چكيده فارسي :
اين مطالعه با هدف بررسي اثرات تناوب‌هاي مختلف بر عملكرد دانه و برخي خصوصيات زراعي گندم (Triticum aestivum L.) در شرايط ديم انجام گرديد. آزمايش در قالب طرح بلوك‌هاي كامل تصادفي با چهار تكرار، در دو قطعه زمين مجاور هم در ايستگاه تحقيقات كشاورزي ديم سرارود- كرمانشاه به مدت شش سال از پاييز 1385 تا تابستان 1391 اجرا گرديد. تيمارها شامل پنج تناوب دو ساله گندم-گندم، آيش-گندم، نخود-گندم، ماشك–گندم و گلرنگ-گندم بود. در قطعه زمين اول در سال اول گندم كشت گرديد و در قطعه زمين دوم ساير گياهان زراعي كه در تناوب با گندم قرار مي‌گرفتند كشت شدند، به طوري‌كه در هر سال هر دو جز تناوب وجود داشتند. براي بررسي اثر تناوب‌هاي زراعي بر صفات مختلف مورد بررسي در گندم در هر سال از داده‌هاي مربوط به قطعه زميني كه تمام تيمارها در آن سال گندم بود استفاده گرديد. نتايج تجزيه واريانس نشان داد كه اثر سال بر ارتفاع بوته و اجزا عملكرد دانه گندم معني‌دار بود كه حاكي از شرايط مختلف آب و هوايي در سال‌هاي آزمايش بود. اثر متقابل تناوب در سال نيز بر ارتفاع بوته و تعداد سنبله در متر‌مربع معني‌دار بود و در آخرين دوره تناوب‌ها (سال 91-1390) اثر كشت مداوم گندم بر تعداد سنبله در متر‌مربع نمايان شد به طوري‌كه در اين سال كمترين تعداد سنبله در متر‌مربع در تيمار كشت متوالي گندم در مقايسه با ساير تناوب‌ها به دست آمد. نتايج عملكرد بيولوژيك و عملكرد دانه گندم نيز نشان داد كه اثر سال و تناوب زراعي بر آن‌ها معني‌دار بودند و تيمار گندم- گندم كمترين عملكرد را توليد نمود و ساير تناوب‌ها در كلاس بالاتر قرار گرفتند. طبق نتايج فوق كشت مداوم گندم بايد به طور كلي در منطقه حذف گردد و تناوب گندم با هر كدام از گياهان نخود (Cicer arietinum L.)، ماشك (Vicia dasycarpa Ten.) و گلرنگ (Carthamus tinctorius L.) با در نظر داشتن اهميت تنوع زراعي و عملكرد اضافي اين محصولات نسبت به آيش در منطقه كرمانشاه و ساير مناطق اكولوژيكي مشابه توصيه مي‌گردد.
چكيده لاتين :
Introduction
Crop sequencing with a particular arrangement in a 2-3 or more yearly period is known as crop rotation.
Considering crop diversity and soil fertility crop rotation is essential because it prevents soil degradation which
is a result of sequential cultivation of one crop causing nutrients imbalance, exudation of different compounds
and antibiotics from crop roots. Determining crops sequencing, affects crops yield and its quality. It was
reported by many researchers that including the forage crops and legumes as a winter crop in rotation either for
forage production or green manuring, i.e. growing two or three crops annually was a necessary practice for
improving the soil fertility as well as increasing the annual revenue. So, this study was conducted to investigate
effects of different crop rotations on grain yield and some agronomic traits of wheat in dryland conditions.
Materials and methods
The experiment was carried out based on randomized complete block design (RCBD) with four replications
in two neighbor sites in dryland agricultural research sub-institute Sararood - Kermanshah during six years from
autumn 2006 fall to 2012 summer. Treatments were concluded five crop rotations as wheat (Triticum aestivum
L.) - wheat, fallow - wheat, chickpea (Cicer arientinum L.) - wheat, vetch (Vicia dasycarpa Ten.) - wheat and
safflower (Carthamus tinctorius L.) - wheat. All crop rotations were included wheat so in one site the first year
wheat was cultivated in all plots and in other site the other components of crop rotations were cultivated. Plot
area was 10×20 m2. Plant height (10 randomized plants), number of spikes per meter square, number of seeds per
spike, thousand seeds weight, biologic yield and grain yield were analyzed.
Results and discussion
Main effect of year on wheat plant height and yield components were significant and showed different
climatically conditions in experiment years. Interaction effect of rotation × year was significant on wheat plant
height and number of spikes per m2, and in the end of rotation period (2011-12) effect of continuous wheat
appeared on number of spikes per m2 as in this year the lowest number of spikes per m2 in continuous wheat
observed compare to other rotations. Ghaffari (2002) considered the rotation of chickpea, sunflower (Helianthus
annuus L.) and fallow with wheat and reported no significant effect on plant height of wheat in three period of
rotation. The results of thousand kernel weight showed non significance difference among rotations and year ×
rotation interaction that were similar to results of Dogan et al. (2008) in two rotation period of wheat and
sunflower, canola (Brassica napus L.), chickpea and forage pulses. Results of composite ANOVA for biologic
and grain yield of wheat showed significant effect of year and treatment × year on these traits; and continuous
wheat had the lowest yield and other rotations were located in higher classes. Continuous wheat treatment at the
last year had the lowest spikes per meter square among rotations. Stevenson and Kessel (1996) stated an
increasing trend in wheat grain yield in pea (Pisum sativum L.) – wheat rotation compared to continuous wheat
due to breaking of diseases cycles and availability of potas, phosphorous and sulfur. Correlation between wheat
grain yield in different rotations with total precipitation showed that in all rotations except continuous wheat,
there was a positive significant correlation between precipitation and wheat grain yield. So, it can be concluded
that continuous wheat has reduced the potential usage of optimum growing conditions.
Conclusion Rotation of wheat with each of these crops (chickpea, vetch and safflower) can be proposed, considering the importance of crop diversity and additional yield of these crops.
