Contribution of phytoecological data to spatialize soil erosion: Application of the RUSLE model in the Algerian atlas

Among the models used to assess water erosion, the RUSLE model is commonly used. Policy makers can act on cover (C-factor) and conservation practice (P-factor) to reduce erosion, with less costly action on soil surface characteristics. However, the widespread use of vegetation indices such as NDVI does not allow for a proper assessment of the C-factor in drylands where stones, crusted surfaces and litter strongly influence soil protection. Two sub-factors of C, canopy cover (CC) and soil cover (SC), can be assessed from phytoecological measurements that include gravel-pebbles cover, physical mulch, annual and perennial vegetation. This paper introduces a method to calculate the C-factor from phytoecological data and, in combination with remote sensing and a geographic information system (GIS), to map it over large areas. A supervised classification, based on field phytoecological data, is applied to radiometric data from Landsat-8/OLI satellite images. Then, a C-factor value, whose SC and CC subfactors are directly derived from the phytoecological measurements, is assigned to each land cover unit. This method and RUSLE are implemented on a pilot region of 3828 km² of the Saharan Atlas, composed of rangelands and steppe formations, and intended to become an observatory. The protective effect against erosion by gravel-pebbles (50%) is more than twice that of vegetation (23%). The C-factor derived from NDVI (0.67) is higher and more evenly distributed than that combining these two contributions (0.37 on average). Finally, priorities are proposed to decision-makers by crossing the synthetic map of erosion sensitivity and a decision matrix of management priorities.     

Phaseolus vulgaris-rhizobia symbiosis increases the phosphorus uptake and symbiotic N2 fixation under insoluble phosphorus

Five north Tunisian native rhizobia were tested in symbiosis with ‘Coco-blanc’ variety under two phosphorus (P) supplies [P-sufficient and insoluble P (IP)] at 250 μmol P plant^?1. At flowering stage, responses against IP were assessed and indicated that inoculation with P.Ps.09 produced a high nodule biomass (0.12g). Similarly, P.Tb.09 produced 0.08 g nodule biomass under both P and P.Bj.09 that significantly increased nodule number under IP. Shoot biomass exhibited high dry weight with P.Tb.09 and CIAT899 (1.6 g plant^?1). Inoculation with CIAT899 produced a high root biomass under both P. Analysis of a halo diameter of clear zone rounding each colony under IP indicated that P.Tb.09 has developed high halo Ø (1.7cm). These variations were associated under IP with a decrease of pH by P.Ar.09 and with increase in shoot phosphatase activity by P.Ar.09, P.Bj.09, P.OM.09 and P.Ps.09. The use of P-efficient rhizobia may constitute an adaptive mechanism against P-deficiency tolerance.     

Effect of cooking time on some nutrient and antinutrient components of bambaragroundnut seeds

The proximate composition, gross energy, mineral composition, percentage sugar, oligosaccharides and antinutrient substances of bambaragroundnut seeds subjected to different cooking times were determined. The seeds were cooked for 30, 60, 90 and 120 min. Results of the proximate analysis showed that only the ether extract and ash were significantly ( P  < 0.05) reduced as the cooking time increased. In contrast, gross energy values significantly ( P  < 0.05) increased with increased cooking time. Amongst, the mineral elements assayed, calcium, magnesium and iron were significantly ( P  < 0.05) increased, while phosphorous, potassium, sodium and copper were reduced significantly ( P  > 0.05) with inreased cooking time. Percentage sucrose and glucose of bambaragroundnut seeds were significantly ( P  < 0.05) lowest in the raw form, but increased progressively with increased of cooking time. Raffinose and stachyose levels were reduced significantly by increased cookinf time ( P  < 0.05) with the least value in seeds cooked for 120 min. Trypsin inhibitor, hemagglutinin and tannin were completely eliminated in seeds cooked for 60 min or longer, but the phytin level was reduced significantly ( P  < 0.05) by cooking. For a significant detoxification of antinutrient substances and for optimal bioavailability of the component nutrients of bambaragroundnut seeds, an optimum cooking time of 60 min at 100°C is therefore recommended.     

A 50 kDa maize gamma-zein has marked cross-reactivity with the almond major protein

Cross-reactivity of antibodies against almond major protein (AMP, a legumin), the major almond allergen, with cereal proteins may cause problems in detecting almond contaminants in cereal products when antibody-based assays are used. Rabbit polyclonal IgG antiserum produced against AMP was used to test cross-reactivity with protein extracts from maize, a cereal commonly found in breakfast and snack foods. Gradient SDS-PAGE followed by Western blotting was performed, and two cross-reactive proteins were detected by chemiluminescence. A fraction of maize proteins purified by elution from an IgG anti-AMP affinity column followed by electrophoreseis and immunoblotting showed a high degree of cross-reactivity with a minor 50 kDa protein of maize, as well as low cross-reactivity with the 27 kDa gamma-zein. The 50 kDa cross-reactive protein was identified as the 50 kDa gamma-zein by immunoreaction with anti-50 kDa gamma-zein antiserum. Notably, the 50 kDa maize gamma-zein also reacted with IgE from pooled human sera from patients with self-reported severe almond allergies. The high immunoreactivity of the 50 kDa gamma-zein should be considered in maize quality improvement programs, and such notable cross-reactivity is of relevance in the design of antibody-based assays for almond allergen detection.     

