土壤灭菌-生物有机肥联用对连作马铃薯及土壤真菌群落结构的影响

甘肃省中部沿黄灌区是全国重要的加工型马铃薯生产基地,然而因集约化生产带来的连作障碍问题已经严重影响到当地马铃薯种植业的健康发展。结合田间试验和相关的室内分析,从马铃薯块茎产量和品质、植株生理特征和土壤真菌群落结构等角度,初步评估土壤灭菌和生物有机肥联用(Ammonia Disinfection plus Bio-organic Fertilizer Regulation,ABR)对马铃薯连作障碍的防控效果。同对照相比,ABR处理的块茎产量和商品薯率分别显著增加约71.1%—152.1%和39.2%—53.3%,但块茎化学品质变化不大。ABR处理叶绿素含量和根系活力较CK均显著增加,而叶片和根系丙二醛含量显著下降。PCR-DGGE分析发现,ABR处理显著影响了马铃薯连作土壤的真菌群落结构,表现为真菌群落的多样性指数较CK相比显著下降。ABR处理还有效抑制了土传病害的滋生,植株发病率和收获后的病薯率较CK分别显著下降约67.2%—82.2%和69.1%—70.5%。采用Real-time PCR评估连作土壤中3种优势致病真菌的数量变化,显示ABR处理下立枯丝核菌、茄病镰刀菌和接骨木镰刀菌的数量在生育期内较CK均有不同程度的下降。综合来看,土壤灭菌和生物有机肥联用技术在防控甘肃省中部沿黄灌区马铃薯连作障碍上具有较大的应用潜力,而对土传病害的抑制和微生物群落结构的改善是其主要的作用机理。

Combination of the application of soil disinfection and bio-organic fertilizer amendment and its effects on yield and quality of tubers, physiological characteristics of plants, and the soil fungal community in a potato monoculture system

The irrigated areas along the Yellow River in central Gansu Province form one of the main potato growing regions in China. However, continuous monoculture practices, which are required for intensive production in order to maximize profits, have already impaired the development of the potato industry in the region. This is reflected in severe production losses in terms of tuber yield and quality, in the poor growth and development of potato plants, and in rapidly increasing problems related to fungal soil-borne diseases. In this study, we combined the application of soil disinfection and bio-organic fertilizer amendment to recover potato plant productivity in a continuously monoculture system. Additionally, efforts were made to improve the micro-environment of the potato rhizosphere by inhibiting soil-borne pathogens via soil disinfection prior to sowing the potatoes and then directly irrigating plants with bio-organic fertilizer mixed with water injected into potato rhizosphere after potato emergence. The commercial bio-organic fertilizer used contained a large amount of plant growth-promoting rhizobacteria as well as antagonistic microorganisms active against known soil-borne fungal pathogens. Irrigation with bio-organic fertilizer was performed three times at 20 day intervals during the entire growing period of the potato plants. Field experiments were conducted in two plots that had previously displayed severe continuous monoculture-related problems, one of which had been continuously planted with potato crops for over five years and the other for over six years. The goal was to evaluate the effects of a combined application of soil disinfection and bio-organic fertilizer amendment (ABR treatment) on the management of problems related to continuous potato monoculture. The field experiment included a control (CK) and an ABR treatment with three replicates of both. Specifically, the study examined tuber yield and quality, physiological characteristics of potato plants, and the structure of the soil fungal community in a long-duration monoculture system with and without soil treatment. Compared with CK, the ABR treatment significantly increased tuber yield and the ratio of marketable tubers by 71.1% to 152.1% and 39.2% to 53.3%, respectively. No distinct differences were observed between the chemical qualities of potato tubers produced by ABR or CK treatments. In terms of the physiological characteristics of potato plants, the ABR treatment significantly increased the chlorophyll content of leaves and the root vigor as compared to CK, but decreased the MDA content both in leaves and in roots, indicating that the ABR treatment could improve growth and development of potato plants in a continuous monoculture system. Based on Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE), the ABR treatment significantly affected the structure of soil fungal community, since fungal diversity index was significantly lower in ABR than in CK. Additionally, the ABR treatment effectively suppressed soil-borne diseases, with plants exhibiting a lower incidence of disease and a lower ratio of diseased tubers from 67.2% to 82.2% and 69.1% to 70.5%, respectively, when compared with CK. Real-time PCR assessment confirmed that the abundance of several pathogenic soil fungi (Rhizoctonia solani, Fusarinm solani, and Fusarium sambucinum) in the ABR treatment was significantly lower than that in CK during the potato growth stage. In the present study, the highly significant linear correlation were revealed between tuber yield and plant disease incidence, fungal diversity index, and the abundance of soil-borne pathogens, respectively. The combined application of soil disinfection and bio-organic fertilizer amendment is a potential approach to managing problems related to continuous potato monoculture in the irrigated areas of the Yellow River floodplain in central Gansu Province since it suppresses soil-borne diseases and improves the structure of the soil microbial community.