Apple microbial communities and differences between two main Chinese producing regions

Microbes on fresh apples are closely associated with fruit disease, preservation and quality control. Investigation into the microbial communities on apples from different producing regions could reveal the microbial specificity and help disease prevention and quality control. In this paper, the apple surface microbes of forty-four samples from two main Chinese apple-producing regions, Bohai Bay (BHB) and the Loess Plateau (LP), were investigated by sequencing fungal internal transcribed spacer (ITS) and bacterial 16S rRNA hypervariable sequences. BHB and LP apples contained significantly different bacterial and fungal communities. BHB apples had a higher fungal diversity than LP apples. A total of 102 different fungal and bacterial taxonomies were obtained between apples from the two regions, in which 24 genera were predominant. BHB apples had higher phytopathogenic fungal genera, such as Tilletiopsis, Acremonium, Candida and Phoma, indicating the higher phytopathogenic risks of apples from the humid climate of the BHB region. LP apples contained more bacterial genera identified as gut microbes, indicating the potential risks of contaminating apples with foodborne pathogens in the arid environment of the LP. This study highlighted the environment-oriented microbial specificity on apples from two main apple-producing regions, and provided a basis for further investigation.

Rotational grazing increases purple prairie clover frequency in the rangeland plant communities under semi-arid environment

Purple prairie clover (PPC, Dalea purpurea Vent.) is a grazing tolerant perennial legume with good nutritional quality and is widely distributed across North America. Deferred rotational grazing (DR) and continuous grazing (CG) are the most widespread grazing systems on North American grasslands. We conducted a 10-year grazing study to assess the effects of environmental factors and grazing on the frequency of PPC in plant communities. The results showed that the frequency of PPC decreased and then increased with increasing precipitation under CG (P<0.05), while there was no significant change under DR (P>0.05). Meanwhile, PPC frequency increased with temperature under DR (P<0.05), but did not change under CG (P>0.05). Both grazing systems and the number of grazing years had a significant effect on PPC frequency (P<0.05), and there is no interaction between those two factors (P>0.05). We found that from 2011 to 2020, the growth rate of PPC population is 18.24% and 11.69% per year under DR and CG grazing, respectively. Moreover, after 10 years of grazing, the PPC increase in DR was 22.86% higher than that of CG. Thus, selecting the DR grazing system can increase PPC and is an effective practice for coping with environmental changes.

Drainage Density and Its Controlling Factors on the Eastern Margin of the Qinghai–Tibet Plateau

The drainage density (Dd) is an important index to show fluvial geomorphology. The study on Dd is helpful to understand the evolution of the whole hydrological and geomorphic process. Based on the Shuttle Radar Topography Mission 90-m digital elevation model, the drainage network of basins along the eastern margin of the Qinghai–Tibet Plateau is extracted using a terrain morphology-based method in ArcGIS 10.3, and Dd is calculated. The spatial characteristics of Dd are analyzed, and the relationship between Dd and its influencing factors, e.g., the topography, precipitation, and vegetation coverage, is explored. Our results show that terrains with a plan curvature ≥3 can represent the channels in the study area. Dd ranges from 2.5 to 0.1 km/km2, increases first, and then decreases from north to south on the eastern margin of the Qinghai–Tibet Plateau. Dd decreases with increasing average slope and average local relief. On the low-relief planation surfaces, Dd increases with increasing altitude, while on the rugged mountainous above planation surfaces, Dd decreases rapidly with increasing altitude. Dd first increased and then decreased with increasing mean annual precipitation (MAP) and normalized difference vegetation index (NDVI), and Dd reaches a maximum in the West Qinling Mountains with a semi-arid environment, indicating that Dd in different climatic regions of the eastern margin of the Qinghai–Tibet Plateau was mainly controlled by precipitation and vegetation.

Carbon balance of sandy loam soils in arid landscapes of the Chechen Republic

The spatial variability of the stability of soil aggregates and its relationship with runoff and soil erosion were studied in a semi-arid environment in the field in order to assess the validity of the stability of structures as an indicator of soil erosion in soils of sandy loam ridges. The influence of soil and relief properties on the variability of aggregate stability was also investigated. Significant relationships were found in the number of water droplets required to break down the aggregate, as well as the rate of runoff and erosion. The most significant correlation was found between the number of droplet impacts and the soil organic matter content. The stability of aggregates in the upper soil layer is apparently a valuable indicator of field runoff and inter-season soil erosion of sandy loamy ridges in semi-arid conditions.