Low pH and aluminum (Al)-toxicity often coexist in acidic soils. Citrus sinensis seedlings were treated with nutrient solution at a pH of 2.5, 3.0, 3.5 or 4.0 and an Al concentration of 0 or 1 mM for 18 weeks. Thereafter, malate, citrate, isocitrate, acid-metabolizing enzymes, and nonstructural carbohydrates in roots and leaves, and release of malate and citrate from roots were measured. Al concentration in roots and leaves increased under Al-toxicity, but it declined with elevating nutrient solution pH. Al-toxicity increased the levels of glucose, fructose, sucrose and total soluble sugars in leaves and roots at each given pH except for a similar sucrose level at pH 2.5–3.0, but it reduced or did not alter the levels of starch and total nonstructural carbohydrates (TNC) in leaves and roots with the exception that Al improved TNC level in roots at pH 4.0. Levels of nonstructural carbohydrates in roots and leaves rose with reducing pH with a few exceptions with or without Al-toxicity. A potential model for the possible role of root organic acid (OA) metabolism (anions) in C. sinensis Al-tolerance was proposed. With Al-toxicity, the elevated pH upregulated the OA metabolism, and increased the flow of carbon to OA metabolism, and the accumulation of malate and citrate in roots and subsequent release of them, thus reducing root and leaf Al and hence eliminating Al-toxicity. Without Al-toxicity, low pH stimulated the exudation of malate and citrate, an adaptive response of Citrus to low pH. The interactive effects of pH and pH on OA metabolism were different between roots and leaves.

For the first time, we used targeted metabolome to investigate the effects of pH-aluminum (Al) interactions on energy-rich compounds and their metabolites (ECMs) and phytohormones in sweet orange (Citrus sinensis) roots. The concentration of total ECMs (TECMs) was reduced by Al-toxicity in 4.0-treated roots, but unaffected significantly in pH 3.0-treated roots. However, the concentrations of most ECMs and TECMs were not lower in pH 4.0 + 1.0 mM Al-treated roots (P4AR) than in pH 3.0 + 1.0 mM Al-treated roots (P3AR). Increased pH improved the adaptability of ECMs to Al-toxicity in roots. For example, increased pH improved the utilization efficiency of ECMs and the conversion of organic phosphorus (P) from P-containing ECMs into available phosphate in Al-treated roots. We identified upregulated cytokinins (CKs), downregulated jasmonic acid (JA), methyl jasmonate (MEJA) and jasmonates (JAs), and unaltered indole-3-acetic acid (IAA) and salicylic acid (SA) in P3AR vs pH 3.0 + 0 mM Al-treated roots (P3R); upregulated JA, JAs and IAA, downregulated total CKs, and unaltered MEJA and SA in P4AR vs pH 4.0 + 0 mM Al-treated roots (P4R); and upregulated CKs, downregulated JA, MEJA, JAs and SA, and unaltered IAA in P3AR vs P4AR. Generally viewed, raised pH-mediated increments of JA, MEJA, total JAs, SA and IAA concentrations and reduction of CKs concentration in Al-treated roots might help to maintain nutrient homeostasis, increase Al-toxicity-induced exudation of organic acid anions and the compartmentation of Al in vacuole, and reduce oxidative stress and Al uptake, thereby conferring root Al-tolerance. In short, elevated pH-mediated mitigation of root Al-stress involved the regulation of ECMs and phytohormones.

Orange trees are widely cultivated in regions with high concentrations of tropospheric ozone. Citrus absorb ozone through their stomata and emit volatile organic compounds (VOC), which, together with soil emissions of NO, contribute to non-stomatal ozone removal. In a Valencia orange orchard in Exeter, California, we used fast sensors and eddy covariance to characterize water and ozone fluxes. We also measured meteorological parameters necessary to model other important sinks of ozone deposition. We present changes in magnitude of these ozone deposition sinks over the year in response to environmental parameters. Within the plant canopy, the orchard constitutes a sink for ozone, with non-stomatal ozone deposition larger than stomatal uptake. In particular, soil deposition and reactions between ozone, VOC and NO represented the major sinks of ozone. This research aims to help the development of metrics for ozone-risk assessment and advance our understanding of citrus in biosphere-atmosphere exchange.

