Terrestrial-marine continuum of sedimentary natural organic matter in a mid-latitude estuarine system

Journal of Soils and Sediments - Humic acids (HA) have several environmental roles, but are particularly important in aquatic environments, being recognized as redox active natural organic matter...     

Co-inoculation of selected nodule endophytic rhizobacterial strains with Rhizobium tropici promotes plant growth and controls damping off in common bean

Production of common bean(Phaseolus vulgaris)is limited by the occurrence of damping off(rhizoctoniosis),which is caused by the fungus Rhizoctonia solani.However,the co-inoculation of plant growth-promoting rhizobacteria(PGPR)involved in biological control along with diatomic nitrogen(N2)-fixing rhizobia can enhance N nutrition and increase production.In this context,finding microorganisms with synergistic effects that perform these two roles is of fundamental importance to ensure adequate yield levels.The aim of this study was to evaluate the effects of co-inoculation of nodule endophytic strains of the genera Bacillus,Paenibacillus,Burkholderia,and Pseudomonas with Rhizobium tropici CIAT 899,an N2-fixing rhizobial strain,on the biocontrol of damping off and growth promotion in common bean plants.Greenhouse experiments were conducted under axenic conditions using the common bean cultivar Pérola.The first experiment evaluated the potential of the 14 rhizobacterial strains,which were inoculated alone or in combination with CIAT 899,for the control of R.solani.The second experiment evaluated the ability of these 14 rhizobacterial strains to promote plant growth with three manners of N supply:co-inoculation with CIAT 899 at low mineral N supply(5.25 mg N mL^-1),low mineral N supply(5.25 mg N mL^-1),and high mineral N supply(52.5 mg N mL^-1).The use of rhizobacteria combined with rhizobia contributed in a synergistic manner to the promotion of growth and the control of damping off in the common bean.Co-inoculation of the strains UFLA 02-281/03-18(Pseudomonas sp.),UFLA 02-286(Bacillus sp.),and UFLA 04-227(Burkholderia fungorum)together with CIAT 899 effectively controlled damping off.For the common bean,mineral N supply can be replaced by the co-inoculation of CIAT 899 with plant growth-promoting strains UFLA 02-281/02-286/02-290/02-293.Nodule endophytes UFLA02-281/02-286 are promising for co-inoculation with CIAT 899 in the common bean,promoting synergy with rhizobial inoculation and protection against disease.     

Does the application of silvicultural management models drive the growth and stem quality of sweet chestnut coppices towards sustainability?

New Forests - The coppice is a very flexible cultural system producing several calibers adapting to the demands of the market. Small-caliber roundwood from sweet chestnut (Castanea sativa Mill.)...     

Some effects of light intensity and photoperiod on the sea bass larvae (Dicentrarchus labrax (L.)) reared at the Centre Oceanologique de Bretagne

Four experiments were performed to determine the effects of light intensity on the growth and survival of sea bass larvae; two experiments dealt with the photoperiod and two with the combined effects of light intensity and the photoperiod. Recently hatched larvae from the same spawning were used within each experiment.The light intensity experiments show that there is better growth but poorer survival at higher light intensities. The photoperiod experiments show a better growth at 18 h photoperiod and a better survival at 12 h exposure to light. The study of the combined effects of light intensity and photoperiod confirmed the hypothesis that strong light intensities are lethal to newly hatched larvae (with no pigmentation). If the light intensity is lowered during the first week, the best rearing conditions were found to be continuous lighting relative to survival rate, and 14–16 h photoperiod relative to growth.     

Effect of dietary carbohydrate-to-lipid ratios on growth, lipid deposition and metabolic hepatic enzymes in juvenile Senegalese sole (Solea senegalensis, Kaup)

A study was undertaken to determine the effect of various dietary carbohydrate‐to‐lipid ratios on growth performance, whole‐body composition and tissue lipid content in Senegalese sole (Solea senegalensis) juveniles. Data on the dietary regulation of key hepatic enzymes of the lipogenic and glycolytic pathways (glucose‐6‐phosphate dehydrogenase, G6PD; malic enzyme, ME; fatty acid synthetase, FAS; pyruvate kinase, PK and glucokinase, GK) were also generated. Four isonitrogenous (crude protein: 52% dry matter (DM)) diets were formulated to contain one of two lipid levels (11% and 21% DM). Within each dietary lipid level, the nature of the carbohydrate fraction (raw or extruded peas) was varied. Triplicate groups of 54 sole (initial body weight: 23.6±1.2 g) were grown in recirculated seawater over 67 days. Fish were fed using automated feeders. At the end of the study, whole‐body, liver, viscera and muscle samples were withdrawn for analyses. During the experimental period, the mean fish weight about doubled in all treatments. No significant differences were found in growth performance (ranging from 1.1% to 1.4% body weight day^?1) among dietary treatments. High‐fat diets increased whole‐body fat content. Similarly, daily fat gain ranged from 0.54 to 0.78 g kg^?1 day^?1 and highest values were found in fish fed high‐lipid diets. Dietary treatments also affected tissue lipid content (liver, viscera and muscle), with highest values in fish fed high‐fat diets. The nature of dietary carbohydrates had little influence on performance criteria, but affected tissue lipid deposition. The activities of G6PD, ME and FAS were depressed by elevated levels of dietary lipid, confirming the inhibitory effect of dietary fats on lipid biosynthesis. At both dietary lipid levels, ME and FAS activities were little affected by dietary carbohydrate. Activities of PK and GK were not affected by the starch level of the diets. In Senegalese sole juveniles, the lipogenic pathway is more susceptible to modulation by dietary means (particularly through lipid intake) than the glycolytic pathway.     

