根际促生菌的筛选及其在尾矿改良中的应用

Screening of rhizosphere growth promoting bacteria and their application in tailings improvement

为探索经济高效且应用推广性强的尾矿改良和植被恢复措施,筛选了来自尾矿原生植被的根际促生菌,并将其组配形成混合促生菌液。采用盆栽试验,研究了混合促生菌液(B)、生物炭(C)和粪肥(F)及不同组合(BC、BF、CF、BⅠCF、BⅡCF,其中BⅠCF是三者复合处理;BⅡCF是在BⅠCF基础上增加1倍的混合促生菌液)对千叶蓍种子萌发和植株生长,根际微生物群落组成,矿砂养分、酶活性以及盆栽系统中的氮素转移和可利用磷、钾总量的影响。筛选得到4株具有固氮、溶磷、解钾、合成吲哚乙酸或分泌1-氨基环丙烷羧酸脱氨酶的根际促生菌,分别为KSB1、KSB2、KSB7和KSB21。盆栽试验结果表明:与CK(空白对照)相比,接种混合促生菌能够强化矿砂磷酸酶活性,并提高假单胞菌属和根瘤菌属在根际环境中的丰度;添加生物炭对矿砂养分和千叶蓍生长的影响有限;施用粪肥可促进千叶蓍生长,强化矿砂酶活性,显著提高蓝细菌属丰度(P<0.01)、盆栽系统氮素总量及可利用磷、钾总量。与单独施用粪肥(F)相比,接种混合促生菌+粪肥(BF)与添加生物炭+粪肥(CF)均能进一步提高部分千叶蓍生长指标和矿砂酶活性。此外,BF处理盆栽系统氮素总量增加了11.18%,可利用磷、钾总量分别增加了22.54%和22.00%;而CF仅有可利用钾总量增加了8.32%。BⅠCF和BⅡCF处理下各指标均高于其他处理,BⅡCF矿砂碱解氮、磷酸酶活性以及千叶蓍植株生物量等指标较BⅠCF有显著提高(P<0.05),且盆栽系统氮素总量增加了9.54%,千叶蓍植株钾总量增加了19.12%,蓝细菌属和假单胞菌属的相对丰度提高了51.96%和13.62%。试验条件下,直接接种促生菌或添加生物炭对尾矿基质改良和植被恢复效果不显著;施用粪肥对改善矿砂养分供给和促进绿垦作物千叶蓍的生长有关键作用;促生菌液和生物炭的功能发挥与粪肥的施用与否存在直接关系;BⅡCF处理是一种有效的矿砂改良措施,其中的多功能混合促生菌发挥了固氮、溶磷和解钾作用,并增强了千叶蓍对钾元素的吸收利用能力。

This research was aimed at developing economic and effective methods which have strong applicability and adoption prospects for tailings improvement and vegetation restoration using plant growth-promoting rhizobacteria(PGPR).PGPR from tailings primary environments were screened and a single factor pot experiment with a control and eight treatments was conducted to test their effects on seed germination and growth of Achillea millefolium.The treatments were:an assembly of mixed PGPR(B),biochar(C),manure(F)and their combinations[BC,BF,CF,a compound treatment of B,C and F(BⅠCF),and BⅡCF(the same as BⅠCF,but with doubled mixed PGPR content)].Measurements included rhizosphere microbial community composition,tailings nutrients,and for plant tissues,enzyme activities and the total amount and distribution of tailings nutrients including total nitrogen and available phosphorus and potassium.The screened PGPR comprised KSB1(Pseudomonas sp.),KSB2(Pseudomonas sp.),KSB7(Pseudomonas sp.)and KSB21(Rhizobium sp.)selected for their ability to fix nitrogen,dissolve phosphorus,hydrolyze potassium,synthesize indoleacetic acid or secrete 1-aminocyclopropane carboxylic acid deaminase.The pot experiment showed that:1)The abundance of Pseudomonas and Rhizobium in the rhizosphere environment and the phosphatase activity in tailings can be increased by inoculating mixed PGPR.2)The effect on tailings nutrients and the growth of A.millefolium of adding biochar alone,was not obvious.3)The application of manure promoted the growth of A.millefolium,enhanced the activities of tailings enzymes,and significantly increased the abundance of Cyanobacteria(P<0.01),the total amount of nitrogen in the potted system,and the total amount of available phosphorus and potassium.4)Compared with F alone,both the BF and CF treatments further improved various measures of A.millefolium growth and tailings enzyme activity.In addition,the total nitrogen in the potted system in the BF treatment increased by 11.18%,and the total available phosphorus and potassium increased by 22.54% and 22.00% respectively,while the total available potassium only increased by 8.32% in CF.5)The various measures for BICF and BIICF treatments were generally higher than other treatments.Compared with BICF,BIICF had significantly improved indicators including alkaline hydrolysable nitrogen,phosphatase activity and A.millefolium biomass and the total nitrogen in the pot system increased by 9.54%,the total potassium content of the A.millefolium plant tissues increased by 19.12%,and the relative abundances of Cyanobacteria and Pseudomonas were increased by 51.96% and 13.62%,respectively.6)Under these experimental conditions,neither inoculating with mixed PGPR nor adding biochar alone resulted in any significant effect on tailings improvement or vegetation restoration;manure played a key role in improving the nutrient supply of tailings and promoting the growth of A.millefolium.This work indicates the benefits of mixed PGPR and biochar are directly related to the application of manure.The BIICF treatment is effective in tailings improvement and the mixed PGPR at least play the role in enhancing nitrogen fixation,phosphorus solubilization and potassium solubilization,and strengthening the potassium absorption and utilization ability of A.millefolium.