The effect of three carotenoid sources on growth and pigmentation of juvenile freshwater crayfish Cherax quadricarinatus

The effect of adding carotenoids from various sources to feed of juvenile freshwater crayfish Cherax quadricarinatus on pigmentation, growth and survival was examined under laboratory conditions. Juvenile crayfish were fed diets fortified with carotenoids at a level of 100 μg g⁻¹ for a period of either 49 or 55 days. Carotenoid sources were: dried algal cells prepared from Dunaliella salina in which the main carotenoid is β-carotene; a synthetic carotenoid, astaxanthin (Carophyll Pink 8%, manufactured by Hoffman–La Roche) and alfalfa meal. Crayfish receiving feeds fortified with carotenoids exhibited better body colouration than those in the control group, which were fed a diet to which no carotenoids were added. Growth and survival of the crayfish were not affected by the addition of carotenoids to their diet.     

Effect of leaching events on the fate of polyhalite nutrient minerals used for crop fertilization

Abstract

Polyhalite is a natural mineral containing potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S) and is proposed as a fertilizer source for these essential nutrients. Application of polyhalite is expected to be most relevant in soils where the availability of these nutrients is low: in sandy soils, in highly leached soils, or in areas where crops are irrigated by water with low content of these nutrients or are rain-fed. A controlled lysimeter experiment investigated the efficacy of surface applied polyhalite as a fertilizer supplying K, Ca, Mg and S compared to soluble sulfate salts in two soils (sandy and loamy) with or without simulated rain leaching events through two cycles of cropping. In the first cycle, carrot response and nutrient uptake, transport, and loss through leaching were studied, while in the second cycle the residual effect of the fertilizer was considered on maize without additional fertilizer application or leaching. Polyhalite plus rain led to increased carrot yield due to augmented Ca uptake in sandy soil. In both soils, polyhalite behaved as a prolonged availability fertilizer with more nutrients retained in the top soil layer and not leached below the root zone. The treatments did not affect maize growth or nutrient uptake except for lower K and S uptake in soils where rain had been simulated for the previous crop. We conclude that polyhalite shows potential as a commercial fertilizer to supply K, Ca, Mg, and S nutrients under conditions of dryland agriculture where occasionally leaching by rainfall occurs.     

Effects of day length on flowering and yield production of Salicornia and Sarcocornia species

Salicornia is a new vegetable crop that can be irrigated with highly saline water, even at salt concentrations equivalent to full-strength seawater. During leafy vegetable cultivation, the onset of the reproductive phase is an undesired phenomenon that reduces yield and quality and prevents year-round cultivation. Knowledge about the regulation of floral induction in the members of the tribe Salicornieae, however, is lacking. To establish year-round cultivation, we studied the flower induction of five Salicornia and two Sarcocornia varieties. Plants were grown under two day lengths, 13.5 h and 18 h, and harvested by a repetitive harvest regime. A 13.5-h day length prevented flower induction in the Israeli Salicornia varieties, but a longer day length was required to prevent flower induction in two species originating from more northern latitudes. The onset of the reproductive phase under suboptimal short day length conditions severely reduced vegetative growth and yields in Salicornia. In Sarcocornia, the repetitive harvest regime prevented flowering, making it a promising candidate for year-round cultivation. Irrigating the plants with full-strength seawater (electrical conductivity 48 dS m⁻¹) vs. water with moderate salinity (electrical conductivity 10 dS m⁻¹) did not change the general flowering pattern of the studied Salicornieae members.     

贝莱斯芽胞杆菌B006对不同水肥条件下娃娃菜生长及软腐病防效的影响

贝莱斯芽胞杆菌B006是一株高效生防菌株,但其在不同水肥条件下的防病促生效果尚不明确.本研究通过盆栽试验测定了不同土壤含水量和施肥条件下B006菌剂对娃娃菜生长及对软腐病防效的影响,结果表明:在土壤含水量为14％、施肥量为3.57 g/kg土的条件下,播种时沟施5 g B006菌剂(菌含量为1×107 CFU/g),出...     

Identification of QTLs associated with spring vegetative budbreak time after dormancy release in pear (Pyrus communis L.)

Dormancy release is greatly affected by chilling unit (CU) accumulation. Lack of CU has a major impact on spring vegetative budbreak (VB). To understand the genetic mechanism governing the chilling requirement (CR), we conducted a QTL analysis of VB date in F₁ population, derived from a cross between ‘Spadona’ (low CR) and ‘Harrow Sweet’ (high CR). Using a unique methodology of tree mobility, replicates of the same genotypes were exposed during the winter, over two consecutive years, to climates that differ greatly in their CU and to the same heat conditions to induce VB, in order to evaluate CR genetic impact and to distinguish it from the heat factor. Broad‐sense heritability within locations ranged from 0.62 to 0.66. Due to a strong impact of GxE interaction, it was reduced to 0.46 for the overall mean. We examined the previously discovered apple QTLs detected in linkage groups (LG) 9 and 8, based on the synteny between the species. Our analysis confirms significant QTLs in LG8 (R² = 12%–24%) and LG9 (R² = 20%–38%) for all locations and years     

