磁化水处理对苜蓿根瘤菌生长和结瘤固氮的影响

为明确磁化水对根瘤菌生长及结瘤固氮的作用,测定在2万Gs恒定磁场下处理的磁化水对苜蓿根瘤菌生长及其结瘤固氮的影响.结果表明:不同磁化次数的磁化水均能显著影响XGL026菌株生长,降低OD值,磁化水培养基中的活菌数为普通培养基的86.96%～65.72%,菌数降低幅度随磁化次数增加而增大,磁化3次以上的磁化水对活菌数的降低效应极为显著(P<0.01).在盆栽苜蓿上接种绿色荧光蛋白基因(GFP)标记菌株XGL026-GFP,采用磁化水灌溉对根瘤菌在根际土壤中的存活和定殖具有抑制作用,苜蓿单株结瘤数与普通水对照相比平均减少46.4%(P<0.01).磁化水处理的苜蓿地上、地下部分的固氮率分别降低21.06%和20.48%,固氮量分别降低26.64%和37.5%,植株干物质重分别减少27.62%和13.46%.表明磁化水处理对苜蓿根瘤菌的生长、定殖和固氮及植株干物质重均有抑制作用.

Effects of Magnetized Water on the Growth and Nitrogen Fixation of Rhizobial Strain on Alfalfa

The effects of magnetized water treatment on the growth and nitrogen fixation of rhizobial strain on alfalfa under the constant magnetic field of 20000 Gs were investigated. The results showed that magnetization significantly affected the growth of XGL026 and reduced the OD value. The counts of viable bacteria in magnetized water culture media were the 86.96%~65.72% of ordinary culture media, and the counts of viable bacteria decreased with the times of magnetization increasing. The water magnetized more than three times significantly reduced the counts of viable bacteria (P<0.01). Pot alfalfa was inoculated by the marked bacteria strain XGL026-GFP. The irrigation of magnetized water had inhibitory effect on the colonization and survival of the rhizobial in alfalfa rhizosphere and reduced 46.4% nodule number compared to ordinary water (P<0.01). Both above- and below-ground of alfalfa were influenced by magnetized water treatment, the rates of N fixation decreased 21.06% and 20.48%, the amount of N fixation decreased by 26.64% and 37.5%, the dry biomasses were reduced by 27.62% and 13.46%, respectively. Thus the magnetized water treatment had effects on the growth, colonization and nitrogen fixation of rhizobial strain in alfalfa rhizosphere.