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Inoculating rice plants by plant growth promoting rhizobacteria (PGPR) may be used as a practical and eco-friendly approach to sustain the growth and yield of drought stressed rice plants. The effect of rice inoculation using plant growth hormones was investigated under drip full irrigation (FI; 100% of evapotranspiration (ETc), and deficit irrigation (DI; 80% of ETc) on growth, physiological responses, yields and water productivities under saline soil (ECe = 6.87 dS m−1) for 2017 and 2018 seasons. Growth (i.e. shoot length and shoot dry weight), leaf photosynthetic pigments (chlorophyll ‘a’ and chlorophyll ‘b’ content), air–canopy temperature (Tc–Ta), membrane stability index (MSI%), and relative water content, (RWC%) chlorophyll fluorescence (Fv/Fm) stomatal conductance (gs), total phenols, peroxidase (PO), polyphenol oxidase (PPO), nitrogen contents and water productivities (grain water productivity; G-WP and straw water productivity; S-WP) were positively affected and significantly (p < 0.05) differed in two seasons in response to the applied PGPR treatments. The highest yields (3.35 and 6.7 t ha−1 for grain and straw yields) as the average for both years were recorded under full irrigation and plants inoculated by PGPR. The results indicated that under water scarcity, application of (I80 + PGPR) treatment was found to be favorable to save 20% of the applied irrigation water, to produce not only the same yields, approximately, but also to save more water as compared to I100%.

The exogenous application of osmoprotectants [e.g., proline (Pro)] is an important approach for alleviating the adverse effects of abiotic stresses on plants. Field trials were conducted during the summers of 2017 and 2018 to determine the effects of deficit irrigation and exogenous application of Pro on the productivity, morph-physiological responses, and yield of maize grown under two irrigation systems [surface irrigation (SI) and drip irrigation (DI)]. Three deficit irrigation levels (I 100 , I 85 , and I 70 , representing 100, 85, and 70% of crop evapotranspiration, respectively) and two concentrations of Pro (Pro 1 = 2 mM and Pro 2 = 4 mM) were used in this study. The plants exposed to drought stress showed a significant reduction in plant height, dry matter, leaf area, chlorophyll content [soil plant analysis development (SPAD)], quantum efficiency of photosystem II [Fv/Fm, Fv/F0, and performance index (PI)], water status [membrane stability index (MSI) and relative water content (RWC)], and grain yield. The DI system increased crop growth and yield and reduced the irrigation water input by 30% compared with the SI system. The growth, water status, and yield of plants significantly decreased with an increase in the water stress levels under the SI system. Under the irrigation systems tested in this study, Pro 1 and Pro 2 increased plant height by 16 and 18%, RWC by 7 and 10%, MSI by 6 and 12%, PI by 6 and 19%, chlorophyll fluorescence by 7 and 11%, relative chlorophyll content by 9 and 14%, and grain yield by 10 and 14%, respectively, compared with Pro 0 control treatment (no Pro). The interaction of Pro 2 at I 100 irrigation level in DI resulted in the highest grain yield (8.42 t ha –1 ). However, under the DI or SI system, exogenously applied Pro 2 at I 85 irrigation level may be effective in achieving higher water productivity and yield without exerting any harmful effects on the growth or yield of maize under limited water conditions. Our results demonstrated the importance of the application of Pro as a tolerance inducer of drought stress in maize.

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.

