强还原和淹水处理对地黄连作障碍的消减效应

Alleviating effect of strong reduction and flooding treatment on continuous cropping obstacles in Rehmannia glutinosa

地黄是我国著名的大宗中药材,但是在其栽培过程中存在严重的连作障碍现象,至今尚未得到有效解决。为了开发地黄连作障碍消减技术,本文研究了强还原和淹水处理对连作地黄关键生长指标,连作土壤理化性质、细菌群落结构及其生物学功能的影响。结果表明,强还原和淹水处理提高了连作土壤中瘤胃球菌属和肠球菌属等厌氧异养型细菌的相对丰度,形成了富含Fe^(2+)和有机酸等抑制病原菌的土壤环境;其中,强还原处理后土壤中Fe^(2+)和有机酸含量比连作对照分别提高4.73倍和3.54倍,淹水处理后土壤中Fe^(2+)和有机酸含量比连作对照分别提高1.65倍和1.12倍。同时,假单胞菌属等益生菌群落在处理后的土壤中迅速重建。然而,强还原和淹水处理对土壤理化性质和细菌群落结构的影响存在一定差异,二者对地黄连作障碍的消减效果也有所不同:添加秸秆等有机物的强还原处理后连作土壤的有机质含量、碱解氮、速效磷和速效钾含量均有所提高,而淹水处理效果不明显;淹水处理的细菌香农指数和Chao1指数均有所下降,强还原处理的细菌香农指数有所下降,而Chao1指数有所上升,且细菌群落组成的变化也有所不同。强还原和淹水处理均可有效提高连作地黄的存活率和产量,并且以强还原处理效果较优,其存活率和产量比连作对照分别提高1.94倍和4.04倍。因此,强还原和淹水处理能够改善连作土壤的理化性质及其微生物群落结构,达到消减地黄连作障碍的效果,有效提高连作地黄的存活率和产量。

Rehmannia glutinosa is a popular medicinal herb in China.During R.glutinosa cultivation,serious consecutive monoculture problems are often encountered and have not yet to be effectively resolved.Preliminary studies found that an imbalance in the microbial communities in the rhizosphere soils is the main reason for consecutive monoculture problems;the abundance of pathogenic microorganisms significantly increased,whereas the beneficial microorganisms were inhibited.Therefore,it is important to control and alleviate the consecutive monoculture problem by inhibiting and balancing pathogenic microbes.This study sought to develop critical technology for alleviating the consecutive monoculture problems of R.glutinosa with strong reducing and flooding measures that may effectively inhibit the proliferation of pathogenic microbes.The key indices of treated R.glutinosa were analyzed,including plant growth and development,the physical and chemical properties of continuous cropping soil,the bacterial community structure,and its biological functions.The results indicated that the strong reducing and flooding treatments significantly increased the relative abundance of anaerobic heterotrophic bacteria,including Ruminococcus and Enterococcus,in the continuous cropping soils.This enhanced soil denitrification,creating special soil environments rich in Fe^(2+)and organic acids that inhibited pathogenic bacteria.Compared with the control soils,in the soils treated with strong reducing,the Fe^(2+)and organic acid levels increased by 4.73 times and 3.54 times,respectively,and in the soils treated with flooding,the same values increased by 1.65-fold and 1.12-fold,respectively.Concurrently,the beneficial bacteria community,such as Pseudomonas,was rapidly rebuilt in the treated soils;these bacteria have important roles that inhibit the proliferation of pathogens.The two methods,reducing and flooding,have different effects on the soil physical and chemical properties and the bacterial community structure of the consecutive cropping soils.Thus,the two methods have different efficiencies for alleviating the consecutive monoculture problem of R.glutinosa.Due to addition of straws,the strong reducing method increased contents of organic matter,available nitrogen,available phosphorus and available potassium of the consecutive cropping soils,while the flooding method did not show these effects.The Shannon index and Chao1 index under flooding decreased,while Shannon index decreased and Chao 1 index increased under the strong reduction.Both methods effectively increased the survival rate and yield of replanted R.glutinosa.The survival rate and yield of continuous cropping R.glutinosa treated with strong reducing increased by 1.94 times and 4.04 times,respectively,compared with those of the control plants.In contrast,the strong reducing treatment has more optimized effects that alleviate the consecutive monoculture problems of R.glutinosa.Both treatments alleviate the consecutive monoculture problem and improve the survival rate and yield of replanted R.glutinosa via improvements in the physical and chemical properties of the continuous cropping soils and their microbial communities.This study provides an important theoretical basis and technical reference for future studies of the strategies used to alleviate the consecutive monoculture problem during R.glutinosa production.