Comparative responses of chickpea cultivars to water deficit

Chickpea (Cicer arietinum L.) yields in Mediterranean areas are restricted largely by drought, and little is yet known about adjustments to water deficit among cultivars. A gradient of water availability was imposed on chickpea cultivars differing in drought tolerance to study their differential responses in plant water relations, gas-exchange, growth, water-use, yield and yield components as a step toward increasing the efficiency of cultivar development for drought tolerance;Differences in stomatal conductance among cultivars were more consistently and predictably related to differences in water-use efficiency (WUE) than were genotypic variations in photosynthesis. Selection for increased WUE through reduction in leaf conductance would seem a straightforward proposition; however, photosynthetic limitations due to lowered leaf conductance will tend to limit yield potentials under favorable environments;Osmotic adjustment may have occurred in all the cultivars. However, the differences among cultivars were not large enough to influence plant performance significantly under drought stress. Leaf water potential showed good correlations with important plant functions, and thus, appears to be a better indicator of drought tolerance among cultivars;No significant differences were found among cultivars for crop growth rate, total dry-matter production or dry-matter WUE. The differences among cultivars in seed yield were associated with differences in seed growth rate, effective filling period, harvest index, seed WUE and rooting depth. High yields of droughted chickpea were due less to specific physiological responses than to ability to set pods under drought. Seed yield was improved because of a larger sink size and demand, and by partitioning a larger part of biomass into seed;In conclusion, genetic variation exists in many of the traits examined, offering promise for yield improvement for dryland conditions. While yield stability of the cultivars was associated mainly with physiological attributes, yield potential was determined by sink size, sink demand and partitioning of dry-matter from the vegetative source to the reproductive sink

Effect of tillage practices on the soil carbon dioxide flux during fall and spring seasons in a Mediterranean Vertisol

In this study, we assessed the effect of conventional tillage (CT), reduced (RT) and no tillage (NT) practices on the soil CO2 flux of a Mediterranean Vertisol in semi-arid Morocco. The measurements focused on the short term (0 to 96 h) soil CO2 fluxes measured directly after tillage during the fall and spring period. Soil temperature, moisture and soil strength were measured congruently to study their effect on the soil CO2 flux magnitude. Immediately after fall tillage, the CT showed the highest CO2 flux (4.9 g m-2 h-1); RT exhibited an intermediate value (2.1 g m-2 h-1) whereas the lowest flux (0.7 g m-2 h-1) was reported under NT. After spring tillage, similar but smaller impacts of the tillage practices on soil CO2 flux were reported with fluxes ranging from 1.8 g CO2 m-2 h-1 (CT) to less than 0.1 g CO2 m-2 h-1 (NT). Soil strength was significantly correlated with soil CO2 emission; whereas surface soil temperature and moisture were low correlated to the soil CO2 flux. The intensity of rainfall events before fall and spring tillage practices could explain the seasonal CO2 flux trends. The findings promote conservation tillage and more specifically no tillage practices to reduce CO2 losses within these Mediterranean agroecosystems. (Résumé d'auteur

Évaluation de la résistance de dix porte-greffes d’agrumes résistants à la tristeza vis-à-vis du déficit hydrique

Introduction. In Morocco, citriculture faces up an increasing combination of biotic (Citrus tristeza virus (CTV) / Phytophthora spp.) and abiotic stresses (salinity, alkalinity and drought). Most of these constraints should be individually managed by adapted rootstock choice. However, the spread of CTV in the Mediterranean Basin will soon prohibit the use of the traditional sour orange rootstock, which currently provides sufficient tolerance to salinity and alkalinity. Therefore, the selection of new citrus rootstocks becomes urgent. Our study sought to investigate the effect of different water regimes on growth of ten citrus rootstocks: citrange Carrizo (France), citrange Carrizo (Morocco), citrange Troyer, citrange Yuma, Citrus volkameriana; two Poncirus trifoliata of different origins, citrumelo, Mand. Sunki x Poncirus trifoliata, and Poorman. Materials and methods. For each rootstock, three months old seedlings were grown in plastic pots (0.5 L) in a greenhouse at El Menzeh, INRA, Morocco; they were subjected to three water regimes [(100%, 75% and 50%) moisture field capacity (Hcc) of the substrate]. The experiment was arranged in a split-plot design with three treatments. The morphological parameters measured were the plant height and dry and fresh matter accumulation. Physiological parameters studied were the Relative Water Content, transpiration rates and chlorophyll, soluble sugars and proline contents. Results. The morphological and physiological parameters were affected by the intensity of water stress applied. However, rootstocks behaved differently regarding to this constraint. Water stress induced an increase in the proline and soluble sugars content in the rootstock leaves. Conclusion. Water stress significantly affects the physiological and morphological characteristics of citrus rootstocks and, in conditions of extreme water deficit (50% Hcc), a differential behavior of the rootstock was found. Based on our results, the rootstocks Carrizo citrange (Morocco) and Poorman present the best overall ability to withstand water stress

