نوع مقاله : مقالات پژوهشی
مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان اصفهان
عنوان مقاله [English]
Introduction: More than 7 thousand hectares of wheat and barley fields, in Isfahan province, and 200 thousand hectares of wheat and barley fields in Fars province has been infected by wild barley (Hordeum spontaneum Koch.). Wild barley is an annual, winter, diploid (2n = 14) plants, with the fragile axis and self-pollinating flowers. Wild oat seeds, after being separated from the mother plant at a depth of 1-3 cm left, and later in next winter sprouted. Conservation tillage and crop rotation are including the components of integrated weed management. Crop rotation because of a certain type of plant and its associated management of weeds in the rotation can provide a different habitat for weeds. Summer and winter plant crop rotation, plant diversity in a crop rotation, the use of reduced tillage systems and attention to the impact of plant residues, including those that are important in rotation. Tillage methods are considered as a way to control weeds. Although most researchers have agreed to increase the number of weeds in reduced tillage systems due to scattered non-sexual organs, in the case of annual weeds, some researchers believe the rise, and some believe that reducing the number of weeds in reduced tillage systems.
Materials and Methods: To study changes of weed density of weeds in wheat, especially wild barley, a three-year study (2011 to 2014) by using split plot randomized experiment based on a randomized complete block design with three replications was conducted in the Ardestan city. Main factors were different tillage systems including conventional tillage (moldboard plow use), minimum tillage (using a field cultivator) and no-tillage and six different rotations formed the sub plots. The use moldboard plow tillage with a depth of 25 cm has full buried seeds of wild oats. No tillage system without disturbing the soil, weed seeds will be exposed to the outside environment. The area of the sub-plots of 16 square meters (4 × 4) and an area of about 250 square meters for each replication, which, considering the distance between replication, as well as streams of water the total experiment was 1400 square meters. Seed varieties, were obtained from Seed and Plant Improvement Institute. In every year, wheat grain yield, weed dry weight and density of weeds in different rotations was carried out. Dominant weeds in the experiment were wild barley, wild oat (Avena fatua L.) and Phalaris (Phalaris spp). Other weeds that were less dense and less distribution in experiment and classified as other weeds were: barley mouse (Bromus spp), wild mustard (Sinapis spp), Lepidium Draba (Cardaria draba L.) and wild millet (Setaria spp). Statistical analysis was conducted by using SAS software and statistical tests were compared with Duncan at 5 percent.
Results and Discussion: In the first year of experiment the effect of tillage on the number of wild barley density, wild oats dry weight, Phalaris dry weight, Oats dry weight (all at 5%) and the number of stem Wild Oats (at 1%) was significant statistically. The results showed in the growing season of (2012-2013), conventional tillage systems and barley cropping in the early rotation, respectively, with 5.33 plants, 13.33 stems and 33.33 g dry weights per square of wild barley showed the lowest amounts compared to the other plants in beginning of rotation and also fallow periods. Similar trends were observed for the other tillage systems, except that the amounts of plant, stems dry weight of wild barley in no-tillage were higher than the other two systems. In the crop year of (2013-2014) maximum dry weights of wild barley (284.3 g m-2) was observed in the conventional tillage system and wheat crops in (canola - corn - wheat) rotation, respectively. The number of weed species present in the first and second year crops was respectively 3 and 7 species. In no tillage system compared with cultivator system, wild barley spike length was not significantly different, but in comparison with the moldboard was 13% longer. A similar trend was observed in the number of seeds produced by wild barley, and wild barley seed per square meter in no tillage systems was 40% higher. With regard to the initial contamination wild barely per square meter was 250 seeds per square meter, wild barely seed production after three years (two cropping seasons) and three moldboard plow tillage systems, field cultivator and soil tillage was still a considerable amount and can be a source of pollution for the next year. In simple terms, similar to the present study, short-term rotation despite the positive trend is still not a complete management to control this weed. In summary, the use of conventional tillage systems and the cultivation of crops belong to Poaceae family (except of barley) can be considered as factors increasing wild barley.
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