پديد آورندگان :
داداشي، فهيمه نويسنده دانشجوي سابق كارشناسي ارشد گروه زراعت، دانشكده علوم زراعي، دانشگاه علوم كشاورزي و منابع طبيعي ساري Dadashi, F. , زعفريان، فائزه نويسنده دانشگاه تربيت مدرس,دانشكده كشاورزي , , عباسي، رحمت نويسنده پرديس كشاورزي و منابع طبيعي دانشگاه تهران , , بهمنيار، محمدعلي نويسنده استاد گروه خاكشناسي، دانشكده علوم زراعي، دانشگاه علوم كشاورزي و منابع طبيعي ساري Bahmanyar, M. A.
كليدواژه :
رقابت , گياه پوششي , كود شيميايي , كمپوست
چكيده فارسي :
به منظور ارزیابی تغییرات تراكم و ماده خشك علف‌های هرز، عملكرد و اجزای عملكرد ذرت در حضور سویا و گندم به عنوان گیاهان پوششی با دو منبع كودی شیمیایی و آلی آزمایشی در قالب طرح بلوك‌های كامل تصادفی با سه تكرار در سال 1391 اجرا گردید. تیمارهای آزمایش شامل دو گیاه پوششی (سویا و گندم) و سه تیمار كودی (بدون كود، كود شیمیایی و كمپوست) بود كه مقدار كود بر اساس آزمایش تجزیه خاك و نیاز غذایی ذرت (به‌عنوان گیاه اصلی) لحاظ شد. همچنین كشت ذرت بدون گیاه پوششی در شرایط آلوده و عاری از علف هرز به عنوان شاهد در نظر گرفته شد. كشت ذرت در خرداد ماه و كشت گیاهان پوششی نیز به صورت هم‌زمان با گیاه اصلی و بین ردیف¬های گیاه اصلی صورت گرفت. نتایج نمونه‌برداری از علف‌های هرز نشان داد كه كشت ذرت به همراه گیاه پوششی سویا باعث كاهش تراكم علف‌های هرز نسبت به كشت ذرت بدون گیاه پوششی در شرایط آلوده به علف هرز شد، ولی گندم به علت تولید ماده خشك كمتر و از بین رفتن در اواخر فصل رشد در فرونشانی و كاهش تراكم علف‌های هرز موفق نبود. از این‌رو كمترین ماده خشك علف‌های هرز مربوط به كشت ذرت به همراه گیاه پوششی سویا و كمپوست و بیشترین مربوط به شاهد آلوده به علف‌های هرز بود. همچنین كمترین عملكرد دانه ذرت (3/2733 كیلوگرم در هكتار) مربوط به تیمار شاهد آلوده به علف هرز و بیشترین عملكرد دانه ذرت (به ترتیب 0/12124 و 3/8351 كیلوگرم در هكتار) مربوط به تیمار شاهد عاری از علف هرز و گیاه پوششی سویا با كمپوست بود. در بین تیمارهای كودی، گیاه ذرت در تیمارهای كمپوست و كود شیمیایی در هر دو گیاه پوششی دارای عملكرد بیولوژیك بیشتری نسبت به بدون كود بود و تفاوت این دو نیز از نظر آماری معنی‌دار نبود. از آنجا كه گیاهان پوششی موجب كاهش رشد علف‌های هرز شدند و همچنین تفاوتی بین استفاده از كود شیمیایی و آلی وجود نداشت می‌توان از این دو راهكار برای تولید مطلوب در راستای كشاورزی پایدار استفاده كرد.
چكيده لاتين :
Introduction: According to the importance of corn in supplying the human food directly and indirectly, it is one of the most important plants among crops. One of the major problems in corn production systems, is competition with weeds that reduce corn yield significantly. Weeds not only reduce crop yields but also decrease the commercial quality and the feeding palatability of main crops. They enhance the soil seed bank of weeds, which may cause continuous weed infestation of field crops as well. Herbicide application is a reliable and highly effective method for weed control. However, demand for safe food products that have been produced with a minimum application of chemical inputs is increasing. Therefore, farmers interested in weed management have to rely on other control approaches. An alternative weed control method is the use of cover crops, which can suppress the growth of weeds by preventing them from light and by producing allelopathic compounds. Cover crops successfully have been integrated into conservational agriculture systems in many areas of the world. Legumes are used as cover crop because of their rapid growth, in addition their potential to provide further nitrogen,along with high ability to compete with weeds.
Materials and Methods: In order to study the effect of cover crops (soybean and wheat) and different fertilizers sources on yield of corn and weed control, a filed experiment was conducted in randomized complete block design with three replications in 2012. Treatments included two cover crop (wheat and soybean) and three fertilizer (no fertilizer, chemical fertilizer and compost)..Fertilizer treatments was used according to soil analysis and requirement of corn (as a main plant). Weed-infestation and weed-free plots were used as controls. Study cultivars of corn, wheat and soybean were NS-640, Milan and Sari, respectively. Planting of corn was in June and cover crop was planted with corn simultaneously and between corn rows. The dominant weed species were velvetleaf (Abutilon theophrasti Medic.), johnson grass (Sorghum halepense (L.) Pers.), wild melon (Cucumis melo var. agrestis) and giant foxtail (Setaria glauca L.) in the field. In order to determine the dry weight and density of weeds, three-stage sampling was performed from the middle rows of corn. Corn yield was also measured by mechanical harvesting in middle rows and adjusting to 14% moisture. A week before the final harvest, ten plants of corn were selected randomly from the three middle rows of each plot and yield components including the number of rows in corn, number of kernels per row, weight of 1000 grains was measured.
Results and Discussion: The results showed that soybean cover crop reduced weed density compared to control in weed infestated plots, but wheat was not successful in suppressing weeds and reducing their density due to poor biomass and dying at the end of growing season . So, the lowest dry matter of velvetleaf, wild melon and other weeds were related to planted corn with soybean and compost and the maximum was related to monoculture of corn with weed infestation. Results of analysis of variance indicated treatments had significant effect on grain yield. The lowest yield of corn (2733.3 Kg ha-1) was in weed-infestation control while the highest one (12124.0 and 8351.3 Kg ha-1 respectively) was in weed-free control and soybean’ cover crop plus compost. For both cover crops between fertilizer treatments, compost and chemical fertilizer had more corn biological yield than no fertilizer and differences between this two fertilizer treatments wasn’t significant. Reduction of yield under no fertilizer treatments was due to competition for nutrients, light between weed and corn. The maximum and minimum number of rows in corn and number of kernels per row respectively was obtained with monoculture of corn in weed free and weed infestation, while the maximum weight of 1000 grains was observed in soybean with applying compost. Generally, the living mulch as cover crops can reduce competition between weeds and the main crop.
Conclusion: As cover crops reduce weeds growth, and there was no significant difference between chemical and organic fertilizer in corn yield, so we can use these two options for producing optimum yield in sustainable agriculture. Results showed application of soybean as cover crop, especially integrated with organic fertilizers, can be an alternative approach for herbicides and are more effective than the others.
