Document Type : Research Paper - Agronomy
Authors
1 MS Graduated of Agroecology
2 faculty member
3 Assistant Professor, Department of Agronomy and Plant Breeding, Faculty of Agriculture, University of Jiroft, Jiroft, Iran.
4 Faculty member
Abstract
The first and most important step in weed management is to know the structure of communities, flora and their geographical distribution. In fact, by knowing the biodiversity, density and dominance of weeds in each region, we can manage weeds and prevent the growth of noxious weed species in different region. In order to study the effects of chickpea pre sowing and different levels of nitrogen fertilizer on weed biodiversity indicators, relative abundance, density and biomass of weeds in three genus of millet, an split factorial experiment based on randomized complete block design with three replications was conducted in the research field in University of Jiroft during 2018-2019. The treatments included two levels of chickpeas pre sowing and no pre sowing with chickpea, three levels of nitrogen fertilizer 200, 300, 400 kg.ha-1 from the source of urea and three genus of millet, Pearl (Pennisetum glaucum), Foxtail (Setaria italica) and common millet (Panicum miliaceum). In generally, ten weed species were observed in the experimental plots in different treatments which maximum frequency in three sampling stages were Cyperus rotendus L., Poa nemoralis L. and Cichorium intybus L., The highest (3.03) and lowest (0.24) relative abundance belonged to Cyperus rotendus L. and Cichorium intybus L., respectively. The highest stability coefficient of weed species and the treatment of no fertilizer and nano nitrogen fertilizer had the lowest this index. Shannon diversity index was higher in all three sampling stages in chickpea pre-sowing treatments (1.14, 0.72 and 0.63) and 400 kg.ha-1 urea fertilizer (1.29, 0.86 and 0.76). The highest Margalef index (1.08, 2.11) was assigned to the third level of nitrogen fertilizer treatment in the first sampling stage (20 days after millet sowing) and chickpea pre-sowing treatment, respectively. In all treatments and in three stages of weed sampling, the trend of Simpson index changes was variable. The lowest dry weight of weeds belonged to common millet; in the second stage of sampling, it decreased by 14 percent and 21 percent compared to pearl millet and foxtail millet, respectively, and in the third stage, it decreased by 13.5 and 20.8 percent. The lowest and highest populations of weed species were observed in the first and third sampling, respectively. According to the results of this study, which chickpea pre-sowing treatments, different levels of nitrogen fertilizer and millet species are effective on weed populations and biodiversity indices, it is suggested that in order to prevent weed invasion and competition with the target plant, In order to prevent weed invasion and competition with the target plant, by selecting the right plants before and after planting the target plant in monoculture systems and properly managing the nutritional elements required by plants, the abundance of weeds and their contribution to the absorption of nutrients in the soil, as well as the use of chemical herbicides as environmental pollutants, can be reduced and the application of macro nutrients can be based on the needs of the plant and the application of macro nutrients specially nitrogen fertilizers should be based on the plant's needs.
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