Monitoring of imidacloprid residues in fresh fruits and vegetables from the central parts of Jordan.

Imidacloprid pesticide is widely utilized in agriculture due to its effectiveness in controlling a broad spectrum of insect pests. However, its usage has raised concerns about potential environmental impacts, and requires careful monitoring and responsible application to ensure sustainable agricultural practices. Thus, Gas chromatography-mass spectrometry (GC-MS) was utilized to analyze imidacloprid in 300 vegetable and fruit samples obtained from 15 major wholesalers in four regions of Amman, Jordan's capital city. Among the examined samples, 39.7 % were found to be contaminated with imidacloprid residues. Imidacloprid levels in different edible fruits and vegetables ranged from less than the Limit of Quantification (LOQ) to 0.40 mg kg-1. Significantly, eggplant and apples exhibited the highest average values (0.40 and 0.25 mg kg-1, respectively). Lower levels were detected in bananas (0.04 mg kg-1), potatoes (0.05 mg kg-1), grapes (0.07 mg kg-1), and cabbage (0.07 mg kg-1). Imidacloprid was below the method detection limit (BD) in samples of okra, peaches, apricots, and carrots. Overall, 25 samples (8.3 %) exceeded the Codex maximum residue limit (MRL) for imidacloprid. Moreover, 8 out of the 300 samples (2.7 %) exceeded the MRL established by the Pest Management Regulatory Agency (PMRA). Notably, the fruits of eggplant and apple contained the highest residual levels (1.30 and 0.83 mg kg-1, respectively), markedly exceeding the CODEX and PMRA MRLs. Additionally, the maximum detected imidacloprid residue concentration in bananas (0.25 mg kg-1) was 500 % higher than the CODEX MRLs. The estimated average daily intake (EDI) of the Amman population varied from 0.00 to 0.144 µg kg-1 body weight day-1 across various products. The hazard index (HI) for imidacloprid ranged from 0.00 to 0.24, all of which were below unity in all samples (<1). In conclusion, this investigation reveals low HI levels of imidacloprid residues in commonly consumed fruits and vegetables. However, the significant presence of imidacloprid residues in some samples highlights the urgent need for comprehensive measures to limit potential health hazards to consumers.

Salinity level influenced morpho-physiology and nutrient uptake of young citrus rootstocks.

Soil and irrigation water salinity are major limiting factor to citrus industry in arid environments. The objective of this study was to assess the effects of different salt stress levels on growth and ion uptake of three-month-old citrus rootstocks; sour orange (Citrus aurantium) and Volkamer lemon (Citrus volkameriana). Six levels of NaCl-salinity were used, 0.7 (control), 2, 4, 8, 12 and 15 dS m-1. Salinity increment from 2.0 to 15.0 dS m-1 significantly reduced seedlings height, stem diameter, leaf area, root dry weight, leaf relative water content, chlorophyll content index and chlorophyll fluorescence by one to three folds. In addition, leaf and root N concentration reduced by 10%-50%, P 6%-50%, K 8%-47%, Ca+2 7%-51% and Mg+2 7%-50% when salt stress in the irrigation water increased from 2.0 to 15.0 dS m-1. Conversely, salt stress increment (2.0-15.0 dS m-1) increased leaf stomatal resistance (5 folds), proline concentration (1 fold), Na+ and Cl- in the leaf (10 fold) and root (4 fold) when compared to control (0.7 dS m-1). In term of rootstock, Volkamer had higher seedling height, stem diameter, and root constituents (length, fresh and dry weight) than sour orange. While sour orange had higher leaf Cl-, Ca+2 and Mg+2, Volkamer lemon had higher N, Na+, K+, and P. However, root nutrient (N, Na+, Cl-, P and Mg+2) from Volkamer had consistently higher concentration compared to sour orange at 4.0, 8.0, 12.0 and 15.0 dS m-1. Therefore, we believe that the Volkamer rootstock is more tolerant to salt stress than sour orange.

Performance of six different soilless green roof substrates for the Mediterranean region.

