Combined effects of salinity and phosphorus availability on growth,gas exchange,and nutrient status of Catapodium rigidum

The combined effects of NaCl-salinity and phosphorus deficiency on biomass production, nutritional status, and photosynthetic activity were studied in Catapodium rigidum: an annual Poacea with fodder potential. Plants were grown in hydroponic conditions for 55 days under two phosphorus (P) supply: 5 (low) or 180?µmol KH₂PO₄ (sufficient), in the absence or presence of 100?mM NaCl. Obtained results demonstrated that both salinity and P deficiency treatments applied separately reduced substantially plant growth and CO₂ assimilation rate with a more marked impact of salt stress. Salinity has no substantial effect on both shoot P concentrations and phosphorus acquisition efficiency independently of P availability. The highest decrease in plant growth (?91%) was observed in plants simultaneously submitted to both stresses suggesting an additive effect of the two stresses and that P deficiency increased the susceptibility of C. rigidum to salinity. This may be linked to a significant decrease in potassium acquisition (?95%), K/Na selectivity ratio (?73%), stomatal conductance (?66%), CO₂ assimilation rate (?64%), and shoot water content (66%). Furthermore, plants cultivated under combined salinity and sufficient P supply displayed higher stomatal conductance, CO₂ assimilation rate, K/Na selectivity ratio, and plant growth than plants cultivated under combined effects of salinity and P deficiency. These results suggest that adding P to saline soils could be an alternative for alleviating the negative effects of salinity and may ameliorate salinity tolerance.     

Effects of salt treatment on growth,lipid membrane peroxidation,polyphenol content,and antioxidant activities in leaves of Sesuvium portulacastrum L.

Changes in growth, leaf contents of proline, oxidative stress-related parameters, and phenolic compounds, and antioxidant activities were investigated in the halophyte species Sesuvium portulacastrum L. under saline conditions. Rooted cuttings were individually cultivated in sandy soil. After five weeks of pre-treatment, seedlings were submitted during one month to different salt concentrations ranging from 0 to 800?mM NaCl. The plant growth was significantly improved by salt at 200–600?mM concentration. This trend was associated with (i) the stimulation of photosynthetic activity, (ii) the protection of membrane integrity (leaf MDA content 50% lower than the control), and (iii) higher total antioxidant activity, especially at 400?mM NaCl. At this salt concentration plants accumulated high contents of proline, polyphenols, antocyanins, and carotenoids. These compounds could be implied in the protection of the photosynthetic system and in the improvement of growth. Exposure to 800?mM NaCl impaired significantly photosynthesis, proline, polyphenol, antocyanin, and carotenoid accumulation. Yet, the strong antiradical activity (DPPH) observed at this extreme salinity might partly explain the plant survival. S. portulacastrum could be used in the rehabilitation and the stabilisation of saline or saline arid land. Additionally, under saline conditions, S. portulacastrum accumulate a large amount of proline and exhibits important antioxidant potentialities.     

Non-curative, but prophylactic effects of paromomycin in Histomonas meleagridis-infected turkeys and its effect on performance in non-infected turkeys

Histomonosis (blackhead or infectious enterohepatitis) is a disease of gallinaceous birds, especially of turkeys, and is caused by the protozoan Histomonas meleagridis. Since the ban of all chemoprophylactic and chemotherapeutic products against this disease in the European Union, this parasite causes a considerable amount of economical problems in the poultry industry. Research which could ultimately lead to the discovery of new drugs against this disease is thus highly necessary. Hence, in this study, the efficacy of paromomycin against histomonosis in turkeys was investigated.First, the prophylactic and therapeutic efficacy of this drug against H. meleagridis and its effect on the weight gain of turkeys was determined. Adding paromomycin to the feed (400 ppm as well as 200 ppm paromomycin) or to the drinking water (420 mg paromomycin per liter water, added prior to or on the day of challenge) significantly lowered the mortality rate and the caecal and liver lesion scores after an intracloacal infection compared to infected untreated birds. However, when paromomycin was administered to turkeys in the drinking water after the challenge, no significant differences in mortality or in lesion scores could be observed compared to the infected untreated control group. This demonstrates that paromomycin exerts a purely preventive action against histomonosis in turkeys. Additionally, the weight gain of the treated birds was positively influenced by the use of the drug, as the average weight gain of all treated groups (except for the group treated at the day of first mortality) was significantly higher than that of the untreated control group. Finally, the target site of paromomycin was detected in the SS rRNA gene of H. meleagridis. Consequently, the susceptibility to paromomycin can be correlated to the presence of the binding site of the drug at the 3′ end of the small subunit rRNA gene of the parasite. In conclusion, paromomycin can be used as a new prophylactic measure in the control of histomonosis in turkeys.     