Raising soil contamination with cadmium (Cd 2+ ) and salinization necessitates the development of green approaches using bio-elicitors to ensure sustainable crop production and mitigate the detrimental health impacts. Two field trials were carried out to study the individual and combined effects of foliage spraying of Moringa leaf extract (MLE) and soil application of effective microorganisms (EMs) on the physio-biochemical, osmolytes, antioxidants, and performance of sweet potato grown in Cd 2+ -contaminated salty soil (Cd 2+  = 17.42 mg kg −1 soil and soil salinity ECe = 7.42 dS m −1 ). Application of MLE, EMs, or MLE plus EMs significantly reduced the accumulation of Cd 2+ in roots by 55.6%, 50.0%, or 68.1% and in leaves by 31.4%, 27.6%, or 38.0%, respectively, compared to the control. Co-application of MLE and EMs reduced Na + concentration while substantially raising N, P, K + , and Ca 2+ acquisition in the leaves. MLE and EMs-treated plants exhibited higher concentrations of total soluble sugar by 69.6%, free proline by 47.7%, total free amino acids by 29.0%, and protein by 125.7% compared to the control. The enzymatic (SOD, APX, GR, and CAT) and non-enzymatic (phenolic acids, GSH, and AsA) antioxidants increased in plants treated with MLE and/or EMs application. Applying MLE and/or EMs increased the leaf photosynthetic pigment contents, membrane stability, relative water content, water productivity, growth traits, and tuber yield of Cd 2+ and salt-stressed sweet potato. Consequently, the integrative application of MLE and EMs achieved the best results exceeding the single treatments recommended in future application to sweet potato in saline soil contaminated with Cd 2+ .

Potassium is an essential macronutrient, where its availability regulates numerous biochemical, phenological, and physiological responses in plants. Synchronizing potassium supply with plant demand is a key factor to enhance growth and grain production of wheat grown in cadmium-contaminated saline soils. Field experiments were conducted in El Fayoum province, Egypt, between latitudes 29° 02′ and 29° 35′ N and longitudes 30° 23′ and 31° 05′ E, during the cropping seasons of 2017–2018 and 2018–2019 to determine the influence of different applied potassium rates and times on nutrient uptake and wheat yield grown under Cd-contaminated saline soil (ECe = 8.53 dS m −1 and Cd = 18 mg kg −1 soil). Four K levels (K 0 , K 40 , K 80 , and K 120 representing 0, 40, 80, and 120 kg ha −1 ) were applied at different application times [full dose (basal) at sowing (100% S), two equal split doses at sowing and flowering stage (50% S + 50% F), and full dose at flowering stage (100% F)]. The experimental treatments were arranged in a randomized split complete block design and replicated three times. The applied K rates, times, and their interaction induced significant differences in nutrient uptake and physiological responses which in turn improved the growth and yield of the wheat crop. Potassium addition with 120 kg ha −1 at two equal split doses (50% S + 50% F) resulted in the highest values of plant height (97 cm), Fv/Fm (0.83), PI (5.49), SPAD (58.63), MSI (34.57), seed yield (5.04 t ha −1 ), straw yield (9.04 t ha −1 ), and water productivity (0.99 kg m −3 ). Similarly, the uptake of N, P, K, Ca, Mg, Fe, Mn, and Zn was increased, while the uptake of Na and Cd decreased as the K supply increased under the split application. The addition of potassium by 120 kg ha −1 in two equal split doses at the sowing and flowering stage could be a valuable approach to improve yield and yield quality of wheat crop grown under cadmium-contaminated saline soils.

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.

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.