Effect of Grapevine Training Systems on Development of Powdery Mildew

The effects of two training systems and row spacing on development of powdery mildew caused by Uncinula necator on clusters of 'Chardonnay' and 'Cabernet Sauvignon' grapevines were examined. Disease development was monitored in blocks with two different row spacing (2 and 3 m) in vertical shoot positioned vines (VSP) and in free-positioned, topped vines (FC) with no foliage support wires. The FC vines were hedged to about one meter shoot length. No fungicides were applied and disease powdery mildew level was recorded four to seven days after appearance of the first disease symptoms. During five consecutive years (1994–1998), disease incidence was higher in the VSP system than the FC vines. The difference was high when disease level was low (30% of the clusters in VSP vines infected, compared to 5% in the FC vines) and decreased when disease pressure was high (79% in VSP compared to 46% in FC vines). In the 'Cabernet Sauvignon', in four of the years, disease incidence was higher in the narrow spacing of 2 m between the rows than that in the wider 3 m spacing. Microclimate (temperature, relative humidity and light intensity) was monitored in the cluster zone near the spurs of 'Chardonnay' vines during three weeks in the 1998 season. In VSP vines light intensity was lower then that in FC vines both four and one week before disease symptoms appeared (72% and 18% respectively). The differences in temperature and relative humidity were less than 1°C and 3%, respectively, and most likely did not affect disease development. The results suggested that high light intensity is the primary factor, which limits powdery mildew growth development on field-grown grapevines in the Golan region of Israel. The use of the FC system might be useful in reducing the need of fungicides.     

Understory woody vegetation in manmade Mediterranean pine forests: variation in community structure along a rainfall gradient

Natural regeneration that occurs in the understory of Mediterranean pine monocultures provides the basis for the transition of these simply structured systems toward a more complex and sustainable state. However, the course and consequences of this process, and its relationships with environmental and silvicultural variables, are still inadequately understood. We investigated the relationship between rainfall amount and understory woody vegetation (UWV) structure in mature (40–50 year) Pinus halepensis plantations in the Mediterranean zone of Israel, where rainfall ranges from 280 mm/year in the south to 900 mm/year in the north. We measured abundance, diversity and species composition on south- and north-facing slopes, in forest sites distributed along the rainfall gradient. UWV abundance, as measured by cover percentage and height, increased with rainfall amount along the entire gradient (2–113% and 0.1–3.4 m, respectively), more rapidly on north-facing slopes. Species composition varied along the rainfall gradient, with ranges of species occurrences corresponding to those in unforested habitats. The relationship between rainfall and UWV species richness was positive throughout most of the rainfall gradient, possibly with a shift in pattern at the highest rainfall levels. UWV richness increased sharply with increasing abundance, up to a certain point with no further increase in richness as abundance increased further. We concluded that UWV structure in the studied forest environment and climatic range is strongly determined by rainfall and suggested that the design and management of Mediterranean forests should focus more on optimizing water availability for the various components.     

Prior Inoculation with Non-pathogenic Fungi Induces Systemic Resistance to Powdery Mildew On Cucumber Plants

A spray inoculation of the first leaf of 2-leaf stage cucumber plants with a non-pathogenic isolate of Alternaria cucumarina or Cladosporium fulvum before a challenge inoculation with the pathogen Sphaerotheca fuliginea induced systemic resistance to powdery mildew on leaves 2–5. Systemic resistance was expressed by a significant (p < 0.05) reduction in the number of powdery mildew colonies produced on each leaf of the induced plants, as compared with water-sprayed plants. Systemic resistance was evident when a prior inoculation with each of the inducing fungi was administered 1, 3 or 6 days before the challenge inoculation with S. fuliginea. Increasing the inoculum concentration of A. cucumarina or C. fulvum enhanced the systemic protection and provided up to 71.6% or 80.0% reduction, respectively, in the number of colonies produced on upper leaves, relative to controls. Increasing the inoculum concentration of S. fuliginea used for challenge inoculation, increased the number of powdery mildew colonies produced on both induced and non-induced plants. Pre-treated plants, however, were still better protected than controls, indicating that the level of systemic protection was related to the S. fuliginea inoculum concentration. The induction of systemic resistance against powdery mildew by biotic agents, facilitates the development of a wide range of disease management tools.     

Lipid peroxidation and coupled vitamin oxidation in simulated and human gastric fluid inhibited by dietary polyphenols: health implications

The Western diet contains large quantities of oxidized lipids, because a large proportion of the food in the diet is consumed in a fried, heated, processed, or stored form. We investigated the reaction that could occur in the acidic pH of the stomach and accelerate the generation of lipid hydroperoxides and cooxidation of dietary vitamins. To estimate the oxygen content in the stomach after food consumption, oxygen released from masticated bread (20 g) into deoxygenated water (100 mL) was measured. Under these conditions, the oxygen concentration rose by 250 microM and reached a full oxygen saturation. The present study demonstrated that heated red meat homogenized in human gastric fluid, at pH 3.0, generated hydroperoxides and malondialdehyde. The cross-reaction between free radicals produced during this reaction cooxidized vitamin E, beta-carotene, and vitamin C. Both lipid peroxidation and cooxidation of vitamin E and beta-carotene were inhibited at pH 3.0 by red wine polyphenols. Ascorbic acid (44 mg) at a concentration that represented the amount that could be ingested during a meal inhibited lipid peroxidation only slightly. Red wine polyphenols failed to prevent ascorbic acid oxidation significantly but, in conjunction with ascorbic acid, did inhibit lipid peroxidation. In the presence of catechin, a well-known polyphenol found in red wine, ascorbic acid at pH 3.0 works in a synergistic manner preventing lipid peroxidation and beta-carotene cooxidation. The present data may explain the major benefits to our health and the crucial role of consuming food products rich in dietary antioxidants such as fruits, vegetables, red wines, or green tea during the meal.