Interactive effects of foliar applied biostimulants and different fertilizer levels on Nutrient Content and Uptake (NPK) of aerobic rice (Oryza sativa L.)

Introduction

Agriculture is the foundational bridge between natural ecosystems and human civilization, increasingly defined by the synergy between chemical precision and biological enhancement (Dodiya et al., 2025) [6,7,8] . As demonstrated by the research on aerobic rice, modern farming is no longer just about the bulk application of NPK fertilizers; it is a sophisticated management system where foliar-applied biostimulants act as physiological catalysts (Dodiya et al., 2023) [5] . Rice (Oryza sativa L.) is an important cereal crop belonging to the family Poaceae with a chromosome number 2n = 24. It is one of the most widely cultivated staple food crops globally and serves as the primary dietary source in about 17 countries, particularly in Asia. More than two billion people in Asia depend on rice for nearly 80 percent of their daily energy intake. Globally, rice provides calories to approximately 40 percent of the population (Ghosh and Bhat, 1998) [9] , although it occupies only about 11 percent of the total cultivated area. In Asia, rice is grown under diverse agro-ecosystems, including irrigated conditions (56.1%), rainfed lowlands (26%), uplands (9.2%) and deep-water systems (8.7%) (Swain et al., 2005) [20] . The escalating cost of chemical fertilizers and the instability in crop production necessitate the adoption of more sustainable and economically viable nutrient management strategies. In this context, partial substitution of inorganic fertilizers with innovative approaches such as foliar application of biostimulants offers a promising solution. Biostimulants enhance nutrient use efficiency, improve plant growth and increase tolerance to abiotic stresses, thereby contributing to stable yields. Furthermore, to ensure these yields are protected from biotic pressures, innovative biotechnological interventions like CRISPR/Cas9-mediated gene disruption have emerged as a novel strategy to manage devastating pests (Dodiya et al. 2025, Dodiya et al. 2025) [6,7,8] . In this context, integrated nutrient management through the judicious use of inorganic fertilizers along with foliar application of bio stimulants has emerged as a promising approach to enhance soil productivity and sustain crop production systems over the long term (Patra et al., 2000 and Kumar et al., 2001) [14,12] .

Materials and Methods

A field experiment entitled "Interactive effects of foliar applied biostimulants and different fertilizer levels on nutrient content and uptake (NPK) of aerobic rice (Oryza sativa L.)" was conducted at College Farm, N. M. College of Agriculture, Navsari Agricultural University, Navsari (Gujarat) during kharif seasons of the year 2023 and 2024. The experiment was laid out in a randomized block design with ten treatments viz., T 1: control, T 2: 100 percent RDF, T 3: 100 percent RDF + three foliar spray of 3 percent panchgavya, T 4: 100 percent RDF + three foliar spray of 2 percent vermibed-wash, T 5: 100 percent RDF + three foliar spray of 1 percent NOL, T 6: 100 percent RDF + three foliar spray of 0.25 percent seaweed extract, T 7: 75 percent RDF + three foliar spray of 3 percent panchgavya, T 8: 75 percent RDF + three foliar spray of 2 percent vermibed-wash, T 9: 75 percent RDF + three foliar spray of 1 percent NOL and T 10: 75 percent RDF + three foliar spray of 0.25 percent seaweed extract and three replications. RDF was 100-30-00 N-P 2 O 5 -K 2 O kg/ha (Nitrogen: 40% as basal, 40% at tillering stage and 20% at panicle initiation stage; Phosphorus: 100% as basal). Foliar application of biostimulants was given at 30, 45 and 60 DAS. During the experimentation spacing between row to row was 30 cm with 50 kg/ha seed rate and variety used in the experiment was GNR-8 (Aarti). The soil of the experimental field in Navsari campus is classified under order 'Inceptisols' comprising of montmorillonitic, iso-hyperthermic family of Vertic Ustrochrepts and soil series Jalalpor (Desai and Patel, 1970) [4] . The predominant clay mineral is montmorillonite. A representative soil samples were drawn from 0 to 15 cm depth covering entire area of experimental field before sowing of the crop. The samples were thoroughly mixed and composite sample was obtained and then analysed for physico-chemical properties of the soil as represented in Table 1.