Tillage system affects soil organic carbon storage and quality in Central Morocco

Stabilizing or improving soil organic carbon content is essential for sustainable crop production under changing climate conditions. Therefore, soil organic carbon research is gaining momentum in the Mediterranean basin. Our objective is to quantify effects of no tillage (NT) and conventional tillage (CT) on soil organic carbon stock (SOCs) in three soil types (Vertisol, Cambisol, and Luvisol) within Central Morocco. Chemical analyses were used to determine how tillage affected various humic substances. Our results showed that, after 5 years, surface horizon (0–30 cm) SOC stocks varied between tillage systems and with soil type. The SOCs was significantly higher in NT compared to CT (10% more in Vertisol and 8% more in Cambisol), but no significant difference was observed in the Luvisol. Average SOCs within the 0–30 cm depth was 29.35 and 27.36 Mg ha−1 under NT and CT, respectively. The highest SOCs (31.89 Mg ha−1) was found in Vertisols under NT. A comparison of humic substances showed that humic acids and humin were significantly higher under NT compared to CT, but fulvic acid concentrations were significantly lower. These studies confirm that NT does have beneficial effects on SOCs and quality in these soils

First draft genome assembly of the Argane tree (Argania spinosa)

Background: The Argane tree (Argania spinosa L. Skeels) is an endemic tree of southwestern Morocco that plays an important socioeconomic and ecologic role for a dense human population in an arid zone. Several studies confirmed the importance of this species as a food and feed source and as a resource for both pharmaceutical and cosmetic compounds. Unfortunately, the argane tree ecosystem is facing significant threats from environmental changes (global warming, over-population) and over-exploitation. Limited research has been conducted, however, on argane tree genetics and genomics, which hinders its conservation and genetic improvement. Methods: Here, we present a draft genome assembly of A. spinosa. A reliable reference genome of A. spinosa was created using a hybrid de novo assembly approach combining short and long sequencing reads. Results: In total, 144 Gb Illumina HiSeq reads and 7.2 Gb PacBio reads were produced and assembled. The final draft genome comprises 75 327 scaffolds totaling 671 Mb with an N50 of 49 916 kb. The draft assembly is close to the genome size estimated by k-mers distribution and covers 89% of complete and 4.3 % of partial Arabidopsis orthologous groups in BUSCO. Conclusion: The A. spinosa genome will be useful for assessing biodiversity leading to efficient conservation of this endangered endemic tree. Furthermore, the genome may enable genome-assisted cultivar breeding, and provide a better understanding of important metabolic pathways and their underlying genes for both cosmetic and pharmacological purposes

Short-term residual effects of occasional tillage on crop performance, soil water, and water-use efficiency in a 10-year no-till system under a dry Mediterranean climate

Conservation Agriculture is a farming system based on no mechanical soil disturbance, permanent soil cover, and crop diversification. A study was carried out in an on-farm field trial set up in Meknes (Morocco) under a long-term no-till (NT) system to evaluate the residual effect of one-time occasional tillage (OT) on crop performance, soil water, and water-use efficiency (WUE) one and two years after OT implementation. Shallow and deep options of OT were compared with common NT practices (with crop residue retention and with crop residue removal) for two consecutive seasons of 2021–2022 (year 1) and 2022–2023 (year 2). The four tillage practices were implemented in November 2020. Three crops were studied each year: durum wheat (Triticum durum), faba bean (Vicia faba minor), and chickpea (Cicer arietinum) all grown under NT in both the years and arranged in four crop rotations. Our findings show that grain yield of wheat and chickpea was negatively affected by OT for all years considered. In wheat, there was a grain yield loss of 18 and 20% for shallow and deep OT, respectively compared to NT with crop residue retention. In chickpea, the grain yield loss was as high as 47 and 49% for shallow and deep OT, respectively. Average soil water storage measured at 0–60 cm at sowing was also lower in deep OT (133 mm) compared to NT with crop residue retention (151 mm) for all years and rotations considered. Yet, in wheat year 1, deep OT slightly improved soil water content at 30 cm depth compared to NT treatments. The comparison of WUE between treatments showed that, under NT with crop residue retention, the crops produced more grain and aboveground biomass per mm of water. Wheat/faba bean rotation had a greater grain yield and WUE (all years considered) and overall greater soil water content (year 1), compared to the wheat/chickpea rotation. The results suggest that the effects of OT on crop performance and water productivity in the short term can be adverse. On the other hand, grain yield of wheat can be improved by a judicious choice of legume to be used as a preceding crop

First draft genome assembly of the Argane tree (Argania spinosa) [version 2; peer review: 2 approved]