Growth comparison of Asian Nile and red tilapia strains in controlled and uncontrolled farm conditions

Growth of several genetically improved Nile tilapia (GIFT or Genetically Improved Farmed Tilapia, FaST or Freshwater Aquaculture Center Selected Tilapia, SEAFDEC-selected) and domesticated red tilapia (BFS or Binangonan Freshwater Station, NIFI-red or National Inland Fisheries Institute red, HL or Hacienda Luisita) stocks were compared in controlled (tank) and uncontrolled farm conditions (lake-based cages) with unselected NIFI or Chitralada Nile tilapia as control. Specific growth rate differed significantly (P = 0.009) in tank-reared Nile tilapia stocks where GIFT grew best at 1.358%/day followed by FaST (1.307%/day), control stock NIFI (1.257%/day) and SEAFDEC-selected (1.202%/day). Genetic effect explained 84.4% of the variance in growth of Nile tilapia in tanks. Although Nile tilapia growth in cages followed the same trend where GIFT grew best at 1.570%/day, no significant stock differences (P = 0.479) were noted. Meanwhile, red tilapia reared in either tanks or cages showed no significant stock differences in terms of growth. However, survival of the red tilapia stocks in cages differed significantly with HL having the highest percentage survival at 93.3%. The different growth responses of the Nile tilapia stocks especially under controlled (tank) farm conditions were largely due to genetic factors (stock differences).Under uncontrolled farm conditions, environmental factors were generally observed to have also affected the survival and to some extent, the growth of Asian Nile and red tilapia stocks.     

Natural Stable Isotopes for Determination of Gastrointestinal Transit Time in Fish

This study evaluated the application of stable isotopes of carbon as an alternative and more accurate method to determine gastrointestinal transit time (GTT) in fish by comparing it to the inert marker method. The stable isotope method detects alterations of the normal carbon flow in a biological system by analyzing naturally occurring isotopes of carbon, contrary to studies based on conventional techniques that apply external markers to the diet to determine GTT through visual observation of the color change in feces. Therefore, 320 pacu, Piaractus mesopotamicus juveniles were reared in 32 tanks under two different temperatures (25 and 29 C). The pacu juveniles received two different diets, one based on ingredients derived from C₃ photosynthetic cycle plants and the other based on C₄ plant ingredients, both containing titanium oxide (TiO₂) as a marker. After 40 d, the isotopic signature of the diets was changed, and the marker was replaced by chromic oxide (Cr₂O₃). In the isotopic technique, the feces were analyzed to determine the exchange in the isotopic ratio of carbon δ¹³C. Both methods found that GTT was faster (nearly 6 h) in fish at 29 C when using the C₄/C₃ feeding strategy and slower in fish at 25 C using the C₃/C₄ strategy (15 h by inert marker and 18 h by the isotopic method). In conclusion, GTT determination in pacu juveniles using the stable isotope technique exhibits the same accuracy obtained with the inert marker method at temperatures suitable (nearly 29 C) for the metabolism of these animals.     

Identification of genetic regions associated with black point in barley

Black point (BP) can cause severe losses to the barley industry through downgrading and discounting of malting barley. The genetic improvement in BP resistance of barley is complex, requiring reliable screening tools, an understanding of genotype by environment interactions and an understanding of the biochemical mechanisms of melanisation involved in BP development. Thus the application of molecular markers for resistance to BP may be a useful tool for plant breeders. We have investigated the genetic regions associated with BP resistance in the barley F₂ population, Valier/Binalong. Quantitative trait loci (QTLs) contributed by the resistant parent Valier, were detected on chromosomes 2HS, 2HC, 3HL, 4HL and a QTL contributed by the susceptible parent, Binalong was detected on 5HL. Three of the four QTLs were detected in two distinctly different environments. The differences observed in BP resistance between these two environments and the implications for accelerated screening are discussed. Identified SSR markers in these regions may be useful for selecting black point resistance in related breeding materials.     

Determination of total amitraz residue in honey by electron capture capillary gas chroma tography–a simplified method

A gas chromatographic method using a capillary column is described for the determination of total amitraz residue in honey samples. The method consists of a preliminary extraction of the sample, an alkaline hydrolysis, an extraction of the 2, 4-dimethylaniline formed, without the aid of steam distillation/continuous extraction, its derivatisation with heptafluorobutyric anhydride and a gas chromatographic determination using an electron capture detector. The method is very rapid and can be carried out in a test tube. The detection limit is 0.020 mg kg^?1 and recoveries are of the order of 85%.