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Rapeseed is one of the most important oilseed crops in the world and, in Morocco, it may contribute to the improvement of food security in edible oils through developing performant cultivars and optimizing the crops management including nitrogen fertilization. The objective of this study was to evaluate the response of different Moroccan varieties to nitrogen application. Field trials were carried out at the experimental station of National School of Agriculture in Meknes, during two cropping seasons (2017–2018 and 2018–2019). Five varieties (“Narjisse”, “Moufida”, “Alia”, “Adila”, and “Lila”) were combined to different nitrogen rates (0, 30, 60, and 90 kg N ha−1). The experimental design adopted is a split split-plot with three replications, where nitrogen treatment was affected to main plot, variety to subplot, and year to sub-subplot. Results showed that dry matter, harvest index, oil content, seed yield per plant and yield components were significantly affected by nitrogen rates, with an upward trend in seed yield as the nitrogen rates increased. On average, seed yield increased by 50.33% for application of 90 kg N ha−1 compared to the control (without N fertilization). However, oil content declined from 41.08% to 37.81% with the increase of nitrogen level from 0 to 90 kg N ha−1. Additionally, for the other traits studied, the highest mean values were observed for 90 kg N ha−1, except harvest index which exhibited the greatest value for 60 kg N ha−1. Variation among the varieties was significantly large for all traits studied with a superiority of the variety “Alia” for seed yield per plant (9.82 g plant−1), number of pods per plant (151), and number of seeds per pod (24.05).

The main objective of this work was to evaluate use efficiency of nitrogen, phosphorus, potassium, calcium and magnesium in adult apple orchards in the Middle Atlas of Morocco and to establish preliminary reference norms for fertilizing this crop under local conditions. The study was based on soil and leaf analysis and data with regard to farming practices and yield on forty apple orchards (cv. Golden delecious/MM106) where nineteen are growing on silty-clay soil and twenty-one on sandy-loam soil. The results showed significant correlations between leaf content for each nutrient and yield level following polynomial equations, thereby indicating local reference norms for apple leaf analysis. Moreover, correlations were significant between leaf and soil contents that permitted to determine apple needs in nitrogen fertilizer and references norms for soil richness in phosphorus, potassium, calcium and magnesium to obtain yield potential in the study region. However, the found norms are less than international standards because of feebleness of yield level in the study region, largely related to deficient cultural practices adopted by farmers. In addition, investigation of leaf nutrients ratios N/K, N/Ca, K/Ca, K/Mg and Ca/Mg showed that there was disharmony in uptake of these nutrients originating particularly from high soil richness in Ca and Mg. Taking into account these considerations, the found references norms can be applied only under the adopted farming practices. Nevertheless, by improving local practices, reference values may change.

International audience; Faba bean plants in the 1/8 mixture with soil had the ability to accumulate Pb, Zn and Cu. 95% of the absorbed Pb were in the roots, and Cu and Zn were found in the shoots by 35% and 45%, respectively. There was a decrease in the root hairs and the number of cell layers of the root cortex alongside epidermis lesions. From the 50 tested rhizobacterial strains, 20 were able to grow at 150 mg/dm3 of Pb, 6 were resistant to 150 mg/dm3 of Zn and 8 resisted to 20 mg/dm3 of Cu. Best four strains had adsorption potentials and the biosorption was higher for Cu. These strains were capable of producing auxin and exopolysaccharides. The most tolerant strains (FD1 and FD2) isolated near the mining site produced siderophores and high amounts of exopolysaccharides. The use of such strains and V. faba could be of important biotechnological value in decreasing heavy metal pollution of mining soils.

After nitrogen, phosphorus is the main element for plant growth. Most agricultural soils worldwide are deficient in phosphorus and therefore require a contribution of phosphorus for the plant needs. There is a continuing need to improve soil fertility, to increase yields and agricultural productivity. During the application of phosphate fertilizers, soluble phosphorus assimilated by plants is rare because of its precipitation and then become unavailable to the plant. Rhizospheric bacteria including the plant growth promoting rhizobacteria (PGPR) are of growing interest for their potential role in improving soil fertility and enhancing an increase of crop yields and their nutrients contents. These bacteria make the insoluble phosphorus in soluble forms during the application of phosphate fertilizers and make the phosphorus available to the plant. This work gives a review of methodology and techniques used for the research of phosphate solubilization bacteria (PSB), their molecular characterization and the biochemical mechanisms and genes tools involved in solubilization of phosphate and their relationships with symbiotic plants.