BACKGROUND : The Argane tree (Argania spinosa L. Skeels) is an endemic tree of mid-western Morocco that plays an important socioeconomic and ecologic role for a dense human population in an arid zone. Several studies confirmed the importance of this species as a food and feed source and as a resource for both pharmaceutical and cosmetic compounds. Unfortunately, the argane tree ecosystem is facing significant threats from environmental changes (global warming, over-population) and over-exploitation. Limited research has been conducted, however, on argane tree genetics and genomics, which hinders its conservation and genetic improvement. METHODS : Here, we present a draft genome assembly of A. spinosa. A reliable reference genome of A. spinosa was created using a hybrid de novo assembly approach combining short and long sequencing reads. RESULTS : In total, 144 Gb Illumina HiSeq reads and 7.6 Gb PacBio reads were produced and assembled. The final draft genome comprises 75 327 scaffolds totaling 671 Mb with an N50 of 49 916 kb. The draft assembly is close to the genome size estimated by k-mers distribution and covers 89% of complete and 4.3 % of partial Arabidopsis orthologous groups in BUSCO. CONCLUSION : The A. spinosa genome will be useful for assessing biodiversity leading to efficient conservation of this endangered endemic tree. Furthermore, the genome may enable genome-assisted cultivar breeding, and provide a better understanding of important metabolic pathways and their underlying genes for both cosmetic and pharmacological.DATA AVAILABILITY: All of the A. spinosa datasets can be retrieved under BioProject accession number PRJNA294096: http://identifiers.org/ bioproject:PRJNA294096. The raw reads are available at NCBI Sequence Reads Archive under accession number SRP077839: http://identifiers.org/insdc.sra:SRP077839. The complete genome sequence assembly project has been deposited at GenBank under accession number QLOD00000000: http://identifiers. org/ncbigi/GI:1408199612. Data can also be retrieved via the International Argane Genome Consortium (IAGC) website: http://www.arganome.org.https://f1000research.compm2021BiochemistryGeneticsMicrobiology and Plant Patholog

Ecosystem services to promote Conservation Agriculture practices in Morocco: Challenges and opportunities

In Morocco, the low-input cropping systems dominated by cereal monoculture and intensive tillage have a marked negative impact on pressure from diseases, weeds and pests resulting in decreased profit margins. This form of agriculture is considered to act as a major driver of biodiversity loss and to speed up the loss of soil by increasing the mineralization of organic matter and erosion rates. It is also causing adverse effects on major soil functions, viz. primary productivity, carbon sequestration and regulation, nutrient cycling and provision, water regulation and purification, and habitat for functional and intrinsic biodiversity. Conservation agriculture (CA) is an alternative to enhance and optimize the provision of soil functions. Conservation Agriculture practice constitutes no-till combined with residue retention and crop rotation, CA is practiced to optimize available resources (soil, water and biological) whilst minimizing external inputs and soil degradation. Despite reported benefits, such as improved soil fertility, crop growth, better water infiltration, increased biological activity, decreased soil erosion and reduced labor, machinery use and fuel costs, CA is practiced only in less than 1% of cereal agricultural lands, well below the land areas of similar continental farming landscape

Comparative responses of chickpea cultivars to water deficit

Chickpea (Cicer arietinum L.) yields in Mediterranean areas are restricted largely by drought, and little is yet known about adjustments to water deficit among cultivars. A gradient of water availability was imposed on chickpea cultivars differing in drought tolerance to study their differential responses in plant water relations, gas-exchange, growth, water-use, yield and yield components as a step toward increasing the efficiency of cultivar development for drought tolerance;Differences in stomatal conductance among cultivars were more consistently and predictably related to differences in water-use efficiency (WUE) than were genotypic variations in photosynthesis. Selection for increased WUE through reduction in leaf conductance would seem a straightforward proposition; however, photosynthetic limitations due to lowered leaf conductance will tend to limit yield potentials under favorable environments;Osmotic adjustment may have occurred in all the cultivars. However, the differences among cultivars were not large enough to influence plant performance significantly under drought stress. Leaf water potential showed good correlations with important plant functions, and thus, appears to be a better indicator of drought tolerance among cultivars;No significant differences were found among cultivars for crop growth rate, total dry-matter production or dry-matter WUE. The differences among cultivars in seed yield were associated with differences in seed growth rate, effective filling period, harvest index, seed WUE and rooting depth. High yields of droughted chickpea were due less to specific physiological responses than to ability to set pods under drought. Seed yield was improved because of a larger sink size and demand, and by partitioning a larger part of biomass into seed;In conclusion, genetic variation exists in many of the traits examined, offering promise for yield improvement for dryland conditions. While yield stability of the cultivars was associated mainly with physiological attributes, yield potential was determined by sink size, sink demand and partitioning of dry-matter from the vegetative source to the reproductive sink.</p