بررسی ساختار و خصوصیات سیستم ریشه‌ای ارقام گندم (triticum aestivum l.) دیم تحت کاربرد منابع مختلف کودی

به منظور بررسی تاثیر باکتری های افزاینده رشد گیاه روی سیستم ریشه ای گندم در شرایط دیم، آزمایشی به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار در مزرعه مرکز تحقیقات کشاورزی سرابله استان ایلام در سال زراعی 99- 1398 اجرا شد. تیمار های آزمایش شامل ارقام مختلف گندم (سرداری، کریم، کوهدشت و ریژاو) و منابع مختلف کودی شامل شاهد (عدم مصرف کود)، کود شیمیایی اوره (تامین 50 درصد نیاز گیاه)، باکتری آزوسپیریلیوم + کود شیمیایی اوره تامین 50 درصد نیاز گیاه)، باکتری ازﺗﻮﺑﺎﮐﺘﺮ + کود شیمیایی اوره (50 درصد نیاز گیاه)، باکتری آزوسپیریلیوم + ازﺗﻮﺑﺎﮐﺘﺮ + کود شیمیایی اوره (50 درصد نیاز گیاه) و تامین 100 درصد نیاز گیاه با اوره بود. صفات مورد ارزیابی در این پژوهش شامل طول ریشه، وزن تر و خشک ریشه، حجم ریشه، سطح ریشه، قطر ریشه، طول مخصوص ریشه، تراکم طول ریشه، حجم مخصوص ریشه، تراکم بافت ریشه و چگالی سطح ریشه بود. بیشترین طول ریشه (115.6 سانتی متر)، حجم ریشه (13.3 سانتی مترمکعب)، سطح ریشه (137.2 سانتی مترمربع)، طول مخصوص ریشه (46.9 سانتی‌متر طول ریشه بر گرم وزن خشک ریشه)، حجم مخصوص ریشه (0.0045 گرم وزن خشک ریشه بر سانتی مترمکعب حجم خاک)، تراکم طول ریشه (0.214 سانتی متر طول ریشه بر سانتی مترمکعب خاک)، تراکم بافت ریشه (32.4 گرم ریشه بر مترمکعب حجم خاک) و چگالی سطح ریشه (127.5 سانتی متر مربع بر سانتی مترمکعب) در رقم ریژاو × باکتری آزوسپیریلیوم + ازﺗﻮﺑﺎﮐﺘﺮ + 50 درصد کود شیمیایی اوره نسبت به شاهد(عدم مصرف کود) و کمترین طول ریشه، حجم ریشه، سطح ریشه، طول مخصوص ریشه، حجم مخصوص ریشه، تراکم طول ریشه، تراکم بافت ریشه و چگالی سطح ریشه در رقم سرداری × شاهد (عدم مصرف کود) مشاهده گردید. با توجه به نتایج به دست آمده در شرایط دیم، گندم رقم ریژاو با توجه به ساختار ریشه ای گسترده و مناسب تر در حضور باکتری آزوسپیریلیوم + ازﺗﻮﺑﺎﮐﺘﺮ عملکرد قابل قبولی را توانست به‌دست آورد، بنابراین می توان این رقم را پیشنهاد داد.

study root system structure and characterstics in wheat (triticum aestivum l.) cultivars influenced by applications of sources of fertilizer under dryland farming

introductionamong the nutrients used by the plant for the growth of nitrogen due to its participation in the structure of proteins, amino acids, coenzymes and nucleic acids are the main factors involved in plant growth and fertility. in recent decades, a group of soil bacteria in the rhizosphere has been introduced as plant growth-promoting bacteria that have been able to improve crop growth. in addition to the positive effects on soil properties, these bacteria are economically and environmentally beneficial and a good alternative to chemical fertilizers. azotobacter and azpirillum are the most important plant growth-promoting rhizobacteria (pgpr) in plants that, in addition to bio-stabilizing nitrogen, produce growth-promoting hormones such as auxin, gibberellin, and cytokines. modification of root system architecture by pgpr implicates the production of phytohormones and other signals that lead to enhanced secondary root branching and development of the root system. since accessible water is the main factor limiting growth in rainfed agriculture, so one of the ways to improve nutrition and plant growth is to use pgpr. therefore, this study was carried out on the role of azospirillum + azetobacter on root traits of new wheat cultivars in ilam province.materials and methodsin order to investigate the effect of growth-promoting bacteria on root system criteria in wheat under dryland conditions, a field experiment was carried out as a factorial arrangement based on a randomized complete block design with three replications at the farm station of sarablah agricultural research center during 2019-2020 cropping season. experimental treatments include different wheat cultivars (sardari, karim, koohdasht and rijaw) and treatment of different fertilizer sources, including control (without fertilizer treatment), 50% urea chemical fertilizer (50% of required), azospirillum + 50% 50% urea chemical fertilizer (50% of required), azetobacter + 50% n fertilizer, azospirillum + azetobacter + 50% urea chemical fertilizer (50% of required) and 100% urea chemical fertilizer (100% of required). each experimental plot consisted of eight planting rows with a row spacing of 20 cm and a length of 4 m. nitrogen fertilizer (120 kg.ha-1) was applied at planting and stalking stage based on soil test. phosphorus fertilizer was applied from triple superphosphate source at the recommended rate of 50 kg.ha-1at planting time. in this study, root length, root fresh and dry weight, root volume, root surface, root diameter, specific root length, root length density, root specific mass, root tissue density and root surface area density were evaluated. experimental data were analyzed using sas statistical program. comparison of means were done by duncan test and graphs were drawn with excel software. results and discussionthe results of this study showed that the interaction between cultivar × fertilizer sources was significant in root characteristics of dryland wheat, so that the maximum root length (115.6 cm), root volume (13.3 cm3), root surface (137.2 cm2), specific root length (46.9 cm root length.g-1 dw root), specific root mass (0.0045 g of dw roots.cm-3 soil volume), root length density (0.214 cm root length.cm-3 soil volume), root tissue density (32.4 g root.cm-3 soil volume) and root surface area density (127.5 cm2.cm-3) was obtained in rijo cultivar × azospirillum + azetobacter + 50% 50% urea chemical fertilizer (50% of required) compared to control treatment (without fertilizer sources). conclusionthe results showed that due to the lack of rainfall in most rainfed fields of the province and also due to the positive effect of fertilizer biofertilizer in maintaining soil moisture, improving the physical and chemical quality of soil, to achieve proper grain yield in rainfed conditions of biofertilizer with chemical fertilizer used nitrogen. in this study, it was observed that in the combined system of biochemical and chemical fertilizers, the rooting system increases so that the maximum root length, root volume, root area, root-specific volume, root length density, root tissue density and root surface density was observed from rijaw cultivar × azospirillum + azetobacter + 50% n chemical fertilizer.  bacteria increase plant growth by affecting the plant by improving physiological and biochemical conditions to increase resistance to adverse environmental factors in rainfed agriculture. therefore, the results of this study can be concluded that in rainfed conditions where the intensity and fluctuations of rainfall are not predictable, having a strong root system can greatly reduce the harmful effects of water deficit against environmental stresses in the region and cause an acceptable increase in the yield of dryland wheat grain.