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Drought stress ranks among the most critical environmental challenges facing agriculture today, causing significant impairments to plant growth and development. In Morocco, these negative impacts are projected to intensify further under the combined pressures of climate change and the worsening water shortage crisis. The imperative need for sustainable arganiculture (cultivation of Argane trees) in dry lands necessitates the expeditious identification of drought-tolerant elite Argania spinosa trees. In this context, we investigated the drought tolerance of 2-year-old A. spinosa seedlings from two contrasting provenances Lakhssas (LKS) and Aoulouz (ALZ) under severe stress by evaluating their antioxidative defense mechanisms. A total of 24 parameters related to reactive oxygen species (ROS), oxidative damage, and enzymatic and non-enzymatic antioxidant defense were measured and compared between both provenances. The results showed that the drought-stressed conditions significantly increased the activity of enzymatic antioxidants, including superoxide dismutase, catalase, peroxidase, polyphenoloxidase, glutathione peroxidase, glutathione S-transferase, and ascorbate-glutathione cycle enzymes, as well as the content of non-enzymatic antioxidants, including reduced glutathione (GSH), ascorbic acid (AsA), α-Tocopherols (α-toc), polyphenols, anthocyanins, and group thiols. The ability of A. spinosa trees to greatly enhance their antioxidant system to limit cellular damage caused by ROS production might be an important attribute linked to drought tolerance. Regarding the inter-provenance variation under drought stress conditions, LKS provenance exhibited superior antioxidative capacity through enhanced AsA-GSH cycle activity and elevated levels of AsA-GSH, α-toc, and polyphenols. However, ALZ demonstrated elevated anthocyanin levels and reduced peroxidative stress markers (hydrogen peroxide and malonyldialdehyde). Significant and positive correlations were recorded between studied ROS and antioxidants. Investigating the multifaceted antioxidative defense system underpinning drought tolerance in A. spinosa can facilitate the identification of drought-tolerant argane trees for the development of a future breeding program allowing sustainable arganiculture in dry lands.

Agricultural spreading of olive mill wastewater (OMW) can represent a promising alternative solution, provided that the operation is controlled and the doses applied are respected. However, a reserve toward OMW spreading remains, for fears of possible microbiological negative incidences on the soil. To contribute to assessing this area, we have tried to study their microbiological impact and the fate of OMW polyphenols in soil in a greenhouse. In comparison with untreated soil with OMW (control), the application of 50, 100, and 200 m3/ha was studied for two months. The results obtained revealed that phenolic extracts from raw OMW showed five major peaks by HPLC at 280 nm, which were present only in trace amounts after 2 weeks of treatment at neutral pH. The phenols and organic matter (OM) from OMW were biodegraded or reorganized, and the bacterial population of soil treated with 50 and 100 m3/ha OMW was significantly higher compared to the soil that received water. However, a dose of 200 m3/ha did not affect soil microflora. Consequently, using OMW by direct spreading can be recommended at doses of 50 and 100 m3/ha. Doses higher than those studied, which are considered excessive and not recommended, could have undesirable repercussions. HIGHLIGHTS Soil microflora is responsible for biodegradation of OMW polyphenols.; Spreading OMW to 100 m3/ha on alkaline soil stimulated the activity of soil microflora.; Application of OMW to 100 m3/ha could be recommended as a soil biofertilizer.; For 200 m3/ha of OMW, particular attention must be paid to polyphenols and to electrical conductivity.; This study has removed all fears and ambiguities about the spreading of OMW on the soil.;

