Effect of intercropping alfalfa on physiological and biochemical parameters of young grapevine plants cultivated on agricultural and contaminated soils

Our research aimed to reveal the capacity of intercropping with Medicago sativa-rhizobia in the amelioration of grapevine growth in agricultural and a Cd/Pb contaminated soils. A local variety of grapevine was cultivated in monocropping and in intercropping with Medicago sativa inoculated or not with its associated rhizobia. Intercropping with alfalfa induced a significant increase in shoot and root biomass of grapevine in the agricultural soil. However, in the contaminated soil, a slight increase in root biomass was observed. Concerning photosynthesis apparatus, we showed that the presence of Cd and Pb in the soil induced a significant decrease in both CO2 assimilation rate and stomatal conductance. Interestingly, intercropping with alfalfa only and with rhizobia alleviate this effect. Similar results are obtained for chlorophyll and carotenoid content. This was associated with a significant decrease in the malondialdehyde level in leaves and roots of grapevine cultivated in intercropping with alfalfa with and without inoculation in the two soils as compared the monoculture treatment. Comparison between treatments revealed also that intercropping with alfalfa induced a decrease in the activities of some enzymes implicated in the defence to the oxidative stress such as catalase and superoxide dismutase. Regarding soluble protein content, it is needed to signal the improvement of this parameter with the intercropping system in the contaminated soil when compared to the monocropping treatment. This work highlights the importance of the use of legumes in intercropping with grapevine as intercrop plant non-competitive for soil nutrient and proving N supply for associated plants.         &nbsp

Effect of increasing zinc levels on Trigonella foenum-graecum growth and photosynthesis activity

Zinc is an indispensable element for the plant growth and the cellular metabolism. However, this mineral element becomes harmful athigh quantities. The effects of high zinc supply on different physiological parameters were investigated in fenugreek. Seedlings were grown in plastic pots filled with inert sand under five ZnSO4 treatments (C: control :1.5 μM Zn; 1mM, 2 mM, 3 mM and 4 mM ZnSO4). Results showed a decrease of 56% to 75% in shoot dry weight and a decrease of 65% to 90% in roots dry weight, relatively to the control. In addition we showed a significant reduction in photosynthetic parameters, with the highest value of CO2 assimilation under 1 mM Zn (3.3 μmol CO2, m-2·s-1) and a lower value under 4 mM Zn (0.5 μmol CO2, m-2·s-1). The concentration of zinc in plant shoot was around two folds the control under 1, 2 and 3 mM Zn and about four folds under the maximal concentration, 4 mM Zn. In roots, we showed a progressive increase of zinc content. Increasing zinc concentration induced a significant decrease of phosphorus concentration in shoot. Fenugreek was mainly affected by zinc excess greater than 1 mM ZnSO4, however at the highest concentration, fenugreek plants exhibited different adaptation strategies

Composición, calidad y estabilidad oxidativa de aceite de oliva virgen procedente de algunas variedades salvajes seleccionadas de aceitunas (Olea europaea L. subsp. oleaster)

A study on the characterization of virgin olive oils from wild olives (Olea europaea L. subsp. oleaster) was conducted in order to define new cultivars which are welladapted to the Tunisian environment and yield high quality oils. The study was done during the crop years 2003/04, 2004/05 and 2005/06. The main analytical parameters of the oils were evaluated: fatty acid compositions, chlorophylls, carotenoids, tocopherols and phenolic compounds as well as their relationship with oxidative stability. The fatty acid composition of all the wild olive trees tested produced virgin olive oil which complies with commercial standards, as well as for their appreciable amounts of tocopherols and phenolic compounds. Tocopherol analysis by HPLC revealed the presence of α, β, γ and δ tocopherols in all the studied olive oils. Total tocopherol content was significantly influenced by the varietal factor. It ranged from 310 (SB12) to 780 mg/kg (H3). As for total tocopherols, the amount of each tocopherol varied according to genotype. α tocopherol is the most prominent, whereas β, γ and δ tocopherols are less represented. Results showed a clear influence of total phenols and o-diphenols on virgin olive oil stability (R = 0.905, 0.963 PEn este trabajo se han caracterizado los aceites obtenidos a partir de siete acebuches previamente seleccionados entre varias poblaciones de Olea europea L. Subsp. oleaster. El estudio se llevó a cabo durante las campañas de producción 2003/04, 2004/05 y 2005/06.Varios parámetros analíticos fueron evaluados: composiciones en ácidos grasos, pigmentos, tocoferoles, fenoles; así mismo, se investigó la relación de estos parámetros con la estabilidad de los aceites. Los resultados obtenidos mostraron que todas las muestras de frutos de acebuche produjeron aceites cuya composición de ácidos grasos, tocoferoles y compuestos fenólicos cumplió las normas comerciales para aceite de oliva virgen del Comité Oleícola Internacional. El análisis de los tocoferoles con el HPLC reveló la presencia de las formas α, β, γ y δ en todos los aceites de oliva estudiados. El contenido total de tocoferoles estuvo claramente influido por la variedad, oscilando entre 310 mg/kg en SB12 hasta 780 mg/kg en H3. La forma α de los tocoferoles fue la más importante mientras que de las formas β, γ y δ se hallaron menores contenidos. Los resultados indicaron una clara influencia de los fenoles y de los o-difenoles en la estabilidad de los aceites vírgenes de oliva (R = 0.905, 0.963 con P < 10-3, respectivamente), y una contribución mucho más baja de los tocoferoles (R = 0.568) y de los ácidos grasos (R = 0,563)

