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Morphological variation in Astragalus hamosus L. and Coronilla scorpioides L. populations of Tunisia
Morphological variation between Astragalus hamosus and Coronillascorpioides populations was studied using local germoplasm collected in northern and central Tunisia. Twenty-one morphological traits
were recorded and data were analysed using complementary statistical analysis. Considerable variation based on morphological
and agronomical traits was found between populations and for both species. Pod and peduncle lengths as well as flowers number
were the most discriminant variables between populations. Differences were also found for variables like seed number per pod,
seed yield and dry matter production. Significant correlations were found between plant traits and the environmental parameters
of the origin sites. This study revealed enough variation among populations to initiate a selection programme for pasture
improvement in arid and semi-arid areas of Tunisia, where the two species are well adapted.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Using conventional soil and foliar spray applications to correct micronutrient deficiency in citrus has not been completely satisfactory. Therefore, this study was developed to test the effectiveness of micronutrient application through microirrigation (fertigation) at rates similar to those recommended for foliar spray application. Three field experiments were conducted on ‘Valencia’ orange [Citrus sinensis (L.) Osb.] trees to study the absorption of Fe, Mn, Zn, and Cu by periodically analyzing leaf samples. The effectiveness of fertigation with micronutriems was found to depend on the fertilizer source. Application of chelated Fe, Mn, and Zn through irrigation systems increased the concentrations of these micronutrients in the leaves. The nitrate forms of Fe, Mn, and Zn were ineffective, as was the sulfate form of Zn. The sulfate form of Mn was occasionally effective, but the sulfate form of Cu was very effective. The application of chelated micronutrients through fertigation shows promise in central Florida. 相似文献
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Mongi Zekri 《Journal of plant nutrition》2013,36(6):1087-1102
An experiment was conducted to study the effects of polyethylene glycol (PEG) on citrus growth and mineral composition. Seedlings of 7 citrus rootstock cultivars were treated with three osmotic potential levels (‐0.10, ‐0.20, and ‐0.35 MPa) of PEG for five months under greenhouse conditions. Increasing the concentration of PEG in the nutrient solution proportionally reduced root and shoot growth in all rootstocks. Although roots were in direct contact with PEG, their growth was less affected by PEG treatments than that of shoots. Seedling growth was reduced the most in Carrizo citrange and Milam lemon. Significant differences in root and leaf mineral concentrations among cultivars were found under PEG stressed and non stressed conditions. Furthermore, no consistent relationship in mineral absorption, translocation and accumulation seemed to exist between citrus roots and leaves. Root and leaf mineral concentrations were also significantly altered by PEG in all rootstock cultivars. Nitrogen (N), potassium (K), and magnesium (Mg) were reduced in the leaves and calcium (Ca) was reduced in the roots but zinc (Zn) and manganese (Mn) were noticeably increased in the roots. The results of this study demonstrated that some of the deleterious effects of PEG could be attributed to nutritional imbalances, N and Mg deficiency in the leaves and Zn and Mn toxicity in the roots of citrus cultivars. 相似文献
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Fatma Mbarki Aida Kesraoui Mongi Seffen Philippe Ayrault 《Water, air, and soil pollution》2018,229(3):95
The potential to remove methylene blue (MB) basic dye and indigo carmine (IC) acidic dye, from wastewater treatment systems using corn stigmata through biosorption was investigated in batch experiments. The effects of contact time, solution pH, biosorbent dosage, initial dye concentration, salts, and temperature were sought. Results showed that the maximal uptakes of MB were 106.3 mg g?1 at pH?=?7 and 63.7 mg g?1 for IC at pH?=?2. In order to determine the properties and surface structure of the biomass physicochemical properties (pHpzc, elemental analysis, Boehm’s titration, and chemical composition), spectral (FTIR analysis) and morphological characteristics (SEM) were investigated. Random distribution of the active sites was described by the new biosorption fractal model of Brouers–Sotolongo. The thermodynamic study demonstrated the favorable character of the biosorption of MB and of IC, which was inhibited by the presence of salts. The elucidation of the biosorption mechanism showed that the biosorption of MB onto corn stigmata was mainly controlled by chemisorption and the biosorption of IC was described by physisorption. 相似文献