Escherichia coli ghosts or live E. coli expressing the ferri-siderophore receptors FepA, FhuE, IroN and IutA do not protect broiler chickens against avian pathogenic E. coli (APEC)

The aim of this study was to investigate if immunization with the ferri-siderophore receptors FepA, FhuE, IroN and IutA could protect chickens against avian pathogenic Escherichia coli (APEC) infection. The antigens were administered as recombinant proteins in the outer membrane (OM) of E. coli strain BL21 Star DE3. In a first immunization experiment, live E. coli expressing all 4 recombinant ferri-siderophore receptors (BL21(L)) were given intranasally. In a second immunization experiment, a mixture of E. coli ghosts containing recombinant FepA and IutA and ghosts containing recombinant FhuE and IroN was evaluated. For both experiments non-recombinant counterparts of the tentative vaccines were administered as placebo. At the time of challenge, the IgG antibody response for BL21(L) and a mixture of E. coli ghosts containing recombinant FepA and IutA and ghosts containing recombinant FhuE and IroN was significantly higher in all immunized groups as compared to the negative control groups (LB or PBS) confirming successful immunization. Although neither of the tentative vaccines could prevent lesions and mortality upon APEC infection, immunization with bacterial ghosts resulted in a decrease in mortality from 50% (PBS) to 31% (non-recombinant ghosts) or 20% (recombinant ghosts) and these differences were not found to be significant.     

Ameliorative Effect of Municipal Solid Waste Compost on the Biological Quality Of Mediterranean Salt Lake Soil

Different loads of municipal solid waste compost (MSWC) were applied to hyper saline salt lake soil under laboratory conditions to monitor biological soil quality. Microbial biomass-C (MBC), catalase, dehydrogenase, urease, alkaline phosphatase, arylsulfatase, and β-glycosidase activities were analyzed following 14, 30, and 50 days of incubation. In general, MBC and the oxidoreductase and hydrolase enzyme activities were significantly enhanced by addition of MSWC at 20 and 40 t ha^?1 doses, but they decreased at 120 t ha^?1. Overall, the results show that the addition of MSWC to hyper saline soils can improve soil biological quality, in spite of its high salt content, which is an important step in any attempt to use them as biosaline agricultural soils. However, substances such as heavy metals in MSWC could limit the use of compost for this purpose; consequently, analysis of MSWC is recommended prior to its use.     

Life-stage-dependent side effects of selected insecticides on <Emphasis Type="Italic">Trichogramma cacoeciae</Emphasis> (Marchal) (hymenoptera: Trichogrammatidae) under laboratory conditions

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is classified as one of the most harmful pest of tomato crops. Many species of predators and parasitoids including Trichogramma cacoeciae (Marchal) (Hymenoptera: Trichogrammatidae) are noted as potential candidates used for biological control of this pest. Therefore, the use of selective insecticides is critical to conserve and protect natural enemies in the field. This study assessed the side effects of insecticides on different development stages of T. cacoeciae under laboratory conditions. For this, eleven pesticides such as: Indoxacarb, spiromesifen, cyromazin, chlorfenapyr, cypermethrin, diafenthiuron, chlorantraniliprole, spinosad, azadirachtin, Bacillus thuringiensis (Bt) and virus HaNPV were tested. This study shows that indoxacarb, spiromesifen, chlorfenapyr, cypermethrin, diafenthiuron and spinosad had a negative effect on immature stages of Trichogramma. All insecticides residues on tomato leaves were found to be toxic to Trichogramma adults except azadirachtin, Bt and virus HaNPV. Therefore, the use of the tested natural products (azadirachtin, Bt and HaNPV) at the recommended doses is viable, having no negative impact on T. cacoeciae in tomato crops.     

Differential responses to phosphorus availability in the halophytes Aeluropus Littoralis,Catapodium rigidum,and Hordeum maritimum

The objective of this experiment was to explore the variability of response to phosphorus (P) availability in three fodder Poaceae species native of saline biotopes, Aeluropus littoralis, Catapodium rigidum, and Hordeum maritimum. The behavior of these wild species has been compared to that of a cultivated one, Hordeum vulgare. Plants were grown in plastic pots filled with inert sand. The experiment was carried out in a greenhouse with six P levels: 0, 5, 15, 60, 180, and 360?µM P concentration supplied as KH₂PO₄. Results showed that the growth of the four species is strongly affected by the low phosphorus availability in the medium. Furthermore, to reach 80% of their maximum yield expressed as shoot dry weight (DW), a soil phosphorus concentration of approximately 40?µM P concentration is sufficient for Hordeum maritimum, whereas approximately 66, 120, and 132?µM P concentration are needed for C. rigidum, A. littoralis, and Hordeum vulgare plants, respectively. Thus, our results showed that spontaneous species are more tolerant to P deficiency than cultivated barley. The relative performance of the three wild Poaceae species is likely related to their capacity to maintain higher P acquisition efficiency (PAE) under low P concentration conditions. These native Poaceae species may therefore represent genetic resources for the improvement of barley.