Root distribution during rice cultivation is a governing factor that considerably affects soil water content (SWC) and root water uptake (RWU). In this study, the effects of activating root growth (using growth function) and assigning a constant average root depth (no growth during simulation) on SWC and RWU for rice cultivation under four deficit drip irrigation treatments (T90, T80, T70, and T60) were compared in the HYDRUS-2D/3D model version 3.03. A secondary objective was to investigate the effect of applied deficit irrigation treatments on grain yield, irrigation water use efficiency (IWUE), and growth traits of rice. The simulated DI system was designed to reflect a representative field experiment implemented in El-Fayoum Governorate, Egypt, during two successive seasons during 2017 and 2018. The deficit treatments (T90, T80, T70, and T60) used in the current study represent scenarios at which the first irrigation event was applied when the pre-irrigation average SWC within the upper 60 cm of soil depth was equal to 90%, 80%, 70%, and 60% of plant-available water, respectively. Simulation results showed that as water deficiency increased, SWC in the simulation domain decreased, and thereby, RWU decreased. The average SWC within the root zone during rice-growing season under different deficit treatments was slightly higher when activating root growth function than when considering constant average root depth. Cumulative RWU fluxes for the case of no growth were slightly higher than for the case of root growth function for T90, T80, and T70 accounting for 1289.50, 1179.30, and 1073.10 cm2, respectively. Average SWC during the growth season (24 h after the first irrigation event, mid-season, and 24 h after the last irrigation event) between the two cases of root growth was strongly correlated for T90, T80, T70, and T60, where r2 equaled 0.918, 0.902, 0.892, and 0.876, respectively. ANOVA test showed that there was no significant difference for SWC between treatments for the case of assigning root growth function while the difference in SWC among treatments was significant for the case of the constant average root depth, where p-values equaled 0.0893 and 0.0433, respectively. Experimental results showed that as water deficiency decreased, IWUE increased. IWUE equaled 1.65, 1.58, 1.31, and 1.21 kg m−3 for T90, T80, T70, and T60, respectively. Moreover, higher grain yield and growth traits of rice (plant height, tillers number plant−1, panicles length, panicle weight, and grain number panicles−1) were obtained corresponding to T90 as compared with other treatments. Activating the root growth module in HYDRUS simulations can lead to more precise simulation results for specific dates within different growth stages. Therefore, the root growth module is a powerful tool for accurately investigating the change in SWC during simulation. Users of older versions of HYDRUS-2D/3D (version 2.05 and earlier) should consider the limitations of these versions for irrigation scheduling.

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 (I 100 , I 80 , and I 60 ) representing 100%, 80%, and 60% of crop evapotranspiration (ETc), respectively as sub-plot factor; and 3) biochar amendment with three application levels (B 0 as control, B 10 , and B 20 ) 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 (B 20 ) 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.

Filter mud (FM) as an organic ameliorant might benefit in improving soil- and water-stressed crop productivity. However, the beneficial FM’s effects on soil and crop performance under deficit irrigation have not yet been fully comprehended. Our objective was to investigate the effect of FM under two irrigation regimes on soil quality, morpho-physiological and stem anatomical responses, antioxidant capacity, and ionic homeostasis of lupine grown under saline calcareous soil conditions. FM with three rates (0, 10, and 20 t ha −1 ) under two irrigation regimes (deficit irrigation water; DIW = 60% of crop evapotranspiration; ET c and full irrigation; FI = 100 of ET c ) on soil quality, lupine crop, and water productivity (WP) in saline calcareous (EC e  = 7.12 dS m −1 and CaCO 3  = 15.3%) soil in both 2019–2020 and 2020–2021 seasons. Compared with FI, DIW drastically reduced lupine’s morpho-physiological responses, leaf nutrients (nitrogen, N; phosphorus, P; potassium, K + ; and calcium, Ca 2+ ) except sodium (Na + ), and stem anatomical aspects, resulting in a 29.6% reduction in seed yield (SY), respectively. Amending soil with 10 or 20 t FM ha −1 noticeably attenuated the negative influences of DIW stress through recovering various physiological and anatomical responses, antioxidant defense system, and ionic homeostasis, resulting in higher SY (by 72.4 or 116.4%) and WP (by 92.7 or 112.2%), respectively. This is primarily due to FM’s positive effects on soil physicochemical properties, which include decreasing EC e , pH, and bulk density and increasing total porosity, cation exchange capacity, and water and nutrient retention capacities, which improved root nodulation. Lupine’s growth and stem anatomical responses, nutrient uptake, and SY were improved by soil amending with 10 or 20 t FM ha −1 under FI or DIW strategies. Conclusively, 20 t FM ha −1 may be recommended as a soil amendment, even under DIW strategy, for improving lupine yield and WP in saline calcareous soil.