تنوع ژنتيكي ژنوتيپ‎هاي يولاف از نظر مقادير آهن و روي در شرايط آبياري كامل و تنش رطوبتي آخر فصل

Genetic Diversity of Oat Genotypes for Iron and Zinc Content under Complete Irrigation and Terminal Moisture Stress Conditions

با توجه به آهكی‌بودن خاك‌های استان كرمانشاه و هم‌چنین اهمیت نقش آهن و روی در جوامع انسانی و تلاش برای یافتن راه‎حل‌های مناسب جهت رفع مشكل، آزمایشی با هدف بررسی تنوع ژنتیكی به‌ترتیبی یولاف از نظر مقادیر آهن و روی و نیز صفات زراعی در دو شرایط آبیاری كامل و تنش رطوبتی در قالب طرح بلوك‌های كامل تصادفی به تعداد 33‌ژنوتیپ در سه تكرار در مزرعه تحقیقاتی پردیس كشاورزی و منابع طبیعی دانشگاه رازی كرمانشاه به اجرا در آمد. در این تحقیق دامنه تغییرات آهن دانه در شرایط آبیاری كامل و تنش رطوبتی به‌ترتیب از 59/63 (Wandering) 26/159(ND873364) و 94/57 (Preston)تا 28/114(Mortlock) و دامنه تغییرات روی دانه در شرایط آبیاری كامل و تنش رطوبتی به‌ترتیب از 07/30(Wallaroo) تا 71/52 (IA91098-2) و 81/27 (Wallaroo) تا 98/54(Mortlock) میلی‌گرم بر كیلو‌گرم بود. نتایج نشان‌داد كه ژنوتیپ‌ها از نظر مقادیر آهن و روی برداشت شده توسط دانه در هكتار در شرایط تنش رطوبتی، تفاوت معنی‎داری نشان‌دادند. رقم Quoll به‌دلیل عملكرد بالا، در شرایط تنش رطوبتی بیشترین مقدار آهن و روی در هكتار داشت. مقایسه بین صفات در شرایط آبیاری كامل و تنش رطوبتی نشان‌داد كه اغلب صفات اندازه‌گیری شده در شرایط تنش رطوبتی نسبت به شرایط آبیاری كامل كاهش یافتند، اما این كاهش برای غلظت آهن و روی دانه قابل‌توجه نبود.

<strong > Introduction </strong > Oat is an important crop which is cultivated in 9,679,190 hectares and produced as much as 22,504,708 ton worldwide (FAO. 2011). This crop is used mainly as forage cereal; however, it is also used for human consumption in the form of oatmeal and rolled oats because of high amounts of B and E vitamins (25). Regarding to calcareous soils of Kermanshah province (Iran) and the importance of iron and zinc functions in human societies and efforts to find out a way to solve the problems caused by their deficiencies, an experiment was performed to investigate the genetic diversity among oat genotypes in term of iron and zinc contents in grain and agronomical traits under complete irrigation and moisture stress conditions. <strong > Materials and Methods </strong > The experiment was carried out with 33 oat genotypes (Table1) in a randomized blocks design with two replications under complete irrigation and terminal drought stress conditions at the Research Farm of Campus of Agriculture and Natural Resources of Razi University, Kermanshah during 2011-2012 cropping seasons. Oat genotypes collected from different countries of the world were obtained from South Australian Research and Development Institute (SARDI). Sowing was performed by hand at five row plots, 1.2 m length, and 0.20 m row spacing. Regarding the amount and distribution of rainfall (Figure 1), irrigation was carried out five and two times at complete irrigation and terminal moisture stress conditions, respectively. Terminal (end-season) moisture stress was imposed at flowering stage. The rainfall at the cropping year of the experiment was 308 mm. Chemical fertilizer, herbicide and pesticide were not used at both sites. Before planting, the soil samples were collected from 0-30 cm depth from different parts of the field, air dried, passed a 2 mm sieve, and different physiochemical characteristics (Table 2) such as pH, EC, organic matter, zinc and iron contents of the sampled soil were determined (Page et al., 1982). At full physiological maturity, two middle rows of each plot were harvested to determine agronomic traits, grain’s iron and zinc concentrations. Grain Fe and Zn concentrations were measured by Atomic Absorption Spectrometer. <strong > Results and Discussion </strong > The stress intensity was calculated as much as 30.1% (Table 4). In complete irrigation condition, the average grain yield was 4951 kg/ha and “Wintaroo” (7163 kg/ha) performed better grain yield than others. In moisture stress condition, the average grain yield was 3485 kg/ha and “Quoll” (6491 kg/ha) showed better grain yield than others. The reported average grain yields were much higher than oat’s average grain yield in world which was 2325 kg/ha for 2011 (9). Results showed that oat genotypes did not significantly differ in grain’s Fe and Zn concentrations in both conditions. But, the range of data for iron in oat grain was from 63.59 (Wandering) to 159.26 (ND873364) and from 57.94 (Preston) to 114.28 mg/kg (Mortlock) in complete irrigation and moisture stress conditions, respectively. This range for zinc in oat grain were from 30.07 (Wallaroo) to 52.71 (IA91098-2) and from 27.81 (Wallaroo) to 54.98 mg/kg (Mortlock) in complete irrigation and moisture stress conditions, respectively. The analysis of variance showed significant variation among genotypes for iron and zinc uptakes under moisture stress condition. Due to higher grain yield of “Quoll” under moisture stress condition and acceptable grain yield in complete irrigation condition, the highest amount of iron and zinc of grain per hectare was found in “Quoll” under both conditions. The comparison of traits between complete irrigation and moisture stress conditions indicated that stress reduced most of traits, although these reductions were not considerable for iron and zinc in oat grains. As these reductions varied among genotypes, therefore, it could be concluded that the reductions or even increases in iron and zinc concentrations due to moisture stress were highly genotypic dependent. The results of coefficient correlations indicated that there was a positive significant correlation between zinc and iron uptake which could be helpful in breeding programs. The positive correlations between the concentration of zinc and iron in grains were also reported in the previous studies (Cakmak et al., 2004; Welch and Graham, 2005). <strong > Conclusions </strong > According to the results of this research, it can be concluded that the ranges of variations in iron and zinc in oat genotypes were considerable and useful which can be applied in continuing breeding programs. Moreover, “Quoll” (south Australian cultivar) could be introduced as a cultivar with high grain yield, high grain iron and zinc per hectare under moisture stress condition in Kermanshah province (Iran).