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The diversity and prevalence of Fusarium species and their chemotypes on wheat in the North-West and North of Iran was determined. Wheat in these areas is severely affected by Fusarium head blight, with Fusarium graminearum as prevalent species causing 96% of the infections in the North-West and 50% in the Northern provinces. Fungal isolates were identified based on morphological characters and sequences of the internal transcribed spacer region, and parts of translation elongation factor 1-? and RNA polymerase subunit II sequences. Phylogenetic and phylogeographic analyses show little haplotype variation between the F. graminearum strains collected from the different locations, but the isolates differ significantly in their trichothecene chemotypes as determined with a multilocus genotyping assay. F. graminearum strains producing 15-acetyldeoxynivalenol were abundant in Ardabil (North-West of Iran), while in Golestan province (North of Iran) at the other side of the Caspian Sea especially nivalenol producing strains and a variety of other Fusarium species were observed. Strains producing 3-acetyldeoxynivalenol were rarely found in both areas. This is the first detailed study on Fusarium infections in Iranian wheat, showing large differences in prevalent etiological agents and in mycotoxin chemotypes geographically.

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In the present study, the toxicity of essential oils of Mentha piperata L. and Mentha pulegium L. and pathogenicity of Lecanicillium muscarium (Zare & Gams) were studied in the melon aphid, Aphis gossypii Glover. Analyses of the essential oils by GC-MS indicated limonene (27.28%), menthol (24.71%), menthone (14.01%), and carvol (8.46%) in the M. piperata essential oil and pulegone (73.44%), piperitenone (5.49%), decane (4.99%), and limonene (3.07%) in the essential oil of M. pulegium as the main components. Both essential oils and the pathogenic fungus had useful toxicity against A. gossypii. Probit analysis indicated LC50 values (lethal concentrations to kill 50% of population; 95% confidence limits in parentheses) of M. piperata and M. pulegium essential oils as 15.25 (12.25-19.56) and 23.13 (19.27-28.42) µl/liter air, respectively. Susceptibility to the pathogenic fungus increased with exposure time. Aphid mortality also increased when the essential oils were combined with L. muscarium, although the phenomena was additive rather than synergistic. Mycelial growth inhibition of L. muscarium exposed to the essential oils was also very low. Based on our results, M. piperata and M. pulegium essential oils and the pathogenic fungus L. muscarium have some potential for management of A. gossypii.

The effects of water deficit and nitrogen fertilizer were studied on antioxidant enzymes activity and quantum yield of barley. An experiment carried out in greenhouse in factorial subject based on a completely randomized design with three replications. Irrigation schedules imposed at three levels of 85%, 60% and 35% field capacity (FC), and nitrogen were applied in quantities of 40, 80 and 120 kg N ha-1. We determined Catalase (CAT), Peroxidase (POX) Polyphenol oxidase (PPO) activities, proline, chlorophyll and carotenoid content, quantum yield and grain yield. The results showed that severe stress (35% FC) increased the activities of CAT, POX and PPO enzymes and proline content, whereas the carotenoids, chlorophyll a and chlorophyll b decreased. Water deficiency caused the reduction in the quantum yield and the grain yield by 34%. Application of 80 kg of N during stress treatments resulted in higher enzyme activity and proline content. High amount of nitrogen reduced carotenoids, chlorophyll a, chlorophyll b, and in contrast, enhanced quantum yield. Application of 120 kg N ha-1 increased the yield up to 37% under mild stress (35% FC). Correlation coefficient and path coefficient showed that, grain yield was affected directly by amount of carotenoids and quantum yield.

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