The current experiment was conducted to evaluate the effects of feeding dried sweet orange peel (SOP) and lemon grass leaves (LGL) as feed additives on broiler growth performance, serum metabolites, and antioxidant status. A total of 192-day-old (Ross 308) broiler chickens were distributed randomly into 4 dietary treatments with 4 replicates per each treatment. The dietary treatments included a control diet without any feed additive (T1), a diet containing 0.8 % SOP (T2), a diet containing 0.8 % LGL (T3), and a diet containing combination of 0.4 % SOP + 0.4 % LGL (T4) was fed during the growth period from 22 to 42 days. Feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), carcass traits, serum components, and antioxidant status were measured. At the end of the experimental period, the results indicated that supplementation of SOP and LGL alone or in combination did not significantly (P > 0.05) affect BWG, FI, FCR, and carcass characteristics in broiler chickens. Serum total protein was increased significantly (P < 0.05) in T3 and T4 compared to the other treatments. Also, serum globulin increased significantly (P < 0.05) in the treated groups. Serum glucose, low density lipoprotein, triglyceride, and very low density lipoprotein decreased significantly (P < 0.05) in the treatment groups, while cholesterol and high-density lipoprotein decreased in T2 compared to the other groups. Significantly (P < 0.05) higher total antioxidant status was observed in T2 compared to the other treatments. In conclusion, these results indicate that SOP, LGL, and their combination may positively modify some serum components and the antioxidant status without any beneficial effect on growth performance and carcass traits in broiler chickens.

The present study explores the efficient management of non-degradable polystyrene foam wastes (PSFW) by transforming into a microbial responsive material for an effective biodegradation process. In brief, the study involves three steps, viz., (i) preparation of citrus fruit peel extract from peel wastes; (ii) dissolution of PSFW using the extract and transform to polystyrene sheet (PSS) and characterization of the sheet formed and (iii) finally the microbial adhesion and biofilm formation on PSS. Results revealed that the maximum yield of the peel extract identified as D-limonene was obtained from Citrus sinensis (8.2 ± 0.06 ml/100 g fresh waste). Characterization studies on PSS suggested that there are appreciable changes in the infrared spectrum, thermo gravimetric analysis, gel permeation chromatography analyses, and contact angle measurements in comparison with PSFW. Observations on significant variations in the glass transition temperature of PSFW (100 °C) and PSS (60 °C); decomposition temperature of PSFW (310.93 °C) and PSS (78.18 °C), and molecular weight distribution changes in PSFW (2.00 Mw/Mn) and PSS (1.03 Mw/Mn) suggested the occurrence of structural and molecular changes in PSS. Studies on microbial adhesion and biofilm formation on PSS suggested that amongst six microbial species isolated from the waste dump yard, WD03 strain identified as Lysinibacillus sp., displayed a maximum adhesion and biofilm formation on the surface of the PSS as evidenced through biofilm characterizations, SEM, and fluorescence microscopic analyses respectively. In conclusion, the transformation of PSFW to PSS and the appreciable microbial adhesion and biofilm formation suggested the possibility of the effective management of white nuisance (PSFW) wastes in the environment.

This study was conducted to analyze the residue levels of tepraloxydim in banana and sweet orange. Successive liquid–liquid extraction and cartridge clean-up method for tepraloxydim determination in banana and sweet orange were developed and validated by HPLC. The developed method was validated, and the recovery and LOQ of tepraloxydim were 79.3–99.5% and 0.02 mg kg⁻¹, respectively. Among the 48 banana and 34 sweet orange samples, tepraloxydim was detected in two (0.03 mg kg⁻¹) and four samples (0.03–0.05 mg kg⁻¹), respectively. A risk assessment of tepraloxydim in banana and sweet orange was conducted by calculating the percent ratio of estimated daily intake (EDI) and acceptable daily intake (ADI). The ADI of tepraloxydim was 0.05 mg kg⁻¹ day⁻¹, and the EDIs of it from banana and sweet orange were 6.3 × 10⁻⁶ and 5.1–8.5 × 10⁻⁶, respectively. The percent of EDI to ADI of tepraloxydim was 0.013 and 0.010–0.017%, respectively. These results showed that the tepraloxydim levels in this study might not be harmful to human beings.

