopy development.

Plant height exhibited significant variation in response to nano urea application and potting media (Tables 1a,1b; Fig. 1a,b,c). At 65 DAP, the tallest plants were observed under N₅ (2 ml L⁻¹ nano urea; 24.23 cm), followed by N₄ (1.5 ml L⁻¹; 21.91 cm), whereas the control (N₀) recorded the shortest height (18.24 cm). Among media, M₃ (Red Earth + Cocopeat + FYM, 1:1:1) produced maximum height (24.18 cm), while M₁ (Red Earth alone) was the least effective (17.85 cm). The interaction effect of nano urea and media was significant, with T₂₃ (N₅M₃) yielding the tallest plants (28.32 cm) and T₁ (N₀M₁) the shortest (15.91 cm). This trend persisted at 95 DAP and 125 DAP, where N₅ consistently enhanced height (31.64 and 38.98 cm, respectively), and the N₅M₃ combination produced the maximum height (37.39 and 46.29 cm). The enhanced plant height can be mechanistically explained by the superior foliar absorption and mobility of nano urea. The extremely small particle size (<50 nm) allows nano nitrogen to penetrate stomatal pores efficiently, improving nitrogen assimilation and amino acid synthesis, including tryptophan a precursor of indole-3-acetic acid (IAA), the principal auxin responsible for cell elongation and apical dominance (Sharma et al., 2022; Sai Kumar et al., 2022) [13,12] . Additionally, nano urea provides sustained nutrient release, stimulating enzymatic activity, photosynthate translocation, and vegetative growth. Potting media also played a significant role. The combination of cocopeat and FYM in M₃ enhanced water retention, aeration, and nutrient availability, promoting root proliferation and nutrient uptake. The fibrous nature of cocopeat improved soil porosity and reduced bulk density, supporting optimal plant metabolic activity and vegetative elongation (Awang et al., 2009; Nair and Bharathi, 2015) [5,10] . These results align with El-Shawa et al. (2022) [7] in Philodendron and Abdel-Salam (2018) [3] in lettuce, where nano urea significantly increased plant height.

Number of Leaves per Plant

Leaf number is directly associated with photosynthetic efficiency and ornamental value. Leaf number exhibited significant variation in response to nano urea application and potting media (Tables 2a, 2b; Fig. 2a,b,c). At 65 DAP, N₅ produced the highest number of leaves (12.63), followed by N₄ (10.63), while N₀ recorded the lowest (7.34). Media effect was significant, with M₃ supporting the maximum leaves (11.84) and M₁ the least (7.82). The interaction T₂₃ (N₅M₃) yielded 17.17 leaves at 65 DAP, increasing to 62.13 leaves at 125 DAP, demonstrating cumulative growth benefits of optimized nutrient-media combinations. The physiological mechanism underlying these observations is the promotion of cell division and differentiation by nitrogen, a vital component of chlorophyll, nucleic acids, and proteins. Enhanced chlorophyll synthesis increases photosynthetic activity, providing energy for leaf primordia development. Nano urea's higher surface area and rapid foliar absorption accelerate these processes, resulting in a higher number of fully expanded leaves (Sharma et al., 2022; Minz et al., 2021) [13,9] . Cocopeat and FYM-enriched media further contributed by maintaining optimal moisture and aeration, facilitating nutrient diffusion to roots and sustaining leaf expansion. These findings corroborate those of Choudhary et al. (2020) [6] in field crops and El-Shawa et al. (2022) [7] in Philodendron, where integrated nutrient and media management enhanced foliar development.

 Leaf Length (cm): Leaf length did not show significant differences among treatments (Tables 3a,3b), suggesting a strong genetic regulation of this trait that is less responsive to foliar nitrogen or media composition. Similar observations were reported by Qureshi et al.

