Document Type : Research Paper
Authors
1
Department of Plant Production Engineering and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili , Ardabil, Iran.
2
Professor of Agriculture and Plant Breeding Department of Mohaghegh Ardabili University
3
Director of Department of Agriculture and Plant Breeding of Mohaghegh Ardabili University
4
Associate Professor at the Research and Education Center for Agriculture and Natural Resources in Ardabil Province (Moghan), Iran
5
Research Associate Professor Plant Protection (Ecology-Weed) Protection Department, Ardabil Agricultural and Natural Resources Research Centre, AREEO, Ardabil (Moghan), Iran
Abstract
Background and Objectives: The present research was conducted in order to investigate the effect of planting cover crops at different dates and densities on soybean yield and yield components in competition with weeds and also to introduce the best treatment during two growing seasons.
Materials and Methods: The experiment was conducted as a factorial design in the form of a randomized complete block design with three replications during growth seasons of 2020-2021 and 2021-2022 in the research farm of the Agricultural and Natural Resources Research and Training Center of Ardabil Province (Moghan). The studied factors include the date of planting cover crops in two levels (at the same time and three weeks after soybean planting), their planting density in two levels (recommended and triple recommended) and the type of cover crop in 12 levels (including autumn barley, oats, autumn rye, autumn wheat, berseem clover, Persian clover, crismon clover, yellow sweet clover, red clover, annual alfalfa, bitter vetch and hairy vetch). Also, two control treatments were considered in the form of pure soybean cultivation (without cover crop cultivation) along with spraying and without spraying against weeds next to each replication.
Results: The variance analysis of the data showed that the simple and intraction effect of the study treatments was significant in most of the traits. The lowest density of weeds in the first and third stages of sampling was obtained in the treatment of Berseem clover among the soybean rows on the second date and the second density (10.50 and 5.50 plants per square meter, respectively). In the second stage, the sampling of bitter vetch cultivation treatment among soybean rows on the second date and the second density had the lowest weed density (11.17 plants per square meter). Also, the lowest amount of weed biomass in all three stages of sampling related to the cultivation treatment of Berseem clover among soybean rows on the second date and second density (1.40, 3.47 and 4.14 grams per square meter, respectively). All the cover crops studied had the highest biomass on the first sowing date and the second density. Berseem clover with the highest biomass production (137.02 grams per square meter) was ranked first. The maximum values of plant height, number of pods per plant, number of seeds per pod, weight of 100 seeds and seed yield traits were obtained in the treatment of hairy vetch among the rows of soybeans on the sowing date with a delay and triple recommended density. These traits was showed an increase of 51.72, 70.31, 28.93, 36.17 and 79.45 percent, respectively compared to the minimum value of these traits in the first control treatment.
Conclusion: The use of cover crops led to the control of weeds and increased soybean yield and yield components compared to the control treatment (no cover crop and no spraying against weeds). Among the cover crops, the cultivation of hairy vetch among the rows of soybeans, due to its fast growth and better adaptation to the region, minimal competition with the main plant and also better control of weeds, increased the seed yield in soybeans. Therefore, it is recommended to use this cover crop in order to achieve the goals of sustainable agriculture in these areas.
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