بررسی واکنش کاهش عملکرد گندم به رقابت یولاف وحشی در سطوح مختلف نیتروژن

نوع مقاله: علمی - پژوهشی

نویسنده

استادیار، گروه کشاورزی، واحد رامهرمز، دانشگاه آزاد اسلامی، رامهرمز، ایران

چکیده

به‌منظور بررسی کاهش عملکرد گندم (Triticum aestivum) ناشی از تداخل یولاف وحشی (Avena fatua) در سطوح مختلف کود نیتروژن، یک پژوهش مزرعه‌ای به‌صورت کرت‌های خرد شده در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در سال زراعی 91-1390 در مزرعه‌ای در شهرستان رامهرمز اجرا شد. تیمارهای آزمایش شامل کود نیتروژن، به‌عنوان فاکتور اصلی، در سه سطح و تراکم یولاف وحشی، به‌عنوان فاکتور فرعی، در پنج سطح بودند. برای توصیف رابطه کاهش عملکرد-تراکم یولاف وحشی از معادله هایپربولیک دو پارامتره استفاده شد. نتایج نشان داد افزایش تراکم یولاف وحشی تأثیر معنی‌داری روی کاهش عملکرد دانه گندم داشت. شیب اولیه مدل هایپربولیک (i)، در کرت‌هایی که نیتروژن در آن‌ها استفاده شد به‌طور معنی‌داری بیشتر بود. به‌علاوه، اثرات معنی‌دار کاربرد نیتروژن روی حداکثر کاهش عملکرد برآورد شده گندم (پارامتر A) نیز مشاهده شد. مصرف 150 کیلوگرم نیتروژن در هکتار قبل از کاشت گیاه زراعی (تیمار N1) نسبت به سایر تیمارها باعث افزایش قابلیت رقابت علف هزر یولاف وحشی با گندم  شد. نتایج این مطالعه نشان داد که کاربرد کود نیتروژن در گندم مورد هجوم یولاف وحشی، باعث افزایش توانایی رقابت یولاف وحشی گردید، اگرچه کاهش عملکرد گندم با مصرف کود نیتروژن در واحد سطح افزایش یافت ولی چنین کاهشی در کاربرد یک مرحله‌ای نیتروژن (تیمار N1) بیشتر از کاربرد چندمرحله‌ای نیتروژن (تیمار N2) بود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluating the Wheat (Triticum aestivum) Yield Loss Caused by Wild Oat (Avena fatua) Interference at Nitrogen Different Levels

نویسنده [English]

  • j. pourreza
Assistant Professor, Department of Agriculture, Rmhormoz Branch, Islamic Azad University, Ramhormoz, Iran
چکیده [English]

Abstract
Background and Objectives
Wild oat was described as a vigorously growing weed with a capability to attain greater height, and establish and develop extensive leaf area and horizontal branches when moisture and nutrients are not limiting. Fertilization is an important agronomic strategy used extensively to increase crop yield. Although, the effect of fertilizers is extensively investigated in wheat, there is little information to assess the effect of fertilizer application on wheat yield loss due to wild oat interference. The objective of this study was to investigate the wheat yield loss caused by wild oat interference at nitrogen different levels.
Materials and methods
In order to evaluate the wheat yield loss caused by wild oat interference at different nitrogen levels, a field experiment was conducted at a farm in Ramhormoz city (latitude 31.16°N, longitude 49.36°E and 151 m asl), south-west of Iran in 2011-2012. The experiment was designed as a randomized complete block with a split plot arrangement with nitrogen fertilizer
(N0: unfertilized control, N1: the use of 150 N Kg ha-1 before wheat seeding and N2: the use of 50 N Kg ha-1 before wheat seeding + 100 N Kg ha-1 at late tillering stage of wheat) as the main plot and wild oat density (D0: weed- free control, D1: 25, D2: 50, D3: 75 and D4: 100 plants m-2) as the subplot with three replications.
Results
A hyperbolic function was used to describe yield loss-density relationship. Increasing wild oat density had asymptotic-type effect on wheat yield loss. Initial slope (i) of the rectangular hyperbola model was a significantly greater when nitrogen fertilizer was applied. Moreover, for the rectangular hyperbola model, there was significant effect of nitrogen application on estimated maximum wheat yield loss (A). Application of 150 N Kg ha‑1 (N treatment) before crop seeding resulted in a greater competitive ability of wild oat than other treatments.
Discussion
The results of this study suggest that the application of nitrogen fertilizer increases wild oat competitions when wheat fields infest with wild oat. Although the wheat yield loss was increased by N application, a such reduction was more recorded at N application than multistage-applied N. Greater knowledge of the effect of N on weeds and crop grown in competitive mixtures may allow a better understanding of why differences occurred among previous studies and aid development of fertilization strategies to reduce weed competition with crops. 

کلیدواژه‌ها [English]

  • Competition
  • Fertilizer
  • Hyperbola model
  • Interference
  • Weed
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