Faba bean (Vicia faba L.) is one of the most important food legumes grown in Morocco under rainfed conditions. This crop requires phosphorus (P) fertilizers to produce higher yields. However, many farmers use low quantities of P because of its cost and the risk of drought. Consequently, the use of varieties with high P use efficiency (PUE) can improve productivity and farmers' income under erratic conditions where the application of high amounts of P is not economically justified. The genetic variation of PUE among Moroccan faba bean varieties was studied under different levels of available phosphorus to orientate the choice of adapted varieties. Two experiments were conducted, under rainfed conditions, at the experiment station of Douyet (Morroco) in 2000-2001 (year 1) and 2002-2003 (year 2). In both years, four P treatments 0, 40, 80 and 120 kg P 2O 5 ha -1 as fertilizer and four faba bean varieties (G) were tested. In year 1, the varieties tested were Aguadulce, Defès, Karabiga and Lobab. The same varieties were used in year 2 with the exception of Aguadulce, which was replaced by a determinate genotype with smaller straw production. Results showed that the G effect on PUE was significant in year 1, but not in year 2. In the conditions of the moderate P availability (year 1), the variety Defes had the highest PUE and grain yield. Where P availability was lower (year 2), the highest PUE was reached by Karabiga; however, the difference with Defes was not significant. Data showed also that PUE was positively correlated with harvest index (HI) and phosphorus harvest index (PHI). In year 1, genotypic variation for PUE was mainly explained by phosphorus utilization efficiency; but not by phosphorus uptake efficiency. From this study, we can conclude that for rainfed conditions, the breeding strategy is to develop genotypes like Defes with high HI and improved PUE. © 2012 Copyright Taylor and Francis Group, LLC.

Low Phosphorus availability in soil is worldwide a frequent major constraint for crops. Rhizobial strains, beneficial N2-fixing symbiotic partners of legumes, were reported to solubilize both organic and inorganic complex phosphates. Thus they may play a significant role as plant growth-promoting rhizobacteria (PGPR) in the biofertilization of crops. Natural rock phosphate may play a key role in sustainable agriculture, resulting in economic and environmental benefits. This work aims to evidence the capacity of rhizobial strains nodulating Vicia faba L. plants in Marrakech-Haouz region (Morocco) to solubilize Moroccan rock phosphate in vitro in either agar or liquid medium and to evaluate and compare the effect of these strains on growth and phosphorus uptake by V. faba plants of two Moroccan varieties (Defes and Aguadulce). Four rhizobial strains, contrasting for phosphate solubilization on agar medium, were further studied on liquid medium. RHOF147 and RHOF174 strains formed clear halos around colonies (1.37 cm and 1.2 respectively after 15 days); opposite RHOF170 and RHOF171 strains did not produce halo. The four strains were able to mobilize rock phosphate for growth in liquid medium (up to 0.59 mg/L of assimilated phosphorus). Lower pH values and most mobilized phosphorus production were registered for RHOF147 and RHOF174 strains. By screening the four rhizobial strains for growth on Chrome Azurol S (CAS) medium, only RHOF171 strain formed orange halo indicating its capacity to produce siderophores. Greenhouse experiments were undertaken including comparison of inoculated plants with these four rhizobial strains in the presence of rock phosphate as sole P source versus non-inoculated plants growing on KH2PO4 as sole P source (P-fertilized plants). Results show that the root length, the root dry weight and the ratio root /shoot dry weights were generally higher in the inoculated plants than in the P-fertilized plants, indicating the adaptation of the inoculated plants to phosphorus deficiency conditions. The effect of rock phosphate-solubilizing bacteria on plant growth depends on the symbiotic combination of the inoculated strain and the plant genotype. As for phosphorus uptake, rhizobial strains made phosphorus available to the plant at significant increased concentrations in some symbiotic combinations (e.g. Aguadulce-RHOF147). The use of selected symbiotic combinations having the capacity to solubilize rock phosphate may improve soil fertility and phosphorus availability to plants. (Resume d'auteur)

A better understanding of mineral application and use by crops is fundamental for enhancing crop yields with a minimum impact on environment and for reducing costs. However, efficiency of phosphorus utilization is dependent on genetic variability within the crop. Hence, the objective of this study is to assess responsiveness of different potato varieties to mineral phosphorus application.A field trial was conducted at El Annaceur (experimental station of the National Institute for Agricultural Research (INRA, Morocco)). Seven potato varieties (V) (Desiree, Nicola, Barna, Pamela, Daifla, Labella and Marguarita) were combined with two phosphorus (P) treatments (P0 : without any P application as fertilizer and P+ : 100kg P2O5/ha as super triple phosphate (45%)). The experimental design was a split plot with three replications, P on main plots and varieties on subplots.Re--sults showed a significant separate effect of V and P on tuber yield while no interaction effect (P*V) was recorded. Variety Pamela gave the highest main tuber yield (34 t/ha) and the variety Labella was the lowest one (19 t/ha). The variety Desiree was considered as check giving 24 t/ha.The variety Desiree showed the most significant response to P application with an average of 71% increase compared to control. The variety Barna comes in second position with 49% of response to P application while varieties Labela, Pamela and Daifla showed lower improvements (approximately 10%) comparatively to control.Within the framework of this experiment, the variety Pamella gave the highest yield in both situations of phosphorus application. While variety Desiree required an additional application of P to express its potential yield.