Effect of Water Quality on Heavy Metal Redistribution and Mobility in Polluted Agricultural Soils in a Semi-Arid Region

Mornag Plain is a coastal area of the Mediterranean basin, which has undergone an agricultural industrial boom. The aim of this study was to investigate the different water qualities used for irrigation on heavy metal mobility in these polluted agricultural soils. The geo-accumulation indices for heavy metals (Ni, Cr, Pb, Cd, Cu, and Zn) revealed that industrial activities and used treated wastewater (TWW) contributed to soil pollution, and water irrigation always decreased this contamination. After long-term use of different water types, high perturbation of heavy metal redistribution has occurred. Groundwater use altered all heavy metal redistributions in the irrigated soil among various soil-solid and soil-solution fractions, as compared to the unirrigated soil. Slight acid water use transferred some metals from different solid phase components into water-soluble and exchangeable fractions. However, TWW use transformed some Ni, Cr, Cd, Cu, and Zn from water-soluble and exchangeable fractions to less labile fractions, particularly into organically bound fractions. Reuse of conventional water within the same soil decreased the whole soil redistribution index values, indicating tendency to return to the pattern of distribution of groundwater-irrigated soil.     

Reproductive Responses of Holstein–Friesian Cattle to the Climatic Conditions of Central Sudan

Data were evaluated from a purebred Holstein herd (n = 1274) kept near Khartoum, a hot and dry area, from 1990 to 1996. The mixed model procedure in SAS was used to analyse the reproductive traits. The mean gestation length, days dry, number of services per conception, days from calving to first oestrus, days from calving to conception, calving interval and breeding efficiency were 279 days, 104 days, 4.2, 85.8 days, 208.9 days, 486.2 days and 74.9%, respectively. Factors that had significant effects (p<0.01) on all the reproductive measures under study were the year and month of calving, and parity.The heritability estimates for all traits under investigation were zero. The repeatability estimates for the numbers of services per conception, days from calving to conception, days from calving to first oestrus and calving interval were 0.21±0.021, 0.12±0.024, 0.03±0.018 and 0.00, respectively. The phenotypic correlation for calving interval with numbers of service per conception was 0.05, that with days from calving to first oestrus was 0.06 and that with days from calving to conception was 0.07. Other correlations ranged from 0.00 to 0.28. The simple correlation coefficients between production and reproductive measures ranged from –0.06 to 0.45.     

Effect of three irrigation regimes on Arbequina olive oil produced under Tunisian growing conditions

This study investigated the effect of irrigation amount on the concentration of phenolic compounds in olive (Olea europaea L., cv. Arbequina) oil obtained from an intensively-managed orchard in a semi-arid area with a Mediterranean climate in Tunisia. Different irrigation treatments 50% Etc, 75% Etc and 100% Etc were applied to the olive orchard. Oil quality, evaluated using the parameters established to determine the quality level of virgin olive oils (acidity, K232, K270 and peroxide index) was slightly affected by irrigation. However, results showed that irrigation positively affected both fruit and oil quality. In fact, the least irrigation regime (T1), showed a significantly higher content of oleic acid (70.08%), whereas olive oils from more irrigated trees (T2 and T3) had higher contents of palmitic acid (11.64% and 13.14%, respectively) and lower of linoleic acid (approximately 12.7%). However, content of phenolic compounds (hydrophilic and lypophilic), in the oils extracted, strongly differed. In fact, different irrigation regimes applied not only affected the total amount of phenols which were proportional to irrigation (193.2 and 271.87 mg kg⁻¹ for T1 and T3, respectively) except for T2 but also their HPLC profiles. Contrarily to phenols, insignificant differences were observed in the concentration of α-tocopherol between the irrigation treatments studied.     

Larval rearing of calico scallops, Argopecten gibbus, in a flow-through system

A flow-through (FT) culture system is described for calico scallop, Argopecten gibbus, larvae. Its performance was assessed by larval survival rate, shell growth, settlement rate and post-larval shell growth for the duration of larval life (13 days). Comparisons were made with larvae reared in standard static system (S). Effect of increased larval density on FT performance was also investigated. With comparable larval densities, survival rate of Day 2 larvae to pediveliger stage was similar in both larval rearing systems. Shell growth for FT-reared larvae was comparable or significantly higher than in the static system (P < 0.01). Settlement rate of pediveligers was comparable for both systems, averaging 30.7%, and no significant difference was seen in shell growth of FT- and static-reared pediveligers. Increased initial larval density did not affect survival rate in FT, but did negatively affect larval shell growth, settlement rate and post-larval shell growth yielding lower growth and minimal settlement rate (10.9 ± 2.8%) compared to the static system. This FT system was successful as larval rearing system, optimising space allocation in the hatchery, reducing labour, and eliminating the use of antibiotics. Optimising initial larval density within the system needs to be investigated in association with food ration.     

