Phosphorus Efficiency of Winter Canola Cultivars and Rhizosphere Properties in Rhizobox Technique

Production of oilseed crops requires balanced fertilization, while environmental problems of applied fertilizers must be considered. We evaluated seven winter canola cultivars (Brassica napus L.) for their relative efficiency to use or acquire phosphorus (P) under deficient and sufficient conditions. Average root mean diameter (RMD), total root length (RL) and root surface area (RA), of plants were measured as well as rhizosphere properties in rhizobox technique. Water-soluble P (WSP) and phosphatase activity of treatments containing plant were higher than control. WSP increased by 2.86 mg kg^?1 soil in Gabriela and 2.63 mg kg^?1 soil in Elvis at P deficient condition, compared to the control soil. The Olsen extractable P of the treatments decreased compared to control. Variations in total dry weights of cultivars were mainly explained by the differences in P solubilizing bacteria (PSB) population, pH, and phosphatase activity. The responsible mechanism for the P efficient (PE) cultivars can be higher P uptake through larger root and changes in rhizosphere properties.     

Epizootiological investigation if strangles in the equine stables in tehran

Strangles is an acute disease of horses caused by infec- tion with Streptococcus equi. It is characterized by inflamma- tion of the upper respiratory tract and abscessation in the adjacent lymph nodes. The distribution of strangles is world- wide. When an outbreak does occur in a large group of horses, it is usually restricted to the younger age groups, under adverse climatic conditions, and when shelter is inadequate. When the group is made up of predominantly young horses, up to 100% may be affected. Such a high incidence is encountered soon after large numbers of susceptible horses, which may have come from many localities, are stabled to get her. The source of infection is the nasal discharge from infected animals, which contaminates the pasture and feed and water troughs. Infection occurs by ingestion or by inhalation o f droplets. During April (1990), two cases of strangles were diag- nosed at Veterinary Faculty Teaching Hospital in Tehran. An epizootiological survey commenced immediately and showed 89-100% of horses were affected. The clinical symp- toms were severe in young horses and the mortality rate was zero. All of the infected horses responded to treatment with intramuscular injection of penicillin/streptomycin.     

Molecular and morphological characterisation of <Emphasis Type="Italic">Aphelenchoides paraxui</Emphasis> n. sp. (Nematoda: Aphelenchoididae) isolated from <Emphasis Type="Italic">Quercus brantii</Emphasis> in western Iran

Aphelenchoides paraxui n. sp. is described and illustrated from bark samples of an oak tree (Quercus brantii L.) in Kermanshah province, western Iran. The new species is characterized by body length of 500–660 μm (females) and 630–665 μm (males), lip region set off from body contour, lateral fields with four lines, and total stylet 8–9 μm long with small basal swellings. The excretory pore is located ca one body diam. Posterior to metacorpus valve. The spicules are relatively large (29–33 μm in dorsal limb) with apex and rostrum rounded and well developed and the end of the dorsal limb clearly curved ventrad like a hook. The female tail is conical, the terminus having a complicated step-like projection, usually with many tiny nodular protuberances. Male tail bearing six (2 + 2 + 2) caudal papillae and a well-developed mucro. The new species belongs to the Group 2 category of Aphelenchoides species sensu Shahina (1996) in which eight known species among Group 2–4 sensu Shahina namely: A. arcticus, A. asteromucronatus, A. blastophthorus, A. lichenicola, A. saprophilus, A. seiachicus, A. silvester and A. xui, are the most closed species. Molecular analyses of the partial small subunit rDNA gene (SSU), D2/D3 expansion segments of the large subunit rDNA gene (LSU) and internal transcribed spacer (ITS) revealed this as a new species and supported the morphological results.     

The effect of twinning on milk yield,dystocia, calf birth weight and open days in Holstein dairy cows of Iran

Calving records of Iranian Holsteins from April 1998 to September 2006 comprising 16 herds with 104 572 calving events representing 4045 twin births were used to evaluate reported open days, calving difficulties and calf birth weight in single‐ and twin‐births and the relationship exists between twinning and milk production. A logistic regression model was constructed to analyse dystocia for single‐ and twin‐births. In addition, statistical analyses of 305‐day milk yield, open days and calf birth weight were performed using the general linear models procedure. The odds of dystocia was greater after twin births [p < 0.0001; odds ratio (OR) = 2.32]. The odds of dystocia decreased from parity 1 to parity 2 and beyond (p < 0.0001; OR = 0.44). Open days were significantly different between single (129.28 days) and twin (144.88 days) births (p < 0.05). Calf birth weights were significantly greater for singletons than twins (43.33 kg vs. 34.36 kg; p < 0.05). In addition, twin‐calved cows had greater 305‐day milk production than single‐calved cows (p < 0.05). In general, development of practical management strategies to cope with the negative effects associated with twinning on dairies is critical, especially if the trend towards increased twinning in the dairy cattle population continues.     