The nitrogen concentration of plant and grain sample was analyzed by the micro-Kjeldahl technique by using kelplus N analyser. Finely grounded samples were digested with concentrated H₂SO₄ along with a catalyst mixture as per the procedure outlined by Piper (1943) [15] .

The phosphorus content of the sample was analyzed after digestion with a di-acid mixture (HNO₃:HClO₄ in 9:4 proportion) following the procedure of piper (1943) [15] . Phosphorus was quantified by the vanadomolybdophosphoric acid yellow colour method as described by Jackson (1973) [10] and absorbance was recorded at 420 nm using a spectrophotometer. The values were expressed in percentage.

The potassium content in the diacid digested mixture was determined by using flame photometer (Jackson, 1973) [10] . N, P and K uptake by grain and straw (kg/ha) N, P and K uptake in grain and straw were obtained in kg/ha by using following formula:

Nutrient uptake by grain (kg/ha) = Nutrient content in grain (%) × Grain yield (kg/ha) 100

Nutrient uptake by straw (kg/ha) = Nutrient content in Straw (%) × Straw yield (kg/ha) 100

Total nutrient uptake (kg/ha) = Nutrient uptake by grain + Nutrient uptake by straw

Soil analysis

Representative soil samples from each treatment were collected replication-wise from a depth of 0-15 cm using an auger. Sampling was carried out from five randomly selected locations within each net plot and the collected samples were composited and thoroughly mixed. The composite samples were placed in separate polythene bags, properly labelled and transported to the laboratory. The samples were then shade-dried, grounded using a mortar and pestle and passed through a 2 mm sieve. Finally, the processed samples were stored in polythene bags for subsequent analysis. The standard methods adopted for analysing the physical and chemical properties viz., pH, EC, organic carbon (OC) and available nitrogen, P 2 O 5 and K 2 O as described in Table 1.

The results regarding major nutrient content, i.e. N, P and K in grain and straw were analysed and depicted in Tables 2 to 4.

The mean data on nitrogen content in grain and straw of rice crop as influenced by different treatments are presented in Table 2.

A detailed analysis of the data revealed that significantly higher nitrogen content in rice grain (1.04, 1.07 and 1.05%) was obtained with the application of 100 percent RDF + three foliar sprays of 0.25 percent seaweed extract (T₆) during 2023, 2024 and in pooled analysis, respectively. However, this treatment was found to be statistically at par with 100 percent RDF + three foliar sprays of 3 percent panchgavya (T₃), which recorded nitrogen contents of 1.02, 1.03 and 1.03 percent, respectively, as well as with 100 percent RDF + three foliar sprays of 1 percent NOL (T₅), showing values of 1.01, 1.03, and 1.02 percent, respectively. In contrast, the lowest nitrogen content in rice grain (0.62, 0.65, and 0.64%) was observed under the control treatment (T₁) during both years and in the pooled data. International pipette method (Piper, 1966) [15] Silt (%) Olsen's method (Jackson, 1973) [10] Available K2O (kg/ha) 345.11 370.82 Flame photometric method (Jackson, 1973) [10] A similar trend was observed in rice straw. The data presented in Table 2 indicated that significantly higher nitrogen content in straw (0.51, 0.52 and 0.52%) was recorded with the application of 100 percent RDF + three foliar sprays of 0.25 percent seaweed extract (T₆) during 2023, 2024 and in pooled analysis, respectively. This treatment remained statistically at par with 100 percent RDF + three foliar sprays of 3 percent panchgavya (T₃), which registered nitrogen content of 0.51, 0.51 and 0.51 percent, respectively, and with 100 percent RDF + three foliar sprays of 1 percent NOL (T₅), which recorded 0.49, 0.50 and 0.50 percent nitrogen, respectively. However, significantly lower nitrogen content in rice straw (0.31, 0.32 and 0.32%) was observed under the control treatment (T₁) during the first year, second year and in pooled analysis, respectively. The nitrogen content in grain and straw was significantly influenced by the combined application of RDF and biostimulants. The increase in nitrogen content under these treatments might be attributed to improved nitrogen uptake, assimilation and translocation due to the synergistic effect of RDF and biostimulant application. Consequently, plants under these treatments absorbed and assimilated more nitrogen, resulting in higher N content in both grain and straw. These findings are consistent with those reported by Siddaram et al. (2010) [18] , Layek et al. (2018) [13] in rice, Shah et al. (2013) [17] in wheat, Chaudhary et al. (2021) in pearl millet and Joshi et al. (2023) [11] in black gram.