In present study, the essential oils such as Mentha piperita (mentha oil, M.O), Cymbopogan citratus (lemongrass oil, LG.O), Citrus sinensis (orange oil, O.O), and Eucalyptus globulus (eucalyptus oil, E.O) were evaluated for repellency against housefly (Musca domestica) in a specially designed chamber. Further, to study any synergistic effect, essential oil combinations, i.e., M.O + LG.O, M.O + O.O, and M.O + E.O, were screened at 50:50 and 70:30 ratios. The results showed superior repellency of mentha and mentha + lemongrass (70:30) with RC₉₅ value of 0.009 μl/cm³. The other oils and combinations showed higher values of RC₉₅ (0.010–0.041 μl/cm³). The order of repellency was observed to be mentha = mentha + lemongrass (70:30) > mentha + lemongrass (50:50) = lemongrass = mentha + orange (50:50) = mentha + orange (70:30) > mentha + eucalyptus (70:30) > orange > mentha + eucalyptus (50:50) > eucalyptus. Chemical composition of selected essential oils indicated various monoterpenes as active components for efficient repellency. The essential oil of mentha marked the presence of menthol (38%) and menthone (27%) in major fractions, whereas citral (49%) was found dominating in lemongrass oil. Eucalyptus and orange oils showed the presence of 1,8-cineole (85%), and limonene (87%), respectively, as major components of oils. Further, monoterpenes (menthol and limonene) were also evaluated for repellency against housefly. The data showed 90 ± 5 and 60 ± 5% repellency from menthol and limonene, respectively, after 1 h, indicating the vital role of monoterpenes in overall efficacy of essential oil.

This study reports the physicochemical characterization of clover (Trifolium hybridum) and citrus (Citrus sinensis) honeys produced in Fayoum, Egypt, by evaluating the analysis of moisture content, pH, total soluble solids (TSS), electric conductivity (EC), total sugars, crude protein, ash content, total acidity, hydroxymethylfurfural (HMF), and total phenolic compounds (TPC). Antioxidant and antimicrobial activities of honey extracts and their flower extracts were determined. The results clearly indicated that ethanol gave the highest extraction yield of both clover and citrus flowers, while ethyl acetate showed the highest extraction recovery for the phenolic compounds, with TPC amounting to 338.5 and 536.4 mg gallic acid equivalent kg⁻¹ fresh weight in clover and citrus flower extracts, respectively. Honey samples have less TPC than their flowers. The results showed that the TPC of citrus honey and its flowers was higher than clover honey and its flowers, respectively. Antioxidant activity was higher in extracts obtained from citrus flower than extracts of clover flower. The same trend was noticed for honey samples. Both clover and citrus honeys showed antimicrobial effects against tested microorganisms. HPLC analysis showed that p-coumaric acid was the main phenolic component in ethanol extracts of clover and citrus honeys, contributing about 83.0% and 52.2%, respectively. In citrus and clover flower extracts, syringic acid and quercetin were the main phenolics, respectively. It would be expected that characteristics of honey samples are mainly depended on the floral origin of nectar foraged by bees.

Seedlings of ‘Shatian pummelo’ (Citrus grandis) and ‘Xuegan’ (Citrus sinensis) were supplied daily with nutrient solution at a concentration of 0.5 (control), 100, 200, 300, 400, or 500 μM CuCl₂ for 6 months. Thereafter, seedling growth; leaf, root, and stem levels of nutrients; leaf gas exchange; levels of pigments; chlorophyll a fluorescence (OJIP) transients and related parameters; leaf and root relative water content; levels of nonstructural carbohydrates; H₂O₂ production rate; and electrolyte leakage were comprehensively examined (a) to test the hypothesis that Cu directly damages root growth and function, thus impairing water and nutrient uptake and hence inhibiting shoot growth; (b) to establish whether the Cu-induced preferential accumulation of Cu in the roots is involved in Cu tolerance of Citrus; and (c) to elucidate the possible causes for the Cu-induced decrease in photosynthesis. Most of the growth and physiological parameters were greatly altered only at 300–500 μM (excess) Cu-treated seedlings. Cu supply increased the level of Cu in the roots, stems, and leaves, with a greater increase in the roots than that in the stems and leaves. Many of the fibrous roots became rotten and died under excess Cu. These findings support the hypothesis that Cu directly damages root growth and function, thus impairing water and nutrient uptake and hence inhibiting shoot growth, and the conclusion that the preferential accumulation of Cu in the roots under excess Cu is involved in the tolerance of Citrus to Cu toxicity. The lower CO₂ assimilation in excess Cu-treated leaves was caused mainly by nonstomatal factors, including structural damage to thylakoids, feedback inhibition due to increased accumulation of nonstructural carbohydrates, decreased uptake of water and nutrients, increased production of reactive oxygen species, and impaired photosynthetic electron transport chain. Also, we discussed the possible causes for the excess Cu-induced decrease in leaf pigments and accumulation of nonstructural carbohydrates in the roots and leaves.