Use of foliar symptoms and plant height to predict yield loss in potatoes due to metribuzin injury

A model to predict yield loss due to metribuzin injury was developed using data from four experiments involving postemergence applications of metribuzin to numerous cultivars and breeding selections. Two explanatory variables, plant height proportion (PHR), defined as injured/uninjured, and percent foliar injury (FI), were used to predict yield loss. Three multiple regression models, including linear, quadratic, and a linear-log were considered and evaluated. Acceptance of the best model was based on comparison of fit as indicated by Residual Mean Squares, Adjusted R², and Predicted Sums of Squares. The best fit was for a linear-log model utilizing percent foliar injury and a natural log transformation of the plant height proportion (injured/uninjured). The predictive model was statistically validated by utilizing residual analysis on an independent data set. The model can be used to simply and quickly predict yield losses due to metribuzin injury     

Genetic diversity in populations of wild diploid wheat Triticum urartu Tum. ex. Gandil. revealed by isozyme markers

Genetic variation and its distribution within and among 23 populations of Triticum urartu collected from Syria, Lebanon, Turkey, Armenia, and Iran was estimated using isozyme markers at eight polymorphic loci. The number of alleles per locus (A= 1.21), percentage polymorphic loci (P= 20.1%), and mean gene diversity (H_e= 0.024) were relatively low. In a population from Lebanon, a high number of alleles per locus (A= 2.13) and percentage polymorphic loci (P= 87.5%) was found. On average, genetic variation among populations (G_ST= 0.407) was smaller than within-population variation (0.593). However, different patterns of genetic structure were found among various geographic regions. Interpopulation variation was highest for the Iranian populations (0.89) followed by the Turkish populations (0.66). A reverse pattern was observed for the Syrian (0.11) and for the Lebanese (0.13) populations. The Armenian populations exhibited similar interpopulation and within-population variation. Principal component and cluster analyses resulted in distinct grouping of the geographically proximal populations, with the exception of the two Iranian populations. The Turkish populations were different from the neighboring Armenian populations compared to other countries. The populations from southern Syria and those from Lebanon also exhibited a high degree of genetic diversity. The two most heterozygous loci, Mdh-2 and Pgi-2, separated the populations along the first and second principal components, respectively. Most of the rare alleles were scattered sporadically throughout the geographic regions. Rare alleles with high frequencies were found in the Turkish and Armenian populations. These results indicated that different geographic regions require specific sampling procedures in order to capture the range of genetic variation observed in T. urartu populations.     

Prevalence and risk factors for subclinical coccidiosis in broiler chicken farms in Mazandaran province,Iran

Coccidiosis is a disease of almost universal importance in Poultry production. The subclinical form of coccidiosis has most significant economic impact due to impaired growth rate and feed conversion. Some factors such as: age, size of flock, season, etc., may effect on severity of this disease. In this study, the relationships between some major risk factors and prevalence of subclinical coccidiosis were investigated. This study was done in 120 broiler farms in five different cities of Mazandaran province, north of Iran. Five chicks (3–8 weeks of ages) were taken randomly from every 120 farms and post-mortem and parasitological examinations were performed. Five Eimeria spp. were recognized: Eimeria tenella, Eimeria maxima, Eimeria acervulina, Eimeria brunetti, and Eimeria necatrix. The prevalence rate of subclinical coccidiosis among them is 75% (90 farms out of 120). E. acervulina was the most prevalent species (65.5%) followed by E. maxima (17.7%), E. tenella (15.5%), E. brunetti (10%), and E. necatrix (5.5%). According to what the results approve, the occurrence of subclinical coccidiosis is significantly related to the age and size of flock, whereas the other factors such as the season of year, industrial strains, chicken’s keeping system, and anticoccidial drugs do not affect this phenomenon remarkably.     

Root‐lodging resistance in maize as an example for high‐throughput genetic mapping via single nucleotide polymorphism‐based selective genotyping

Large‐scale selective genotyping and high‐throughput analysis are two important strategies for low‐cost and high‐effective genetic mapping. In this study, selective genotyping was applied to four maize F₂ populations. Thirty plants were selected from each of the two tails of the original F₂ populations to represent extreme resistant and susceptible plants to root lodging, and genotyped individually with 1536 single nucleotide polymorphisms (SNPs). A quantitative trait locus (QTL) was declared when at least three closely linked SNPs showed significant allele frequency difference between the two tails. Nine QTL were identified for root lodging across the four populations, which were located on chromosomes 2, 4, 5, 7, 8 and 10 and one of them was shared between two populations. A total of 20 segregation distortion regions (SDRs) were identified across the four populations, one of which was co‐localized with a QTL on chromosome 4. The tightly linked SNPs identified in this study can be used for marker‐assisted selection for root lodging. Selective genotyping, when combined with pooled DNA analysis, can be used to develop strategies for high‐throughput genetic mapping for all crops.     

Antibacterial activity of Pulicaria dysenterica extracts

Aqueous, methanolic and chloroformic extracts of Pulicaria dysenterica aerial parts were tested for their antibacterial activity using the disc-diffusion assay technique. The methanolic extract was found to be the most effective extract against three out of six tested bacteria. All of the extracts were active against Vibrio cholera.     