Results depicted in Table 3 revealed that phosphorus content in rice grain and straw was not significantly influenced by the treatments, as only marginal differences were observed across all treatments.

Data presented in Table 4 revealed that potassium content in rice grain and straw was not significantly affected by varying levels of RDF along with foliar application of biostimulants.

The results regarding nutrient uptake by rice crop i.e., N, P and K as affected by different treatments are summarized in Tables 5 to 7.

The results of the experiment on total nitrogen uptake by rice crop as affected by different treatments are presented in Table 5.

A detailed analysis of the data revealed that the application of 100 percent RDF + three foliar sprays of 0.25 percent seaweed extract (T₆) resulted in significantly higher total nitrogen uptake by rice (61.77, 64.25 and 63.01 kg/ha) during 2023, 2024 and in pooled analysis, respectively. This treatment was found statistically at par with T₃ (100 percent RDF + three foliar sprays of 3 percent panchgavya), which recorded total nitrogen uptake of 56.98 and 58.97 kg/ha during 2023 and 2024, respectively. However, in pooled analysis, T₆ proved significantly superior over the remaining treatments. The lowest total nitrogen uptake (16.05, 16.91 and 16.48 kg/ha) was observed under the control treatment (T₁) during both years and in pooled results.

Total phosphorus uptake by the rice crop was significantly affected different treatments are presented in Table 6.

The data on phosphorus uptake by the rice crop indicated that the application of 100 percent RDF + three foliar sprays of 0.25 percent seaweed extract (T₆) resulted in significantly higher total phosphorus uptake ( Potassium uptake (kg/ha) Data regarding total potassium uptake by rice crop as influenced by different treatments are presented in Table 7.

A critical analysis of the data revealed that the application of 100 percent RDF + three foliar sprays of 0.25 percent seaweed extract (T₆) resulted in significantly higher total potassium uptake (77.72, 79.81 and 78.77 kg/ha) during 2023, 2024 and in pooled analysis, respectively. However, this treatment remained statistically at par with T₃ (100 percent RDF + three foliar sprays of 3 percent panchgavya), which recorded total potassium uptake of 72.08, 75.50 and 73.79 kg/ha during both years and in pooled analysis, respectively. It was also comparable with T₅ (100 percent RDF + three foliar sprays of 1 percent NOL) during 2024, which registered total potassium uptake of 72.65 kg/ha. In contrast, the control treatment (T₁) recorded significantly lowest total potassium uptake (35.69, 35.86 and 35.77 kg/ha) during the first year, second year and in pooled results, respectively. The total uptake of nitrogen, phosphorus and potassium by the crop (grain + straw) were significantly affected by the combined application of RDF and biostimulants. The enhanced nutrient uptake under these treatments may be attributed to improved nutrient availability, uptake and assimilation resulting from the synergistic interaction between RDF and biostimulants. Biostimulants, being rich in plant growth-promoting substances, beneficial microorganisms and micronutrients, likely stimulate root development, thereby enhancing nutrient absorption and translocation within the plant system. Additionally, increased biomass production and grain yield under these treatments further contributed to higher total nutrient uptake. Similar findings were also reported by Layek et al. (2018) [13] and Borgohainl et al. (2020) [2] in rice.

Conclusion

Based on two years experimentation, it can be concluded that aerobic rice fertilized with 100 percent RDF + three foliar spray of 0.25 percent seaweed extract or 3 percent panchgavya or 1 percent NOL (Novel organic liquid) at 30, 45 and 60 DAS resulted higher NPK content and NPK uptake. Therefor, integration of inorganic fertilizer application with foliar application of biostimulants is reaccommodate to optimize NPK content and uptake of aerobic rice.

