Integrated weed management improves weed suppression, yield and profitability of sunflower (Helianthus annuus L.)

Introduction

Sunflower is an important short-duration oilseed crop valued for its high-quality edible oil, broad adaptability and suitability for diversified cropping systems. Its wider row spacing and slow initial canopy development, however, favour rapid establishment of weeds. Early weed competition reduces the availability of moisture, nutrients, light and space and may cause substantial yield loss. Wanjari et al. (2001) [9] identified approximately 20-49 days after sowing as a critical period of crop-weed competition in sunflower, while Stefanić et al. (2023) [6] reported severe yield reductions under uncontrolled weed interference. Hand weeding is effective but costly and often constrained by labour availability. Pre-emergence herbicides suppress the first flush of weeds, whereas a selective post-emergence herbicide or mechanical operation can control later-emerging weeds. Integrated weed management therefore offers a practical means of extending the weed-free period and reducing dependence on repeated manual weeding. Previous studies have shown that sequential herbicide application and herbicide-mechanical integration can provide yield comparable with weed-free conditions while improving economic efficiency (Mohapatra et al., 2020; Das et al., 2023; Thambiyannan et al., 2024) [2,4,8] . Information on the relative performance of oxyfluorfen-, oxadiargyl-and pendimethalin-based schedules under the rabi conditions of central India remains limited. Therefore, the present study was undertaken to evaluate their effects on weed dynamics, crop growth, yield attributes, yield and economics of sunflower.

Nitrogen, medium in organic carbon and available phosphorus, and high in available potassium. Sunflower hybrid FB-Sun 777 F₁ was grown in a randomized block design with eight treatments and three replications. Gross and net plot sizes were 5.0 m × 4.0 m and 4.0 m × 3.5 m, respectively. The crop was sown at 60 cm × 30 cm spacing with a seed rate of 8 kg ha⁻¹ and received 80:60:40 kg N:P₂O₅:K₂O ha⁻¹.

Treatments

Observations and statistical analysis

Weed density and weed dry matter were recorded at harvest using quadrats. Weed-control efficiency was calculated from the reduction in weed dry matter relative to the weedy check. Plant height, leaf area index, head diameter, filled seeds head⁻¹, test weight, seed yield, stalk yield, biological yield and harvest index were recorded using standard procedures. Gross return was calculated from seed and stalk values, net return as gross return minus cost of cultivation, and benefit:cost ratio as gross return divided by cost of cultivation. Data were subjected to analysis of variance for a randomized block design, and treatment means were compared using the critical difference at P = 0.05.

Results and discussion

Weed flora and weed suppression

The field was infested with a mixed flora of grasses, broadleaved weeds and sedges. Broad-leaved weeds formed 60.0% of the population, followed by grasses (33.5%) and sedges (6.5%). Weed-management treatments significantly affected weed density, weed dry matter and weed-control efficiency (Table 2). The weed-free check recorded the minimum weed density and dry matter because repeated hand weedings continuously removed newly emerged weeds. Among practical treatments, T₆ recorded the lowest weed density and dry matter and remained statistically comparable with T₇ and T₅. The performance of T₆ can be attributed to suppression of the first weed flush by oxyfluorfen and control of later-emerging weeds by imazethapyr. Similar advantages of sequential herbicide application were reported by Mohapatra et al. (2020) [4] . [1,8] .

Yield response

Seed, stalk and biological yields differed significantly among treatments (Table 4). The weed-free check produced the highest seed yield (2130 kg ha⁻¹), but remained statistically at par with T₆, T₇ and T₅. The comparable yield under these integrated treatments resulted from sustained weed suppression, greater leaf area, larger heads and improved seed filling. The weedy check produced only 1180 kg ha⁻¹ seed yield, representing a 44.6% reduction relative to the weed-free check. Harvest index was not significantly influenced, indicating that the treatments altered total biomass and seed yield in similar proportions. [1,3,4] .

Conclusion

The weed-free check provided the greatest weed suppression and the highest numerical seed yield. However, oxyfluorfen 30% EC at 250 g a.i. ha⁻¹ as pre-emergence followed by imazethapyr 10% SL at 100 g a.i. ha⁻¹ as postemergence produced statistically comparable seed yield and recorded the highest net return and benefit:cost ratio. This sequence was therefore the most remunerative treatment under the experimental conditions. Because the study was conducted for one season and at one location, the treatment should be validated across environments and used only where crop tolerance and herbicide registration permit.

Acknowledgement

AcknowledgementThe authors acknowledge the School of Agricultural Sciences, G H Raisoni University, Saikheda, for providing the field and laboratory facilities required for the investigation.

References

1. Bharati V, Kiran Kumar S, Prasad SS, Singh UK, Hansraj, Dwivedi DK. Effect of integrated weed management in sunflower (Helianthus annuus L.) in Bihar. J Pharmacogn Phytochem. 2020;9(6):356-359.
2. Das SS, Mohapatra A, Mohapatra BK. Integrated weed management in sunflower under lowland paddy-fallow situation of coastal Odisha. J Pharm Innov. 2023;12:3041-3045.
3. Mahapatra A, Mohapatra BK, Das SS. Weed management in zero-till rice-fallow sunflower of coastal Odisha. J Oilseeds Res. 2025;42:1-7.
4. Mohapatra S, Mohapatra BK, Das SS, Tripathy S. Weed management in sunflower through sequential application of herbicides in western Odisha. Indian J Weed Sci. 2020;52(2):197-199.
5. Selvakumar T, Srinivasan K, Rajendran L. Performance of chemical weed management in irrigated sunflower. Int J Agric Sci. 2018;10(20):7395-7397.
6. Stefanić E, Štefanić I, Antunović S. Critical period of weed control in sunflower under contrasting environments. Agronomy. 2023;13:2054.
7. Sujathamma P, Reddy GP, Reddy APK, Naidu MVS. Integrated weed management for sunflower under modified spacing in paddy-fallow systems. Plant Sci Today. 2026;13:1-10.
8. Thambiyannan K, Kumar VS, Somasundaram E, Arthanari PM. Band application of pendimethalin integrated with power weeding in sunflower. J Oilseeds Res. 2024;41:154-160.
9. Wanjari RH, Yaduraju NT, Ahuja KN. Critical period of crop-weed competition in rainy-season sunflower (Helianthus annuus). Indian J Agron. 2001;46(2):309313.