玉米根际多功能促生菌的筛选及其对冬小麦-夏玉米轮作体系产量提升效果

Screening Multi-functional Rhizobacteria from Maize Rhizosphere and Their Ehancing Effects on Winter Wheat-Summer Maize Rotation System

【目的】黄淮海平原小麦玉米生产区主要实行冬小麦-夏玉米轮作种植模式。砂质潮土是广泛分布于黄淮海地区的土壤,属性和衍生障碍较多,包括结构性较差、蓄水保肥能力较弱等。为了提高肥料利用率、改善土壤肥力,综合实现作物产量提升和品质优化,筛选了一株多功能促生菌,并在该轮作体系验证其广谱促生效应。【方法】从玉米根际砂质潮土中筛选多功能促生菌,测定其产吲哚乙酸(IAA)、溶有机磷、解钾能力。通过形态学、生理生化及16SrDNA序列分析方法对其种属进行鉴定。摇瓶条件下探究其产IAA的最适条件,通过玉米盆栽验证其促生能力,通过冬小麦-夏玉米大田试验验证其在轮作体系中的广谱性增产效果。【结果】(1)试验筛选得到一株命名为YM3的多功能根际促生菌枯草芽孢杆菌(Bacillus subtilis),其产IAA能力达到59.21 mg/L、解有机磷能力达到0.72 mg/L、解钾能力达到18.56 mg/L。当装液量为25 mL/250 mL,pH 6-8范围内,分别以麦芽糖、蛋白胨为碳、氮源时,YM3产IAA能力最佳。(2)玉米盆栽试验结果可见,与接种灭活菌相比,接种YM3菌水剂的土壤IAA、速效磷、速效钾含量分别显著提高75.00%、48.66%、20.00%。玉米幼苗的根长、根表面积、根体积、根尖数、根分枝数分别显著增加67.95%、59.21%、51.13%、71.34%、92.06%。玉米植株的鲜重、株高、相对叶绿素含量、全氮、全磷、全钾分别显著提高了39.86%、23.51%、18.27%、17.68%、52.26%和36.53%。(3)小麦玉米轮作大田试验结果表明,接种YM3菌剂的小麦大田土壤有效氮、速效磷、速效钾分别显著增加了9.08%、13.78%、16.66%,增产率达到42.18%。玉米大田土壤速效磷和速效钾含量分别显著增加了19.18%和15.95%,增产率达到13.22%。【结论】筛选得到的枯草芽孢杆菌YM3菌株兼具产IAA、溶有机磷、解钾功能,在黄淮海平原小麦玉米轮作体系土壤中适应性强,广谱性强,能够提升砂质潮土土壤肥力,提高冬小麦-夏玉米轮作体系的产量。

【Objective】In China's wheat-maize production region,the Huang-Huai-Hai Plain primarily employs a winter wheat-summer maize rotation cropping system.Sandy loam soil,widely distributed in the Huang-Huai-Hai region,demonstrates various properties and associated challenges,including poor structural integrity,and weak water retention and nutrient-holding capabilities.To improve fertilizer utilization,enhance soil fertility,optimize crop yields,and improve quality,we identified a multi-functional plant growth-promoting rhizobacteria(PGPR)and validated its broad-spectrum growth-promoting effects within this rotation system.【Method】From the sandy loam soil within the maize rhizosphere,we isolated a multi-functional PGPR bacterium and evaluated its ability of producing indole-3-acetic acid(IAA),organic phosphorus solubilization,and potassium release ability.We identified the bacterium at the species level using morphological,physiological,biochemical,and 16S rDNA sequence analysis.Under shaken culture conditions,we determined the optimal conditions for IAA production by PGPR YM3.Subsequently,we assessed its growth-promoting ability through maize pot experiments.We verified its broad-spectrum yield-increasing effects in a field trial within the winter wheat-summer maize rotation system.【Result】(1)a multi-functional root-associated growth-promoting bacterium named YM3 was isolated,identified as Bacillus subtilis,and found to produce 59.21 mg/L IAA,solubilizing 0.72 mg/L organic phosphoruing,and releasing 18.56 mg/L potassium.The optimal conditions for IAA production by YM3 were achieved when using maltose and peptone as carbon and nitrogen sources,respectively,within a pH range of 6-8 and a liquid volume of 25 mL/250 mL.(2)Maize pot experiments revealed that soil IAA,available phosphorus,and available potassium levels significantly increased by 75.00%,48.66%,and 20.00%,respectively,compared to soils treated with heat-inactivated YM3 bacterial suspension.Maize seedlings exhibited substantial improvements in root length,root surface area,root volume,root tip number,and root branch number,by 67.95%,59.21%,51.13%,71.34%,and 92.06%,respectively.Additionally,maize plants had significant increases in fresh weight,plant height,relative chlorophyll content,total nitrogen,total phosphorus,and total potassium,with enhancements of 39.86%,23.51%,18.27%,17.68%,52.26%,and 36.53%,respectively.(3)Field trials within the winter wheat-summer maize rotation system demonstrated that soil available nitrogen,available phosphorus,and available potassium levels significantly increased by 9.08%,13.78%,and 16.66%,respectively,with a yield increase rate of 42.18%upon YM3 bacterium agent application.Maize field soil showed notable increments of 19.18%and 15.95%in available phosphorus and available potassium,respectively,with a yield increase rate of 13.22%.【Conclusion】The isolated B.subtilis strain YM3,possessing the ability to produce IAA,solubilize organic phosphorus,and release potassium,demonstrates strong adaptability and broad-spectrum growth-promoting effects in sandy loam soil of the Huang-Huai-Hai Plain.Moreover,it enhances soil fertility and elevates yields within the winter wheat-summer maize rotation system.