Effects of smoke,ash and heat shock on seed germination of seven species from Central Zagros rangelands in the semi-arid region of Iran

Fire products have been widely identified as germination cues for a number of species from both fire-prone and fire-free ecosystems. However, there is uncertainty about the effects of fire products on seed germination of semi-arid rangeland species. We examined the germination of seven dominant species from Central Zagros rangelands in the semi-arid region of Iran under various heat shock (60, 80 and 120 °C), aerosol smoke, ash and control treatments. Our findings showed that fire products could enhance, inhibit or not affect the seed germination of rangeland species in this area. The germination percentage of Astragalus adscendens increased following 60 °C heat treatment in comparison with the control. The germination of Astragalus verus, Bromus tectorum, B. tomentellus and Phlomis olivieri were increased significantly using smoke treatment (P<0.0001). The seed germination of B. tomentellus and B. tectorum was promoted by ash treatment, whereas the other species exhibited no response or were inhibited by fire products. In addition, smoke treatment shortened the overall germination time of B. tectorum. These findings suggest that fire products affect the germination of several species and can serve as potential tools for understanding the vegetation dynamics and restoration of disturbed semi-arid rangelands.     

Effect of strip-intercropping potato and annual alfalfa on populations of Leptinotarsa decemlineata Say and its predators

Intercropping systems are practiced to reducing pest density, enhancing predator's diversity and stabling crop yield. We evaluated the effect of strip-intercropping potato and annual alfalfa on populations of Leptinotarsa decemlineata Say, predator's biodiversity and potato yield over two seasons (2014 and 2015). Our results revealed that the densities of egg masses, eggs, larvae and adults of Colorado potato beetle (CPB) were significantly lower in intercrops than in monoculture. The main CPB predators recorded on potato plants (ladybirds and the green lacewing) showed a significant increase in the density at each of the three intercrops than in monoculture. The percentage of dry tubers weight loss was 40.9%–42.6% in monoculture, 16.3%–18.7% in 6P: 2A and <10% in 2P: 2A and 4P: 2A in two studied years. Our results suggest that strip-intercropping potato with annual alfalfa, particularly in 2P: 2A and 4P: 2A patterns may be an effective way in integrated management of CPB for reducing pest density, enhancing the presence of predators in potato fields and improving potato yield.     

Agrobacterium pusense,a new plant tumour‐inducing pathogen isolated from Lawson cypress

Lawson cypress (Chamaecyparis lawsoniana), an important landscape tree, is widely planted in gardens and parks throughout Iran. Crown gall disease on Lawson cypress trees was observed in Sari and Juybar Counties, Mazandaran province, northern Iran, in 2017. Isolation from galls on potato dextrose agar (PDA) containing CaCO₃ yielded bacterial colonies, the predominant types of which were purified and selected for characterization. The isolates were Gram‐negative, oxidase positive, able to grow in 2% NaCl and produced 3‐ketolactose. They hydrolysed esculin, casein and arbutin but not starch, gelatin or Tween 80. Two representative isolates were selected for PCR amplification and sequencing of DNA gyrase subunit B (gyrB) gene. In the phylogenetic tree based on the partial sequence of the gyrB gene, isolates KH1 and KH2 clustered with Agrobacterium pusense. The pathogenicity of all isolates was confirmed by inoculation on Jimsonweed (Datura stramonium) and carrot discs (Daucus carota). Confirmation of the presence of genes involved in pathogenicity was made by performing PCR with the virD2A/virD2C and VCF/VCR primer pairs which resulted in amplification of the expected 224 and 730 bp fragments in all studied isolates, respectively. A. pusense was therefore identified as the causal agent of crown and stem gall of Lawson cypress. This appears to be the first report on the natural occurrence of crown gall disease on Lawson cypress and the first record of a plant disease caused by A. pusense.     

New selection strategies for determining the traits contributing to increased grain yield in wheat (Triticum aestivum L.) under aluminum stress

Genetic Resources and Crop Evolution - Finding the suitable traits that mediate grain yield under stress condition represent an important challenge to plant breeders in order to improve production....     

Effects of dietary administration of Echinacea purpurea on growth indices and biochemical and hematological indices in rainbow trout (Oncorhynchus mykiss) fingerlings

This study was conducted to evaluate the effects of Echinacea purpurea (EP) on growth and some hematological and blood biochemical indices of rainbow trout fingerlings. A basal diet was supplemented with 0 (control), 0.25, 0.5, 1, and 2 g EP kg?1 to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish with an initial average weight of approximately 8 g. After 8 weeks of feeding trial, fish fed diets with 0.25 and 0.5 g EP kg?1 showed highest final weight and SGR and fish fed with the control diet indicated the lowest final weight and SGR. There was a significant (P < 0.05) decrease in FCR between the control group and the groups fed with diets of 0.25 and 0.5 g EP kg?1. Biochemical parameters such as serum total protein content, albumin content, globulin content, and albumin/globulin ratio in the fish were evaluated. There were significant differences between hematological parameters including RBC, WBC, HB, lymphocyte, and neutrophil percentage in fish fed with dietary nucleotide compared with control treatment (P < 0.05). The results suggest that EP administration at 0.25 and 0.5 g EP kg?1 exerted positive effects on growth and biochemical and hematological indices in rainbow trout.     

Effects of drought stress on concentration of macro- and micro-nutrients in Castor (Ricinus communis L.) plant

This study evaluated effects of drought stress on the concentrations of mineral elements in the leaves of different ecotypes of castor plant. The experimental design was a split-plot randomized complete block with three replications. It was carried out at Fozveh Agricultural Research Station located 20 km from Esfahan, Iran in 2014. The main plot was four levels of water stress (30%, 45%, 60%, and 75% moisture content) and the sub-plot was six castor plant ecotypes (Esfahan, Ardestan, Arak, Naein, Yazd, and Ahwaz). The potassium (K), magnesium (Mg), calcium (Ca), sodium (Na), iron (Fe), copper (Cu), and zinc (Zn) contents were measured and found to be significantly affected by drought stress. Drought stress increased K, Ca and Na contents and decreased Fe, Cu, Zn, and Mg contents of the plants. Various ecotypes of castor plant showed different reactions to drought stress and the Fe concentration varied significantly by the castor plant ecotypes. Interaction between water stress and ecotypes was significant only for Cu and Zn. Understanding the element concentrations under drought stress can be useful for predicting growth and development of castor plants.     

Contact network structure explains the changing epidemiology of pertussis

The epidemiology of whooping cough (pertussis) remains enigmatic. A leading cause of infant mortality globally, its resurgence in several developed nations--despite the availability and use of vaccines for many decades--has caused alarm. We combined data from a singular natural experiment and a detailed contact network study to show that age-specific contact patterns alone can explain shifts in prevalence and age-stratified incidence in the vaccine era. The practical implications of our results are notable: Ignoring age-structured contacts is likely to result in misinterpretation of epidemiological data and potentially costly policy missteps.