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Biofertilizers and biocontrol agents have been improved for several decades as microbiological tools that can provide beneficial outcomes in the growth and health of plants. Two field experiments were performed in the Scientific Farm of the Horticulture Department, Faculty of Agriculture, Minia University, Egypt during the winter of 2022/2023 using clay loam soil. Control plots were treated with the recommended rates of mineral fertilizer of NPK (100%) without inoculation, while other plots were inoculated with Egyptian isolates of effective microorganisms (EMs) (a mixture of Azotobacter chroococcum and Azospirillium brasilense) and strains of Bacillus spp.; the biofertilizers were applied to the soil through mixing with irrigation water. For mycorrhizae, Glomus mosseae and Glamus fasiculatum isolation stock cultures were combined to create the mycorrhizal inoculum. The results showed that biofertilizers with 75% NPK were the best. Biofertilizers changed the properties of soil, increased its content of beneficial microorganisms, increased the total good quality production of onion and potato and decreased the stress of chemical pesticides and mineral fertilizers on crop growth and productivity. [ABSTRACT FROM AUTHOR]

In recent decades, several products have been proposed for estimating precipitation amounts. However, due to the complexity of climatic conditions, topography, etc., providing more accurate and stable precipitation products is of great importance. Therefore, the purpose of this study was to develop a multi-source data fusion method to improve the accuracy of precipitation products. In this study, data from 14 existing precipitation products, a digital elevation model (DEM), land surface temperature (LST) and soil water index (SWI) and precipitation data recorded at 256 gauge stations in Saudi Arabia were used. In the first step, the accuracy of existing precipitation products was assessed. In the second step, the importance degree of various independent variables, such as precipitation interpolation maps obtained from gauge stations, elevation, LST and SWI in improving the accuracy of precipitation modelling, was evaluated. Finally, to produce a precipitation product with higher accuracy, information obtained from independent variables were combined using a machine learning algorithm. Random forest regression with 150 trees was used as a machine learning algorithm. The highest and lowest degree of importance in the production of precipitation maps based on the proposed method was for existing precipitation products and surface characteristics, respectively. The importance degree of surface properties including SWI, DEM and LST were 65%, 22% and 13%, respectively. The products of IMERGFinal (9.7), TRMM3B43 (10.6), PRECL (11.5), GSMaP-Gauge (12.5), and CHIRPS (13.0 mm/mo) had the lowest RMSE values. The KGE values of these products in precipitation estimation were 0.56, 0.48, 0.52, 0.44 and 0.37, respectively. The RMSE and KGE values of the proposed precipitation product were 6.6 mm/mo and 0.75, respectively, which indicated the higher accuracy of this product compared to existing precipitation products. The results of this study showed that the fusion of information obtained from different existing precipitation products improved the accuracy of precipitation estimation. [ABSTRACT FROM AUTHOR]

Recently, dust has created many problems, including negative effects on health, and environmental and economic costs, for people who live both near to and far from sources of dust. The aim of this study is to evaluate and quantify the impact of dust sources located inside Saudi Arabia on the physical growth and vegetation status of cities. In order to do so, satellite data sets, simulated surface data, and soil data for Saudi Arabia from 2000 to 2021 were used. In the first step, a dust sources map of the study area was generated using multi-criteria decision analysis. Land surface temperature (LST), vegetation cover, soil moisture, precipitation, air humidity, wind speed, and soil erodibility factors were considered as effective criteria in identifying dust sources. In the second step, built-up land and vegetation status maps of major cities located at different distances from dust sources were generated for different years based on spectral indicators. Then, the spatiaotemporal change of built-up land and vegetation status of the study area and major cities were extracted. Finally, impacts of major dust sources on urban physical growth and vegetation were quantified. The importance degrees of soil erodibility, wind speed, soil moisture, vegetation cover, LST, air humidity, and precipitation to identify dust sources were 0.22, 0.20, 0.16, 0.15, 0.14, 0.07, and 0.05, respectively. Thirteen major dust sources (with at least 8 years of repetition) were identified in the study area based on the overlap of the effective criteria. The identified major dust sources had about 300 days with Aerosol Optical Depth (AOD) values greater than 0.85, which indicates that these dust sources are active. The location of the nine major dust sources identified in this study corresponds to the location of the dust sources identified in previous studies. The physical growth rates of cities located <400 km or >400 km from a major dust source (DMDS) are 46.2% and 95.4%, respectively. The reduction rates of average annual normalized difference vegetation index (NDVI) in these sub-regions are 0.006 and 0.002, respectively. The reduction rate of the intensity of vegetation cover in the sub-region close to dust sources is three times higher than that of the sub-region farther from dust sources. The coefficients of determination (R2) between the DMDS and urban growth rate and the NDVI change rate are 0.52 and 0.73, respectively, which indicates that dust sources have a significant impact on the physical growth of cities and their vegetation status. [ABSTRACT FROM AUTHOR]

