Fusarium head blight (FHB) is one of the biotic stresses that causes a significant reduction in wheat grain yield and its quality. The main objective of this study was to screen a set of 53 high yielding Nebraska wheat lines (DUP15 - F6:7) for resistance to FHB using visual scoring and confirm the results using a Kompetitive Allele Specific PCR (KASP) marker for the Fhb1 gene. The experiment was conducted at Lincoln Field Station of the University of Nebraska-Lincoln. A high genetic variation was found between genotypes for their resistance to FHB. The phenotypic correlation S_FHB and grain yield was -0.61**. The results of the KASP assay revealed that only three genotypes NE15648, NE15674 and NE15569 had the predicted Fhb1 gene. KASP genotyping was a very effective technology which helped in screening valuable QTLs and associated trait markers. The three lines having the Fhb1 gene can be used in the wheat breeding program at the University of the Nebraska-Lincoln to improve resistance to FHB.

Abstract Frost stress causes a significant damage to winter faba bean yield. Root traits of faba bean seedlings play an important role in resistance to frost tolerance. The main objective was to study the genetic variation in root traits of faba bean seedlings after frost stress. A set of 208 diverse genotypes was tested. The experiments were conducted in a Frost Growth Chamber (FGCh). Root frost susceptibility (RFS), root fresh matter (RFM), and root dry matter (RDM) were scored on all plants after frost stress. A selection index was calculated to improve RFS using RDM and RFM. The results revealed a high genetic variation was found between all genotypes for all traits scored. The repeatability estimates was ranged from 0.52 (RDM) to 0.60 (RFM). Such a high genetic variation and repeatability estimated could be used for selection to improve frost tolerance in winter faba bean through breeding programs. Keywords: Faba bean, Frost tolerance, Roots, Selection index

An incubation experiment was conducted to study the effects of farmyard manure (FYM) and elemental sulfur (S) on availability, fractionation and transformation of phosphorus in calcareous sandy soil. Soil samples were treated with FYM at levels: 0 (FYM0), 2.5 (FYM1), 5 (FYM2) and 7.5 (FYM3) g pot−1 and S at levels: 0 (S0), 0.1 (S1), 0.2 (S2) and 0.3 (S3) g pot−1. The soil was incubated for ten weeks under field capacity conditions. Additions of FYM caused significant increases in the amount of available P (Olsen−P) from 34.57 to 44.54 mg kg−1. The S with FYM application significantly increased Olsen−P of this soil at S1FYM1 from 42.95 to 52.70 mg kg−1. Significant reduction in Olsen−P was observed at S2 and S3 levels, but the addition of S at S1 level led to its insignificant increase. FYM application transformed HCl-Pi, NaOH II-Pi and residual P to NH4Cl-P, NaHCO3-Pi, NaHCO3-Po, NaOH I-Pi, NaOH I-Po and NaOH II-Po fractions. Application of S converted the NH4Cl-P, NaOH I-Pi and HCl-Pi fractions to NaHCO3-Pi, NaHCO3-Po, NaOH I-Po, NaOH II-Pi, NaOH II-Po and residual P fractions. It’s recommended adding FYM to calcareous sandy soils as well as adding S combined with FYM to improve the soil properties.

NULLGroundwater is considered an important water source for agricultural, drinking and domestic uses in many regions of the world including Libya, especially in its coastal area. This study aims to assess the quality of groundwater in north-western area of Libya for drinking and agricultural through examining its physico-chemical characteristics such as pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness, cations and anions. These parameters are used to assess the suitability of groundwater for domestic purposes by comparing their current values with the maximum permissible limits of these parameters that are recommended by World Health Organization (WHO). The EC, sodium adsorption ratio, soluble sodium percentage, Kelly’s ratio and magnesium adsorption ratio of the groundwater are also used to evaluate its suitability for irrigation. Gibbs diagram shows the evaporation–crystallization dominance in controlling the quality of groundwater. The main hydrochemical facies is Ca–Mg–SO4–Cl type of water in both methods of Piper and Chadha’s diagram. The results revealed that most groundwater samples were not suitable for drinking and household uses due to their high levels of most cations and anions, total hardness, EC and TDS. Most of the collected water samples showed the investigated parameter levels exceeded the permissible limits of WHO. Therefore, most of the groundwater samples are considered unsuitable for irrigation due to its high salt content, unless certain measures for salinity control are undertaken.