The argan (Argania spinosa L. Skeels) ecosystem is severely degrading in arid and semi-arid lands due to climate change, particularly in terms of density loss and reforestation failure. Thus, it is important to adopt innovative effective sustainable practices to optimize the densification and reforestation success of the argan tree. The purpose of the present research was to investigate the combined effect of subsurface water retention technology (SWRT) and the use of native arbuscular mycorrhizal fungi (AMF) on edaphic, growth, physiological and biochemical parameters of field-grown argan seedlings in the Essaouira region, Morocco. In this experiment, one-year-old argan seedlings were transplanted in the absence and presence of biodegradable plastic and AMF. Our findings revealed that the application of SWRT enhanced soil profile moisture up to 640% at 40 cm depth compared to the control. The combination of this technology with AMF also improved soil fertility. Furthermore, the application of SWRT, with or without AMF, significantly enhanced argan seedling height (208 and 168%, respectively), stomatal conductance (54 and 33%, respectively), and chlorophyll fluorescence (21 and 20%, respectively). Similarly, the combined application of SWRT and AMF significantly improved protein and sugar content (36 and 57%, respectively), as well as antioxidant enzyme activities (peroxidase and polyphenol oxidase) and chlorophyll pigments content compared to the control. However, this treatment reduced malondialdehyde and H2O2 content in the argan leaves. As a summary, SWRT technology combined with AMF may be used as a valuable strategy to promote the success of argan reforestation and to limit soil erosion and desertification in arid and semi-arid climates.

In the Mediterranean region, reforestation programs record failures following successive drought periods. The use of different plant-growth-promoting amendments and the understanding of drought-induced physiological and biochemical responses of carob will contribute to the reforestation program’s success. In this study, the effects of arbuscular-mycorrhizal-fungi (AMF), vermicompost (VC), and rock phosphate (RP) on carob seedlings under drought stress (DS) and recovery (REC) conditions were evaluated. A greenhouse experiment was conducted with carob seedlings grown in the presence of AMF, VC, and RP, applied alone or in combination under well-watered (WW), DS (by stopping irrigation for 12 days), and recovery (REC) conditions. The obtained results indicated that the triple combination (AMF + VC + RP) presented the highest improvement in water potential, photosynthetic pigment content, stomatal conductance, and chlorophyll fluorescence compared to the controls under DS and after REC. In addition, this combination resulted in improved tolerance of carob seedlings to DS and a high potential for rapid recovery after rehydration due to a high accumulation of sugars, proteins, and antioxidant enzymes. In summary, the results underline the importance of inoculating carob with AMF in combination with (in)-organic amendments in improving its tolerance to DS and its recovery performances.

Purpose In this study, the role of compost application in alleviating salt stress effects on date palm seedlings growth and development was investigated.Method The experiment was set in a randomized design, with or without green waste-based compost, and under two salinity levels (0 and 240 mM NaCl). Growth, mineral uptake, photosynthetic pigments content, oxidative stress markers' accumulation and antioxidant activity were assessed.Results Plants grown under saline condition showed low values of growth attributes while the application of compost increased these attributes under 240 mM NaCl. Salinity increased sodium (Na+) and chlorine (Cl-) ions concentration in plants and reduced phosphorus (P), nitrogen (N), potassium (K+) and calcium (Ca2+) uptake. The presence of compost mitigated these effects by improving the concentrations of the essential elements (P, K+, N and Ca2+) in both plant shoots and roots and by limiting salt ion (Na+ and Cl-) toxicity and thereby induced higher K/Na and Ca/Na ratios. Furthermore, leaf water status, stomatal conductance and photosynthetic efficiency were increased and were coupled with high chlorophyll and protein concentrations in plants amended with compost under salt stress. NaCl stress induced high lipid peroxidation and H2O2 accumulation; however, the application of compost lowered these two parameters in stressed plants through stimulation of the antioxidant enzymes activity and increasing soluble sugars and proline accumulation.Conclusion Results suggest that the green waste-based compost can boost date palm seedlings tolerance in salt-affected soils by mitigating the different adverse effects of salinity stress.

