Effects of oxygen-enriched nutrient solution on greenhouse cucumber and pepper production

A series of experiments were conducted with greenhouse cucumber and pepper plants to determine the effects of oxygen enrichment of the irrigation water on yield and fruit shelf-life. The experiments were carried out in soilless culture in research greenhouses. Depending on the experiment, treatments included sub-ambient (2 mg L⁻¹), ambient (5–6 mg L⁻¹), medium (16 mg L⁻¹) and high (30–40 mg L⁻¹) levels of oxygen in the supply tank. Cucumber plants were grown in yellow cedar sawdust and pepper plants in either sawdust or perlite. Oxygen enrichment resulted in a promotion of cucumber yield in only one experiment; in two other experiments, none of the oxygen treatments, including those at sub-ambient levels, had an effect. There were no effects of oxygen enrichment on pepper yield. However, in both cucumber and pepper, fruit shelf-life was extended in oxygen-enriched treatments. In terms of system efficacy, oxygen levels in the irrigation water were measured at the dripper and found to decrease by 20–67% of initial values compared to the supply tank values, depending on the initial oxygen concentration and on the experiment. Oxygen concentrations decreased even further to virtually ambient levels when measured in the drain water or in the substrate reservoir. Cucumber plant growth was promoted under conditions which facilitated consistently high oxygen in the root zone, achieved through heavy irrigation (1 min in two) with oxygen-enriched nutrient solution of plants grown in saturated substrate (pumice). However, those extreme irrigation rates would not be practical for commercial cucumber or pepper production. Overall, this study demonstrates that oxygen enrichment of porous substrates under typical hydroponic conditions is difficult and possibly because of this, effects on yield are infrequent. However, fruit shelf-life may be improved.     

Fate of polyphenols and antioxidant activity of barley throughout malting and brewing

Phenolic contents of barley and malt extracts and their corresponding antioxidant activities were investigated using a chromatographic online antioxidant detection system. Ethyl acetate extracts of barley and malt were separated using reverse phase HPLC and compounds eluting from the column were submitted to two UV–visible detections: one for the phenolic compounds; and the other for the reduced form of the radical cation 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^•+) after the compounds were allowed to react online with it. Prodelphinidin B3 and procyanidin B3 were identified as two major contributors in the antioxidant activity of barley, in addition to catechin. Malting had a dramatic impact on these three compounds by resulting in a sharp decrease in their detected amounts and the associated antioxidant activities. Two other antioxidants, ferulic and sinapic acids, showed a better ability to withstand not only malting but also brewing steps. As for the overall phenolic content and antioxidant capacity, the study showed that malting allowed a better release and/or extraction of phenolic compounds, while the first brewing step caused the most significant damage by drastically decreasing the total polyphenols and their activity. Hopping however did not significantly affect neither the phenolic content nor the antioxidant activity.     

Relaxations Below Glass Transition Temperature in Bread and Its Components

Dry glassy bread, cooked gluten, and gelatinized wheat starch-sucrose mixtures were prepared. Dielectric properties were studied as a function of temperature at different frequencies ranging from 100 to 1,000 kHz. Both bread and starch samples exhibited a tan δ peak at -53°C at 10 kHz, which is associated with a secondary relaxation characterized by an activation energy of 50 kJ/mol. The gluten sample did not show any relaxation in the temperature range studied. The magnitude of the relaxation peak was sensitive to the sucrose concentration of the starch sample. The higher the sucrose content, the greater the amplitude of the peak. Such an effect is attributed to a greater β-relaxation induced by an increasing number of relaxing units or increasing size of the loosely packed regions of the glass. However, it cannot be concluded whether the relaxation is associated with a group present on both starch and sucrose or that the sucrose has an enhancing effect on starch mobility.     

Sustained exercise improves vertebral histomorphometry and modulates hormonal levels in rainbow trout

Abnormal compressions and fusions of vertebral bodies are frequently observed in reared rainbow trout and could result from chronic and unbearable muscle pressures acting on the axial skeleton during intensive growth. Sustained swimming at moderate speeds was shown to induce many positive effects on growth and swimming performances in salmonids, but yet little is known about its effects on vertebral remodeling processes and related hormonal regulation. Rainbow trout were subjected to three different swimming speeds (0, 1.0 and 1.5 body length (BL) s^− 1), starting one month after they were first fed (65 mm) and ending when they reached 260 mm in size (market-size of 275 g). At the end of the experiment, 20 trout were sampled in each lot (N = 60) and blood samples were taken. Vertebrae abnormalities were assessed by radiological examinations. Vertebrae from the middle axial region (V32–38) were selected to evaluate bone mineralization (BM) and total bone area (Tt-B.Ar.) on radiographed transverse sections (125 ± 10 μm). Assays were performed to evaluate mineral homeostasis (calcemia and phosphatemia), bone cell activities (alkaline phosphatase, ALP, and tartrate-resistant acid phosphatase, TRAP) and bone regulating hormones (calcitonin, CT and thyroid hormones, THs). Sustained exercise reduced the appearance of fused vertebrae, enhanced vertebral BM and decreased vertebral Tt-B.Ar., while it increased circulating CT and TH levels. No variations were observed on mineral homeostasis and bone cell activities. Increasing the swimming speed up to 1.5 BL s^− 1 had positive effects on the vertebral skeleton, and therefore, seems to be a suitable approach to prevent aggravation of vertebral abnormalities in juvenile trout. The changes observed in vertebral features are interpreted as a compromise between the necessity to mobilize vertebral mineral ions in response to various physiological demands and to maintain vertebral strength against mechanical constraints.     

