پديد آورندگان :
گلستاني فر، فرزانه دانشگاه بيرجند - دانشكده كشاورزي , محمودي، سهراب دانشگاه بيرجند - دانشكده كشاورزي - گروه زراعت و اصلاح نباتات , زماني، غلامرضا دانشگاه بيرجند - دانشكده كشاورزي - گروه زراعت و اصلاح نباتات , سياري زهان، محمدحسن دانشگاه بيرجند - دانشكده كشاورزي - گروه زراعت و اصلاح نباتات
كليدواژه :
رقابت , سري هاي افزايشي , كم آبي , علف هرز
چكيده فارسي :
يكي از مهم ترين عواملي كه باعث كاهش توليد گياهان زراعي در سراسر جهان مي شود، كمبود آب در طي فصل رشد است، در اين راستا
به منظور بررسي اثر تنش خشكي و رقابت درون و برون گونه اي بر وزن خشك ريشه و كارايي مصرف آب گندم و چاودار، مطالعه اي در بهار سال ۱۳۹۱ در گلخانه تحقيقاتي دانشكده كشاورزي دانشگاه بيرجند به صورت فاكتوريل سه عاملي در قالب طرح كاملا تصادفي با سه تكرار اجرا شد. عامل هاي آزمايش شامل چهار تراكم گندم (صفر، ۸، ۱۶، ۲۴ بوته در گلدان)، چهار تراكم چاودار (صفر، ۲، ۴، ۶ بوته در گلدان) و دو سطح تنش خشكي شامل آبياري در ۲۰٪ و ۶۰ ٪ تخليه رطوبت ظرفيت زراعي خاك بود. براساس نتايج تجزيه واريانس، تمامي اثرات متقابل، تأثير معني داري (۰/۰۱>P) بر كارايي مصرف آب گندم داشتند اما تنها اثر متقابل رقابت برون گونه اي و تنش خشكي بر كارايي مصرف آب چاودار معني دار (۰/۰۱>P) بود. همچنين اثر متقابل سه گانه نيز تأثير معني داري (۰/۰۱>P) بر وزن خشك ريشه گندم داشت. نتايج نشان داد كه با افزايش تنش خشكي كارايي مصرف آب در گندم به ميزان ۱۶/۹۸درصد كاهش و در چاودار ۳۳/۹۵ درصدافزايش يافت. كارايي مصرف آب در گندم و چاودار تحت تاثير رقابت درون گونه اي به ترتيب ۱۰/۴۳ و ۲۸/۱۶
درصد افزايش و تحت تأثير رقابت برون گونه اي به ترتيب ۵۷/۳۹ و ۸۱/۰۳ درصد كاهش يافت. وزن خشك ريشه گندم تحت تأثير تنش خشكي قرار نگرفت ولي با افزايش تراكم چاودار و تراكم گندم به ترتيب ۶۴/۲۹ و ۴۸/۹۵ درصد كاهش يافت همچنين وزن خشك ريشه چاودار تحت تأثير تنش خشكي و رقابت برون گونه اي و درون گونه اي به ترتيب ۳۷/۱۴، ۴۷/۴۳ و ۳۳/۶۰ درصد كاهش يافت.
چكيده لاتين :
Introduction: Deficiency of water during the plant growth is one of the main factors which reduce the crops
production around the world. Drought stress is one of the most important tensions that may occur around the low
rainfall, high temperature and wind blowing environments. Plant response to this stress depends on the stage of
plant growth and drought intensity. Weeds are unwanted and harmful plants with disturbance in agricultural
practices which make increase the cost of crop production and reduce the crop yields. Rye (Secale cereal L.) is
one of the most important weeds at wheat fields in Iran (Baghestani and Atri, 2003). Low expectations,
allelopathic effects and similarity of life cycle and morphology, caused increasing of rye density in winter wheat
fields. Water use efficiency (WUE) as an important physiological characteristic indicates the ability of plants to
water stress. WUE may be affected by climatic and soil or plant factors. In plant communities, competition is
one of most important physiological topics (Evans et al, 2003). At Inter-specific competition, weeds interfere to
absorbing of light, water and nutrients through the adjacency with crop and so affect the growth and yield of
crops. Weeds often compete with crops for soil water and reduce the accessibility of water. Competition between
weeds and crops decrease the soil moisture and cause water stress which might decrease the weeds and crops
growth. When the supply of water is limited, water drainage overlap areas in soil profile could be occurred
relatively fast at early of in the crop life cycle.
Materials and Methods: In order to study the effects of drought stress on water use efficiency and root dry
weight of wheat (Triticum aesativum L.) and rye (Secale cereale L.) in competition conditions, a pot experiment
was conducted in the greenhouse of Agriculture Faculty , University of Birjand in 2012. The experiment was
arranged as factorial based on completely randomized design with three replications. The treatments were
included four wheat density (0, 8, 16 and 24 plants per pot), four rye density (0, 2, 4 and 6 plants per pot) and
two levels of drought stress (irrigation after depletion of 20 and 60 % of field capacity moisture).
Results and Discussion: The results showed that all interaction effects were significant (P < 0.01) on water
use efficiency of wheat, but only the interaction effect between inter-species competition and drought stress was
significant (P < 0.01) on water use efficiency of rye. Interaction effect between drought stress, wheat and rye
density was significant (P < 0.01) on root dry weight of wheat. The results revealed that water use efficiency
decreased 17 % in wheat and increased 34 % in rye by increasing of drought stress. The water use efficiency of
wheat and rye increased 10.4 and 28.2 % under intra-species competition and decreased 57.4 and 81 % under
inter-species competition, respectively. Drought stress did not affect root dry weight of wheat, but with
increasing of rye and wheat density, root dry weight decreased 64.3 and 48.9 %, respectively. Also root dry
weight of rye decreased 37.1, 47.4 and 33.6 % under drought stress conditions, inter and intra-species
competition, respectively. Intra-specific competition decreased biological yield and water use efficiency through
decreasing growth characters, yield and components yield of wheat. Increasing stress intensity reduced leaf
photosynthesis and increased sugar requirements for cell osmotic adjustment, so availability of assimilates
reduced and root growth stopped. In the other words, root dry mater of plants reduced in drought stress
conditions.
Conclusions: The results of this study indicated that drought stress reduced root dry mater of rye and water
use efficiency of wheat and rye. Increasing inter-specific competition between wheat and rye reduced water use
efficiency and root dry matter in two plants, but increasing intra-specific competition increased the studied traits.
Generally, because of the overlap area of root development in wheat and rye, and more extensive root system of rye than the wheat, rye has higher competitive strength for water uptake.