Abstract In the current study, an eco-friendly management technology to improve young carob (Ceratonia siliqua L.) tree tolerance to water deficit was set up by using single or combined treatments of arbuscular mycorrhizal fungi (AMF) and/or compost (C). Two groups of young carob have been installed: (i) carob cultivated under well-watered conditions (WW; 70% field capacity (FC)) and (ii) where the plants were drought-stressed (DS; 35% FC) during 2, 4, 6, and 8 months. The effect of used biofertilizers on the course of growth, physiological (photosynthetic traits, water status, osmolytes, and mineral content), and biochemical (hydrogen peroxide (H2O2), oxidative damage to lipids (malondialdehyde (MDA), and membrane stability (MS)) traits in response to short- and long-term droughts were assessed. The dual application of AMF and C (C + AMF) boosted growth, physiological and biochemical parameters, and nutrient uptake in carob under WW and DS. After eight months, C + AMF significantly enhanced stomatal conductance by 20%, maximum photochemical efficiency of PSII by 7%, leaf water potential by 23%, chlorophyll and carotenoid by 40%, plant uptake of mineral nutrients (P by 75%, N by 46%, K+ by 35%, and Ca2+ by 40%), concentrations of soluble sugar by 40%, and protein content by 44% than controls under DS conditions. Notably, C + AMF reduced the accumulation of H2O2 and MDA content to a greater degree and increased MS. In contrast, enzyme activities (superoxide dismutase, catalase, peroxidase, and polyphenoloxidase) significantly increased in C + AMF plants under DS. Overall, our findings suggest that the pairing of C + AMF can mediate superior drought tolerance in young carob trees by increasing leaf stomatal conductance, cellular water content, higher solute concentration, and defense response against oxidative damage during the prolonged period of DS.

In agriculture, chitosan has become popular as a metabolic enhancer; however, no deep information has been obtained yet regarding its mechanisms on vegetative tissues. This work was conducted to test the impact of chitosan applied at different plant growth stages on plant development, physiology, and response to wounding as well as fruit shape and composition. Five concentrations of chitosan were tested on tomato. The most effective chitosan doses that increased leaf number, leaf area, plant biomass, and stomatal conductance were 0.75 and 1 mg mL−1. Chitosan (1 mg mL−1) applied as foliar spray increased the levels of jasmonoyl–isoleucine and abscisic acid in wounded roots. The application of this dose at vegetative and flowering stages increased chlorophyll fluorescence (Fv/Fm) values, whereas application at the fruit maturation stage reduced the Fv/Fm values. This decline was positively correlated with fruit shape and negatively correlated with the pH and the content of soluble sugars, lycopene, total flavonoids, and nitrogen in fruits. Moreover, the levels of primary metabolites derived from glycolysis, such as inositol phosphate, lactic acid, and ascorbic acid, increased in response to treatment of plants with 1 mg mL−1- chitosan. Thus, chitosan application affects various plant processes by influencing stomata aperture, cell division and expansion, fruit maturation, mineral assimilation, and defense responses.

The current work aims to perform a feasibility study of sustainable urban wastewater reuse in agroforestry domain of Marrakesh city in order to assess the environmental and the sustainability of urban wastewater reuse in agroforestry irrigation. To this end, wastewater physicochemical characteristics from Marrakesh full-scale wastewater treatment plant, soil physicochemical analysis and climate analysis were investigated. Finally, treated urban wastewater potential production in Marrakesh WWTP and challenge related to its reuse are provided. The obtained results of the present study reveals the feasibility of this practice in Marrakesh region. Regarding the actual situation, climate analysis highlight that the local climatic conditions is an ultimate challenge for water resources; soil analysis reveals a loss of soil fertility due to the decline in soil organic matter. To face this condition, treated urban wastewater reuse is a sustainable and promising strategy to face water scarcity, enhance soil fertility, preserve natural resources, develop local products and improve living conditions of agriculture and farmers. Keywords: Urban wastewater, Physicochemical analysis, Wastewater reuse, Climate analysis, Arid climate, Marrakesh

