كليدواژه :
خاك آهكي , رشد ذرت , سوپرفسفات تريپل , سودوموناس , كودهاي زيستي
چكيده فارسي :
اين پژوهش با هدف بررسي تاثير استفاده از باكتري هاي جنس Pseudomonas با توانايي حلكنندگي فسفر، در جهت افزايش حلاليت فسفر در محيط جامد، مايع و خاك، افزايش عملكرد و جذب عناصر غذايي گياه ذرت و بهبود برخي ويژگي هاي خاك در يك خاك آهكي با محتواي فسفر پائين انجام شد. نتايج اثر سويه هاي مختلف باكتري سودوموناس در ميزان انحلال فسفاتهاي نامحلول معدني در محيط جامد و مايع اسپربر نشان داد كه بعد از روز چهاردهم سويه 1-21P بيشترين قطر هاله ) 11 / 19 ميليمتر( و سويه 1-55P بيشترين ميزان انحلال فسفر ) 25 / 156 % نسبت به شاهد( و كاهش pH ( 5 / 45 - 3 / 47 %( را داشتند. اثرات متقابل باكتريها و كود سوپرفسفات تريپل بر عملكرد كمي و كيفي گياه ذرت و خصوصيات خاك تحت كشت به صورت فاكتوريل در قالب طرح كاملا تصادفي شامل 7 باكتري ) , 3B, 2B, 1B, 0B7B, 6B, 5B, 4B( و 4 سطح كود سوپر فسفات تريپل ) 0P ، 40P ، 70P و 100P درصد مقدار حد بحراني فسفر خاك( با 3 تكرار در شرايط گلخانه بررسي شد. نتايج مقايسه ميانگين نشان داد تيمار 3B0P توانست وزن خشك اندام هوايي را 45 / 47 درصد و تيمار 1B40P توانست 62 / 61 درصد وزن خشك ريشه را افزايش دهد. تيمار 2B70P نيز توانست فسفر اندام هوايي را 64 / 17 درصد افزايش دهد. تيمار 4B100P باعث افزايش فسفر ريشه به مقدار 160 درصد گرديد. علاوه بر اين استفاده تلفيقي از كود زيستي و فسفره موجب افزايش عناصر آهن، روي، منگنز، فسفر و كاهش هدايت الكتريكي خاك شد. يافته هاي اين پژوهش بيانگر اين است كه كاربرد زادمايه هاي زيستي حاوي باكتري Pseudomonas مي- تواند به عنوان مكمل مناسب كود سوپرفسفات تريپل در استراتژي هاي كشت محصولات زراعي در نظر گرفته شود.
چكيده لاتين :
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. Pots including different treatments were irrigated, up to 80% moisture content of field capacity (FC), by distilled water using a weight method. After 90 days, the dry weight of the plant was calculated (oven at 70 ° C for 48 hours). To analyze the nutrients in the plant, roots and shoots were powdered separately by mill and digested through dry burning method. The amount of phosphorus, potassium, nitrogen, iron, zinc, copper and manganese were
