Melatonin is effective in modulating metabolism and regulating growth and development in many plants under biotic and abiotic stress. However, there is no systematic quantification of melatonin effects on maize growth, gas exchange, chlorophyll content, and the antioxidant defense system. A meta-analysis was conducted on thirty-two currently available published articles to evaluate the effect of stress types, study types, and maize varieties on response ratio (lnRR₊₊) of “melatonin” to “control (no melatonin)” on plant growth, enzyme activities, gas exchange parameters, and photosynthetic pigments. Our findings revealed that melatonin application overall increased plant height, leaf area, root length, fresh and dry root weight and shoot weight, superoxide dismutase (SOD), peroxide (POD), catalase (CAT), ascorbate peroxidase (APX), soluble sugar and protein, photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll, and carotenoid in maize leaf under stress conditions. In contrast, melatonin application decreased the levels of hydrogen peroxide (H₂O₂), superoxide anion (O_2⁻), malondialdehyde (MDA), and electrolyte leakage. The categorical meta-analysis demonstrated that melatonin application to chilling stress resulted in higher SOD activity followed by salt stress. Melatonin application to all stress types resulted in higher POD, CAT and APX activities, except Cd stress, which had no effect on POD and decreased CAT by 38% compared to control. Compared to control, melatonin resulted in lower reactive oxygen species (ROS) and electrolyte leakage under no stress, Cd, drought, salt, lead, heat, and chilling stress in all study types (pot, growth chamber, hydroponic, and field), except O₂ content which was not affected in pot and growth chamber studies. It was concluded that melatonin alleviates oxidative damage by improving stress tolerance, regulating the antioxidant defense system, and increasing leaf chlorophyll content compared to control.

Sugar beet (Beta vulgaris L.), accounting for 30 percent of the total world sugar production, maybe affected by soil fertility and nutrition supply in terms of both its yield and quality. Humic substances have a direct and indirect effect on plants, is it possible to raise this effect by integrate it with mineral nitrogen fertilization in saline soils? Two field experiments were conducted during two seasons. The treatments in split-plot design included without humic substances, soil-addition of humic acid and soil-addition of fulvic acid as main plots and 71, 142 and 213 kg N ha⁻¹ as subplots. Soil-additions of humic substances increased root length, top and root content of α-N and K, the concentration of sucrose, sugar loss and sugar recovery and yield of sucrose, sugar loss and sugar recovery but reduced root content of Na and sugar quality index percentage. Increasing nitrogen fertilization level from 71 to 213 kg N ha⁻¹ significantly increased all traits, except sucrose, sugar recovery and sugar quality index percentage. The highest root yield values were with soil-addition of humic acid with 213 kg N ha⁻¹. On the other hand, the soil-addition of humic acid and fulvic acid with 213 kg N ha⁻¹ increased the recoverable sugar yield of sugar beet by 16.1 and 15.2%, respectively. Therefore, it is preferable to use soil-addition of humic acid at 30 kg ha⁻¹ with 213 kg N ha⁻¹ to obtain the highest yield from the root yield and the extracted sugar yield, especially in saline soils.

The problem of soil salinity poses a significant challenge to global agriculture, adversely affecting crop development and yield. Triticale, a hybrid cereal crop, shows promise due to its resilience and adaptability. However, high soil salinity can hinder its full potential. Humic substances, derived from organic matter decomposition, have been found to enhance plants' ability to withstand environmental stress. This research aims to investigate the impact of humic compounds, particularly humic and fulvic acids, on triticale development, yield components, and biochemical composition. The study was conducted in three locations with varying salinity levels in northern Egypt over two consecutive winter seasons. The results showed that humic substances had a positive effect on various growth parameters, including plant height and root length. Additionally, they led to significant increases in fresh fodder production, relative water content, and 1000-grain weight, mitigating the detrimental effects of soil salinity. The presence of humic substances also positively influenced several physiological aspects of plants, such as increased chlorophyll content, reduced proline accumulation, and enhanced protein and carbohydrate levels, particularly under saline conditions. Correlation analysis revealed significant positive associations between plant characteristics influenced by humic substances, indicating their potential to improve growth, photosynthesis, and yield. These findings underscore the potential benefits of supplementing triticale crops with humic materials to enhance productivity and quality in saline soils. Further research is needed to elucidate the underlying mechanisms and optimize their application in practical agricultural settings.

Salinity is a negative abiotic stress that produces drastic disorders on soils and plants causing a critical reduction in plant growth and yield parameters, particularly maize plant, which considers a moderately sensitive plant to soil and water salinity. Although proline and nitrogen are well known to protect plants and improve their tolerance against various abiotic stresses including salinity, the interaction between proline and nitrogen fertilizer under saline conditions remained unclear. Two field experiments were conducted, on a clay saline soil in a split-plot design with four replicates. The main plots were arranged to study the effect of exogenous of proline applications at 0, 50 and 100 mM during seedling and vegetative stages, and mineral of nitrogen fertilization rates were 0, 140, 280, and 420 kg N ha⁻¹ occupied the subplots. A significant response to fertilizer N was observed at 420 kg ha⁻¹, while the optimum N rate of 50 mM of proline was 410.3 kg ha⁻¹ and the economic optimum dose was 403.43 kg ha⁻¹. Therefore, we recommend using 403.43 kg N ha⁻¹ to get an optimum economic yield of maize, especially in saline soil, when used 50 mM exogenous of proline at seedling and vegetative stages.

Salinity and alkaline stress pose major constraints for crop production. The use of soil amendments can help alleviate salinity and alkaline stress and improve productivity in salt-affected soils. A field experiment was conducted in 2021 and 2022 in Damietta, Egypt, to evaluate the effect of different organic and inorganic amendments on the growth, yield, quality, and nutrient uptake of okra (Abelmoschus esculentus L. cv. Balady) grown in alkaline soil. Treatments included gypsum (GP), organic matter (poultry manure; OM), fulvic acid (FA), humic acid (HA), and their combinations. The application of humic acid + organic matter + gypsum resulted in the tallest plants, the highest number of leaves, the greatest leaf area, the maximum pod yield, and increased nutrient uptake over control. It also gave the highest marketable yield, which was over 100% greater than control. The organic and inorganic amendments caused an appreciable improvement in soil properties like pH, EC, CEC and ESP. The results demonstrated that the integrated application of humic acid, organic matter, and gypsum could effectively reclaim the alkaline soil and improve the growth, yield, and nutritional quality of okra. The synergistic effects of the amendments in enhancing soil physical, chemical, and biological properties led to better plant growth and productivity under salinity stress conditions. The use of organic residues also helped sustain soil health. Despite greater amendment costs, HA+OM+GP had higher incremental yields (108–112%) over the farmer's practice of applying only organic matter and attractive returns on investment. The study showed that a holistic approach combining organic and inorganic amendments was most effective for okra cultivation in problematic soils.