根际促生菌对石漠化地区造林苗木的促生效应

曹彦强 张中峰 蒋士宋 唐金荣 周龙武 滕秋梅 徐广平

摘 要：  西南岩溶石漠化山区水土流失严重、养分贫瘠，导致植被恢复困难。为探究固氮菌对岩溶石漠化地区造林苗木的生长促进效应，该文以广西石漠化地区常见造林树种香樟、任豆、喜树和台湾相思苗木为材料，利用平板稀释法从石漠化乡土植物根际土壤筛选固氮菌，通过测定固氮酶活性及鉴定固氮菌菌种，选择固氮酶活性较高的菌种制成复合菌剂接种到试验苗木进行盆栽试验。结果表明：共筛选得到6株具有固氮能力的根际促生菌，分别属于根瘤菌属（Rhizobium）、中华根瘤菌属（Sinorhizobium）和黄杆菌属（Flavobacterium），其中归类为根瘤菌属的3株固氮菌酶活性较高。复合菌剂接种试验表明接种固氮菌对造林苗木的生长具有明显促进作用。与未接种处理相比，接種处理苗木的株高、叶面积、生物量以及叶绿素含量均显著增长;同时苗木的氮、磷、钾含量也有不同程度的增加。其中，香樟、任豆、喜树和台湾相思的氮含量分别提高了28.9%、53.1%、37.0%和31.6%;香樟、台湾相思的磷含量分别增加了25.6%和42.5%;任豆、台湾相思的钾含量分别增加了57.5%和49.7%。接种石漠化乡土固氮菌能够显著促进造林苗木生长和养分含量，在石漠化植被修复中具有较好的应用前景。

关键词： 石漠化， 固氮菌， 造林苗木， 促生效应， 植被修复

中图分类号：  Q948.12

文献标识码：  A

文章编号：  1000-3142（2021）05-0738-08

Abstract：  Extensive soil erosion and vegetation degradation are common in karst rocky desertified area， and presenting a serious challenge of restoration of degraded habitats. In order to explore the promoting effect of PGPR （plant growth promoting rhizobacteria） on the growth of afforestation seedlings， seedlings of Cinnamomum camphora， Zenia insignis， Camptotheca acuminata and Acacia confusa  which are common in Guangxi rocky desertified region  were used as experimental materials. The plate dilution method was used to screen nitrogen-fixing bacteria from rhizosphere soil of rocky desertification native plants. The strains with higher nitrogenase activities were selected and inoculated into experimental seedlings for pot experiment. The results were as follows： Six strains of nitrogen-fixing bacteria from rhizosphere soil were obtained， and the 16S rDNA sequence analysis showed that the tested strains belong to Rhizobium， Sinorhizobium and Flavobacterium. Among them， the nitrogenase activity of three strains of Rhizobium was the highest. Pot experiment showed that inoculating nitrogen fixing bacteria could promote the growth of afforestation seedlings. Plant height， leaf area， leaf dry weight and chlorophyll content increased significantly compared to control. Nitrogen content of Cinnamomum camphora， Zenia insignis， Camptotheca acuminate and Acacia confusa seedlings significantly increased by 28.9%， 53.1%， 37.0% and 31.6%， respectively. Phosphorus contents of Cinnamomum camphora and Acacia confusa was increased significantly by 25.6% and 42.5%， respectively， while the potassium contents of Zenia insignis and Acacia confusa  was increased significantly by 57.5% and 49.7%， respectively. The nitrogen-fixing bacterial strains of karst rocky decertified areas in Guangxi have growth promoting effect on local tree seedings used for afforestation. They provide a strong potential for forest restoration through seedling inoculation.

Key words： rocky desertification， nitrogen-fixing bacteria， afforestation seedlings， growth promotion， vegetation restoration

我国西南岩溶石漠化地区生态环境十分脆弱，由于受到土壤层薄、干旱、养分缺乏等环境因子的限制，当地植被抗逆性差，生长缓慢，造林成活率低，易退化难修复，严重制约石漠化地区生态恢复与可持续发展（彭晚霞等，2008;王克林等，2019）。……