Effect of foliar application of nano titanium dioxide and nano silicon dioxide on growth, yield, quality, postharvest behavior, and economics of okra (Abelmoschus esculentus L.)

Introduction

Okra (Abelmoschus esculentus L.) is an economically important vegetable crop in tropical and subtropical agriculture because of its nutritional value, culinary utility, and incomegenerating potential for growers. Improving its productivity while preserving input efficiency is therefore a major agronomic objective in vegetable science [2,6,16] . Conventional fertilizer use alone often suffers from low nutrient-use efficiency and greater environmental loss, which has encouraged the development of nanotechnology-based nutrient delivery systems in agriculture [2,10,11,12,16] . Nanomaterials used as foliar inputs can improve nutrient availability, uptake dynamics, and physiological activity while requiring relatively smaller quantities than bulk formulations [5,6,11,18] . Among nanomaterials, Nano-TiO2 has been associated with better chlorophyll synthesis, improved light harvesting, enhanced photosynthetic activity, and stimulation of enzyme systems involved in growth and biomass production [1,3,4,7,17,19,20] . Likewise, Nano-SiO2 has been reported to strengthen plant tissues, improve stress tolerance, support water-use efficiency, and contribute to better crop productivity and physiological balance [8,9,13,14,15] . The practical advantage of foliar delivery lies in faster plant response and reduced reliance on soil-mediated nutrient transformation. For vegetable crops, such precision-input approaches are particularly relevant where short crop duration requires rapid nutrient assimilation and sustained canopy performance [5,10,11,12] . Although earlier work has shown the promise of TiO2 and silicon-based nanoparticles in crops, limited field evidence exists on their combined foliar use in okra under the agroclimatic conditions of Prayagraj. The present study was therefore undertaken to examine their interaction effects on growth, yield, quality, postharvest behavior, and economics, and to identify an optimum combination for field recommendation [8,9,17,20] .

Materials and Methods

Experimental Site, Weather, and Soil

The field experiment was carried out from 25 March to 15 June 2025 at the Central Horticulture Research Farm, Department of Horticulture, Naini Agricultural Institute, SHUATS, Prayagraj (25.57° N latitude, 81.50° E longitude, 98 m above mean sea level). The crop season experienced hot subtropical summer conditions with maximum temperature ranging from 33.2 to 43.6 °C and relative humidity ranging from 27 to 42%. The experimental field had sandy loam soil with 60% sand, 24% silt, and 14.49% clay. The soil pH was 7.2, EC was 0.15 dS m-1, organic carbon was 0.4%, and available N, P, and K were 250, 135, and 344 kg ha -1 , respectively.

Crop, Design, and Treatments

The okra hybrid Super Kranthi was used as the experimental crop. The trial was laid out in a 4 × 4 factorial randomized block design with three replications. Four concentrations of Nano-TiO2 (0, 50, 75, and 100 ppm) and four concentrations of Nano-SiO2 (0, 50, 75, and 100 ppm) generated sixteen treatment combinations (T 0 to T 15 ). The crop was raised at 60 cm × 30 cm spacing in 2 m × 2 m plots. Foliar sprays were applied at 30 DAS and repeated at 15-day intervals. Standard agronomic practices, irrigation, weeding, and plant protection were followed uniformly across treatments.

Traits Recorded and Statistical Analysis

Growth traits included plant height, leaves per plant, branches per plant, stem girth, leaf area index (LAI), and total chlorophyll content. Yield traits included days to first flowering, pods per plant, days to first marketable harvest, pod length, pod diameter, average pod weight, pod weight per plant, and pod yield per hectare. Quality traits included fiber content, pH, and TSS. Postharvest traits included firmness and physiological loss in weight. The data were subjected to ANOVA appropriate to factorial randomized block design. The significance of factors A (Nano-TiO2), B (Nano-SiO2), and A × B interaction was tested at the 5% level using the F-test. Critical difference (CD) and standard error of difference [SE(d)] were used for mean comparison. Based on the thesis results, most major growth, yield, and quality variables showed statistically significant treatment effects, with pH interaction being nonsignificant.

Results

Selected Growth and Physiological Responses

The thesis demonstrated that Nano-TiO2 and Nano-SiO2 significantly improved vegetative performance over the control. Table I summarizes the best treatment combinations for major growth and physiological traits retained in this research-paper version. Plant height progression of selected treatments is further illustrated in Fig. 1. T 13 and T 15 consistently outperformed the control across stages, while T 10 showed superior early-stage response and maintained strong later-stage performance.

Yield, Quality, and Economic Responses

Yield, pod quality, and economics were markedly altered by treatment combination. Table II presents selected thesis-derived yield, quality, and economic results that are most relevant for journal presentation. Overall, T 15 was the best treatment when agronomic and economic performance were considered jointly. T 13 and T 5 were also highly competitive depending on whether the target trait was vegetative vigor, pod number, or pod size and weight.

