Sustainability of rice production under flooding conditions has been challenged by water shortage and food demand. Applying higher nitrogen fertilization could be a practical solution to alleviate the deleterious effects of water stress on lowland rice (Oryza sativa L.) in semi-arid conditions. For this purpose, field experiments were conducted during the summer of 2017 and 2018 seasons. These trials were conducted as split-split based on randomized complete blocks design with soil moisture regimes at three levels (120, 100 and 80% of crop evapotranspiration (ETc), nitrogen fertilizers at two levels (N₁—165 and N₂—200 kg N ha⁻¹) and three lowland Egyptian rice varieties [V₁ (Giza₁₇₈), V₂ (Giza₁₇₇) and V₃ (Sakha₁₀₄)] using three replications. For all varieties, growth (plant height, tillers No, effective tillers no), water status ((relative water content RWC, and membrane stability index, MSI), physiological responses (chlorophyll fluorescence, Relative chlorophyll content (SPAD), and yield were significantly increased with higher addition of nitrogen fertilizer under all water regimes. Variety V₁ produced the highest grain yield compared to other varieties and the increases were 38% and 15% compared with V₂ and V₃, respectively. Increasing nitrogen up to 200 kg N ha⁻¹ (N₂) resulted in an increase in grain and straw yields by 12.7 and 18.2%, respectively, compared with N₁. The highest irrigation water productivity (IWP) was recorded under I₂ (0.89 kg m⁻³) compared to (0.83 kg m⁻³) and (0.82 kg m⁻³) for I₁ and I₃, respectively. Therefore, the new applied agro-management practice (deficit irrigation and higher nitrogen fertilizer) effectively saved irrigation water input by 50–60% when compared with the traditional cultivation method (flooding system). Hence, the new proposed innovative method for rice cultivation could be a promising strategy for enhancing the sustainability of rice production under water shortage conditions.

This study aimed to determine the effects of compost amendment on the soil properties, as well as the morphophysiological responses, seed yield, oil content, and fatty-acid profile. of Nigella sativa plants under drought stress conditions. In a split-plot design, the field experiment was carried out during two seasons (2020/2021 and 2021/2022), involving three irrigation regimes (named I₁₀₀, I₇₅, and I₅₀ of crop evapotranspiration) with three levels of compost application (C₀, C₁₅, and C₃₀). Soil porosity, permeability, pore geometry, water-holding capacity, organic content, and soil cation exchangeable capacity were improved in response to applied compost levels. The growth, physiology, biochemistry, and yield characteristics of Nigella sativa plants were positively affected by compost addition but negatively affected by increasing water stress severity. Deficit irrigation regimes increased osmoprotectant substances (i.e., proline, total free amino acids, carbohydrates, and total soluble sugar). Compared to the control (I₁₀₀), deficit irrigation (I₅₀) reduced fixed and essential oil by 16.64% and 39.57% over two seasons. Water stress increased the content of saturated fatty acids, while unsaturated fatty acids decreased. Compost application of (C₃₀) resulted in a significant increase in seed yield, fixed oil, and essential oil of Nigella sativa plants by 34.72%, 46.55%, and 58.11% respectively, compared to the control (C₀). Therefore, this study concluded that compost amendment improved soil properties and significantly mitigated the detrimental effects of drought on Nigella sativa plants, resulting in a considerable increase in seed yield and its oil content, particularly polyunsaturated fatty acids, which are distinguished by their beneficial effects on human health.

