Document Type : Research Article
Authors
1
Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran
2
Department of Horticultural Science and Engineering, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran
Abstract
Introduction
Crown vetch (Coronilla varia) is a perennial tetraploid leguminous plant (2n=24) belonging to the Fabaceae family. Widely used as a decorative ground cover and in erosion control along roadsides, it also plays a vital role in nitrogen fixation, environmental improvement, and soil microclimate enhancement. Native to Central and Southern Europe, its cultivation has expanded to the Mediterranean, Russia, Middle East, and the United States. In Iran, it is found in various provinces such as Mazandaran, Ilam, Lorestan, Guilan, Qom, Kermanshah, Golestan, Kurdistan, and Chaharmahal and Bakhtiari, primarily in pastures, orchards, and field margins. Although primarily valued as forage with nutritional quality comparable to alfalfa, Crown vetch contains toxic compounds like cyanogenic glycosides, notably "croneoline", which pose risks to non-ruminant animals, especially horses. The herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) is used post-emergently for controlling broadleaf weeds in various crops, particularly in no-till systems. Common broadleaf herbicides used in alfalfa fields in Iran include chlorotoluron, paraquat, glyphosate, imazethapyr, topramezone, and bentazone, along with grass herbicides such as fluazifop-p-butyl and haloxyfop-methyl. Atlantis is a herbicide containing methylsulfuron-methyl and iodosulfuron-methyl-sodium from the sulfonylurea active ingredient group; it is widely used for controlling broadleaf weeds as well as some annual weeds in wheat fields. The use of Crown vetch as a cultivated crop in Iran remains limited, and its potential as a weed or a cover crop warrants further investigation.
Materials and Methods
To evaluate the effects of herbicides on different ecotypes of Medicago sativa subsp. falcata, a factorial experiment was conducted in a completely randomized design with four replications in the greenhouse of the University of Kurdistan in 2024. The experimental factors included ten ecotypes (collected from the provinces of Hamadan, Kermanshah, Kurdistan, Ilam, and Semnan) and five herbicide treatments (control without herbicide, Totril, 2,4-DB, Granstar, and Atlantis). Seeds were germinated using the top-paper method, and uniform seedlings were transplanted into pots under controlled greenhouse conditions. At the four-leaf stage, plant density was thinned to two plants per pot, and herbicides were applied at the recommended wheat dosages during the branching stage. Spraying was carried out at 22 ± 2 °C, 60–65% relative humidity, and a spray volume of 300 L.ha⁻¹. After 21 days, visual injury ratings were recorded, and shoot dry weight was measured after oven-drying samples at 72 °C for 48 h. Plant height and leaf area index (LAI) were also recorded. Changes in LAI were measured using an LAI meter and analyzed by fitting a logistic growth model. Data were subjected to ANOVA using SAS (version 9.4), mean comparisons were performed by LSD test at the 1% level, and data normality was checked using Minitab. Graphs were prepared using Microsoft Excel.
Results and Discussion
In the evaluation of leaf area index, the highest value was observed in the control treatment of the Paveh ecotype (1.45), while the lowest value was recorded in the 2,4-DB treatment of the Marivan ecotype (0.24). Overall, the average reduction in leaf area index compared with the control treatment for the herbicides 2,4-DB, Totril, Granstar, and Atlantis was 58.03%, 48%, 41.4%, and 21.03%, respectively. Visual assessment results indicated that the herbicides 2,4-DB (99%) and Totril (95.5%) had the greatest effect on controlling the Medicago sativa ecotypes, whereas Atlantis (53.7%) showed the lowest control efficiency. The highest percentage reduction in plant height compared to the control treatment was observed as follows: 2,4-DB (68.52% in the Hamedan ecotype), Totril (58.68% in the Saqez ecotype), Granstar (38.71% in the Nahavand ecotype), and Atlantis (26.02% in the Hamedan ecotype). In the evaluation of leaf area index (LAI), the highest value was recorded in the control treatment of the Paveh ecotype (1.45), and the lowest value in the 2,4-DB treatment of the Marivan ecotype (0.24). Overall, the average reduction in LAI compared with the control for 2,4-DB, Totril, Granstar, and Atlantis was 58.03%, 48%, 41.4%, and 21.03%, respectively. Regarding shoot dry weight, the highest value was observed in the control treatment of the Paveh ecotype (28.67 g), and the lowest in the 2,4-DB treatment of the Saqez ecotype (5.11 g). In general, Totril and 2,4-DB caused the greatest reduction in shoot dry weight of Medicago sativa, whereas Atlantis had the least reduction compared to the other herbicides.
Conclusion
The study demonstrated that Totril and 2,4-DB herbicides were the most effective in controlling Medicago sativa as a weed, while Granstar and Atlantis showed lower efficacy. Considering the potential phytotoxicity of 2,4-DB in orchards, Totril is recommended as a safer option for weed management in such environments. Furthermore, the Paveh and Semnan ecotypes, with higher shoot dry weight and leaf area index, were identified as herbicide-resistant and high-performing, making them suitable for cultivation purposes. Pre-emergence application of effective herbicides like Totril is advised to control weeds without reducing crop performance.
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