بررسي عملكرد و اجزاي عملكرد ژنوتيپ‌هاي مختلف ارزن تحت دو رژيم آبياري

Evaluation of Yield and Yield Components of Different Millet Genotypes Under Two Irrigation Regimes

به منظور بررسی عملكرد، اجزاء عملكرد ژنوتیپ‌های مختلف ارزن و تعیین متحمل‌ترین ژنوتیپ براساس شاخص‌های تحمل به خشكی تحت رژیم‌های مختلف آبیاری آزمایشی به‌صورت كرت‌های خرد شده در قالب طرح بلوك‌های كامل تصادفی با سه تكرار در دانشكده كشاورزی دانشگاه شهید باهنر كرمان اجرا گردید. سطوح آبیاری براساس تبخیر تجمعی از تشتك تبخیر كلاس A شامل سطح اول آبیاری، بدون تنش (50 میلی‌متر تبخیر) و سطح دوم آبیاری، تنش (100 میلی‌متر تبخیر) به‌عنوان فاكتور اصلی و ژنوتیپ‌های مختلف ارزن معمولی و ارزن دم روباهی به‌عنوان فاكتور فرعی در نظر گرفته شدند. نتایج تجزیه واریانس حاكی از كاهش معنی‌دار همه صفات زراعی تحت تنش خشكی بود. مقایسه میانگین گروهی بین ژنوتیپ‌های مختلف ارزن بیانگر آن بود كه ژنوتیپ‌های ارزن معمولی نسبت به ژنوتیپ‌های ارزن دم روباهی برتری داشتند. از بین شاخص‌های تحمل به خشكی شاخص میانگین بهره‌وریMP ، میانگین هندسی بهره‌وری GMP، شاخص تحمل تنش STI و شاخص عملكرد YI همبستگی مثبت و معنی‌داری با عملكرد در شرایط تنش و بدون تنش نشان دادند و شاخص‌های مناسبی برای شناسایی ژنوتیپ‌های ارزن متحمل به تنش خشكی می‌باشند. در این آزمایش اكوتیپ گلباف پتانسیل عملكرد زیادتر و تحمل نسبی بیشتری نسبت به تنش خشكی نشان داد و می‌تواند به‌عنوان اكوتیپ امید بخش در معرفی ارقام جدید متحمل به خشكی به‌كار رود.

<strong >Introduction </strong > Drought stress is the most important factor limiting plant growth throughout the world so that the slowdown in drought is far more than other environmental stress (1). Following wheat, rice, maize, barley millet and sorghum, are the world 's most important annual crops. <strong >Materials and Methods </strong > In order to evaluate the yield and yield components of millet genotypes and determine the most tolerant genotype based on indicators of drought tolerance a field experiment was conducted at the research farm of the Faculty of Agronomy of the University of Shahid Bahounar university of Kerman-Iran in 2012. The experiment was carried out as split plot based on the randomized complete block design with three replications. Main plots were dedicated to drought, water levels (50 and 100% field capacity) and in the subplots millet cultivars(including Common Millet: Pishahang cultivar, Rabor and Golbaf ecotypes and common promising lines P69, P101, as well as foxtail millet, Bastan cultivar and foxtail promising lines S79, S81, S85 lines) were planted. Irrigation levels was calculated based on the cumulative evaporation from class A evaporation pan. First irrigation was done after 50 mm evaporation and second was done after 100 mm evaporation. The irrigation method was conventional (flooding). <strong >Results and Discussion </strong > Analysis of variance showed significant difference for tiller number among the genotypes and stress reduced number of tillers. Foxtail millet such as Bastan cultivar, S79, S81 and S85 lines had the maximum number of tillers, while common millet genotypes including: Rabor ecotype and P69 had the lowest number of tillers in drought stress conditions. Analysis of variance showed significant differences between genotypes in terms of plant height. Foxtail millet showed higher plant height than common millet, among the under studied genotypes, S85 line had the highest plant height whilst Golbaf and Rabor had the lowest plant height. Different irrigation regimes showed highly significant effect in plant height. Result indicated that there is no significant interaction of each millet genus by irrigation treatment in plant height, while foxtail and common millet showed significant difference in interaction by irrigation treatments. Different genotypes had different number of branches. Among the genotypes in this experiment, the number of branches in Bastan was the highest and lowest was belonged to S85 line under drought stress, respectively. Effects of water stress also showed a significant decrease in the number of branches. Analysis of variance showed that the interaction of genotype by irrigation treatments on the number of branches was significant. Drought caused a reduction in the number of panicle and the result showed there was no significant difference between genotypes. Among genotypes in this experiment, Rabor ecotype had the highest number of panicle in terms of stress and foxtail millet including: Bastan cultivar, S79, S81 and S85 had minimum number of panicle in drought stress conditions. Irrigation in genotype interaction was significant on a number of panicle. Results showed that there was a significant difference between genotypes for harvest index. Among genotypes in this study, S79 and Golbaf genotypes had the lowest harvest index under drought stress. Drought stress effect on harvest index showed a significant decrease, also interaction effect was significant. Analysis of variance showed significant differences between different genotypes of millet based on seed weight. Among genotypes in these experiments, Golbaf and Bastan had the highest seed weight while genotype, S79, S81 and S85 with no statistically significant difference had the lowest seed weight, respectively. There was no significant interaction between genotype by irrigation. Seed weight reduction due to drought stress has been reported in several studies (3). Analysis of variance showed a significant difference between millet genotypes about biological yield. Among genotypes in this study, genotype P101 showed highest biological yield in drought stress conditions but Rabor and S79, showed lowest biological yield in drought stress condition. Drought stress effect on biological yield showed a significant decrease. Genotype by irrigation interaction on biological yield was significant. Biological yield loss due to drought stress has been reported in several studies (2). Mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI) and performance index (YI), by a significant positive correlation with grain yield in stress and non-stress conditions were the best indicators for identification of superior varieties. Using mentioned Indices, a genotype with high yield potential was Golbaf as the most tolerant ecotypes to drought stress, S79 was more sensitive to drought than the other genotypes More details is described in the text as it is original. <strong >Conclusions </strong > Based on this experiment it can be concluded that at drought condition cultivation of common millet has advantage than foxtail millet. Among common millet genotypes Golbaf ecotype showed the highest yield potential and relative tolerance to drought stress. It can be introduced as a promising line in breeding programs for drought tolerance studies.