This study focused on the mitigation of the negative impact of salinity stress over time on the growth and development of Phoenix dactylifera plants using compost and/or arbuscular mycorrhizal fungi (AMF). The experiment had eight treatments in a randomized design. The treatments consisted of a control, AMF (native consortium) and compost (produced from green waste). The treatments were applied separately or in combination in the presence of 240 mM NaCl (saline condition) or 0 mM NaCl (non-saline condition) after 10 and 14 months of cultivation. Our results show that saline stress increased toxic ion (sodium and chlorine), proline, soluble sugars and stress marker (H2O2 and MDA) contents. At the same time, it lowered growth traits, mycorrhizal colonization, leaf water potential and nutrients (nitrogen (N), potassium (K), phosphorus (P), calcium (Ca)) and photosynthetic pigment concentrations. The application of compost and AMF individually or in combination alleviated salt-induced effects through mechanisms such as an increase in nutrient absorption (P, N, K and Ca), photosynthetic pigment content, relative water content, stomatal opening, leaf water potential, photosystem II efficiency, organic osmolyte content (proline and soluble sugars) and antioxidant enzyme activities (SOD, APX, CAT and POD) and reduction in lipid peroxidation and H2O2 content. Our results also show that the tolerance strategies of date palm to salinity were progressively improved over time in treated plants and especially in date palms grown in the presence of the two biofertilizers. Between 10 and 14 months of cultivation, growth parameters increased with a significant improvement in nutrient contents, a reduction in the concentrations of toxic ions and stress markers, and regulation of the antioxidant system (antioxidant enzyme activity and osmolyte content) in both leaves and roots. In conclusion, this investigation highlights the effectiveness of dual application of compost and native AMF in mitigating the deleterious effects of salinity on date palm with an improvement in the tolerance over time.

In the present research, an alternative eco-efficient biotechnology system, both selective and environmentally viable, is proposed and compared to a conventional scheme. The results showed an optimal process function and a significant difference (p < 0.001) in wastewater measured quality parameters compared to the conventional scheme. Indeed, the treated wastewater from the eco-efficient process revealed significant concentrations of organic matter and nutrients. Accordingly, there was an improvement in soil and plant quality parameters as a result of irrigation with raw urban wastewater and treated wastewater from the eco-efficient system compared to ground water.

The date palm is a commercially important woody crop and is a good target plant for improving agricultural yields in extreme environments. However, salinity has been the primary abiotic stress complicating its cultivation and damaging its production worldwide. This study investigated the effect of alleviating salt stress on date palm growth and development by using arbuscular mycorrhizal fungi (AMF) and/or compost. The experiment was arranged in a completely randomized design with eight treatments. The treatments comprised control without inoculation or amendment and application of compost (made from green waste) and AMF (an autochthonous consortium) individually or in combination under non-saline (0 mM NaCl) or saline (240 mM NaCl) conditions. Growth, physiological characteristics, nutrient uptake, chlorophyll content, oxidative stress markers, and antioxidant enzyme activities were assessed. Salt stress increased sodium (Na+) and chlorine (Cl−) content, lipid peroxidation and proline, soluble sugar, and H2O2 content. However, it reduced growth parameters, AMF colonization, leaf water potential, nitrogen (N), phosphorus (P), potassium (K+), calcium (Ca2+), and chlorophyll content. The application of AMF and compost separately or in combination mitigated the deleterious effects induced by salinity. AMF inoculation contributed to plant salt tolerance through strategies such as increased nutrient uptake (particularly P and Ca2+), chlorophyll content, relative water content, stomatal conductance, antioxidant enzymatic activities (superoxide dismutase, ascorbate peroxidase, catalase) and by decreasing lipid peroxidation and H2O2 content. Plants grown in soil amended with compost under salt stress showed an improvement particularly in K+ and proline content and a decrease in H2O2 concentration compared to controls under the saline condition. In the presence of NaCl stress, the dual application of the compost and AMF consortium maximized plant growth, stomatal conductance, leaf water potential, all antioxidant enzyme activities and P, K+, N, and Ca2+ uptake as well as proline and soluble sugar content. However, it reduced Na+ and Cl− uptake and oxidative stress marker content. In conclusion, our study suggests that the application of AMF with compost has the potential to improve the tolerance of date palm seedlings to salt stress more than AMF or compost applied separately.