The objectives of this research were to assess the physical properties of six different growing substrate mixtures destined for roof gardens and determine the influence of these substrates on the morphology, physiology, growth and flower quality of pansy (Viola × wittrockiana), Madagascar periwinkle (Catharanthus roseus), and Pavia lily (Longiflorum×Asiatic lilies (Lilium) 'Pavia'). Six green roof growing substrate mixtures (by volume) were used [T1: coarse tuff+fine tuff+cocopeat (5:1:4), T2:coarse tuff+medium tuff+fine tuff+cocopeat (5:5:2:8), T3: medium tuff+fine tuff+cocopeat (5:1:4), T4:medium tuff+fine tuff + peat moss (5:1:4), T5: perlite+medium tuff+fine tuff+cocopeat (5:5:2:8), and T6: lightweight expandable clay aggregates+fine tuff+cocopeat (5:1:4)]. The T6 (LECA-cocopeat) had the lowest weight at field capacity and good aeration and WHC to sustain optimal plant growth. Medium tuff-peat moss (T4) produced the highest pansy flowers number per plants. However, peat moss (T4) has been identified by environmentalists as an unsustainable media. LECA-cocopeat (T6) had a higher number of lily flowers and leaf area than T1-T4. The cost of the LECA substrate ($US 215 m-3, T6) is extremely higher than that of volcanic tuff ($US 36 m-3, T1-T4), and perlite ($US 100 m-3, T5). Overall, T6 can be an ideal option in terms of physical properties of growing substrate and flower quality but it might not be the best option for green roofs when cost is the primary concern. In addition, certain growing substrates could be used to satisfy specific growing requirements without sacrificing performance. For example, the combination of medium tuff and peat moss (T4) produced the highest pansy flower numbers per plant but required a longer period to flower (95 days). So, this growing substrate could be used where plentiful blooms are desired and the time to bloom is not a concern.

Isolation and Characterization of Halotolerant Plant Growth Promoting Rhizobacteria From Durum Wheat (Triticum turgidum subsp. durum) Cultivated in Saline Areas of the Dead Sea Region.

Plant growth promoting rhizobacteria (PGPR) are beneficial microorganisms that can be utilized to improve plant responses against biotic and abiotic stresses. In this study, 74 halotolerant bacterial isolates were isolated from rhizosphere and endorhizosphere of durum wheat (Triticum turgidum subsp. durum) plants cultivated in saline environments in the Ghor region near the east of the Dead Sea. 16S rDNA partial sequences and phylogenetic analysis of 62 isolates showed clear clustering of the isolates into three phyla: Firmicutes (61.3%), Proteobacteria (29.0%), and Actinobacteria (9.7%). At the genus level, the majority of them were grouped within the Bacillus, Oceanobacillus, and Halomonas genera. The isolates, which possessed plant growth promoting traits including nitrogen fixation, ACC deaminase activity, auxin production, inorganic phosphate solubilization and siderophore production, were selected. The effect of the inoculation of selected PGPR strains on growth of salt sensitive and salt tolerant durum wheat genotypes under high salt stress conditions was evaluated. Six halotolerant PGPR strains were able to improve survival in inoculated plants under high salinity stress conditions as reflected in higher germination percentages and seedling root growth when compared with non-inoculated plants. Furthermore, three halotolerant PGPR strains were able to improve durum wheat tolerance to water deficit stress. In addition, antagonistic effect in four halotolerant PGPR strains against an aggressive pathogenic isolate of Fusarium culmorum that causes crown rot disease was observed in a dual culture assay. In conclusion, the halotolerant PGPR strains described in this study might have great potential to improve durum wheat productivity under different stress conditions.

Over-expression of SlSHN1 gene improves drought tolerance by increasing cuticular wax accumulation in tomato.

Increasing cuticular wax accumulation in plants has been associated with improving drought tolerance in plants. In this study, a cDNA clone encoding the SlSHN1 transcription factor, the closest ortholog to WIN/SHN1 gene in Arabidopsis, was isolated from tomato plant. Expression analysis of SlSHN1 indicated that it is induced in response to drought conditions. The over-expression of SlSHN1 in tomato under the control of the constitutive CaMV 35S promoter produced plants that showed mild growth retardation phenotype with shiny and dark green leaves. Scanning electron microscopy showed that the over-expression of SlSHN1 in tomato resulted in higher cuticular wax deposition on leaf epidermial tissue when compared to non-transformed plants. Expression analysis in transgenic lines over-expressing SlSHN1 indicated that several wax-related synthesis genes were induced. Transgenic tomato plants over-expressing SlSHN1 showed higher drought tolerance when compared with wild type plants; this was reflected in delayed wilting of transgenic lines, improved water status and reduced water loss rate when compared with wild type plants. In conclusion, the SlSHN1 gene can modulate wax accumulation and could be utilized to enhance drought tolerance in tomato plant.