铝胁迫对不同林分土壤中杉木幼苗根际土壤酶活性和微生物的影响

探讨在铝胁迫下,不同林分土壤中杉木(Cunninghamia lanceolate)根际土壤酶活性和微生物数量变化特征及其相互关系,揭示杉木对铝胁迫的响应机理,以杉木1代林、次生杉木2代林及次生阔叶林土壤为培养基质,通过室内盆栽试验,研究了不同质量分数铝处理对杉木幼苗根标土壤酶活性和微生物数量的影响。结果表明:随着铝质量分数的增加,蔗糖酶活性呈降低趋势,真菌数量呈上升趋势,脲酶、过氧化氢酶和多酚氧化酶活性以及细菌和放线菌数量则具有低促高抑现象;随着胁迫时间的延长,蔗糖酶活性不断下降,多酚氧化酶活性和真菌数量不断提升,而脲酶和过氧化氢酶活性以及细菌和放线菌数量则在低质量分数铝处理下普遍呈上升趋势,中高质量分数铝处理下普遍呈下降趋势;铝胁迫下的3种林分类型土壤的杉木幼苗根系微环境中,土壤酶活性以及细菌和放线菌数量均呈次生阔叶林中最大、杉木1代林其次、次生杉木2代林最小,真菌数量则与之相反;4类土壤酶活性与细菌和放线菌数量基本呈正相关,与真菌数量基本呈负相关。综上所述,杉木具有通过调节根系分泌应对铝胁迫逆境的应对机制,并进而影响根系土壤酶的活性和微生物的种群结构和数量。土壤中铝的质量分数对于杉木幼苗根际微生态环境具有低促进、高抑制的调控作用。次生阔叶林土壤具有较高的耐铝性,杉木1代林其次,次生杉木2代林最低。

Effects of Al Stress on Enzyme Activity and Microorganism in Rhizosphere Soil of Cunninghamia lanceolate in Different Stand Soil

We investigated the changes of enzyme activity and microbial quantity and their relationship in the rhizosphere soil of Cunninghamia lanceolate under Al stress in different stand soils, reveal the response mechanism of C. lanceolate to Al stress. With the soil of the first generation of C. lanceolate, the second generation of C. lanceolate and evergreen broad-leaf forest as substrates, by the method of pot culture, we studied the effects of different Al contents on enzyme activity and microbe quantity in soil of C. lanceolate seedlings. As the content of Al increasing,the activity of invertase decreased and the number of fungi increased, the activities of urease, catalase, polyphenol oxidase and the number of bacteria and actinomycetes were increased under low content of Al and decreased under higher content. With the extension of stress time, the activity of sucrase decreased, the activity of polyphenol oxidase and the number of fungi increased, while the activity of urease and catalase, and the number of bacteria and actinomycetes generally showed an increasing trend under low content of Al and a decreasing trend under high and medium content of Al. The enzyme activity and the number of bacteria and actinomycetes in the rhizosphere soil of C. lanceolate seedlings in broad-leaved forest were the highest, followed by the first-generation forest, and the second-generation forest was the lowest, while the number of fungi changed with a contrary tendency. The four soil enzymes were positively correlated with the number of bacteria and actinomycetes, and negatively correlated with the number of fungi. Therefore, C. lanceolate has a coping mechanism to cope with Al stress by regulating root secretion, which will further the enzyme activity and the population structure and quantity of microorganisms in the rhizosphere soil. The effect of Al in soil on C. lanceolate seedling presents to be low-promoting and high-repressing. The broad-leaved forest soil has high Al resistance, the first generation of C. lanceolate is the second, and that of the second generation is the lowest.