Salinity and drought are two commonly occurring major threats to agricultural yields worldwide, including sugar beet production. Therefore, this work aimed to determine the effectiveness of biochar amendment in improving soil health and alleviating the combined effects induced by salinity and drought on morphological, physiological and biochemical responses of sugar beet plants. Two field studies were established at the experimental farm of Fayoum University, Egypt over two successive winter seasons (2019/2020 and 2020/2021). The experiments were carried out in a split-split plot design with triplicate including three factors: 1) soil salinity, with two levels of ECe (< 4 dS m⁻¹ as control and 10 dS m⁻¹) as main-plot factor; 2) deficit irrigation regimes (I₁₀₀, I₈₀, and I₆₀) representing 100%, 80%, and 60% of crop evapotranspiration (ETc), respectively as sub-plot factor; and 3) biochar amendment with three application levels (B₀ as control, B₁₀, and B₂₀) corresponding to 0, 10, and 20 t ha⁻¹, respectively as sub-sub plot factor. Drought and salinity stress induced significant reduction in growth attributes, relative water content, membrane stability, relative chlorophyll content (SPAD), yield and yield components of sugar beet plants. Meanwhile, the contents of sucrose, proline, Na, K, α amino-N were substantially increased with increasing stress severity. The application of biochar amendment improved the soil physical and chemical properties, resulting in better morphological, physiological and biochemical responses of saline-drought stressed sugar beet plants. Biochar at level (B₂₀) produced the highest values of root yield (95.02 t ha⁻¹) and sugar yield (20.24 t ha⁻¹) for full irrigated sugar beet plants in non-saline soil. Moreover, the application of biochar enhanced water productivity for drought and saline stressed sugar beet plants. Biochar amendment could be effectively used as a helpful agro-management strategy in alleviating the detrimental impacts of salinity and water stress on sugar beet plants, improving soil quality and enhancing water productivity to ensure water sustainability and food security, especially in areas of limited water supply.

Two successive field trials were carried out at the experimental farm of the Agriculture Department of Fayoum University, Fayoum, Egypt, to investigate the sole or dual interaction effect of applying a foliar spray of Aloe saponaria extract (Ae) or potassium silicate (KSi) on reducing the stressful salinity impacts on the development, yield, and features of roselle (Hibiscus sabdariffa L.) plants. Both Ae or KSi were used at three rates: 0% (0 cm³ L⁻¹), 0.5% (5 cm³ L⁻¹), and 1% (10 cm³ L⁻¹) and 0, 30, and 60 g L⁻¹, respectively. Three rates of salinity, measured by the electrical conductivity of a saturated soil extract (ECe), were also used: normal soil (ECe < 4 dS/m) (S1); moderately-saline soil (ECe: 4–8 dS/m) (S2); and highly-saline soil (ECe: 8–16 dS/m) (S3). The lowest level of salinity yielded the highest levels of all traits except for pH, chloride, and sodium. Ae at 0.5% increased the values of total soluble sugars, total free amino acids, potassium, anthocyanin, a single-photon avalanche diode, stem diameter, fruit number, and fresh weight, whereas 1% of Ae resulted in the highest plant height, chlorophyll fluorescence (Fv/Fm), performance index, relative water content, membrane stability index, proline, total soluble sugars, and acidity. KSi either at 30 or 60 g L⁻¹ greatly increased these abovementioned attributes. Fruit number and fruit fresh weight per plant also increased significantly with the combination of Ae at 1% and KSi at 30 g L⁻¹ under normal soil conditions.

Phosphorus (P) is an essential macronutrient necessary for plant growth, development, and reproduction. Two field experiments were carried out in 2018/2019 and 2019/2020 on P-deficient soil to evaluate the impact of foliar fertilization with nanophosphorus (nP) on growth, yield, and physio-biochemical indices, as well as trigonelline content of fenugreek plants under deficient irrigation (dI) stress (a deficit of 20 and 40% of crop evapotranspiration; dI-20 and dI-40). The growth and yield traits, leaf integrity (relative water content and membrane stability index), photosynthetic pigment contents, leaf and seed P contents, and stem and leaf anatomical features significantly decreased under dI-20, with greater reductions recorded under dI-40. In contrast, water-use efficiency, osmoprotective compounds, including free amino acids, soluble sugars, proline, and trigonelline, along with antioxidant contents (ascorbate, glutathione, phenolics, and flavonoids) and their activity increased significantly under both dI-20 and dI-40. However, foliar feeding with nano-P considerably increased plant growth and yield traits, leaf integrity, photosynthetic pigments contents, leaf and seed P contents, and anatomical features. Besides, water-use efficiency, osmoprotectant contents, and antioxidant content and activity were further increased under both dI-20 and dI-40. The positive effects were more pronounced with the smaller nP (25 nm) than the larger nP (50 nm). The results of this study backed up the idea of using foliar nourishment with nP, which can be effective in modulating fenugreek plant growth and seed production.