تعیین ارزش غذایی علوفه کوشیا (kochia scoparia l.) تحت شرایط شوری و کم آبیاری

کاهش کمی و کیفی منابع آب همراه با شوری خاک از مهمترین ویژگی های مناطق خشک و نیمه خشک می باشد و تولید گیاهان شور زیست تحت این شرایط جهت تغذیه دام از پایدارترین روش های حفاظت از اکوسیستم های بیابانی محسوب می شود. هدف از این پژوهش بررسی کمی و کیفی علوفه کوشیا (kochia scoparia l.) تحت مدیریت شوری و کم آبیاری بود. این آزمایش به صورت کرت های خردشده در قالب طرح بلوک های کامل تصادفی در سه تکرار در سال 1394 در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد انجام شد. تیمارهای آزمایشی شامل 3 روش مدیریتی شوری: آب غیر شور (0.9 ﺩﺳﻲﺯﻳﻤﻨﺲ ﺑﺮ ﻣﺘﺮ)، مخلوط آب شور و غیر شور (15.45دسی زیمنس بر متر) و آب شور (30 دسی زیمنس بر متر)، 5 تیمار خشکی شامل: آبیاری کامل (100% جبران نقصان رطوبتی خاک)، کم آبیاری سنتی یا تنظیم شده 75% و 50% آبیاری کامل، و کم آبیاری نوین یا بخشی (جویچه ای یک در میان متغیر) 75% و 50% آبیاری کامل بود. نتایج نشان داد که اثر متقابل تنش شوری و خشکی باعث کاهش خاکستر خام و چربی خام و افزایش سدیم و پروتئین خام شد. همچنین اثر متقابل تنش شوری و خشکی بر روی میزان پتاسیم و کلر، ndf و adf، قابلیت هضم و انرژی متابولیسم معنی دار نبود که بیانگر بی تاثیر بودن تنش شوری و خشکی بر کیفیت علوفه کوشیا می باشد. بعلاوه افزایش شوری و خشکی بر عوامل ضد کیفیت علوفه مانند تانن و فنول بی تاثیر بود. در مجموع با توجه به پاسخ گیاه به تنش های شوری و کم آبی، می توان کوشیا را به عنوان گیاه علوفه ای برای بسیاری از مناطق به ویژه مناطق خشک و نیمه خشک که در ایران از وسعت زیادی هم برخوردار هستند، جهت برآورده ساختن نیازهای انواع دام های اهلی توصیه نمود.

The determine of nutrition value of Kochia (Kochia Scoparia L.) forage under salinity and deficit irrigation conditions

Introduction;The conventional water resources and crops do not meet all the requirement of human society in dry and saline areas. Sea water and brackish water and salt tolerant plant should be considered for research. Salt tolerant plants (halophytes) are highly evolved and specialized organisms. They have welladapted morphological, phenological and physiological characteristics allowing them to proliferate in the high salinity conditions and offer a lowcost approach to reclaiming and rehabilitating saline habitats. This approach would lead to the domestication of wild, salt tolerant plants to use as forage crops. Kochia scoparia (L., Schrad) is a highly, drought and salinity resistant plant widely used as emergency forage for livestock. Kochia can establish on saline soils, not only to produce protective shortlived vegetation coverage, but also is being used as an alternative forage crop, especially in regions faced with forage shortage. Kochia also has high forage yield potential; Kafi et al. (2010) reported an annual forage yield up to 11 ton ha1. On the other hand, there is no study on the effect of salinity and drought on the qualitative characteristics of forage in this plant. Therefore, the aim of this study was evaluate the effects of different salinity stress and deficit irrigation on qualitative forage of Kochia scoparia.;Materials and Methods;In order to investigate the effects of different levels of salinity stress and deficit irrigation on quantity and quality forage of Kochia, a randomized complete blocks design used in spilt plot arrangement with three replications. A field study was conducted in Agriculture Research field, College of Agriculture, Ferdowsi University during 2015 growing season. Treatment consisted of three levels of salinity stress (0.9 (nonsalinity water), 15.45 (mixture of nonsalinity and salinity water) and 30 (salinity water) dS/m) and five water deficits (100% full irrigation, 75 and 50 % full irrigation, 75 and 50% PRD). Plant height, number of lateral branch, fresh and dry forage yield was measured. Oven dried (75◦C for 72 h) chopped samples were ground to pass through a 1mm screen. The samples were analyzed according to the standard procedures for chemical composition (The quantities of Na+, K+ and Na+/ K+ ratio, Cl, NDF and ADF , ash amount, ether extract, crude protein, energy metabolism, phenol and tannin.;  ;Results and Discussion;The analysis of variance showed that the effects of salinity and deficit irrigation on ether extract and crude ash were significant and with increasing salinity and drought stress levels decreased, while the quantities of Na+ and crude protein increased. In all saline treatments, by decreasing the water consumption to the treatment of 50 % full irrigation increase in the amount of sodium was observed and after this treatment the amount of this ion was decreased. In addition, to their effects on the quantities of K+ and Na+/ K+ ratio, Cl, dry matter digestibility percent, energy metabolism, ADF and NDF were not significant. On the other hand, due to many leaves of Kochia, digestibility of its dry matter is similar to alfalfa. Also, increased salinity and drought did not effect forage quality factors such as tannin and phenol. These results indicate that, under drought stress and salinity, the qualitative characteristics of Kochia forage are completely preserved and not reduced.;  Conclusion;  Study results indicates that forage of Kochia scoparia can be recommended as a suitable forage for arid or semiarid conditions to provide the nutritional needs of domestic livestock. Therefore, the farmers along the desert areas, two big deserts in the center of Iran for example, are in extreme need of fodder for their animals, and the introduction of this species would provide an impressive economic benefit.