Changes in chloroplast lipid contents and chloroplast ultrastructure in Sulla carnosa and Sulla coronaria leaves under salt stress

5 Figuras.-- 3 TablasThe possible involvement of chloroplast lipids in the mechanisms of NaCl tolerance was studied in leaves of two varieties of Fabaceae: Sulla carnosa and Sulla coronaria, which were subjected to 200 mM NaCl over 20 days. Changes in membrane lipid peroxidation, chloroplast lipids content, fatty acids (FA) composition and the ultrastructure of chloroplasts under salt stress were investigated. Chloroplast lipids were separated and quantified by high performance liquid chromatography coupled to evaporative light scattering detection (HPLC/ELSD). The results showed that salinity induced a significant decrease in digalactosyldiacylglycerol (DGDG), phosphatidylglycerol (PG) and sulfoquinovosylglycerol (SQDG) content in both S. carnosa and S. coronaria leaves, whereas monogalactosyldiacylglycerol (MGDG) content did not change significantly in S. carnosa leaves. The MGDG/DGDG ratio remained stable in S. coronaria leaves but increased in those of S. carnosa. In addition, the unsaturated-to-saturated fatty acids ratio (UFAs:SFAs) did not change under salt stress in S. coronaria leaves, while it decreased significantly in S. carnosa leaves. Moreover, salinity did not induce significant changes in MGDG and DGDG unsaturation level in S. carnosa leaves, in contrast to S. coronaria, in which salinity seems to enhance the unsaturation level in MGDG, DGDG and PG. Furthermore, the level of membrane lipid peroxidation, as expressed by malondialdehyde (MDA) levels, increased at 200 mM in S. carnosa leaves, while it did not change significantly in those of S. coronaria. With respect to the ultrastructure of chloroplasts at 200 mM NaCl, investigated by transmission electron microscopy (TEM), salt-stress caused the swelling of thylakoids in S. carnosa mesophyll. These ultrastructural changes were observed especially in the spongy tissue in S. coronaria. Taken together, these findings suggest that the stability of MGDG/DGDG ratio, the unchanged unsaturation level, and increasing unsaturation level in MGDG, DGDG and PG may be effective to some degree in suppressing the ultrastructural damage caused by salinity effects and may contribute to protect the chloroplast membrane integrity against salt stress.This work was funded by the Ministry of Higher Education and Scientific Research of Tunisia. Imaging was performed at the Bordeaux Imaging Center, member of the national infrastructure France BioImaging

Proximate composition, lipid and phenolic profiles, and antioxidant activity of different ecotypes of Lupinus albus, Lupinus luteus and lupinus angustifolius

Lupine seed represents an interesting, non-genetically modified, and low cost alternative to soybean as an important source of protein and oil. In this study, we compare seed protein, mineral, fiber and starch content, lipid and phenolic profile, and antioxidant properties of three lupine wild species (Lupinus albus, Lupinus luteus, and lupinus angustifolius). For each lupine species, nutritional composition of different Tunisian ecotypes was compared to determine the influence of geographical origin on these compounds. Standard protocols and ultra-high‐performance liquid chromatography/tandem mass spectrometry methods were used. Results revealed that several compounds showed a significant difference between species as well as between local ecotypes and commercialized variety. L. albus seeds were shown characterized by the highest protein and oleic acid content and the lowest starch content. Results revealed that lipids and phenolics were highly influenced by the ecotype factor. Large differences were found between L. luteus ecotypes for oleic acid and linoleic acid content, ranging from 164.97 to 302.73 mg kg−1 DM and from 306.03 to 616.97 mg kg−1 DM, respectively. Little amount of miristoleic acid, lignoceric acid, and margaric acid were found in lupine seeds for the first time. For phenolic profile, interestingly to highlight for the first time the presence of morin dihydrate among lupines species, especially in L. tbk2 which showed the highest antioxidant activity