Drying–rewetting cycles (D/W) occur frequently in topsoils and may mobilize phosphorus (P). We investigated the effect of repeated D/W on the release of dissolved inorganic (DIP) and organic P (DOP) from forest floors and A horizons. Samples were taken from 3 European beech sites and from 3 Norway spruce sites. Soils were desiccated up to pF 6 (–100 MPa) in three D/W cycles in the laboratory, while the controls were kept permanently at 50% water holding capacity. After each drying, P was extracted from the soils in water. D/W caused the release of DIP and DOP especially from O layers. There was no general difference in response to D/W between samples from beech and spruce. The net release of DIP after D/W was largest from the Oe horizons (average 50–60 mg P kg−1) for both beech and spruce forest soils. The net release of DIP from Oi layers was on average 7.8 mg P kg−1 and from spruce Oa layers 21.1 mg P kg−1. In the A horizons, net DIP release was similar in beech and spruce soils with 0.4 mg P kg−1. The release of DOP was less than the release of DIP except for the A horizons. Repeated cycles did not increase the release of DIP and DOP. The release of DIP and DOP was positively correlated with the microbial biomass in Oe and Oa layers but not in Oi layers. Our results suggest that D/W may significantly influence the short term availability of dissolved P in both beech and spruce forest soils.

Background Fungal stem end rot disease of pitaya caused by Alternaria alternata is one of the most destructive diseases in Binh Thuan province, Vietnam. This study aimed to assess the antagonistic effects of some endophytic bacteria isolated from the weed plant (Echinochloa colonum) against A. alternata. Results A total of 19 endophytic bacteria were isolated and 5 of them presented in vitro antagonistic activity against A. alternata. Of five, strain EC80 significantly inhibited the pathogenic growth with a mean inhibition diameter of 11.88 ± 0.08 mm, while the other four (C79, EC83, EC90, and EC97) showed a weak inhibition. Interestingly, the combination of EC79 and EC80 reduced more biomass of pathogenic fungi than the single one did. EC79 showed positive results for amylase, indole acetic acid (IAA), and biofilm production, whereas EC80 presented positive capabilities for IAA and biofilm production and a negative one for amylase production. In addition, the combined filtrate of EC79 and EC80 presented non-antifungal activity on biocontrol tests in vitro, indicating that bacteria cells played a role in defending against the pathogen. Moreover, both isolates EC79 and EC80 significantly increased seedling biomass than the control. Conclusions The results suggest that those two strains in combination had the potential to be used as a biocontrol agent against A. alternata. More studies should be done in the future to evaluate their efficiency under the field conditions.

Stem end rot is the most destructive disease caused by Alternaria alternata YZU in pitaya-growing regions of Vietnam. This study was conducted to characterize antagonistic phosphate-solubilizing bacteria (PSB) from rhizosphere soil for their biocontrol activities against A. alternata YZU and evaluate the effect of temperature, pH, and water activity on that antagonism. Among seven PSB isolated from 45 rhizosphere soil samples, PSB31 (identified as Bacillus sp. strain IMAU61039, Accession number: MF803700.1) exhibited the highest antagonistic activity against A. alternata YZU with an average inhibition diameter of 0.65 ± 0.05 cm. The results also show that the strain PSB31 controlled the mycelial growth of A. alternata YZU by secreting antifungal metabolites. The most potent inhibitory activity was identified under in vitro conditions of 25 °C, pH 7, and aw 1. The isolated PSB31 could be a potential biological control agent against A. alternata YZU.

Rough membership functions in covering approximation space not only give numerical characterizations of covering-based rough set approximations, but also establish the relationship between covering-based rough sets and fuzzy covering-based rough sets. In this paper, we introduce a new method to update the approximation sets with rough membership functions in covering approximation space. Firstly, we present the third types of rough membership functions and study their properties. And then, we consider the change of them while simultaneously adding and removing objects in the information system. Based on that change, we propose a method for updating the approximation sets when the objects vary over time.

Biết được môi trường không thuận lợi cho sự phát triển của mầm bệnh có thể được sử dụng làm thông tin cơ bản để xây dựng các chiến lược thích hợp để ngăn ngừa sự xuất hiện của bệnh trên thanh long. Nghiên cứu nhằm đánh giá một số yếu tố môi trường bao gồm nhiệt độ, độ pH và độ mặn, cũng như yếu tố sinh học bao gồm các loài vi khuẩn nội sinh phân lập từ cây thanh long đối kháng với nấm gây bệnh, Alternaria alternata. Sự phát triển của sợi nấm A. alternata bị ức chế ở nhiệt độ 35°C, trong khi nhiệt độ 25°C khá thích hợp cho sự phát triển của chúng. Nhiệt độ 30°C là thuận lợi cho sự phát triển của A. alternata. Trong điều kiện pH khác nhau, sự phát triển của nấm A. alternata hầu hết bị ức chế cực đại ở pH 4. Hơn nữa, kết quả thử nghiệm độ mặn cho thấy A. alternata không bị ảnh hưởng nhiều bởi các nồng độ muối được thử nghiệm. Trong khi đó, việc kiểm tra vi khuẩn đối kháng trong ống nghiệm cho kết quả là cả EC120 và EC121 đều có hiệu quả cao trong việc ức chế sự phát triển của loại nấm được khảo sát. Các kết quả thí nghiệm cho thấy sự kết hợp thích hợp của việc điều chỉnh môi trường và chế độ chăm sóc có thể rất hữu ích cho...