Agricultural intensification and loss of matrix habitat over 23 years in the West Wimmera, south-eastern Australia

The global trend toward more intensive forms of agriculture is changing the nature of matrix habitat in agricultural areas. Removal of components of matrix habitat can affect native biota at the paddock and the landscape scale, particularly where intensification occurs over large areas. We identify the loss of paddock trees due to the proliferation of centre pivot irrigation in dryland farming areas as a potentially serious threat to the remnant biota of these areas. We used a region of south-eastern Australia as a case study to quantify land use change from grazing and dryland cropping to centre pivot irrigation over a 23-year period. We also estimated rates of paddock tree loss in 5 representative landscapes within the region over the same period. The total area affected by centre pivots increased from 0 ha in 1980 to nearly 9000 ha by 2005. Pivots were more likely to be established in areas which had originally been plains savannah and woodlands containing buloke (Allocasuarina luehmannii), a food source for an endangered bird. On average, 42% of paddock buloke trees present in 1982 were lost by 2005. In the two landscapes containing several centre pivots, the loss was 54% and 70%. This accelerated loss of important components of matrix habitat is likely to result in species declines and local extinctions. We recommend that measures to alleviate the likely negative impacts of matrix habitat loss on native biota be considered as part of regional planning strategies.     

Farmers’ management of peanut (Arachis hypogaea L.) diversity,their varietal preference traits and uses in Southern and Central Benin

Journal of Crop Science and Biotechnology - Peanut (Arachis hypogaea L.) is one of the major oilseed legumes contributing to food security in Benin. Unfortunately, several constraints hamper its...     

Criteria for selecting productive and stable pea cultivars

The beginning and duration of the seed set in the growth cycle determine the level and stability of the yield of a pea (Pisum sativum L.) genotype. The objective of the present study was to identify criteria for selecting genotypes, both in terms of timing of seed set and productivity. Genotypes were initially compared in field experiments for two different levels of inter-plant competition, but using the same photo-thermal conditions. These experiments showed that the initiation and, particularly, the duration of seed set were affected by plant growth rates, indicating that selection on these variables must be done by comparing genotypes under regular cropping conditions. When measuring seed production of the whole plant, we found that mean dry seed weight per podded node all over the plant and the number of podded nodes on any fertile stem were similar to those on the main stem. These results confirmed that branches and main stems have a similar reproductive pattern, and thus that any podded stem of the canopy is representative of every stem of the plant. Lastly, we showed that, when associated, the number of podded nodes, the mean dry seed weight per podded node on the main stem (or on any reproductive stem of the canopy), and the number of basal branches per plant are suitable criteria for selecting for productivity among genotypes with a similar duration of seed set. This revised version was published online in August 2006 with corrections to the Cover Date.     

Prevalence and risk factors for Campylobacter spp. in chicken broiler flocks in Reunion Island (Indian Ocean)

Our objectives were to determine Campylobacter prevalence in broiler chicken flocks in Reunion Island and to define specific practices associated with the presence of Campylobacter spp. Infection in Reunionese broiler flocks. Fifty broiler flocks were studied in Reunion Island from May 2007 to February 2009. A questionnaire was submitted to the farmers and samples of fresh droppings were collected to assess the flock's Campylobacter status. Fifty four percent of the flocks were infected by Campylobacter spp.: 30% (95% CI: 28.71-31.29) were infected with Campylobacter coli and 17% (95% CI: 15.95-18.05) with Campylobacter jejuni; only 7% (95% CI: 6.28-7.72) were infected by both species at the same time. Several poultry houses in the farm (OR=11.2; [1.05-92]) and cleaning without any detergent (OR=13.1; [2.1-78.3]) increased the risk of Campylobacter infection. A distance higher than 500 m between broiler farms (OR=0.27; [0.1-0.8]) and use of disinfectant during the rearing period decreased this risk of infection (OR=0.15; [0.1-0.75]).