بررسی کاربرد تلفیقی سطوح مختلف سوپرفسفات تریپل و باکتری‌های سودوموناس بومی حل کننده فسفات بر شاخص‌های رشد گیاه ذرت

این پژوهش با هدف بررسی تاثیر استفاده از باکتری‌های جنس pseudomonas با توانایی حل‌کنندگی فسفر، در جهت افزایش حلالیت فسفر در محیط جامد، مایع و خاک، افزایش عملکرد و جذب عناصر عذایی گیاه ذرت و بهبود برخی ویژگی های خاک در یک خاک آهکی با محتوای فسفر پائین انجام شد. نتایج اثر سویه‌های باکتری سودوموناس در میزان انحلال فسفات‌های نامحلول معدنی در محیط اسپربر نشان داد که بعد از روز چهاردهم سویه p21-1 بیشترین قطر هاله (19.11 میلی‌متر) و سویه p55-1 بیشترین میزان انحلال فسفر (156.25 % نسبت به شاهد) و کاهش ph (47.3-45.5%) را داشتند. اثرات متقابل باکتری‌ها و کود سوپرفسفات تریپل بر عملکرد کمی و کیفی گیاه ذرت و خصوصیات خاک تحت کشت به صورت فاکتوریل در قالب طرح کاملا تصادفی شامل 7 باکتری (b0, b1, b2, b3, b4, b5, b6, b7) و 4 سطح کود سوپر فسفات تریپل (p0، p40، p70 و p100 درصد مقدار حد بحرانی فسفر خاک) با 3 تکرار در شرایط گلخانه بررسی شد. نتایج مقایسه میانگین نشان داد تیمار p0b3 توانست وزن خشک اندام هوایی را 47.45 درصد افزایش دهد. تیمار p70b2 نیز توانست فسفر اندام هوایی را 17.64 درصد افزایش دهد. تیمار p100b4 باعث افزایش فسفر ریشه به مقدار 160 درصد گردید. علاوه بر این استفاده تلفیقی از کود زیستی و فسفره موجب افزایش عناصر آهن، روی، منگنز، فسفر و کاهش هدایت الکتریکی خاک شد. یافته‌های این پژوهش نشان داد که کاربرد زادمایه‌های حاوی باکتری pseudomonas می‌تواند به عنوان مکمل مناسب کود سوپرفسفات تریپل در استراتژی‌های کشت محصولات زراعی در نظر گرفته شود.

investigating the combined application of different levels of triple superphosphate and native phosphate-solubilizing pseudomonas bacteria on growth indices of maize

introduction phosphorus (p) is one of the most necessary plant nutrients and the second key plant nutrient after nitrogen, which deeply affects the overall growth of plants. most of the present p in calcareous soils is biologically unavailable, therefore mobile p is rare despite the abundance of both organic and inorganic forms of p in soils. it has been well-known that p use efficiency of triple superphosphate (tsp) fertilizer in alkaline soils is low. due to the increase in the price of phosphate fertilizers and their low plant absorption (10–30%), the use of indigenous phosphate solubilizing bacteria (psb) to increase p-fertilizer-use efficiency and reduce its application amount can be a perfect way. the combined use of bio-fertilizers and superphosphate is an important component of integrated nutrient management, which leads to sustainable agriculture. this research was carried out to investigate the contribution of native phosphate solubilizing pseudomonas sp. along with superphosphate application to increase soil p solubility, yield and nutrient concentration of maize and improve some soil properties in a calcareous soil with low organic matter and phosphorus.materials and methods eleven strains of pseudomonas sp (pseudomonas sp. pseudomonas koreensis) bacteria were obtained from the gene bank of iran soil and water research institute. the phosphate solubilizing activity of each bacterium was evaluated in sperber medium quantitatively (liquid) and qualitatively (plates). each bacterium was cultured in two plates with three replications and incubated at 28 °c. then the colony and halo diameter were measured on the third, fifth, seventh, tenth, and fourteenth days after incubation. to evaluate phosphate solubility by bacteria in a liquid medium, 50 ml of sperber medium was prepared and sterilized with three replications. then 1 ml of fresh culture suspension of each bacterium with a population of 107 cells/ml was inoculated into each erlenmeyer flask (treatments and controls) and incubated at 150 rpm and 150 ° c for 14 days. soluble phosphorus (vanadate-molybdate method) and ph on the first, third, tenth and fourteenth days of incubation were measured. to assay the interaction effects of bacteria and triple superphosphate fertilizer on quantitative and qualitative yield of maize plant and characteristics of soil cultivated in a soil with low level of organic matter and phosphorous, a factorial based on randomized completely design including 8 bacteria (b0, b1, b2, b3, b4, b5, b6, b7) and 4 triple superphosphate fertilizer levels (0, 40, 70 and 100% of the critical limit of soil phosphorus) with 3 replications was conducted in greenhouse conditions. sterilized pots containing 7 kg of washed sands and soil (in a ratio of one to three) were prepared. a certain amount of triple superphosphate fertilizer was added to each pot based on the treatments. the k as potassium sulfate and n as urea were used based on soil test and fertilizer recommendations for maize. five germinated seeds (704 single cross cultivar) were planted in each pot. seeds sown were inoculated with 1 ml of the fresh bacterial suspension inoculum (1×108 cfu ml-1). then after two weeks, three plants per pot were preserved and the rest were removed.