Abstract: Maintenance of soil fertility is one of the more important requirements for sustainable agriculture in China because increasing chemical fertilizer use and highly productive systems has created environmental problems and resource overexploitation. In recent years, bio-fertilizers have emerged as an important component of the integrated nutrient supply system and show great promise to improve crop yields. The objective of this paper is to survey the possibility of applying bio-fertilizers to replace chemical fertilizers. Three phosphate-solubilizing bacteria strains (Bacillus sp., Pseudomonas sp. and Azotobacter sp.) and one rhizobium (Sinorhizobium meliloti), isolated from alfalfa and wheat rhizosphere, were used to produce single and compound inoculants. A field experiment based on randomized complete block was designed with three replications in Lanzhou forage experiment station to study inoculant effects on the growth character of alfalfa. Results showed that inoculants fit the quality criterion of agricultural microbial fertilizer of China (NY227-94), and inoculant storage should not exceed six months. Growth-promoting order of alfalfa-specific compound inoculants was: compound inoculants treatments>full amount of phosphate fertilizer treatment (as control)> single inoculants treatments. Compared to the control, compound inoculants had significant effect on the growth character of alfalfa. Jm170+Jm92+Lx191+S7 inoculant was the best compound. The height, stem diameter, chlorophyll content, fresh and dried ratio, leaf and stem ratio and hay yield of alfalfa treated by Jm170+Jm92+Lx191+S7+1/2P increased by 9.00%, 51.98%, 13.79%, 19.57% and 11.98% (1st cut) and 8.26%, 48.08%, 16.87%, 20.07%, 20.95% (2nd cut) compared to control. Strains S7 and Jm170+Jm92+Lx191+S7 supplemented with 50% phosphoric fertilizer were recommended as the best treatments for substitution of 100% phosphoric fertilizer in alfalfa production.

Key words: Effective microbial, Nitrogen-fixing bacteria, Phosphorus-solubilizing bacteria, Inoculants, Alfalfa, Growth character

摘要： 为探讨微生物肥源替代或部分替代化肥的应用潜力,利用前期从苜蓿(Medicago sativa L.)和小麦(Triticum aestivum L.)根际分离的3株溶磷菌(Bacillus sp.,Pseudomonas sp.和Azotobacter sp.)和1株根瘤菌(Sinorhizobium meliloti)研制苜蓿根际新型专用接种剂,并进行田间随机区组试验,测定其对苜蓿生长特性的影响。结果表明:单一菌种接种剂+半量磷肥对苜蓿的促生效果不及复合菌种接种剂+半量磷肥,与对照(全量磷肥)相比,复合菌种接种剂+半量磷肥处理对苜蓿的各项生长指标均有明显的促生效应,其中以复合接种剂+半量磷肥处理的效果最佳:苜蓿株高、叶绿素含量、叶茎比、干鲜比及产量分别较对照增加9.00%,51.98%,13.79%,19.57%,11.98%(第1茬)和8.26%,48.08%,16.87%,20.07%,20.95%(第2茬);单一菌种接种剂+半量磷肥处理的效果不及全量磷肥处理,但处理根瘤接种剂+半量磷肥效果较好。因此,推荐根瘤接种剂和Jm170+Jm92+Lx191溶磷菌+根瘤菌复合接种剂为适用于苜蓿的最佳单一及复合菌株接种剂,研制的各接种剂质量达到农业部微生物肥料行业标准(NY227-94)的要求。

关键词: 有益菌, 溶磷菌, 固氮菌, 接种剂, 苜蓿, 生长特性