NULLAssessment and understanding of soil available phosphorus (P) and potassium (K) content distribution is an important part of deciding whether or not the fertilization is appropriate or even necessary for a soil. So, the main objective of this study is to evaluate and map the spatial variability of the available soil P and K using the geostatistical technique. Georeferencing surface soil samples (0-25 cm) were collected from four sites representing course-textured soils in El- Kharga and El-Dakhla oases. Ordinary Kriging (OK) technique was applied for the spatial interpolation of available soil P and K contents. The spatial distribution of available P and K was analyzed and mapped by Arc GIS (version 10.2.2). The results showed that concentrations of the available soil P and K ranged from 0.35 to 85.02 mg/kg and from 11 to 6204 mg/kg, respectively. The nugget-to-sill ratio suggested a strong spatial dependence for both available soil P and K in all sites of the study area, indicating that the available soil P and K were mainly controlled by intrinsic factors. The interpolation models varied for both P and K as well as from site to another site across the study area. Cross-validation proved that the chosen models were the best fitted semivariogram models to map spatial distribution of the available soil P and K. The produced maps of spatial distributions for soil P and K availability were characterized by high accuracy. So, site specific management can be planned and considered to be applied for this study area. Also, these maps can facilitate and help in making decisions for choose appropriate fertilization policies for these soils as well as to avoid adding fertilizers for sites which do not need to be fertilized. Our results confirmed that the integration of statistics, geostatistics and GIS provides a powerful tool to assess, describe and map the spatial variability of the available soil phosphorus and potassium. As well as to develop high resolution maps that may aid variable rate management (e.g. fertilization).

NULLAssessment and understanding of soil available phosphorus (P) and potassium (K) content distribution is an important part of deciding whether or not the fertilization is appropriate or even necessary for a soil. So, the main objective of this study is to evaluate and map the spatial variability of the available soil P and K using the geostatistical technique. Georeferencing surface soil samples (0-25 cm) were collected from four sites representing course-textured soils in El- Kharga and El-Dakhla oases. Ordinary Kriging (OK) technique was applied for the spatial interpolation of available soil P and K contents. The spatial distribution of available P and K was analyzed and mapped by Arc GIS (version 10.2.2). The results showed that concentrations of the available soil P and K ranged from 0.35 to 85.02 mg/kg and from 11 to 6204 mg/kg, respectively. The nugget-to-sill ratio suggested a strong spatial dependence for both available soil P and K in all sites of the study area, indicating that the available soil P and K were mainly controlled by intrinsic factors. The interpolation models varied for both P and K as well as from site to another site across the study area. Cross-validation proved that the chosen models were the best fitted semivariogram models to map spatial distribution of the available soil P and K. The produced maps of spatial distributions for soil P and K availability were characterized by high accuracy. So, site specific management can be planned and considered to be applied for this study area. Also, these maps can facilitate and help in making decisions for choose appropriate fertilization policies for these soils as well as to avoid adding fertilizers for sites which do not need to be fertilized. Our results confirmed that the integration of statistics, geostatistics and GIS provides a powerful tool to assess, describe and map the spatial variability of the available soil phosphorus and potassium. As well as to develop high resolution maps that may aid variable rate management (e.g. fertilization).

