Effect of nano urea plus and nano DAP on growth and yield attributes and yield of sunflower (Helianthus annus L.) during rabi

Introduction

Sunflower (Helianthus annuus L.), belonging to the family Asteraceae, is an important oilseed crop valued for its high-quality oil rich in unsaturated fatty acids (Heiser, 1978; Rai, 2002) [5,9] . The seeds contain approximately 45-50% oil, 14-19% protein, 21-27% hull, 7-9% soluble sugars and 30-35% carbohydrates. In India, sunflower is the fourth most important oilseed crop, cultivated over 1.51 lakh hectares with a production of 1.73 lakh tonnes and an average productivity of 1144 kg ha -¹ (Indiastat, 2025) [6] . In Telangana, it is grown on about 0.100 lakh hectares with a production of 0.283 lakh tonnes and a higher productivity of 2833 kg ha -¹ (Indiastat, 2025) [6] , indicating its strong potential under favourable conditions. Its short duration, wide adaptability and suitability across diverse cropping systems make it an ideal crop under varied agro-climatic situations. However, despite these advantages, productivity in India remains suboptimal due to factors such as moisture stress, climatic variability and inefficient nutrient management (Rath et al., 2022) [11] . Efficient management of nitrogen and phosphorus is critical for enhancing sunflower productivity. Conventional fertilizer practices are often associated with low nutrient use efficiency, with 40-70% of nitrogen and 80-90% of phosphorus lost through leaching, volatilization and fixation before plant uptake. These losses not only reduce crop yield and farm profitability but also contribute to environmental degradation. Moreover, excessive and imbalanced fertilizer application can deteriorate soil health, disturb microbial activity and impair ecosystem stability. Such limitations restrict sunflower production and contribute to stagnation in oilseed output.

In this context, nano fertilizers offer a promising approach to address these challenges by enhancing nutrient use efficiency, improving crop performance and minimizing environmental impacts. Therefore, the present investigation was undertaken to evaluate the combined effect of nano urea and nano DAP on the growth, yield attributes and productivity of sunflower.

Materials and Methods

The field experiment was conducted at Agricultural research station, Tornala, Siddipet, PJTAU, Telanagana state during the rabi season of 2025-26. The soil of experimental site was well drained which was favourable for optimum growth of the crop. The soil samples from 0 to 30 cm depth were taken from randomly selected plots all over the experimental field before laying out the experiment. The soil pH was 6.8, available nitrogen (184 kg ha - 1 ), available phosphorous (30.1 kg ha -1 ) and available potassium (292 kg ha -1 ). The field experiment was laid out in a Randomized Block Design (RBD) with ten treatments and replicated thrice. The treatments in detailed were T 1 -100% RDF (75: 90: 30 N: P 2 O: K₂O kg ha -1 ), T 2 -60% RDN + nano urea plus @ 4 ml L -1 at 30 &45 DAS, T 3 -80% RDN + nano urea plus @ 4 ml L -1 at 30 & 45 DAS, T 4 -60% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS and 45 DAS, T 5 -80% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS and 45 DAS, T 6 -60% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS + nano urea plus @ 4 ml L -1 at 45 DAS, T 7 -80% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS + nano urea plus @ 4 ml L -1 at 45 DAS, T 8 -100% RDNK (75: 30 N: K₂O kg ha -1 ), T 9 -100% RDPK (90: 30: P₂O₅: K₂O kg ha -1 ), T 10 -Control -No N and P application. Each plot had a gross size of 5.4 m × 4.8 m and a net size of 4.5 m × 4.4 m. Sowing of sunflower hybrid Tillhan Tech SUNH-1 was carried out on 14 th November, 2025, with spacing of 45 cm × 20 cm by using the dibbling method and a seed rate of 5 kg ha -1 . The recommended dose of fertilizer 75:90:30 NPK kg ha -1 was applied as per treatments through urea, DAP and MOP. The foliar application of nano urea plus and nano DAP were taken as per the treatments i.e. at 30 and 45 DAS. Growth and yield parameters were recorded periodically on tagged plants. All recommended agronomic practices and need based plant protection measures were followed to ensure a healthy crop. All observations were recorded according to standard procedures. Data on various variables were statistically analysed by analysis of variance (Panse and Sukhatme, 1967) [8] .

Results and Discussion

Growth attributes Plant Height (cm) Among the different treatments, application of 80% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS and 45 DAS (T 5 ) recorded significantly highest plant height at 30 DAS (43.5) which was on par with (T 7 ) i.e. application of 80% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS + nano urea plus @ 4 ml L -1 at 45 DAS (42.5 cm) and T 1 -100% RDF (37.3 cm) Whereas, at 60 DAS and at harvest T 1 -100% RDF recorded the highest plant height (178.8 cm and 188.8 cm respectively) and was at par with T 7 -(176 cm and 181.1 cm), T 5 -(175.3 cm and 179.1 cm). The increase in plant height might be due to the rapid absorption of nutrients through stomata, which enhances chlorophyll synthesis, photosynthetic ability, enzymatic activity and auxin metabolism in plants, leading to cell enlargement and elongation.