Chickpea (Cicer arietinum) is nodulated by unexpected wide diversity of Mesorhizobium species in Eastern Algeria

Using a local Algerian cultivar of chickpea, from 9 sites in Eastern Algeria, along a sub-humid to arid gradient, we isolated 60 nodulating isolates, among which 19 were assigned to Mesorhizobium species and 41 to Ensifer meliloti. Trapping revealed great differences among sites for their ability to induce nodules on plant, but no correlation with chemical and physical characterizations of soil samples could be found. Based on 16S rRNA gene sequences, 16S-23S IGS, recA, nodC and nifH sequences, Mesorhizobium isolates were assigned to at least 5 different species, among which one had never been described as nodulating chickpea before. The symbiotic diversity is conversely low, and shared by several species, reflecting horizontal gene transfer. The ability of Mesorhizobium genus to recombine and exchange symbiotic clusters among different species must play a great role in this ability to be associated with chickpea. The question to what extent the symbiotic species would end in this genus is discussed.     

Chemical composition,phytotoxic and antifungal activities of <Emphasis Type="Italic">Pinus pinea</Emphasis> essential oil

The chemical composition of essential oils isolated by hydrodistillation from the aerial parts of Tunisian Pinus pinea Linn. was analyzed by GC and GC/MS. Sixty-six compounds were identified, representing 98.5% of total oil, which was found to be rich in monoterpene hydrocarbons (73.1%) particularly limonene (54.1%), α-pinene (7.7%), and β-pinene (3.4%). The yield and the physico-chemical properties were determined. Results of the antifungal activity study by in vitro contact assay showed that P. pinea oil significantly inhibited the growth of ten plant pathogenic fungi. Moreover, herbicidal properties of the oil, tested on Sinapis arvensis L., Lolium rigidum Gaud., and Raphanus raphanistrum L., indicated that the oil completely inhibited the seed germination at a high concentration, while at low doses the oil acted by decreasing and delaying the germination and inhibiting the seedling growth of all tested weeds unlike the commercial herbicide. Our results showed that P. pinea essential oil could be valorized as bioproduct for biocontrol of weeds and fungal plant diseases.     

Screening for Echinococcus granulosus in dogs: Comparison between arecoline purgation, coproELISA and coproPCR with necropsy in pre-patent infections

Echinococcus granulosus is an important zoonotic infection of dogs. The purpose of the present study assessed the performance of two laboratory diagnostic methods with arecoline purgation and necropsy in infected dogs. In total 65 dogs were successfully experimentally infected with protoscoleces of E. granulosus from ovine infection. At 14-34 days post-infection groups of dogs were purged with arecoline hydrobromide and then necropsied. Faecal samples were tested at weekly intervals by coproantigen ELISA and coproPCR. The necropsy infection rate with E. granulosus was 89.2 per cent. Only 43 per cent of dogs were successfully purged after one arecoline dose; this percentage increased to 76.9% for two doses of arecoline purgation. E. granulosus coproantigen was detected by coproELISA in 82.8% of faeces. The positive and negative predictive values for coproantigen ELISA were 96 and 44.4% respectively. E. granulosus DNA was detected in pre-patent faecal samples by coproPCR in 25.9% of dogs. These results indicate that coproELISA is more sensitive than arecoline purgation for the detection of pre-patent E. granulosus infection in dogs. CoproPCR detected E. granulosus DNA in dog faeces by 21 days post-infection before egg production.     

Fruit yield and quality of strawberry plants transformed with a fruit specific strawberry pectate lyase gene

Two transgenic strawberry lines (Pel 1 and Pel 3) containing the open reading frame of a fruit specific strawberry pectate lyase gene (FaplC) under the control of the CaMV35S promoter have been obtained to evaluate the role of this gene on fruit softening. Ripen fruits from both lines showed a significant down-regulation of FaplC, being the percentage of silencing of 84 and 71% on Pel 1 and Pel 3, respectively. The agronomic behaviour of transgenic plants was evaluated during two consecutive years. Fruit set increased in the two transgenic lines when compared with control plants, although Pel 1 showed a significant reduction on fruit weight. Firmness of full ripen fruits from Pel lines was significantly higher than control fruits, while color and soluble solids were not affected. The increase of firmness in Pel lines was maintained when ripe fruits were stored for 3 days at 25 °C. Histological analysis of ripe fruits showed lower intercellular spaces and a higher degree of cell to cell contact area in transgenic fruits when compared with controls. Altogether, these results suggest a direct relationship between pectate lyase gene expression and strawberry fruit softening.