Background: Purple blotch disease is a devastating disease, resulting in significant yield losses in onion. Application of synthetic fungicides is a rapid approach for the control of this disease, but extensive use of synthetic fungicides results in resistance development in pathogen. Thus, it is mandatory to explore alternative approaches to overcome the fungicide resistance challenges. The present study focused on a sustainable biocontrolling approach by using biocontrol yeast. The objective was to develop a management strategy that offers an environmentally acceptable alternative to commonly used fungicides. Results: A total of six pathogenic isolates were obtained from the infected onion leaves, out of all tested isolates, OP-4 recorded as highly virulent with disease incidence (75.2%). Filobasidium wieringae and Pichia kluyveri drastically reduced the in vitro mycelial growth of Alternaria porri (14 and 21 mm, respectively). In the greenhouse experiment, plant inoculated with P. kluyveri suspension was the most effective, resulting in considerable reduction (77.1%) in disease severity, before two days of pathogen inoculation. However, F. wieringae showed a considerable reduction (84.5%) in disease severity when applied in combination with P. kluyveri two days post-inoculation. Conclusions: These findings highlighted the strong biocontrol potential of P. kluyveri and F. wieringae in managing the purple blotch disease of onion and can reduce the reliance on synthetic fungicides. Further research and field trials should be conducted to optimize the application methods and evaluate the long-term effectiveness of these bioagents. [ABSTRACT FROM AUTHOR]

The synoptic and dynamic characteristics of dust storm events over northern Saudi Arabia were studied during the spring season from 1978 to 2008 using surface dust storm observations from 11 stations and meteorological data from the NCEP/NCAR reanalysis dataset. Two-day dust-free periods were selected before and after each event to represent the pre- and post-event stages, respectively. The synoptic study identified two synoptic systems associated with dust events, i.e., frontal systems and shamal systems, and these systems were associated with increases in the pressure and temperature gradient over the northern Arabian Peninsula (AP) and an eastward shift in the maximum wind as a dust storm event progressed from the pre- to post-event stages. The dynamic study also showed that during the pre-event stage, the atmosphere was baroclinic and featured dynamic disturbances by frontal systems. Additionally, frontal systems resulted in slightly greater intensification than the shamal systems. Moreover, the dynamic study demonstrated that the kinetic energy (KE) shifted eastward and the available potential energy (APE) shifted northward through a series of regions importing and exporting KE and APE. The vertical profile of the average energy area indicated that the main layer in which sensible heat was converted into KE was located above the dust cloud. [ABSTRACT FROM AUTHOR]

The monthly and seasonal variability and distribution of dust events over northern Saudi Arabia were studied using ground‐based measurements from 11 surface stations for the period of 1978–2010. Additionally, to study the synoptic climatology of the dust variability, the aerosol index (AI) data from the Total Ozone Mapping Spectrometer (TOMS) satellite and meteorological data from the National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) reanalysis datasets were used. The dust types observed at the surface stations are classified into two categories: weak dust and dust storms. A statistical study of the ground measurements demonstrated that weak dust category events are prevalent in the cold months, whereas storm category events are prevalent in the hot months. Additionally, the annual distribution distinguishes two periods for dust observations, before and after 1989, where the number of events in the first period is lower than the annual average but increases during the second period. The synoptic climate study indicated that two main atmospheric wind patterns, anticyclonic and northerly (shamal) patterns, accompany the dust events in the study area. The dust in winter and autumn is mainly affected by the anticyclonic pattern, while that in spring and summer is mainly affected by the shamal pattern. In addition, a synoptic study of selected cases confirmed the climate results and demonstrated the existence of two atmospheric patterns corresponding to winter and summer. Both patterns include troughs over the Red Sea and Arabian Gulf and a ridge or high‐pressure cell over the eastern Mediterranean region during the summer atmospheric pattern and over the mid‐Arabian Peninsula during the winter atmospheric pattern. The characteristic of non‐dust storm composition demonstrated that the storms exhibit pronounced synoptic systems (winter and summer) with the highest pressure/geopotential gradient near the Arabian Peninsula. [ABSTRACT FROM AUTHOR]

ABSTRACT The synoptic characteristics and statistical variability of seasonal dust over southwestern Saudi Arabia are studied for the period from 1979 to 2006 using the aerosol index ( AI) from the Total Ozone Mapping Spectrometer ( TOMS) satellite, dust observations from surface stations, and meteorological data from the National Center for Environmental Prediction and the National Center for Atmospheric Research ( NCEP/ NCAR) reanalysis data set. The seasonal AI distribution indicates that approximately 80% of each year was dusty and that most of the dust occurred during hot months. In addition, the surface observations of the dust types show that the stations with the largest number of dust observations throughout the year were close to the desert, except during the summer, when the stations near the Red Sea had the largest number of dust observations. The synoptic forces that influenced the dust cases were the relative positions of high-pressure systems (Azores or Siberian) and low-pressure systems (Sudan or Indian), alongside their interactions. The relative positions of the atmospheric systems are highly pronounced at a pressure level of 850 hPa; at this pressure, the systems are oriented from north (anticyclonic system) to south (cyclonic system), turn anticlockwise to become oriented from west (anticyclonic system) to east (cyclonic system) during the summer, and then turn clockwise during the winter. Moreover, the interaction of the atmospheric systems influences the wind pattern of the seasonal composition over the southern Arabian Peninsula, which produces an anticyclonic wind pattern during winter, a cyclonic wind pattern during spring, a northerly/northwesterly wind pattern during summer and an anticyclonic wind pattern during autumn. The dust sources changed because of the relative positions of these atmospheric systems, in which the 'Toker Gap' Sudan was the summer/autumn dust source, and the 'central and eastern' Arabian Peninsula was the winter/spring dust source. [ABSTRACT FROM AUTHOR]