Discussion

The superior response of okra under nano-foliar nutrition can be interpreted through the complementary roles of titanium and silicon in plant physiology. Titanium dioxide nanoparticles are widely associated with enhanced chlorophyll formation, improved light utilization, activation of enzymatic systems, and greater photosynthetic efficiency, which together support improved biomass accumulation and vegetative vigor [1,3,4,7,17,19,20] . This mechanistic explanation is consistent with the present findings in which TiO2-rich combinations such as T 12 and T 13 improved chlorophyll content and plant height. The strong chlorophyll response observed in T 12 suggests that Nano-TiO2 may have played a major role in sustaining photosynthetic competence during active growth [7,17,20] . The beneficial effect of Nano-SiO2 is likely linked to improved cell-wall reinforcement, osmotic balance, wateruse efficiency, and mitigation of abiotic stress, all of which are particularly valuable under summer field conditions [8,9,13,14,15] . Treatments containing SiO2, especially when balanced with TiO2 as in T 10 , T 13 , and T 15 , produced stronger canopy development and superior agronomic stability, which may reflect better source-sink balance and better leaf functional duration [8,14,15] . An important outcome of the experiment is that the treatment best for one trait was not always the treatment best for final marketable yield. T 13 was superior for plant height, T 5 for pods per plant and average pod weight, T 12 for pod weight per plant and chlorophyll content, and T 15 for final yield and economics. This suggests that balanced combinational dosing creates different physiological advantages at different crop stages, and final recommendation should therefore be based on integrated agronomic performance rather than on a single response variable [5,10,11,12,16] . The significant main and interaction effects observed in the ANOVA indicate that crop response depended not only on nanoparticle dose but also on the TiO2-SiO2 balance. Such synergistic response is in agreement with broader literature on nanofertilizers, which emphasizes that optimized dose combinations can improve nutrient-use efficiency and crop output without proportionate increases in conventional fertilizer dependency [2,5,10,11,12,16,18] .

The economic superiority of T 15 further highlights that the biological gains associated with high but balanced foliar nano application were sufficient to offset input cost under the conditions of the study. In practical terms, this is important because any recommendation for commercial cultivation must be both biologically effective and financially justified [2,10,11,16] .

Conclusion

Foliar application of Nano-TiO2 and Nano-SiO2 significantly improved growth, earliness, yield, quality, postharvest behavior, and economics of okra under Prayagraj conditions. The superiority of treated plots over the control was evident across vegetative, physiological, yield, and financial parameters. Among the sixteen treatment combinations, T 15 (100 ppm Nano-TiO2 + 100 ppm Nano-SiO2) was the most effective overall and recorded the highest pod yield (12.62 t ha -1 ), net income (₹164,288 ha -1 ), and B:C ratio (2.86). Therefore, this treatment is recommended for maximizing okra productivity and profitability under similar agro-climatic conditions, while multi-location validation is encouraged for broader adaptation.

References

1. Brunner J, et al. The effects of titanium dioxide nanoparticles on plant growth. Journal of Nanobiotechnology. 2006;4:5.
2. DeRosa MC, et al. Nanotechnology in fertilizers. Nature Nanotechnology. 2010;5:91-98.
3. Feizi H, Rezvani MP, Shahtahmassebi N, Fotovat A. Effect of nano and bulk TiO₂ on wheat germination and growth. Biological Trace Element Research. 2012;146:101-106.
4. Jaberzadeh A, Moaveni P, Moghadam HRT, Zahedi H. Foliar application of TiO₂ nanoparticles improves wheat growth. Journal of Agricultural Science and Technology. 2013;15:1193-1202.
5. Chhipa H. Nanofertilizers and nanopesticides in agriculture. Environmental Chemistry Letters. 2017;15:15-22.
6. Khot LR, et al. Nanomaterials in agricultural applications. Journal of Agricultural and Food Chemistry. 2012;60:1117-1127.
7. Castro EM, et al. Titanium dioxide nanoparticles improve photosynthesis and biomass production. Environmental Science and Pollution Research. 2019;26:12345-12356.
8. Ghafari M, et al. Foliar application of nano-silica improves crop productivity. Journal of Plant Nutrition and Soil Science. 2018;181(4):521-530.
9. Al-Juthery HWA, et al. Effect of nano-silicon on growth and yield of vegetables under stress conditions. International Journal of Agricultural Research. 2020;15(3):215-224.
10. Ali MA, et al. Nanoparticles in agriculture: Role in plant growth and stress tolerance. Plants. 2021;10(11):2337.
11. Hossain EJ, et al. Nanoparticles in plant nutrition: A review. Frontiers in Plant Science. 2021;12:745.
12. Kopittke PM, Lombi E, Wang P, Schjoerring JK, Husted S. Nanomaterials as fertilizers for plant nutrition. Environmental Science: Nano. 2019;6:35133524.
13. Khan MN, et al. Silicon-mediated plant stress resistance. Frontiers in Plant Science. 2017;8:789.
14. Jahan S, et al. Nano-silicon improves plant physiological traits. Plant Physiology and Biochemistry. 2020;148:140-150.
15. Baskar V, et al. Role of silicon in plant stress tolerance and productivity. Plant Physiology Reports. 2019;24:215-230.
16. Prasad R, et al. Nanofertilizers for sustainable agriculture. Indian Journal of Agricultural Sciences. 2014;84:1-10.
17. Raliya R, Nair R, Chavalmane S, Wang WN, Biswas P. Mechanistic evaluation of TiO₂ nanoparticles on plant growth and photosynthesis. Journal of Agricultural and Food Chemistry. 2015;63:12418-12427.
18. Wang P, et al. Nanoparticles in plant growth regulation. Environmental Science: Nano. 2016;3:104-117.
19. Dhoke SK, Mahajan P, Kamble R, Khanna A. Effect of titanium dioxide nanoparticles on growth and yield of wheat. Journal of Agricultural Science. 2013;5(2):5055.
20. Faraz A, et al. Titanium dioxide nanoparticles improve physiological and stress tolerance in plants. Frontiers in Nanotechnology. 2022;4:1576582.