No abstract

Mango fruits sourced from tropical yields have had a high commercial comeback from being viewed as susceptible to chilling injury under long storage durations. When the fruits are exposed to cold storage, this results in physiological changes due to the side effects of the storage on the fruits, expanding the rates of loss during the period between harvest and marketing. It is difficult to harvest mangoes as the fruits show varying maturities and are located in different positions on the trees. The purpose of this study was to test the idea that fruits’ location on the tree influences how the fruit behaves during cold storage. During two seasons (2019–2020), the impact of on-tree fruit location, i.e., sunny side (SUN; fruit exposed to the sun for most of the day), shade (SHA; fruit grown on the shady side of trees), and inside the canopy (INS; fruit grown inside the tree canopy), on the chilling sensitivity and the activities of antioxidant enzymes of ‘Zibda’ mangos stored at a low temperature (4 ± 1 °C) for 35 days was determined. In contrast to SHA and SUN mangos, INS fruits were shown to be progressively tolerant to low storage temperatures. These fruits also showed the highest activities of ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD). In addition, the contents of O2− and H2O2 decreased in INS fruit during storage. Consequently, the cell membrane compartments were maintained, showing low accumulation of both malondialdehyde (MDA) and the protein carbonyl group (PCG) during storage. These results indicate that the fruit positions can also be considered at the time of harvesting for the classification of fruits before cold storage. This classification can also be added to the mango trading protocol to minimize the loss of economic returns by chilling injury.

The present work studied the effect of foliar spray of different concentrations of titanium (Ti, applied as titanium dioxide) and vanadium (V, applied as vanadium pentoxide) on growth, chemical composition, antioxidant contents, antioxidant enzymes, antioxidant capacity, yield and quality criteria of red cabbage plants. For this purpose, 2.0, 4.0 and 6.0 mg L−1 of Ti and V were used to treat red cabbage plants. The control plants were treated with tap water. Our results showed that plants treated with 4.0 mg L−1 of Ti recorded the highest values of plant growth and bioactive compounds, while antioxidant capacity was decreased compared to the other treatments. In addition, plants treated with Ti and V at 2.0 and 4.0 mg L−1, respectively, showed higher values of all of the growth, yield, non-enzymatic antioxidants and antioxidants enzymes’ parameters compared to the untreated plants. Based on the obtained results, it could be concluded that the low concentrations of both Ti and V (2.0 and 4.0 mg L−1) were able to enhance red cabbage growth and yield, as well as the antioxidant contents, enzymes and capacity.

Background Plasmopara viticola, the causal agent of grape downy mildew, is one of the most serious grape diseases. Application of Trichoderma harzianum grown on different potato dextrose supplemented broth media using some chemical inducers (TSDCIS), i.e., thiamine (T2), a mixture of micronutrients (T3) and potassium tartrate (T4), compared to Trichoderma without amendment (T1), was conducted under field conditions to evaluate the potential of T. harzianum against grape downy mildew, improving the growth, as well as the yield quality, and quantity. Results Foliar application of all TSDCIS significantly reduced the disease severity and increased the phenolic content, peroxidase, polyphenol oxidase enzyme activity, growth parameters, and yield parameters. Trichoderma growing on medium supplemented with potassium tartrate (T4) achieved the most significant reduction in the disease severity (78.9, 81.8%) than the control treatment in two growing seasons, respectively. In contrast, it decreased H2O2 content, lipid peroxidation, and cellular electrolyte leakage. Scanning electron microscopy observations revealed that the number of opened stomata, average stomatal area, and stomatal pore area decreased significantly in response to T4 treatment. Conclusions It can be concluded that using Trichoderma growing on medium supplemented with potassium tartrate (T4) to biosafety control the downy mildew disease of grape and improve its growth, yield, and fruit quality is recommended.

Heavy metals may be introduced in agricultural soil by many sources, one of which is sewage sludge application as a fertilizer. Heavy metals in polluted soil can negatively affect plant growth and productivity. Aiming at exploring means to alleviate heavy metals stress on soybean plant, the present study was performed with the objective to test the alleviating effect of ascorbic acid, salicylic acid, yeast extract, thyme oil as well as inoculation with arbuscular mycorrhizal fungi on soybean plants challenged with either cadmium, cobalt or sewage sludge. Results indicated that though all had beneficial effect manifested by maintaining yield and reducing its content from heavy metals as well as elevating stress-related metabolites, especially phenols, application of thyme oil or yeast extract and inoculation with arbuscular mycorrhizal fungi were the most effective and are recommended to be employed to mitigate heavy metals stress on soybean in heavy metals-affected soils. * Mechanical analysis followed the pipette method using sodium hydroxide as a dispersing agent (Piper, 1950). The contents of Cd, Cu and Pb were determined in DTPA (Diethylene triamine pentacetic acid) soil extract (1:2 w/v) by atomic absorption spectrophotometry. Other soil chemical analysis were carried out according to Jackson (1967).