بررسي اثر روش هاي كاشت پياز خوراكي (Allium cepa L.) بر خصوصيات رشدي اويارسلام ارغواني (Cyperus rotundus L.) تحت سطوح مختلف كود نيتروژن

Evaluating the Effect of Onion (Allium cepa L.) Sowing Methods on Growth Characteristics of Purple Nutsedge (Cyperus rotundus L.) under Different Levels of Nitrogen Fertilizer

به منظور بررسی اثر روش¬های كاشت پیاز خوراكی بر خصوصیات رشدی اویارسلام ارغوانی تحت سطوح مختلف كود نیتروژن، آزمایشی در سال 1392 در گلخانه تحقیقاتی دانشكده كشاورزی دانشگاه بیرجند به صورت فاكتوریل در قالب طرح بلوك¬های كامل تصادفی در سه تكرار اجرا شد. فاكتور اول شامل سه روش كاشت پیاز خوراكی (بذر، سوخچه و نشاء) و فاكتور دوم شامل سه سطح مختلف نیتروژن (50، 100 و 150 كیلوگرم نیتروژن خالص در هكتار) بود. نتایج تحقیق حاضر نشان داد در طی فصل رشد حداكثر میزان رشد اویارسلام ارغوانی مربوط به روش كاشت مستقیم بذر و سطوح بالای نیتروژن بود بطوری¬كه بعد از 10 هفته پس از كاشت، بیشترین مقدار ارتفاع (33/92 سانتی¬متر)، سطح برگ (65/446 سانتی¬متر مربع)، وزن خشك اندام هوایی (306/7 گرم در بوته)، تعداد غده (33/15 غده در گلدان) و وزن خشك كل اندام زیرزمینی (369/5 گرم در بوته) در روش كاشت مستقیم بذر و سطوح بالای نیتروژن (100 و 150 كیلوگرم در هكتار) بدست آمد. همچنین در طی فصل رشد كمترین میزان رشد این علف هرز مربوط به روش كاشت سوخچه و سطوح پایین نیتروژن (50 كیلوگرم در هكتار) بود. از طرفی، نتایج این آزمایش حاكی از واكنش مثبت اویارسلام به مقادیر بالای كود نیتروژن می‏باشد و نشان می‏دهد كشاورزان با مصرف نیتروژن بیشتر غده‏دهی اویارسلام را نیز افزایش خواهند داد و این قطعاً به ضرر گیاه زراعی خواهد بود. بنابراین استفاده از روش كاشت سوخچه و سطوح متوسط نیتروژن (50 و100 كیلوگرم در هكتار) در زراعت پیاز جهت به حداقل رساندن خسارت علف‌هرز اویارسلام ارغوانی توصیه می¬شود.

Introduction: 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. Materials and Methods: 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. Results and Discussion: 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. Conclusion: 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.