Saddam A. Al-Dalain

This study was carried out to analyze the population structure of 231 spring barley genotypes from the spring barley core collection and to deepen the understanding of the phenotypic differences of the spring barley core collection based on row type, biological background, and origin. Population structure analysis using single-nucleotide polymorphism (SNP) markers revealed that barley genotypes were separated based on row-type and geographical origin. Agronomic and morphological traits showed limited effectiveness in distinguishing barley genotypes based on their biological background or origin. A neighbor Joining Tree clearly separates the 231 spring barley genotypes based on row-types and the origins. The two main row-type groups were further divided into eight sub-populations distinguished based on origin using concatenated split network tree analysis. The variance components of within and between sub-populations were detected with 57.53% and 30.12% of the total variance based on analysis of molecular variance (AMOVA), indicating a substantial level of variability within and among sub-populations in the spring barley collection. Significant differences were observed between 2-rowed and 6-rowed barley types for most agronomic traits, with 6-rowed genotypes demonstrating higher yield potential, increased plant height, and earlier maturity. Additionally, landraces and genotypes from West Asia and North Africa exhibited increased height and earlier maturity, suggesting strong adaptation to arid environments.

The accumulation of polyaromatic hydrocarbons in plants is considered one of the most serious threats faced by mankind because of their persistence in the environment and their carcinogenic and teratogenic effect on human health. The concentrations of sixteen priority polycyclic aromatic hydrocarbons (16 PAHs) were determined in four types of edible vegetables (tomatoes, zucchini, eggplants, and cucumbers), irrigation water, and agriculture soil, where samples were collected from the Jordan Valley, Jordan. The mean total concentration of 16 PAHs (∑16PAHs) ranged from 10.649 to 21.774 µg kg⁻¹ in vegetables, 28.72 µg kg⁻¹ in soil, and 0.218 µg L⁻¹ in the water samples. The tomato samples posed the highest ∑16PAH concentration level in the vegetables, whereas the zucchini samples had the lowest. Generally, the PAHs with a high molecular weight and four or more benzene rings prevailed among the studied samples. The diagnostic ratios and the principal component analysis (PCA) revealed that the PAH contamination sources in soil and vegetables mainly originated from a pyrogenic origin, traffic emission sources, and biomass combustion. The bioconcentration factors (BCF) for ∑16PAHs have been observed in the order of tomatoes > cucumbers and eggplants > zucchini. A potential cancer risk related to lifetime consumption was revealed based on calculating the incremental lifetime cancer risk of PAHs (ILCR). Therefore, sustainable agricultural practices and avoiding biomass combusting would greatly help in minimizing the potential health risk from dietary exposure to PAHs.

A complete randomized block design with three replications was conducted at two consecutive growing seasons (2014-2015 and 2015-2016) to evaluate the influence of planting date and nitrogen application level on growth parameters and oil yield production of dill plant. Experimental factors included three planting dates (15th of October, 15th of November and 15th of December) and five levels of nitrogen fertilizer (i.e urea) application (0, 30, 60, 90 and 120 kg/hectare). Both studied factors significantly influenced growth parameters (plant height, number of branches per plant, number of umbrellas per plant, 1000 seed weight, above ground biomass yield, seed yield and harvest index) and oil yield and oil percentage The results indicated that early planting date (1st of October) has a positive influence on all studied parameters in this study. Furthermore, this study showed that addition of nitrogen fertilizers significantly improved all studied parameters. Comparing the influence of the two studied factors, it seems that planting date when compared to nitrogen fertilizer application has more pronounced influence on all studied production parameters of dill plant.

Adaptation to drought-prone environments requires robust root architecture. Genotypes with a more vigorous root system have the potential to better adapt to soils with limited moisture content. However, root architecture is complex at both, phenotypic and genetic level. Customized mapping panels in combination with efficient screenings methods can resolve the underlying genetic factors of root traits. A mapping panel of 233 spring barley genotypes was evaluated for root and shoot architecture traits under non-stress and osmotic stress. A genome-wide association study elucidated 65 involved genomic regions. Among them were 34 root-specific loci, eleven hotspots with associations to up to eight traits and twelve stress-specific loci. A list of candidate genes was established based on educated guess. Selected genes were tested for associated polymorphisms. By this, 14 genes were identified as promising candidates, ten remained suggestive and 15 were rejected. The data support the important role of flowering time genes, including HvPpd-H1, HvCry2, HvCO4 and HvPRR73. Moreover, seven root-related genes, HERK2, HvARF04, HvEXPB1, PIN5, PIN7, PME5 and WOX5 are confirmed as promising candidates. For the QTL with the highest allelic effect for root thickness and plant biomass a homologue of the Arabidopsis Trx-m3 was revealed as the most promising candidate. This study provides a catalogue of hotspots for seedling growth, root and stress-specific genomic regions along with candidate genes for future potential incorporation in breeding attempts for enhanced yield potential, particularly in drought-prone environments. Root architecture is under polygenic control. The co-localization of well-known major genes for barley development and flowering time with QTL hotspots highlights their importance for seedling growth. Association analysis revealed the involvement of HvPpd-H1 in the development of the root system. The co-localization of root QTL with HERK2, HvARF04, HvEXPB1, PIN5, PIN7, PME5 and WOX5 represents a starting point to explore the roles of these genes in barley. Accordingly, the genes HvHOX2, HsfA2b, HvHAK2, and Dhn9, known to be involved in abiotic stress response, were located within stress-specific QTL regions and await future validation.