The effect of melatonin (MT) on potato plants under drought stress is still unclear in the available literature. Here, we studied the effect of MT as a foliar application at 0, 0.05, 0.1, and 0.2 mM on potato plants grown under well-watered and drought stressed conditions during the most critical period of early tuberization stage. The results indicated that under drought stress conditions, exogenous MT significantly (p ≤ 0.05) improved shoot fresh weight, shoot dry weight, chlorophyll (Chl; a, b and a + b), leaf relative water content (RWC), free amino acids (FAA), non-reducing sugars, total soluble sugars, cell membrane stability index, superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX) compared to the untreated plants. Meanwhile, carotenoids, proline, methylglyoxal (MG), H₂O₂, lipid peroxidation (malondialdehyde; MDA) and abscisic acid (ABA) were significantly decreased compared to the untreated plants. These responses may reveal the protective role of MT against drought induced carbonyl/oxidative stress and enhancing the antioxidative defense systems. Furthermore, tuber yield was differentially responded to MT treatments under well-watered and drought stressed conditions. Since, applied-MT led to an obvious decrease in tuber yield under well-watered conditions. In contrast, under drought conditions, tuber yield was substantially increased by MT-treatments up to 0.1 mM. These results may imply that under water deficiency, MT can regulate the tuberization process in potato plants by hindering ABA transport from the root to shoot system, on the one hand, and by increasing the non-reducing sugars on the other hand.

Currently, the world is facing many troubles in crop production and the irrigation water deficit is the most harmful among them. Saving irrigation water is the main target for all countries of the world, especially in arid areas. Field trial was executed aiming to assess the influence of irrigation regimes (100, 80 and 60% of irrigation requirements, IR (IR₁₀₀, IR₈₀ and IR₆₀, respectively), water-absorbent substances (control, hydrogel polymer and zeolite as soil addition) and foliar application of glutathione (GSH) [with GSH or without] on the performance of common bean plants. Findings clarified that plant fresh weight obtained with the combination of IR₈₀ × zeolite × GSH had no significant differences with the superior combination of IR₁₀₀ × hydrogel polymer or zeolite × GSH. Hydrogel polymer plus GSH supply showed distinctive enhancements for N, P and K accumulation in common bean leaves. Application of zeolite plus GSH reduced the accumulation of POX and CAT by 21.8 and 15.5% under IR₈₀ and 16.1 and 7.6% under IR₆₀, respectively. Spraying of GSH × hydrogel polymer under IR_100, IR₈₀ and IR₆₀ significantly increased the value of pods yield by 26.5%, 25.23% and 32.80, respectively, as compared to corresponding control treatment. the interaction of IR₁₀₀ and hydrogel polymer whether with or without GSH showed the highest significant values of N, P, protein, fiber, carbohydrates percentages and TDS. Briefly, it can be concluded that water holding amendments i.e., polymer and zeolite as well as low-molecular-weight antioxidants i.e., glutathione can mitigate the hazard impacts of elevated reactive oxygen species production under drought. Practically, common bean growers are advised to treat the soil with available soil amendment (hydrogel polymer, 0.24 t ha⁻¹ or zeolite, 1.20 t ha⁻¹) and spraying common bean plants by glutathione, 1.0 mM to sustain the crop productivity and quality under shortage water conditions

The present work reveals the beneficial role of sodium nitroprusside (SNP; NO donor concentration: 50 and 100 µM) in mitigation of water stress accompanied by a reduction in viral disease incidence in tomato plants subjected to deficit irrigation. The plants were grown under two irrigation regimes: well-watered (WW; irrigated after the depletion of 55–60% of available soil water) and water deficit (WD; irrigated after the depletion of 85–90% of available soil water) in two seasons of 2018 and 2019. The results indicated that under water stress conditions, plant growth, chlorophyll, relative water content (RWC), and fruit yield were decreased. Conversely, water stress significantly increased the MDA, proline, soluble sugars, and antioxidant enzymes’ activities. Moreover, it was obvious a negligible increase in the fruit content from NO₂ and NO₃. Water-deficit stress, however, had a positive impact on reducing the percentage of viral disease (TMV and TYLCV) incidence on tomato plants. Similarly, SNP application in the form of foliar spray significantly reduced the disease incidence, the severity, and the relative concentrations of TMV and TYLCV in tomato plants raised under both WW and WD conditions. The treatment of SNP at 100 µM achieved better results and could be recommended to induce tomato plant tolerance to water stress. Thus, the present work highlights the role of NO (SNP) in the alleviation of water stress in tomato plants and subsequent reduction in viral disease incidence during deficit irrigation.