(2018) [11] , indicating that while nitrogen availability influences overall growth, elongation of individual leaves may be constrained by inherent developmental programming.  Leaf Width (cm): Leaf width was non-significant at 65 and 95 DAP, but significant at 125 DAP (Tables 4a,3b). Maximum leaf width was observed in N₅ (10.12 cm), followed by N₄ (9.69 cm), whereas N₀ was lowest (6.75 cm). Among media, M₃ produced the widest leaves (10.19 cm) and M₁ the narrowest (7.03 cm) (Tables 4a, 4b and fig 3a, b, c) Mechanistically, enhanced leaf width results from improved nitrogen assimilation, stimulating cell expansion and division in the leaf lamina. Increased photosynthate production in leaves promotes cell turgor and elongation, contributing to greater leaf surface area (Singh et al., 2017) [14] . The interaction of nano urea with cocopeat-FYM media likely provided sustained nutrient availability and optimal root-shoot balance, supporting lamina expansion.  Leaf Area (cm²): Leaf area exhibited significant variation in response to nano urea application and potting media (Tables 2a,5b; Fig. 3a,b,c). Leaf area, a crucial determinant of photosynthetic capacity, was significantly influenced by nano urea levels, media composition, and their interaction at all stages. At 125 DAP, N₅ recorded the highest leaf area (169.25 cm²), followed by N₄ (138.17 cm²), while N₀ was the lowest (75.58 cm²). Media effects were significant, with M₃ producing the largest area (167.08 cm²) and M₁ the smallest (77.21 cm²). The N₅M₃ interaction yielded the maximum leaf area (213.49 cm²), demonstrating a synergistic effect of optimal nitrogen supply and balanced substrate composition.

Physiologically, nano urea promotes rapid nitrogen uptake, enhancing amino acid, protein, and chlorophyll synthesis, which stimulates cell division and elongation. FYM contributes additional macro-and micronutrients and improves microbial activity, further enhancing leaf expansion (Ajith Kumar et al., 2021; Abdel-Salam et al., 2018) [4,3] . Reduced bulk density and higher water retention in cocopeat-based media facilitate turgor-driven cell expansion, leading to larger leaves. These findings are in agreement with previous studies in Philodendron (El-Shawa et al., 2022) [7] , maize (Ajith Kumar et al., 2021) [4] , and lettuce (Abdel-Salam et al., 2018) [3] . N4: Nano urea 1.5 ml L -1 M2: Red earth + Cocopeat (1:1) N2: Nano urea 0.5 ml L -1 N5: Nano urea 2 ml L -1 M3: Red earth + Cocopeat + FYM (1:1:1) M4: Red earth + Cocopeat + FYM (2:1:1)

Conclusion

The present study demonstrated that the application of nano urea significantly enhanced the vegetative growth of Heart Leaf Philodendron (Philodendron scandens), as evidenced by improvements in plant height, number of leaves, leaf width, and leaf area. Among the different levels of nano urea, the highest concentration (N5 -2 ml L⁻¹) consistently produced superior growth responses at 65, 95, and 125 days after planting, highlighting the efficacy of nano-fertilizers in improving nutrient uptake and utilization. The enhanced growth can be attributed to the small particle size and high surface area of nano urea, which facilitated efficient penetration through the leaf stomata, stimulated auxinmediated cell division and elongation, and promoted chlorophyll synthesis and photosynthetic activity.

Similarly, the composition of the potting media significantly influenced growth parameters. The combination of Red Earth, Cocopeat, and Farm Yard Manure in the ratio of 1:1:1 (M3) provided an optimal balance of aeration, water retention, and organic nutrient content, resulting in improved vegetative growth compared to other media compositions. The interaction between nano urea application and media composition was statistically significant, with the treatment combination T23-N5M3 (2 ml L⁻¹ Nano urea + Red Earth + Cocopeat + FYM, 1:1:1)

consistently producing the highest plant height, number of leaves, leaf width, and leaf area. Overall, the study indicates that the integrated use of nano urea and a well-structured potting media enhances vegetative growth by improving nutrient availability, water retention, and physiological efficiency in Philodendron. These findings provide valuable insights for commercial cultivation and management of ornamental foliage plants, suggesting that nano-fertilizer application in combination with nutrient-rich media can maximize plant growth, vigor, and overall ornamental quality.

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