Seed germination is the critical stage for species survival. Salinity affects germination and seedling growth and yield of several crop species, such as broad bean. That is why this study was carried to evaluate the effects of NaCl on seed germination and influence of salicylic acid on seed in order to improving salt tolerant on broad bean. Vicia faba L. is an important pulse crop in the Mediterranean region. In many cases broad bean is grown on saline soils where growth and yield are limited by salinity. The results showed that Irrigation with saline water significantly reduced all seed germination parameters in comparison with the respective control. Alleviation of growth arrest was observed with exogenous applications of salicylic acid (SA) under salt stress conditions. Overall, the positive effect of SA towards resistance to the salinity of V. faba L. will provide some practical basis for V. faba L cultivation.

Salinity is one of the devastating abiotic stresses that cause reductions in agricultural production. The increased salinization affects alfalfa growth, metabolism, and rhizobium capacity for symbiotic N2 fixation negatively. This study was undertaken to investigate the efficiency of green compost (C; made from green waste), arbuscular mycorrhizal fungi (M; field-sourced native consortium), and/or rhizobium (R; a salt-tolerant rhizobium strain) individually or in combination as an effective strategy to improve alfalfa productivity under non-saline and high-saline (120 mM NaCl) conditions. In addition, we aimed to understand the agro-physiological and metabolic basis as well as glomalin content in the soil of biofertilizers-induced salt tolerance in alfalfa. Here, we show that mycorrhizal infection was enhanced after MR inoculation, while C application decreased it significantly. Salinity reduced growth, physiological functioning, and protein concentration, but the antioxidant system has been activated. Application of the selected biofertilizers, especially C alone or combined with M and/or R improved alfalfa tolerance. The tri-combination CMR mitigated the negative effects of high salinity by stimulating plant growth, roots and nodules dry matters, mineral uptake (P, N, and K), antioxidant system, synthesis of compatible solutes, and soil glomalin content, sustaining photosynthesis-related performance and decreasing Na+ and Cl− accumulation, lipid peroxidation, H2O2 content, and electrolyte leakage.

Irregular precipitation and drought caused an increase in tree mortality rates in multiple forest biomes with alterations in both ecosystem services and carbon balance. Carob (Ceratonia siliqua) growth and production in arid and semi-arid ecosystems are likely affected by climate change-induced droughts. Understanding the physiological responses of drought-induced early-stage tree death and strategies to enhance drought tolerance and optimize growth will help tree improvement programs. Mycorrhizal inoculation has a pronounced impact on plant growth, water absorption, mineral nutrition, and protection from abiotic stresses. However, a better understanding of these complex interconnected cellular processes and arbuscular mycorrhizal fungi (AMF)-mediated mechanisms regulating drought tolerance in plants will enhance its potential application as an efficient approach for bio-amelioration of stresses. The objectives of this work were to elucidate the different effects of autochthone AMF on inorganic solute and water content uptakes, organic adjustments (sugar and proteins content), leaf gas exchange (stomatal conductance and efficiency of photosystems I and II), and oxidative damage of two contrasting ecotypes of carob seedlings: coastal (southern ecotype (SE)) and in-land (northern ecotype (NE)) under control (C), drought (by cessation of irrigation for 15 days (15D)), and recovery (R) conditions. Our findings showed that AMF promoted growth, nutrient content, and physiological and biochemical parameters in plants of both ecotypes during C, 15D, and R conditions. After four days of recovery, stomatal conductance (gs), the maximum photochemical efficiency of PSII (Fv/Fm), water content, and plant uptake of mineral nutrients (P, K, Na, and Ca) were significantly higher in shoots of mycorrhizal (AM) than non-mycorrhizal (NM) control plants. Consequently, AMF reduced to a greater degree the accumulation of hydrogen peroxide (H2O2) and oxidative damage to lipid (malondialdehyde (MDA)) content in AM than NM plants in NE and SE, after recovery. Altogether, our findings suggest that AMF can play a role in drought resistance of carob trees at an early stage by increasing the inorganic solutes (P, K, Na, and Ca), water content uptake, organic solutes (soluble sugars and protein content), stomatal conductance, and defense response against oxidative damage during re-watering after drought stress.