Physiological and electroencephalographic changes in goats subjected to transportation,lairage, and slaughter

This preliminary trial investigated the effect of transportation and lairage periods on physiological parameters of goats subjected to slaughter. Nine male Boer cross goats aged 8–12 months were transported for 6 h and kept at lairage for 3, 6, or 16 h (n = 3). Blood samples were collected at pre- (pre-T) and post-transportation (post-T), and post-slaughter (post-S) for determination of hematological parameters, serum enzyme, protein, and cortisol concentrations. Electroencephalogram readings were taken at pre-T, post-T, pre-slaughter (pre-S), and post-S to determine the median frequency (F₅₀) and total power (Ptot) values. At post-T, there were manifestations of stress leukogram; increase in hematocrit, total protein, and muscle enzyme concentrations; and decrease in Ptot (p < 0.05). The high pre-T cortisol concentration suggests that the goats were already under stress before transportation. Stress leukogram became less evident after lairage, indicating that the goats had recovered from the stress of transportation. Although the Ptot increased at post-S especially following 3 h of lairage, F₅₀ values at post-S did not differ from pre-L, suggesting that the pre-slaughter stress may have affected the pain threshold. It is suggested that after 6 h of transportation, goats should ideally be placed in lairage for a minimum period of 3 h before slaughter.     

INTERACTIONS BETWEEN COMMON BEAN GENOTYPES AND RHIZOBIA STRAINS ISOLATED FROM MOROCCAN SOILS FOR GROWTH,PHOSPHATASE AND PHYTASE ACTIVITIES UNDER PHOSPHORUS DEFICIENCY CONDITIONS

The improvement of common bean production requires the selection of effective rhizobia strains and Phaseolus vulgaris genotypes adapted to available soil phosphorus limitations. The interactions between bean genotypes and rhizobia were studied in hydroponic culture using six genotypes and four strains, CIAT899 as reference and three strains isolated from nodule of farmer's fields in the Marrakech region. The phosphorus (P) sub-deficiency caused a significant reduction on shoot biomass in some bean genotype-rhizobia combinations. Nodule biomass is significantly more reduced under P limitation for several combinations tested. Bean plants inoculated with these local rhizobial strains showed higher nodulation and an increase of nodules phytase and phosphatase activities under phosphorus sub-deficiency especially for RhM11 strain. It was concluded that the studied bean-rhizobia symbiosis differ in their adaptation to phosphorus sub-deficiency and the nodule phosphatases and phytases activities may constitute a strategy of nodulated bean plants to adapt their nitrogen fixation to P deficiency.     

Assessment of summer drought tolerance variability in Mediterranean alfalfa (Medicago sativa L.) cultivars under Moroccan fields conditions

This study was undertaken to assess levels of tolerance to summer drought in Medicago sativa genotypes and to comment on their abilities to adapt to Moroccan conditions. Sixteen alfalfa cultivars originating from the Mediterranean basin were tested at an experimental station in Morocco, located in the semi-arid bioclimatic area. Trials were conducted over three years and consisted of one continuously irrigated treatment and another irrigated treatment in which summer watering was withheld for 9 weeks. Results showed that summer water stress significantly reduced aboveground biomass in all of the cultivars tested. This reduction ranged between 23.9 and 42.6% compared with fully irrigated treatment. At the end of stress period, mean summer leaf senescence rate was 83.3%, with a significant difference between cultivars. Ground cover, estimated at the end of summer in the third year, decreased dramatically and ranged between 12 and 30.7%, depending on the cultivar. High intrinsic water-use efficiency was associated with a decrease in stomatal conductance rather than an increase in photosynthesis.     

Genetic diversity assessed by SSR markers and chemotyping of Fusarium culmorum causal agent of foot and root rot of wheat collected from two different fields in Tunisia

Fusarium culmorum is a major pathogen able to cause foot and root rot and the incitant of Fusarium head blight in wheat in Tunisia. The aims of the present study were to evaluate by PCR the type of mycotoxins produced, to determine the mating type and to analyse the genetic diversity by microsatellite markers of 82?F. culmorum isolates recovered from two separated Tunisian fields. Specific sequences in the Tri6-Tri5 intergenic region, Tri7 and Tri13 were used to identify 3-AcDON- or 15-AcDON-. All studied F. culmorum isolates, were of the 3-AcDON- type. No 15-AcDON- and NIV types were detected in this research. Both mating types MAT1-1 and MAT1-2 were recovered from the two fields in approximately equal proportions. Five polymorphic microsatellite markers were applied to F. culmorum isolates, to determine the genetic variation in and among populations. Sixty-four haplotypes were identified; the analysis of the population structure did not reveal a strong variation between fields. Total gene diversity (H _T ?=?0.505; H _S ?=?0.497) and analysis of molecular variance confirmed that most of the genetic variability was within populations (Φ _ST ?=?0.033; P?<?0.0039). Gene flow (N _m ?=?31.05) indicated little differentiation among populations. Based on these results, the F. culmorum isolates collected from different fields might be part of one large panmictic population and in addition the low linkage disequilibrium values with high genetic variation within populations suggest that the population is recombining sexually.