ارزيابي عملكرد علوفه و دانه گياهان چند ساله با نياز آبي كم در اراضي زراعي رها شده

Evaluation of Seed and Forage Yield of Perennial Plants with Low Water Requirement in Abandoned Farming Lands

نوسانات بارندگي، محدود شدن منابع آبي و شورشدن چاه ها و رها شدن زمين هاي زراعي و به دنبال آن فرسايش خاك، همگي تهديدات بزرگي براي اراضي زراعي به شمار مي روند. در اين راستا توجه به پايداري توليد از طريق استفاده از گياهان كم توقع (نياز آبي وكودي پايين و كنترل كننده علف هرز) و فرصت طلب در استفاده از بارش هاي فصلي از قبيل گياهان چند ساله مرتعي مي تواند گزينه قابل تاملي باشد. در اين راستا جهت تعيين بهترين الگوي كشت در استفاده بهينه از منابع خاكي و آبي اراضي كشت و صنعت مزرعه نمونه آستان قدس رضوي اقدام به كشت گياهان چند ساله كم توقع از خانواده گندميان و لگومينوز در زمين هاي زراعي رها شده از سال 1391 طي دو سال گرديد. در اين آزمايش 10 گونه از گندميان دائمي شامل چاودار كوهي (Secale montanum Guss.)، چمن گندمي بلند (Agropyron elongatum Host.)، چمن گندمي مياني (Agropyron intermedium Host.)، چمن گندمي تاج خروسي (Agropyron cristatum L.)، چمن گندمي رونده (Agropyron repense L.)، فتان بلند (Festuca arundinaceae Schreb.)، جارو علفي جويباري (Bromus riparius Rehmann.)، علف پشمكي (Bromus inermis Leyss.)، علف باغ (Dactylis glomerata L.)، ارزن پادزهري (Panicum antidotale Retz.) و دو گونه لگوم شامل اسپرس (Onobrychis sativa Lam.) و شبدر قرمز (Trifolium pretense L.) كه در نيمه دوم آبان ماه 1391 كشت و برداشت در مرداد ماه 92 و 93 انجام گرديد. پس از كاشت، آبياري دو نوبت انجام شد و از نيمه ارديبهشت پس از خاتمه بارندگي ها آبياري هر 22 روز يك بار تا مرداد ماه انجام شد. نتايج نشان داد كه متوسط عملكرد ماده خشك در سال هاي 1392 و 1393 به ترتيب 1432 و 3663 كيلوگرم در هكتار بود. در سال 1393 از بين گراس ها، بالاترين عملكرد علوفه خشك مربوط به گونه هاي چمن گندمي بلند و چاودار كوهي (به ترتيب 10584 و 4029 كيلوگرم در هكتار) بود. عملكرد دانه گراس هاي پاياي مورد مطالعه در سال دوم در گونه چمن گندمي بلند 185 و در گونه چمن گندمي تاج خروسي 1085 كيلوگرم در هكتار متفاوت بود. نتايج اين پژوهش نشان داد كه عملكرد گراس هاي پايا در سال اول بسيار اندك بوده و از نظر رقابت با علف هاي هرز ضعيف عمل نمودند، ولي در سال دوم عملكرد ماده خشك افزايش معني داري نشان داد. همچنين مهمترين عوامل موثر در افزايش عملكرد دانه تعداد پنجه در بوته، بالا بودن درصد پنجه بارور و تعداد دانه در سنبله بود. بنابراين استفاده از گونه هاي كم نهاده به ويژه گونه هاي جنس آگروپايرون با كمترين ميزان آبياري در اراضي فارياب به جهت توليد علوفه و يا عملكرد دانه امكان پذير مي باشد.

Introduction: Drought is a natural phenomenon in arid and semi-arid regions of the world. It is created by low precipitation، high evaporation and reduced soil moisture. Today، they are the major threats to agricultural lands due to fluctuations in rainfall، limited water resources، wells salinization and subsequently abandoned farming lands. Iran is located on the world's dry belt and more than 90 percent of its area is located in the arid and semi-arid climatic regions. It has been reported that the annual rate of soil erosion is up to 33 tons per hectare and 5 to 6 times more than the standard limit. Also، 90% of the country's protein production comes from animals sources. Due to the lack of adequate forage production، the main burden of protein production is imposed on the natural resources and pastures. Therefore، In order to enhance soil stabilization and maintain its fertility، optimum use of off-season precipitations، preventing the flow of water and protecting the abandoned farming lands from the flood risk، increasing the water permeability in the soil، and helping to feed the underwater aquifers and finally the production of forage and seeds، the development of perennial plants cultivation is an important conservative practice. The aim of this study is to emphasize on the selection of the best perennial forage species with low water requirements and acceptable performance for renovation of the abandoned farming lands and moving towards sustainable agriculture approaches. Materials and Methods: In this experiment، 10 species of perennial grasses (Agropyron elongatum Host.، Secale montanum Guss.، Festuca arundinaceae Schreb.، Dactylis glomerata L.، Agropyron intermedium Host.، Agropyron repense L.، Agropyron cristatum L.، Panicum antidutale Retz.، Bromus inermis Leyss.، Bromus riparius Rehmann، Agropyron cristatum L.) and two legumes includes Trifolium pratense L.، Onobrychis sativa Lam. were studied at Asatan-e-Ghods Razavi farm in Mashhad from 2013 to 2014. The seeds were sown in early November and well-watered for twice after planting and then irrigated by the end of rainfall from May to August، every 22 days.The harvesting time was late August. Results and Discussion: The results showed that in the first year، the average of seedling establishment was 71% for all species with the lowest 13% for P. antidutale Retz. and the highest 99% for S. montanum Guss. Also، in the years 2013 and 2014 the average of dry forage yield were 1432 and 3663 kg.ha-1، respectively. In the second year، the highest dry forage yield among the species belonged to A. elongatum Host.and B. inermis Leyss. with 10584 and 4029 kg.ha-1، respectively. Also، the grain yield of perennial grasses varied between 185 for A. elongatum Host. to 1085 kg.ha-1for A. cristatum L. In the studied species harvest index was between 2 and 34%. In the first year of perennial species growth، emergence and seedling establishment are one of the most important factors affecting on the increasing seed yield and forage yield. Also، the grain yield was affected by the high number of fertile tillers or stem per plant and number of grains per spike. Another remarkable point was that some grasses showed good seed germination and seedling vigor after immediately harvesting time. The highest seed germination percentage for S. montanum Guss.، A. elongatum Host.، B. inermis Leyss.، A. cristatum L. and B. riparius Rehmann were 96%، 90%، 58%، 55% and 40%، respectively. Conclusion: The results suggest that the yield of perennial species in the first year was very low and weak to compete with weeds (except S. montanum Guss.). But in the second year، dry forage yield has increased up to 2 or 3 times. Due to limited water resources in Iran، area of abandoned lands (low yield) is increasing. Therefore، the selection of Agropyron genera as a drought tolerant species with the aim of increasing the productivity of the land and to prevent soil erosion and to produce forage or grain yield could be considered. Acknowledgements: The authors acknowledge the financial support of the project by Mazra-e-Nemoneh of Astan Ghodes.