Long-term effects of intraperitoneal injection of estradiol-17β on the growth and physiology of juvenile stellate sturgeon Acipenser stellatus

Juvenile stellate sturgeon Acipenser stellatus were intraperitoneally injected with estradiol-17β (E₂; 0 and 5 mg/kg fish) to investigate the possibility of sex reversal and also determine the changes in biochemical parameters. Five-month-old fish (40.9 ± 1.1 g) were injected every 3-week interval during a 190-day trial. At the termination of the experiment, final weight and other growth parameters including weight gain and specific growth rate, hepatosomatic and viscerosomatic indices were not affected by repetitive injection of E₂. Hematological features of E₂-treated fish showed significant reductions in number of red blood cells, hemoglobin concentration, hematocrit value and mean corpuscular hemoglobin (P < 0.05), but no significant changes were observed in number of white blood cells, mean corpuscular volume and mean corpuscular hemoglobin concentration (P > 0.05). Calcium, phosphorus, glucose, triacylglycerol, cholesterol, total protein and estradiol concentrations were significantly increased in fish injected with E₂ (P < 0.001). Plasma progesterone and testosterone levels were noticeably lower in fish injected with 5 mg/kg E₂ rather than the control fish (P < 0.001). Histological observations of gonads showed that all fish injected with 5 mg/kg E₂ apparently feminized, while 66.6 % of the control group was female. These results revealed that the injection of E₂ is an effective method for feminization of stellate sturgeon without having significant inhibitory effects on growth and survival.     

Genetic diversity and relatedness of selected Iranian rice cultivars and disease resistance donors assayed by simple sequence repeats and candidate defense gene markers

As a prerequisite to improving diseaseresistance and grain quality in Iranianrice cultivars, we determined the geneticrelatedness of popular local cultivars andblast-resistance donor germplasm usingfingerprints derived from simple sequencerepeat (SSR) and plant defense genemarkers. Fifty SSR markers and 28 defensecandidate genes were used to assess thegenetic diversity among popular ricecultivars from Iran and donors of blastresistance from breeding programs in Asia.Gene diversity estimate of the 16 corebreeding lines was 0.440 ± 0.028 basedon SSR markers. Genetic relationships amongthe cultivars were determined by clusteranalysis using SSR and candidate genedatasets. DNA fingerprints derived fromSSR and defense gene markers gave similargroupings of cultivars consistent withtheir genetic background: a) Iranian localvarieties, b) improved varieties in Iranplus donor indica germplasm from Asia, andc) japonica germplasm. Within-groupsimilarities for the traditional andimproved cultivars were greater than 80%and 75%, respectively. The traditional andimproved cultivars showed differentialreaction to blast pathogen isolates; alltraditional varieties were susceptible toblast pathogen isolates in Iran butresistant to isolates in the Philippines,whereas the improved varieties showedopposite reaction to pathogen isolates inIran and the Philippines. Both molecularand phenotypic data suggest a narrowgenetic basis in local and improvedcultivars in Iran and the need forincluding more diversity for the breedingprogram. The high degree of polymorphismobserved between local cultivars and donorsof blast resistance provide the neededinformation to follow the transmission ofresistance alleles from the donors inadvancing breeding lines.     

Rice (Oryza sativa L.) plant protection using dual biological control and plant growth-promoting agents: Current scenarios and future prospects

Various microorganisms live in association with different parts of plants and can be harmful, neutral, or beneficial to plant health. Some microbial inhabitants of plants can control plant diseases by contesting with, predating on, or antagonizing plant pathogens and by inducing systems for plant defense. A range of methods, including plant growth-promoting microorganisms(PGPMs) as biological control agents(BCAs)(BCA-PGPMs) are used for the biological management and control of plant pathogens. S...     

Changes in plant growth substances,contents and flower quality of rose cv. ‘Dolce Vita’ in response to nitrogen sources under soilless culture conditions

The aim of this study was to investigate the biochemical responses and vase life of rose cut flowers under different ratios of NO₃:NH₄:urea in soilless culture. In this study, urea was used as the source of nitrogen (N) in solution cultures. For this purpose, an experiment was conducted as completely randomized design with seven ratios of N forms and three replications. The rooted cuttings of rose cv Dolce Vita were supplied with seven different ratios of NO₃^?:NH₄⁺:urea (100:0:0, 70:15:15, 50:25:25, 50:0:50, 0:0:100, 50:50:0 and 0:100:0). Results showed that with the increase in urea and ammonium concentrations, the amounts of cuttings IAA, GA₃, zeatin, ABA and polyamines contents decreased significantly. Plants fertigated with nutrient solution containing NO₃^?:NH₄⁺:urea (50:25:25) had the highest concentrations of growth regulators, the highest stalk length and flower vase life. As the ammonium ratios in the nutrient solution increased, the flower vase life decreased significantly. It was concluded that using NO₃^?:NH₄⁺:urea at the ratio of 50:25:25 had the highest effects on improving the rose cut flowers quality by affecting plants growth regulators and can be recommended for cut rose production in soilless culture systems.     

Variability and association among some pomological and physiochemical traits in spring frost tolerant genotypes of Persian walnut (Juglans regia L.) and selection of genotypes with superior traits based on machine learning algorithms

Genetic Resources and Crop Evolution - Persian walnut (Juglans regia L.) is an economically important species of edible nuts. In the present study, northwest regions of Iran were explored to find...