Pan‐continental invasion of Pseudorasbora parva: towards a better understanding of freshwater fish invasions

In recent years, policy‐makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non‐target species that are unknowingly released alongside intentionally‐introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan‐continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits.     

Effects of fish meal replacement by meat and bone meal supplemented with garlic (Allium sativum) powder on biological indices,feeding, muscle composition,fatty acid and amino acid profiles of whiteleg shrimp (Litopenaeus vannamei)

Shortage of fish meal (FM) resources in the marine environment, high price and high demand for this ingredient led researchers to seek for alternative protein resources such as meat and bone meal (MBM). The effects of adding MBM and garlic powder to the shrimp diet on growth performance, muscle composition, amino acid and fatty acid profiles of whiteleg shrimp (5.00 ± 0.23 g) were investigated. A total of six dietary treatments were formulated: 0%MBM (control without garlic powder), 25%MBM and 50%MBM (treatments without garlic powder; WG treatments); 0%MBM+G (control with garlic powder), 25%MBM+G and 50%MBM+G (treatments with garlic powder; G treatments). Our results indicated that increase MBM level in the diets (up to 50%MBM) impaired growth performance, muscle composition, fatty acid and amino acid profiles in the muscle of shrimp. Interestingly, garlic supplementation improved the aforementioned factors so that shrimp fed 50%MBM+G diet had no significant difference when compared to 0%MBM group. The current results indicated that garlic could increase levels of FM replacement by increasing feed intake, improving protein and amino acid utilization. Overall, 50%MBM+G diet is recommended for use in shrimp production.     

POTASSIUM FERTILIZATION AND FRUIT PRODUCTION OF PAGE CITRUS ON A PUNSIRUS ROOTSTOCK: QUANTITATIVE AND QUALITATIVE TRAITS

Determination of optimum rates of potassium (K) for high citrus production with great qualitative traits is of both agricultural and economical significance, particularly when performing long–term experiments. A five–year field experiment was conducted in the Citrus Research Center of Tonekabon, Iran in a silty clay loam. The objectives were to: 1) to apply different rates of K fertilizer and determine the optimum rates for citrus high production, and 2) to evaluate the effects of K fertilization on the fruit quantitative and qualitative traits for the production of tasty and great quality fruits for fresh or long consumption. Fifteen–year citrus trees were fertilized with five rates of potassium at control, 750, 1500, 2250 and 3000 g tree^?1 on the basis of a completely randomized block design in five replicates. Fruit parameters were determined. Potassium significantly increased fruit yield and qualitative traits at the optimum amount of 1500 g tree^?1.     

Soya bean‐based diets plus probiotics improve the profile of fatty acids,digestibility, intestinal microflora,growth performance and the innate immunity of beluga (Huso huso)

This study was conducted to investigate the effect of different methods of using probiotics Bacillus subtilis and Bacillus licheniformis in soya bean‐based diets on the physiology of beluga (Huso huso) (351 ± 4 g). Five experimental diets were formulated to feed beluga for 10 weeks. The results showed that there was no significant difference in weight gain between control (446 g) and 70%SBM‐SPRAY2 (409 g) treatments. Long‐chain polyunsaturated fatty acids in the muscle of beluga fed control (203.2 g/kg) and 70%SBM‐SPRAY2 (166.4 g/kg) diet did not change statistically. Blood performance as a newly introduced factor in individuals fed dietary control (64.06) and 70%SBM‐SPRAY2 (64.33) had higher value as compared with those fed dietary 70%SBM‐DIET2 (61.90) (p < 0.05). Also, total protein (1.68 g/dl) and RBC (0.74 × 10⁶/mm³) in fish fed 70%SBM were statistically lower than other treatments (p < 0.05). Lysozyme, alternative complement activity and total viable counts in beluga fed dietary probiotics were significantly higher than others. In conclusion, feeding fish with the 70%SBM‐SPRAY2 diet improved fish growth and health.