عنوان مقاله [English]
Introduction: The biodiversity of ago-ecosystems has always been the foundation for the continued functioning of food production systems and has ensured the production system's sustainability. To protect and optimally exploit the biological diversity of agricultural ecosystems, it is essential to understand the characteristics and spatial and temporal distribution of all of its components. In this regard, the role of weeds in creating and developing diversity in agricultural systems is of particular significance, as a large number of crops have close relationships with them and engage in genetic exchange. Among the primary reasons for examining biodiversity are instances of severe damage caused by destructive human activities to a large number of habitats, the commitment of countries to preserve biodiversity, the importance of measuring biodiversity as an indicator of the health of ecological systems, and the importance of measuring biodiversity. Cited as one of the most contentious concerns in the ecological management of ecosystems.
Materials and Methods: An experiment was conducted to examine the diversity and evenness of weed species in the form of split plots using a randomized complete block design with three replications at the Organic Farming Educational and Research Center of Razi University. The Experimental treatments consisted of animal manure (0, 10, and 20 t ha-1) as the main factor and cover crops (control, berseem clover, fenugreek, and Vicia villosa) as the sub-factor. Prior to canopy closure and the end of the growing season, the density and biomass of weeds were measured at two stages. Utilizing animal manure and cover crops increased sesame seed yield. In every treatment, the Margalef evenness index was greater than the Menhinick evenness index. Menhinick and Margalef richness indices revealed a 211 and 140% increase in diversity in the second sampling, compared to the first.
Results and Discussion: Interaction effects of animal manure and cover crop on the two indices of evenness Margalef and Menhinick demonstrate that there are minute differences between each index, so that the treatment involving 20 t ha-1 of animal manure and the cover crop of Vicia villosa exhibited the greatest degree of uniformity. Brillouin and Berger-Parker indices indicate that the weed biodiversity in the first sampling stage was 57% and 87% higher than in the second sampling stage. In the first and second sampling stages, the Shanon-Weiner diversity was 1.688 and 1.685, respectively. The results of this study demonstrated that the use of animal manure and the cultivation of cover plants by improving the physical and chemical condition of the organic farm's soil led to proper nutrition and increased sesame's ability to compete with weeds. Sesame's high level of competitiveness results in a more efficient absorption of environmental resources, which enhances plant performance.
Conclusion: Shanon-Weiner, Brillouin, and Berger-Parker indices in terms of biodiversity and Menhinic and Margalef indices in terms of weed species richness produced nearly identical results in this study; however, the overall results of the calculation of biodiversity measurement indicators indicated that the organic sesame farm has a relatively good biodiversity condition. Farmers can readily benefit from the cultivation of cover plants and the application of animal manure to maintain and improve biodiversity in agricultural ecosystems as one of the most desirable ecological solutions. To obtain a more accurate and reliable result, however, it is recommended that the role of manure application and the cultivation of cover plants be investigated during a multi-year study on the biodiversity of weeds.