ارزیابی بهبود عملکرد گندم دیم (triticum aestivum l.) با استفاده از مایه تلقیح باکتری‌های محرک رشد

به منظور ارزیابی اثر باکتری‌های محرک رشد گیاه در افزایش عملکرد گندم (triticum aestivum l.) دیم، آزمایشی در قالب طرح بلوک‌های کامل تصادفی با 15 باکتری محرک رشد با یک شاهد در چهار تکرار و در شش ایستگاه تحقیقات کشاورزی دیم مراغه، قاملو، سرارود، گچساران، خدابنده و شیروان چرداول در سال زراعی 89-1388 به‌اجرا در آمد. نتایج نشان داد، تلقیح باکتری‌های محرک رشد توانست عملکرد دانه گندم دیم را در هر شش ایستگاه افزایش دهد که این افزایش در اغلب مکان‌های آزمایشی از لحاظ آماری معنی‌دار بود. حداکثر افزایش عملکرد دانه در مراغه، کرمانشاه، کردستان، ایلام، زنجان و گچساران به ترتیب به‌میزان 19.6، 45.1، 12.4، 18.4، 10.2 و 11.6 درصد بود که متوسط این افزایش برای مطلوب‌ترین باکتری‌های محرک رشد در مناطق مورد مطالعه 382 کیلوگرم در هکتار بود. با روش gge بای‌پلات باکتری‌های محرک رشد به دو گروه دارای عملکرد بالا (تیمارهای شماره 2، 3، 6، 8، 9 و 10) و پائین (تیمارهای شماره 1، 4، 5، 7، 11، 12، 13، 14، 15 و 16) و مکان‌های مورد مطالعه به سه گروه (گروه اول کردستان و گچساران، گروه دوم مراغه، زنجان و ایلام و گروه سوم کرمانشاه) تفکیک شد. مناسب‌ترین تیمار برای گروه کردستان و گچساران شماره 9، برای مراغه، زنجان و ایلام شماره 2 و برای کرمانشاه شماره 5 بود، امّا چنانچه هدف معرفی تنها یک باکتری‌ محرک رشد برای کل مناطق باشد، مایه تلقیح شماره 9 مناسب‌ترین است. بنابراین استنباط می‌شود، از باکتری‌های محرک رشد می‌توان در بهبود عملکرد گندم دیم در دیمزارهای ایران استفاده نمود.

Yield Enhancement by Application of Plant Growth Promoting Rhizobacterial (PGPR) Inoculants in Dryland Wheat (Triticum aestivum L.)

IntroductionThe explosion of world population in recent decades has caused excessive application of chemical fertilizers in agricultural systems; resulting in critical environmental and health issues. Integrated Nutrient Management (INM) method or biofertilizers are considered as logical strategies to reduce the rate of chemical fertilizers. . Biofertilizers consist of various types of microorganisms in soil which are in close relation with plant roots and are called Plant Growth Promoting Rhizobacteria (PGPR). Several mechanisms have been postulated to explain how PGPR benefit the host plant, which could be classified into four categories a) The ability to produce plant growth regulators or phytohormones such as indole acetic acid (IAA), cytokines, and gibberellins; b) Enhancing a symbiotic N2 fixation; c) Solubilizing inorganic phosphate and mineralization of organic phosphate and/or other nutrients; d) Antagonistic effect against phytopathogenic microorganisms by production of siderophores, the synthesis of antibiotics, enzymes, and/or fungicidal compounds, and competition with detrimental microorganisms. Therefore, PGPR are commonly used as inoculants for improving the growth and yield of agricultural crops, however screening for the selection of effective PGPR strains is very critical. This study focuses on the screening of effective PGPR strains on the basis of their potential for plant growth promoting activity under water stress conditions in Iran’s cold temperate and warm dryland areas.Materials and MethodsExperiments were carried out in randomized complete block design (RCBD) with four replications in 20092010 cropping year. Treatment included fifteen PGPRs with a control (without inoculation) in six dryland agricultural research stations; including Maragheh, Ghamloo (Kurdistan), Sararood (Kermanshah), Gachsaran, Khodabandeh (Zanjan), Shirvan Chardavol (Ilam). Soil samples collected from 025 cm depths before planting time and was characterized through determination of soil available P, K, Fe, Mn, Zn and Cu, soil texture, organic carbon, pH, EC and calcium carbonates equivalent. Dryland wheat Azar2 cultivar was cultivated with 350 seed per m2 in 5 to 7 cm soil depth. Moreover,plant traits such as grain, straw and biological yields, TKW (1000kernel weight), number of spikes per m2, number of seed per spike, harvest index (HI), plant height and spike length, were measured. All research data was analyzed via GenStat14 statistical software.Results and DiscussionThe results showed that, the plant growth promoting bacteria (PGPR) had increased the grain yield of dryland wheat in the Maragheh, Kermanshah, Kurdistan, Ilam, Zanjan and Gachsaran regions. This increase in most experimental dryland stations has been significant statistically. The maximum grain yield increase in Maragheh, Kermanshah, Kurdistan, Ilam, Zanjan and Gachsaran were in the order amount of 19.6 (treatment no. 2), 45.1 (treatments no’s 4 and 12), 12.4 (treatment no 8), 18.4 (treatment no 11) 10.2 (treatment no. 11) and 11.6 (treatment no. 11) kg.ha1, which was 382 kg.ha1 for the best average plant growth promoting bacteria in all the study regions. With the use of GGE biplot method, the inoculating treatments of plant growth promoting bacteria had 2 groups, including the high yielding groups with treatments (2, 3, 6, 8, 9 and 10), and low yielding treatments (1, 4, 5, 7, 11, 12. 13, 14, 15 and 16).The study locations were separated in 3 groups, first group including; Gachsaran and Kurdistan regions, second group including; Maragheh, zanjan and Ilam regions, and the third group including; Kermanshah region. The suitable treatments were the treatment numbers 9 and 10 for the first group, treatment numbers 2, 3, 8 and 6 for the second group and treatment numbers 7, 4 and 5 for the third group. Among the mentioned treatments, the most suitable treatments for first, second and third groups are treatment number 9, treatment number 2 and number 5, respectively.. According to these results, if the first aim is introducing the growth promoting bacteria for all the regions, this strain is the inoculating bacteria number 9. In the second order, the treatment numbers 13 and 10had the closest conditions to the estimated ideal treatment.ConclusionTherefore, for the plant growth promoting bacteria, we can use them in reducing the effects of environmental stresses, and conducting nonenvironmental stresses on dryland conditions, as well as increasing in grain yield of dryland wheat.