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The rhizome of Polygonatum sibiricum, known as huang-jing (黄精 in Chinese) in traditional Chinese medicine, is consumed to treat various diseases. During surveys in 2017, diseases reducing the productivity and longevity of the herb seedlings were observed on Mount Maoshan, China, including leaf blight caused by Diaporthe spp. This study aimed to identify the fungal species and evaluate the effectiveness of fungicides (prochloraz, tebuconazole, pyraclostrobin, and zhongshengmycin) against the pathogen in vitro. Based on morphological characteristics, pathogenicity tests, and phylogenetic analysis of the combined genes including the internal transcribed spacer (ITS)1-5.8S rRNA-ITS2 (rDNA-ITS), β-tubulin (TUB), translation elongation factor 1-α (EF1-α), and calmodulin (CAL) gene regions, the causal agent of the new disease was identified as Diaporthe eres. Among the tested fungicides, prochloraz, tebuconazole, and pyraclostrobin significantly inhibited the mycelial growth of D. eres on potato dextrose agar, whereas zhongshengmycin was less effective in inhibiting mycelial growth. The leaf blight caused by D. eres represents a potential threat to P. sibiricum nursery productivity and longevity in China, and its management should be further investigated in the field. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) are the mixed community composed of different ratios of cyanobacteria, mosses, and lichens at the slope scale in the Hilly Loess Plateau region. Biocrusts significantly affect water infiltration in this area. The relationship between infiltration rate and community structure of mixed biocrusts is unknown, which would hinder the assessment of soil permeability of biocrusts at the slope scale. We measured the stable infiltration rate of cyanobacteria, moss, and mixed biocrusts with different proportions of cyanobacteria and moss including moss coverage of <15%, 15%-30%, 30%-45%, 45%-60% and >60%, respectively. The principal component analysis and path analysis were used to understand the influencing factors of stable infiltration rate of mixed biocrusts, and to clarify the relationship between the stable infiltration rate and the community structure of mixed biocrusts. The results showed that the saturated hydraulic conductivity of cyanobacteria and moss crusts was 0.66 mm·min -1 and 2.40 mm·min -1 , respectively. The stable infiltration rates of mixed biocrusts with moss coverage <15% to >60% were 0.80-2.30 mm·min -1 . The stable infiltration rate of mixed biocrusts at the slope scale depended on moss coverage and its improvement on soil pore structure, with the correlation coefficients being 0.636 ( P =0.011) and 0.835 ( P =0.000) respectively. Herein, the saturated hydraulic conductivity and coverage of cyanobacteria and moss confirmed the weighted prediction of water infiltration volume ( y ) i.e ., a significant correlation ( r =0.945) with the measured water infiltration volume ( x ) of mixed biocrusts. The linear fitting of measured and predicted water infiltration volume of mixed biocrusts was y =0.85 x ( R 2 =0.98, P <0.05). This study clarified the relationship between water infiltration of mixed biocrust community composition and individual biocrust composition, which provided a scientific basis for accurately evaluating the hydrological process of biocrusts in this area.

Water is the key factor for vegetation restoration in the Loess Plateau region. Biological soil crust (biocrust), a widely distributed soil surface cover, significantly affects soil infiltration. Disturbance would affect soil water infiltration of biocrust. The effects of different intensities of disturbance on soil water infiltration of biocrust are still unclear. By simulating the trampling disturbance of sheep, we examined the effects of disturbance intensity (10%, 20%, 30%, and 40%) estimated by the coverage of broken biocrust on the surface cover of biocrust slope in the Hegou catchment of Wuqi County, Shaanxi Province. Soil water infiltration under different intensities were measured by the linear source infiltration method. The influence mechanisms of disturbance on soil water infiltration of biocrust slope were investigated with a structural equation model and correlation analysis. Results showed that compared to that without disturbance, the coverage of cyanobacterial crust was increased by 33.6% at 10% of disturbance intensity, no difference at 20% of disturbance intensity, and decreased by 36.1% and 75.0% at 30% and 40% of disturbance intensities, respectively. Litter coverage was increased by 34.3% under 40% of disturbance intensity, while that of other treatments were not changed. Surface roughness was decreased by 22.3%, 11.1%, and 5.6% at 10%, 20%, and 30% of disturbance intensities, respectively, but increased by 8.2% at the 40% of disturbance intensity. The initial infiltration rate at 40% of disturbance intensity was 77.1% higher than that without disturbance, while other treatments had no significant difference at the initial infiltration rate. Furthermore, distur-bance did not affect the stable and average infiltration rate. Our results confirmed that disturbance mainly promoted the initial infiltration by reducing the coverage of cyanobacterial crust, increasing the coverage of litter, and changing soil roughness. This study would provide scientific basis for the management of biocrust of rehabilitated lands in the Loess Plateau region.