NULLAssessment and understanding of soil available phosphorus (P) and potassium (K) content distribution is an important part of deciding whether or not the fertilization is appropriate or even necessary for a soil. So, the main objective of this study is to evaluate and map the spatial variability of the available soil P and K using the geostatistical technique. Georeferencing surface soil samples (0-25 cm) were collected from four sites representing course-textured soils in El- Kharga and El-Dakhla oases. Ordinary Kriging (OK) technique was applied for the spatial interpolation of available soil P and K contents. The spatial distribution of available P and K was analyzed and mapped by Arc GIS (version 10.2.2). The results showed that concentrations of the available soil P and K ranged from 0.35 to 85.02 mg/kg and from 11 to 6204 mg/kg, respectively. The nugget-to-sill ratio suggested a strong spatial dependence for both available soil P and K in all sites of the study area, indicating that the available soil P and K were mainly controlled by intrinsic factors. The interpolation models varied for both P and K as well as from site to another site across the study area. Cross-validation proved that the chosen models were the best fitted semivariogram models to map spatial distribution of the available soil P and K. The produced maps of spatial distributions for soil P and K availability were characterized by high accuracy. So, site specific management can be planned and considered to be applied for this study area. Also, these maps can facilitate and help in making decisions for choose appropriate fertilization policies for these soils as well as to avoid adding fertilizers for sites which do not need to be fertilized. Our results confirmed that the integration of statistics, geostatistics and GIS provides a powerful tool to assess, describe and map the spatial variability of the available soil phosphorus and potassium. As well as to develop high resolution maps that may aid variable rate management (e.g. fertilization).

NULLAssessment and understanding of soil available phosphorus (P) and potassium (K) content distribution is an important part of deciding whether or not the fertilization is appropriate or even necessary for a soil. So, the main objective of this study is to evaluate and map the spatial variability of the available soil P and K using the geostatistical technique. Georeferencing surface soil samples (0-25 cm) were collected from four sites representing course-textured soils in El- Kharga and El-Dakhla oases. Ordinary Kriging (OK) technique was applied for the spatial interpolation of available soil P and K contents. The spatial distribution of available P and K was analyzed and mapped by Arc GIS (version 10.2.2). The results showed that concentrations of the available soil P and K ranged from 0.35 to 85.02 mg/kg and from 11 to 6204 mg/kg, respectively. The nugget-to-sill ratio suggested a strong spatial dependence for both available soil P and K in all sites of the study area, indicating that the available soil P and K were mainly controlled by intrinsic factors. The interpolation models varied for both P and K as well as from site to another site across the study area. Cross-validation proved that the chosen models were the best fitted semivariogram models to map spatial distribution of the available soil P and K. The produced maps of spatial distributions for soil P and K availability were characterized by high accuracy. So, site specific management can be planned and considered to be applied for this study area. Also, these maps can facilitate and help in making decisions for choose appropriate fertilization policies for these soils as well as to avoid adding fertilizers for sites which do not need to be fertilized. Our results confirmed that the integration of statistics, geostatistics and GIS provides a powerful tool to assess, describe and map the spatial variability of the available soil phosphorus and potassium. As well as to develop high resolution maps that may aid variable rate management (e.g. fertilization).

Land suitability analysis can help to achieve sustainable crop production with a proper use of the natural resources. The current study was carried out on the soils of north-western area of Libya to assess their morphological, physical and chemical properties and their suitability for growing irrigated crops. The studied area lies between latitudes 32° 30′ 00.9" and 32° 57′ 34.2'' N and between longitudes 11° 35′ 08.4" and 11° 45′ 09.2" E. Two suitability methods (Sys &Verhey and Storie methods) were used to assess the land suitability of this area. According to Sys and Verhye method, the soils of the studied area varied in the suitability for irrigation between highly suitable (S1) to marginally suitable (S3). However, according to modified Storie index method the soils productivity, ranged from excellent (grade 1) for agriculture to non-agricultural (grade 6). The modified Storie index method was more effective in assessing the land suitability of this area. The drip irrigation system was also more suitable than surface irrigation method for most of the soils of the studied area. The indeces of soil suitability rating and percentage for growing alfalfa, sorghum, barley, maize, millets, wheat and safflower were higher compared to those for growing soybean, sunflower and sesame. Onion and green pepper crops were moderately suitable to be grown in 42% of the soils of the studied area while the other vegetables were not suitable to be grown in most of the soils of the studied area. The evaluated fruit trees could be arranged according to the soil suitability rating and percentage in the order of date palm > olives > guava > citrus > banana. The results also revealed that the studied area has a good potential to produce the selected crops under irrigation provided that the water requirements for these crops are met. The main limiting factors for land suitability for growing crops are soil texture, soil depth, calcium carbonate, alkaline pH and soil salinity.

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