References

1. Black CA, Evans DD, Ensminger LE, White JL, Clark FE, editors. Methods of soil analysis. Madison (WI): ASA; 1983.
2. Borgohain L, Borgohain H, Konwar B, Dutta AK, Panging U. Panchagavya: A multidimensional review article through the lens of an agriculture scholar. Asian Soil Res J. 2020;3(4):32-38.
3. Chaudhary MG, Malav JK, Vala YB, Desai NA. Influences of different organic sources and seaweed extract on quality, nutrient content, uptake, soil fertility status and soil microbial population after harvest of summer green gram (Vigna radiata L.). Pharma Innov J. 2021;10(11):1390-1394.
4. Desai RG, Patel MD. Report on soil survey of Navsari Taluka. Tech Bull. 1970;(41):1-7.
5. Dodiya RD, Barad AH, Pathan NP, Raghunandan BL. Trichogramma: A promising biocontrol agent. Int J Econ Plants. 2023;10:192-199.
6. Dodiya RD, Italiya JV, Patel PS, Pathan NP, Barad AH. CRISPR/Cas9-mediated gene disruption: A novel strategy against fall armyworm. Farming Manag. 2025;10(1):1-6.
7. Dodiya RD, Koosi ST, Chaudhary FK, Patel PS, Barad AH. CRISPR/Cas9: A new frontier in biocontrol strategies for insect pest management. In: Bio-control agents for sustainable agriculture: diversity, mechanisms and applications. Singapore: Springer Nature Singapore; 2025. p. 511-530.
8. Dodiya R, Patel P, Pathan N, Deb S. Temporal patterns of aphid infestations in coriander. J Agric Ecol. 2025;20:77-83.
9. Ghosh BC, Bhat R. Environmental hazards of nitrogen loading in wetland rice fields. Environ Pollut. 1998;102(1):123-126.
10. Jackson ML. Soil chemical analysis. New Delhi: Prentice Hall of India Pvt Ltd; 1973. p. 151-498.
11. Joshi D, Yadav LR, Ratore BS, Srivastava H, Verma RS, Gurjar BS, et al. Enhancing nutrient uptake and economics of black gram through vermicompost and vermiwash application. Int J Environ Clim Change. 2023;13(9):3186-3193.
12. Kumar N, Verma LP, Singh R, Prasad K. Soil properties, nutrient uptake and productivity of rice under integrated nutrient management system. Ann Plant Soil Res. 2001;3(1):54-57.
13. Layek J, Das A, Idapuganti RG, Sarkar D, Ghosh A, Zodape ST, et al. Seaweed extract as organic biostimulant improves productivity and quality of rice in eastern Himalayas. J Appl Phycol. 2018;30(1):547-558.
14. Patra AK, Nayak BC, Mishra MM. Integrated nutrient management in rice (Oryza sativa L.)-wheat (Triticum aestivum) cropping system. Indian J Agron. 2000;45(3):453-457.
15. Piper CS. Soil and plant analysis. Soil Sci. 1943;56(1):68-68.
16. Prasad S. Effect of panchagavya and recommended dose of fertilizers on growth, nutrient content and productivity of transplanted rice (Oryza sativa L.) under middle Gangetic plain of India. Indian J Agric Sci. 2018;88(6):931-936.
17. Shah MT, Zodape ST, Chaudhary DR, Eswaran K, Chikara J. Seaweed sap as an alternative liquid fertilizer for yield and quality improvement of wheat. J Plant Nutr. 2013;36(2):192-200.
18. Siddaram S, Murali K, Manjunatha BN, Ramesha YM, Basavaraja MK, Policepatil AS. Effect of nitrogen levels through organic sources on growth, dry matter production and nutrient uptake of irrigated aerobic rice (Oryza sativa L.). Int J Agric Sci. 2010;2:426-429.
19. Subbiah BV, Asija GL. A rapid procedure for the estimation of available nitrogen in soil. Curr Sci. 1956;25:29-29.
20. Swain DK, Herath S, Pathirana A, Mittra BN. Rainfed lowland and flood-prone rice: A critical review on ecology and management technology for improving productivity in Asia. 2005. Available from: www.mekongnet.org/images/e/e9/Dillip.pdf