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Groups of Friesian cattle were infested repeatedly with Rhipicephalus appendiculatus at weekly intervals (eight infestations) and at intervals of 3 weeks (seven infestations) and 6 weeks (seven infestations). The engorgement weight of adults, nymphs and larvae decreased significantly initially, from the second infestation, but rose significantly at later infestations. This rise was more dramatic with larval instars than with any other. A new method for quantifying the resistance status of animals was introduced; this method showed that the resistance acquired by cattle during 6-weekly reinfestations was more stable than that acquired by cattle during weekly and 3-weekly reinfestations. The criteria for assessing natural resistance to ticks was reappraised. These are classified into those serving long- and short-term purposes, and those which have direct and indirect effects. Criteria which could serve long- and short-term purposes include a reduced number of engorged ticks, an increased number of dead male and female ticks, a decreased number of ticks which fed above the critical engorgement weight and an increased number which fed within the pre-mating weight and decreased the number of copulations. The criterion of reduced engorgement weight can serve the short-term purpose only. A new manifestation of resistance to ticks, i.e. decreased moulting weights of nymphs and adults, together with the criterion of decreased egg hatchability, were classified as indirect effects because they were manifested after the ticks had dropped off the resistant cattle. 相似文献
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Mongi Zekri 《Journal of plant nutrition》2013,36(8):1555-1568
Salt tolerance of Carrizo citrange (CC), sour orange (SO), and Cleopatra mandarin (CM) rootstocks during emergence and early seedling stage of development was studied under greenhouse conditions. Increasing salt concentration in the nutrient solution delayed and depressed seedling emergence (SE), increased time to 50% emergence, reduced seedling growth (SD) but did not affect emergence spread. At the first salinity level (5 mmol), emergence of the first seedling (EFS) was delayed by 2–3 days in CC and one day in SO but was not affected in CM. At the two lowest salinity levels (5 and 10 mmol), final percent emergence (FPE) was not affected in CC but was reduced in SO and CM while shoot biomass was reduced in CC but was not affected in SO and CM. This study showed a non‐consistent trend among citrus rootstocks concerning whether the delay in emergence is more sensitive to salt stress than final percent emergence. However, SG was generally more affected by salinity than SE, particularly at high salinity levels. Shoot and root N and Cl concentrations generally increased with increasing salt concentrations. Shoot Cl concentration was found to be a better tool than root Cl concentration in evaluating the extent of the injurious effect of salt stress and a better parameter in ranking salt tolerance of citrus rootstocks. This study also showed that salt tolerance is not a constant character in citrus rootstocks but varies with the stage of seedling development. 相似文献
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Treated, reclaimed municipal wastewater was evaluated on citrus trees in central Florida for over six years. The effects of irrigation with reclaimed wastewater on soil water content, soil chemical analysis, leaf mineral status, and fruit quality were compared with those of irrigation with well water. Irrigation with reclaimed water increased mineral residues in the soil profile, altered leaf mineral concentration and fruit quality, and promoted better tree performance and more weed growth relative to irrigation with well water. Higher accumulation of nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) in soils irrigated with reclaimed water were not significantly reflected in leaf mineral status. Although leaf sodium (Na), chloride (Cl), and boron (B) concentrations were noticeably higher in reclaimed water treatments than in those of well water, they are still far below the toxicity levels. This highly treated wastewater in central Florida has been found to be a very safe and good option for increasing water supplies, but not a significant source of plant nutrients to citrus trees. 相似文献
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This study investigated phosphorus sorption kinetics of three different soils from three sites within the Sahel region of Tunisia; iso-humic soils from Chott-Mariem site, calcic-magnesic soils from Enfidha site and saline-sodic soils from Kondar site. Soils from all sites were sampled (0–25 cm) and analysed for their physico-chemical proprieties. In previous works, we determined the adsorption efficiency of these different soils. In this study, we focused on the influence of contact time on phosphorus adsorption by the different soils. The analytic data were approached from the following kinetics models: pseudo-first-order, pseudo- second-order and Elovich model. The second order model was shown to be the best fit for describing phosphorus adsorption by each soil sample, as seen from the correlation coefficient R2 which ranged from 0.68 to 0.96 for the pseudo-first-order model, 0.91 to 0.99 for pseudo-second-order model and 0.84 to 0.94 for Elovich model. 相似文献
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