解钾促生菌的筛选鉴定及对东北黑土区玉米的促生效应

【背景】东北地区作为全国玉米的主产区,土壤缺钾严重限制了玉米的高产。解钾促生菌可活化土壤中难溶的钾,提高土壤钾的有效性,进而促进植物生长。【目的】从中国东北黑土区的玉米根际土壤中筛选鉴定高效解钾菌,研究其在缺钾条件下对玉米生长的促生效果,为开发适应当地环境的微生物钾肥提供优良的菌种资源。【方法】采用选择性培养基从玉米根际土中筛选解钾菌;采用16S r RNA基因测序方法鉴定菌株的分类地位;采用生理生化特征鉴定培养基测定其生态适应性(耐酸碱、耐盐、耐干旱及耐农药);2年的田间接种试验验证解钾菌在缺钾条件下对玉米的促生效果。【结果】筛选出3株高效解钾促生菌MZ4、KM1和KM2,经鉴定MZ4和KM2属于芽孢杆菌属,KM1属于短小芽孢杆菌属;3株菌可耐受强干旱、强碱、不同浓度的吡虫啉和嘧菌酯,并耐受一定程度的酸和盐;田间试验结果表明,与缺钾区不接种解钾菌相比,接种MZ4、KM1和KM2增加了拔节期、吐丝期玉米的株高、地上生物量、叶面积指数和叶绿素,接种MZ4和KM2显著增加了玉米产量,可增产9.65%-11.50%。【结论】鉴定出适合东北黑土区的高效解钾微生物,为该区域微生物钾肥研发及微生物解钾机理研究提供了优良菌种资源。

Screening and identification of potassium-solubilizing bacteria and their promoting effects on maize in black soil of Northeast China

Background] In Northeast China, a major maize (Zea mays L.) production region, maize yield is limited severely by insufficient soil potassium supply. Potassium-solubilizing bacteria can mobilize insoluble soil potassium, improve soil potassium availability, and promote maize growth. Objective] To identify efficient potassium-solubilizing bacteria from maize rhizosphere in black soil, verify their growth-promoting effects under potassium-deficient field condition, so as to provide elite bacteria resource for producing microbial potassium fertilizers adapted to the local environment. Methods] The bacteria isolated from maize rhizosphere were screened on potassium-solubilizing medium. The taxonomy of the selected potassium-solubilizing bacteria was identified by 16S rRNA gene sequencing. The ecological adaptability (acid and alkali resistance, salt resistance, drought tolerance and pesticide resistance) of the selected bacteria were determined by culturing them on diverse physiological and biochemical mediums. A two-year field inoculation experiment was conducted to verify their effects on maize growth and yield under the condition of potassium deficiency. Results] Three efficient potassium-solubilizing bacteria, MZ4, KM1 and KM2, were selected. MZ4 and KM2 were identified as Bacillus sp., and KM1 was identified as Brevibacilluse sp.. All the three strains can tolerate drought stress, acid and alkali stress, pesticide (imidacloprid), fungicide (azoxystrobin), and salt stress to a certain degree. In the field without potassium application, the inoculation of MZ4, KM1 and KM2 increased plant height, shoot biomass, leaf area index and chlorophyll content of maize at the jointing and flowering stages. Inoculation with MZ4 and KM2 significantly promoted grain yield by 9.65%?11.50%. Conclusion] The efficient potassium-solubilizing bacteria which adapt to the black soil in Northeast China were identified. These bacteria can be used as elite germplasm resource for producing microbial potassium fertilizer and analyzing the mechanism underlying efficient potassium solubilization by microorganism.