Agronomic approaches for increasing food crop yield and quality are crucial for boosting food security due to the depletion of terrestrial resources and the rising worldwide demand for food. As a consequence, the current study looks at ways to improve several essential components of existing onion production technique in Egypt by using two types of potassium fertilizer, KCl and K2SO4, either alone or in combination, as well as two different planting methods, seeding and seedling transplantation. The research focused on the performance of onion cv. Giza 9 through vegetative growth, bulbification (bulbing ratio), dry bulb yield and bulb quality during the successive winter seasons of 2019/2020 and 2020/2021. The obtained results demonstrated that direct seeding of onion produced higher plant growth, bulb yield, and quality than seedling transplantation. Compared to potassium combinations involving chloride, potassium fertilization of onion in the form of K2SO4 produced the best plant growth, bulb production, and their quality. As chloride levels in fertilizer compounds rise, onion plant growth and yield potential decline. On the other hand, chloride had a less negative impact when onion was grown from seeds rather than seedlings. Also, direct seed sowing and fertilization interactions with either pure K2SO4 or a mixture of 75% K2SO4 and 25% KCl resulted in the highest dry bulb yield measurements. Interestingly, supplying the onion plants with KCl fertilizer up to 25% of their potassium requirements without causing a significant decline in plant growth or bulb yield when planting onions by direct seeds but not to seedlings.

Recently, the importance of the beneficial elements for humans, animals, and plants has been clarified. Element fortification in plants is a strategy that supplies elements through the food chain. The beneficial elements promote plant growth in plants which comprise selenium, silicon, cobalt, and sodium. Nowadays, evaluating the impact of beneficial elements such as selenium and silicon on the growth and productivity of various plant species has become a novel approach. An experiment was conducted to evaluate the effect of foliar application of selenium in form of sodium selenite at 10, 20 and 30 μmol, and silicon in form of sodium silicate at 0.5, 1 and 2 mM plus water as control treatment on vegetative growth, chlorophyll, mineral content of leaves and seeds, and seed yield and quality of common bean (Phaseolus vulgaris L.) plants cv. Nebraska during 2020 and 2021 seasons at the Experimental Field of Horticulture Department, Faculty of Agriculture, Ain Shams University, Qalubia Governorate, Egypt. Results showed that all foliar applications of selenium and silicon significantly enhanced all the vegetative growth parameters, yield and yield quality attributes such as pods yield weight/plant and 100 seed weight, mineral contents in leaves, i.e., N, P, K and Ca, and Se and Si in seeds as compared with control treatment. In conclusion, the foliar spraying of common bean plants cv. Nebraska with Si at 2 mM or Se at 20 μmol enhances growth, yield and yield quality of the plants and improve the elements fortification at the food chain to humans.

An experimental investigation was conducted to study the ash particle rebound characteristics and the associated erosion behavior of superalloys and aluminide coatings subjected to gas-particle flows at elevated temperatures. At three-component LDV system was used to measure the restitution parameters of 15 micron mean diameter coal ash particles impacting some widely used superalloys and coatings at different angles. Results show the variation restitution ratios with the impingement angle for the coated and uncoated superalloys. Experimental results were used to develop correlations for the restitution parameters for coated and uncoated superalloys. A theoretical model based on elastic-plastic theory has been developed to simulate single solid particle impacts on solid targets. The erosion behaviors of many superalloys and protective coatings have also been investigated experimentally at high temperatures using a specially designed erosion tunnel. Also, the cumulative effect of the impacting particle mass on the weight loss and erosion rate were investigated. Semi-empirical erosion equations were developed for these materials based on the experimental erosion data and correlations of the restitution parameters. Coatings tested include: platinum alimunides, cobalt aluminides, nickel aluminides, rhodium platinum aluminides, and chromium carbide. Superalloys tested were nickel base alloys Inco in-738 and Mar-M246, as well as Cobalt basemore » alloys X40 and FSX-414. 10 refs., 86 figs., 5 tabs. « less