فهرست مطالب nosratollah karimi arpnahy

Increasing crop competitive ability is an important part of integrated weed management (IWM). In this regard, identifying weeds reaction to soil fertility status for developing fertilizing methods, as components of IWM programs, is a necessity.
In order to evaluate the growth characteristics of purple nutsedge under the conditions of interference with onion, a factorial experiment based on randomized complete block design was conducted with three replications at the Research Greenhouse of University of Birjand in 2013. The first factor included three sowing methods of onion (seed sowing, onion set and transplanting) and the second factor included three levels of nitrogen (50, 100 and 150 kg N ha-1, equivalent to 25, 50 and 75 mg N kg-1 soil), urea fertilizer with a purity of 46% was used for this purpose.
The results of analysis of variance showed that sowing method and nitrogen levels had significant effects on plant height, leaf area, aboveground dry weight as well as tuber number and underground dry weights. Moreover, the interaction between sowing methods and nitrogen levels had a significant effect on plant height, leaf area, aboveground dry weight as well as tuber number and underground dry weights. The results of the comparisons of the mean for the interaction of planting methods and different levels of nitrogen indicated an increased weeds growth in direct seeding method and high levels of nitrogen in weed height trait, so that the greatest nutsedge height during the growing season (92.33 cm) was obtained at direct seeding method and high nitrogen levels . Moreover, the lowest weed height during the growing season was obtained at onion set planting method and 50 kg ha-1 nitrogen. The highest leaf area of purple nutsedge at ten weeks after planting (446.65 cm2), was obtained in direct seeding method and high levels of nitrogen, and the lowest value for this trait (203.38 cm2), was observed in onion set planting method. The greatest shoot dry weight of purple nutsedge during the growing season was observed in direct seeding method and high levels of nitrogen. The maximum amount of this trait at eight and ten weeks after planting was achieved in the level of 100 kg N ha-1 which was about 3.797 and 7.306 gr plant-1, respectively. Also the minimum shoot dry weight of weed was produced in onion set planting method and their amounts were about, 1.161 and 4.229 gr plant-1 at eight and ten weeks after planting, respectively. The greatest tuber number of purple nutsedge during the growing season were observed with seed planting method which were 7 and 15.33 tuber per pot at eight and ten weeks after planting, respectively. Moreover, the minimum tuber number of weed was produced in onion set planting method and were about 1.66 and 5.66 tuber per pot at eight and ten weeks after planting, respectively. The maximum underground dry weight of purple nutsedge during the growing season was obtained at direct seeding method and high levels of nitrogen. The maximum amount of this trait at eight and ten weeks after planting was obtained in the level of 100 kg N ha-1 which were about 2.472 and 5.396 gr plant-1, respectively .The minimum underground dry weight of weed was achieved in onion set planting method which were about, 0.888 and 1.873 gr plant-1 at eight and ten weeks after planting, respectively.
Overall ANOVA results showed that the sowing method and level of nitrogen as well as their interaction had a significant effect on all studied traits of purple nutsedge. Evaluation of growth characteristics of purple nutsedge under the conditions of interference with onion showed that the greatest and lowest growth of purple nutsedge were obtained where seed and onion sets planting methods were implemented, respectively. Moreover, the results indicated a positive response of purple nutsedge to high levels of nitrogen. Thus, in order to minimize the damage caused by purple nutsedge, the application of 100 kg N ha-1 nitrogen in onion set method is recommended as the most appropriate treatment for the management of purple nutsedge in infected onions farms. However, this study was conducted under greenhouse conditions and there is no doubt that repeating the test in the field is essential for verifying the results.

Crop nutritional management is one of the most important components of integrated weed management which maintains crop yield and reduces weeds performance over time. Nitrogen fertilizer is one of the major factors that has a significant effect on plant growth characteristics so that an optimized growth and yield could be achievable by choosing an appropriate type and amount of nitrogen.
In order to study the effect of different types and rates of nitrogen fertilizer on growth characteristics of purple nutsedge (Cyperus rotundus L.), an experiment based on CRD (Completely Randomized Design) was conducted with three replications at the Research Greenhouse of University of Birjand in 2013. 12 different treatment levels consisting of calcium nitrate, ammonium sulphate and urea as well as nitrogen rates of these fertilizers (0, 50, 100, 200 mg N kg-1 soil) were used to conduct the research.
ANOVA results showed that nitrogen fertilizer treatments had a significant effect (P≤0.01) on all study traits of nutsedge. The results of this study showed that different growth characteristics of purple nutsedge responded differently to the nitrogen fertilizer treatments The greatest height of purple nutsedge (94 cm) was observed with 50 mg N kg-1 soil of ammonium sulfate source, which provided a 27.3% height increase compared to the control. The greatest stem number of weed was achieved with 50 mg N kg-1 soil of calcium nitrate, which provided a 37.50% increase in stem number compared to the control. Application of 50 mg N kg-1 soil of ammonium sulfate increased the weed leaf number by 62.37% compared to the control and showed the greatest value of this trait amongst all study treatments. Results showed that increasing urea consumption resulted in a significant increase in plant leaf area, so that using 50 mg N kg-1 soil of this source showed the highest leaf area, which accounted for 59.88% increase compared to the control. Increasing ammonium sulphate usage significantly increased the pre-tuber number, so that utilization of 50 mg N kg-1 of this fertilizer resulted in the highest pre-tuber number and 52.60% increase compared to the control. Application of ammonium sulphate and calcium nitrate fertilizers enhanced the tuber number, so that the maximum tuber number was obtained where 50 mg N kg-1 of these fertilizers were applied. Results showed that applying 50 mg N kg -1 soil of ammonium sulfate provided a 76.3% increase in tuber dry weight compared to the control, and the highest tuber dry weight (3.780 g plant-1) was observed with this treatment. Utilization of 100 mg N kg-1 soil of urea resulted in the highest rhizome dry weight (60.46% increase compared to the control). Moreover, the greatest shoot dry weight (9.729 g plant-1) and underground dry weight (4.634 g plant-1) was obtained with the usage of 50 mg N kg-1 soil of ammonium sulfate. On the other hand, the lowest height (62 cm), stems number (2.66 stem pot-1), leaf number (15 leaf pot-1), leaf area (2310.85 cm2 pot-1), shoot dry weight (1.014 g plant-1), pre-tuber number (2.33 pre-tuber pot-1), tuber number (4.33 tuber pot-1), tuber dry weight (0.218 g plant-1), rhizome dry weight (0.330 g plant-1) and underground dry weight (0.785 g plant-1) were obtained high rates (200 mg N kg-1 soil) of calcium nitrate and urea fertilizers were used.
Overall, the results showed that the application of ammonium sulfate and urea fertilizers at moderate rates (50 and 100 mg N kg-1 soil) can increase growth characteristics and competitive ability of purple nutsedge. It seems that farmers should consider these results and apply fertilizer types and rates resulting in the lowest growth where face purple nutsedge infestation. In this regard, the response of natural and horticultural crops competing with purple nutsedge should also be taken into consideration that will need further studies.