Additionally, nano fertilizer improves carbohydrate transfer from source to sink, providing continuous energy for vegetative growth, ultimately resulting in taller plant height. These results are in accordance with the findings of Vyankatrao et al. (2024) [14] , Gaikwad et al. (2025) [4] and Kumar et al. (2025) [7] in sunflower.

Among the various treatments, T 5 -80% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS and 45 DAS recorded highest stem girth at 30 DAS, 60 DAS and at harvest (3.6 cm, 7.5 cm and 7.8 cm respectively). Further, it was found to be on par with T 1 (3.4 cm, 6.9 cm and 7.3 cm) and T 7 (3.3 cm, 7.2 cm and 7.4 cm). The increased stem girth may be due to balanced nitrogen and phosphorus supply, which enhanced nutrient uptake, photosynthesis and vascular development, leading to improved stem thickness. These findings are consistent with the observations of Rajanikanthreddy et al. (2025) [10] and Vyankatrao et al. (2024) [14] .

Among the different treatments, the maximum head diameter was recorded in T₅-80% RDNP + seed treatment with nano DAP @ 5 ml kg -¹ seed + foliar application of nano DAP @ 4 ml L -¹ at 30 and 45 DAS (16.0 cm), which was statistically at par with T₁-100% RDF (15.6 cm) and T₇-80% RDNP + seed treatment with nano DAP @ 5 ml kg -¹ seed + foliar application of nano DAP @ 4 ml L -¹ at 30 DAS + nano urea plus @ 4 ml L -¹ at 45 DAS (15.1 cm) The increased head diameter attributed to balanced nutrient supply and improved nutrient use efficiency, which enhanced photosynthetic activity and promoted effective translocation of assimilates towards reproductive structures. The inclusion of nano fertilizers likely improved nutrient absorption and utilization, resulting in better head development. The present results are also in conformity with Rajanikanthreddy et al. (2024) [10] and Kumar et al. (2025) [7] .

Among the different treatments, the maximum test weight was recorded in T₁-100% RDF (5.5 g), which was statistically at par with T₅ -(5.3 g) and T₇ -(5.0 g). The higher test weight may be attributed due to balanced nutrient supply, which enhanced photosynthetic efficiency and ensured better translocation of assimilates towards developing seeds, resulting in improved seed filling. The inclusion of nano fertilizers likely enhanced nutrient use efficiency and availability, thereby supporting superior seed development. Similar observations were reported by Devi et al. (2024) [3] , Roy and Singh (2024) [12] and Bhakher et al. (2023) [1] .

Seed Yield

Among different treatments, T 1 (100% RDF) resulted in remarkably higher seed yield (1779 kg ha -¹), which was statistically comparable with T₅-80% RDNP + seed treatment with nano DAP@ 5 ml kg -1 seed +nano DAP @ 4 ml L -1 at 30 DAS and 45 DAS (1703 kg ha -¹) and T₇-80% RDNP +seed treatment with nano DAP@ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS + nano urea plus @ 4 ml L -1 at 45 DAS (1627 kg ha -¹) and these treatments were found to be superior over the remaining treatments. The higher seed yield might be due to improved nutrient availability likely resulted in better vegetative growth viz., plant height, stem girth and improved yield attributes such as larger head diameter, higher seed filling and greater test weight, which ultimately contributed to increased productivity.

These findings align with Bhoomika et al. (2025) [2] in safflower, Shinde et al. (2025) [13] in sunflower.

Stalk yield

The maximum stalk yield was recorded in T₁-100% RDF (2814 kg ha -¹), which was on par with T₅ (2669 kg ha -¹) and T₇ (2658 kg ha -¹). The higher stalk yield might be due to increased higher plant height, no of leaves, stem girth, dry matter accumulation and dry matter partitioning which are closely associated to Stalk yield. These findings are in accordance with Vyankatrao et al. (2024) [14] and Bhakher et al. (2023) [1] . 60% RDNP + seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L -1 at 30 DAS + nano urea plus @ 4 ml L -1 at 45 DAS 12.0 4.6 1499 2523 T7 80% RDNP +seed treatment with nano DAP @ 5 ml kg -1 seed + nano DAP @ 4 ml L - 1 at 30 DAS + nano urea plus @ 4 ml L -

Conclusion

The study showed that sunflower growth and yield were significantly influenced by foliar sprays of nano fertilizers in combination with nutrient management practices. The treatment with 80% RDNP combined with nano DAP at seed treatment and foliar spray @ 30 & 45 DAS improved growth and yield attributes viz., plant height, stem girth, head diameter and was comparable to 100% RDF. Although 100% RDF recorded higher yield attributes, the results were on par with T₅, indicating that 80% RDNP with nano fertilizers can sustain productivity while improving nutrient use efficiency.

References

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