Nowadays, applying bio-organic fertilizer (e.g., chitosan, Ch) or integrating beneficial microorganisms (e.g., arbuscular mycorrhizal fungi, AMF) are among the successful strategies to promote plant growth. Here, the effect of two application modes of Ch (foliar spray or root treatment) and Ch-derived nanoparticles (NPs) on tomato plants colonized with the AMF Rhizophagus irregularis were analyzed, thereby focusing on plant biomass, flowering and mycorrhization. An increase of shoot biomass and flower number was observed in arbuscular mycorrhizal (AM) plants sprayed with Ch. The interaction with AMF, however, was reduced as shown by decreased mycorrhization rates and AM-specific gene expression. To get insights into Ch effect on mycorrhization, levels of sugars, jasmonates, abscisic acid, and the expression of two chitinase-encoding genes were determined in mycorrhizal roots. Ch had no effect on sugar and phytohormone levels, but the reduced mycorrhization was correlated with down- and upregulated expression of Chi3 and Chi9, respectively. In contrast, application of NPs to leaves and Ch applied to the soil did not show any effect, neither on mycorrhization rate nor on growth of mycorrhizal plants. Concluding, Ch application to leaves enhanced plant growth and flowering and reduced interaction with AMF, whereas root treatment did not affect these parameters.

The rate of photosynthesis (A) of plants exposed to water deficit is a function of stomatal (gs) and mesophyll (gm) conductance determining the availability of CO2 at the site of carboxylation within the chloroplast. Mesophyll conductance often represents the greatest impediment to photosynthetic uptake of CO2, and a crucial determinant of the photosynthetic effects of drought. Abscisic acid (ABA) plays a fundamental role in signalling and co-ordination of plant responses to drought; however, the effect of ABA on gm is not well-defined. Rose, cherry, olive and poplar were exposed to exogenous ABA and their leaf gas exchange parameters recorded over a four hour period. Application with ABA induced reductions in values of A, gs and gm in all four species. Reduced gm occurred within one hour of ABA treatment in three of the four analysed species; indicating that the effect of ABA on gm occurs on a shorter timescale than previously considered. These declines in gm values associated with ABA were not the result of physical changes in leaf properties due to altered turgor affecting movement of CO2, or caused by a reduction in the sub-stomatal concentration of CO2 (Ci). Increased [ABA] likely induces biochemical changes in the properties of the interface between the sub-stomatal air-space and mesophyll layer through the actions of cooporins to regulate the transport of CO2. The results of this study provide further evidence that gm is highly responsive to fluctuations in the external environment, and stress signals such as ABA induce co-ordinated modifications of both gs and gm in the regulation of photosynthesis.

Diffusional limitations to photosynthesis, relative water content (RWC), pigment concentrations and their association with reflectance indices were studied in olive (Olea europaea) saplings subjected to water-stress and re-watering. RWC decreased sharply as drought progressed. Following rewatering, RWC gradually increased to pre-stress values. Photosynthesis (A), stomatal conductance (gs), mesophyll conductance (gm), total conductance (gt), photochemical reflectance index (PRI), water index (WI) and relative depth index (RDI) closely followed RWC. In contrast, carotenoid concentration, the carotenoid to chlorophyll ratio, water content reflectance index (WCRI) and structural independent pigment index (SIPI) showed an opposite trend to that of RWC. Photosynthesis scaled linearly with leaf conductance to CO2; however, A measured under non-photorespiratory conditions (A1%O2) was approximately two times greater than A measured at 21% [O2], indicating that photorespiration likely increased in response to drought. A1%O2 also significantly correlated with leaf conductance parameters. These relationships were apparent in saturation type curves, indicating that under non-photorespiratory conditions, CO2 conductance was not the major limitations to A. PRI was significant correlated with RWC. PRI was also very sensitive to pigment concentrations and photosynthesis, and significantly tracked all CO2 conductance parameters. WI, RDI and WCRI were all significantly correlated with RWC, and most notably to leaf transpiration. Overall, PRI correlated more closely with carotenoid concentration than SIPI; whereas WI tracked leaf transpiration more effectively than RDI and WCRI. This study clearly demonstrates that PRI and WI can be used for the fast detection of physiological traits of olive trees subjected to water-stress.