tag:blogger.com,1999:blog-34191097126983499662011-12-07T17:35:06.666-08:00Plant Stress Tolerancehttp://www.blogger.com/profile/07474417279626950772noreply@blogger.comBlogger191100tag:blogger.com,1999:blog-3419109712698349966.post-51654932758814313242008-09-09T14:06:00.000-07:002008-09-09T14:21:35.253-07:00

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Tan SpotCausal organism - Pyrenophora tritici-repentisHostsWheat but can also attack barley, rye and some grasses.SymptomsTan spot can be seed borne and infect seedlings, resulting in small tan to light brown flecks on young leaves. Symptoms are normally seen later in the season in the middle and upper canopy. First symptoms of infection are small tan to light brown flecks, with a chlorotic halo,

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Scoring stripe rustDetailed outlines for recording stripe rust intensities in cereals are based upon: Severity (percentage of rust infection on the plant) andField response (type of disease reaction).Severity is recorded as a percentage, according to the modifed Cobb scale. This recording process relies upon visual observations, and it is common to use the following intervals: Trace / 5 / 10 / 20

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Stripe or yellow rust of wheat caused by P. striiformis f. sp. tritici can be as damaging as stem rust. However, stripe rust has a lower optimum temperature for development that limits it as a major disease in many areas of the world. Stripe rust is principally an important disease of wheat during the winter or early spring or at high elevations.Symptoms of stripe rust are long stripes of small

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Bread Wheat(Triticum aestivum) / Durum Wheat(Triticum turgidum)stem rust - Puccinia graminis f.sp. tritici - Barberry (Berberis vulgaris, B. canadensis)leaf rust - P. triticina (P. recondita f. sp. tritici) - Meadow Rue (Thalictrum speciosissimum = T. flavum ssp. glaucum)leaf rust - P. tritici-duri - Anchusa italica . Occurs only in the Mediterranean Areastripe rust - P. striiformis f. sp.

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Wheat rusts Leaf rust - Stem rust-yellow rustUpdated nomenclature of rust resistant genes (Lr, Sr, Yr)http://www.ars.usda.gov/Main/docs.htm?docid=10342Sequenced / mapped rust resistant genes - grain gene databasehttp://wheat.pw.usda.gov/GG2/rust.shtmlNomen clature systems of rusts -Stem rust- Phytopathology 78:526-533http://www.ars.usda.gov/SP2UserFiles/ad_hoc/36400500Cerealrusts/

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Stem rustStem rust was once the most feared disease of cereal crops. It is not as damaging now due to the development of resistant cultivars, but outbreaks may occur when new pathogen races arise against which the existing kinds of resistance are ineffective. Stem rust remains an important threat to wheat and barley and, thus, to the world food supply. Anton deBary first demonstrated the

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Symptoms - close up Leaf rust (brown rust) Yellow rust / stripe rust CO: Puccinia striiformis Westendorp f. sp. tritici Leaf / brown rust Stem rust Yellow or strip rust Figure . Relative resistances of wheat to stripe (left) and leaf rust (right): R = resistant, MR = moderately resistant, MS = moderately susceptible, and S = susceptible.

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Leaf rust -Leaf rust is one of the most common and most important wheat diseases in wheat growing areas of the world. Leaf rust is caused by a parasitic fungus called Puccinia recondita f. sp. tritici.Leaf rust causes very small (about 1/32 inch long by 1/64 inch wide), orange pustules that erupt through the leaf surface. In some cases, pustules are surrounded by a narrow yellow or white halo.

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Abiotic stresses such as extreme temperatures, low water availability, high salt levels and mineral deficiency and toxicity are frequently encountered by plants in both natural and agricultural systems. In many cases, several classes of abiotic stress challenge plants in combination. For example, high temperatures and scarcity of water are commonly encountered in periods of drought, and can be

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Upland rice, known as Ghaiya Dhan in Nepali, is mainly grown on Tars, and also in, marginal hillside terraces or hillsides newly cleared of forest cover in Nepal. Tars are actually ancient alluvial fans now formed into flat basins with aAt least 9% (constituting a total of about 126,000 ha) of the total rice area in Nepal is upland rice gricultural importance. There were many landraces of upland

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The earth’s climate system is experiencing a warmer phase. Increase in temperature and atmospheric CO2 concentration are two major effects of climate change, besides increase or decrease in the local rainfall. Higher temperatures are expected to improve or retard seed germination, plant growth and/or plant development, depending on the relative sensitivity or tolerance of crop genotypes. The

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Climate change threatens to increase crop losses, increase the number of people facing malnutrition, or worse, and may change the development patterns of animal diseases and plant pests, the United Nations agricultural agency says in a new report.The UN Food and Agriculture Organization (FAO), in collaboration with the International Institute of Applied Systems Analysis (IIASA), has developed the

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Wheat scab or Fusarium head blight (FHB) is a devastating disease for wheat production worldwide, the causal organism is Fusarium graminearum Schevabe [(telomorph: Giberella zeae Schw. (Petch)].Arthur, in 1891, reported that a wheat field which was expected to yield 35–40 bushels/acre yielded only 8 bushels/ acre in 1890, a season in which there was a severe epidemic of Fusarium head blight (FHB)

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Drought tolerance refers to the degree to which a plant is adapted to arid or drought conditions. Desiccation tolerance is an extreme degree of drought tolerance. Drought is one of the most important environmental challenges growers have to face around the world. Droughts are the cause for large grain losses every year, especially in developing countries, and the current trend in global climate

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In many areas, the flowering to maturity period in wheat coincides with the beginning of hot, dry weather. If desiccating winds occur along with high temperatures, major reductions in yield may be experienced. Early heat stress has reduced tillering whereas during flower affects grains / spike whereas late-maturity reduce grain weight. Effects:The effects of high temperatures often are associated

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Foliar blight, also known as HLB, is a serious disease of wheat in the warmer areas of South Asiawhere spring wheat is grown during the winter season (November to April). Yield losses due to foliar blight are variable but significant. In farmers’ fields, losses of up to 20% have been reported. In the Nepal lowlands where most wheat is produced, HLB develops as a complex of spot blotch, caused by

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Heat stress tolerance is one of major breeding objective in tropical environments. Selection for spot blotch has been suggested to be combined with heat tolerance. In many parts of the Asian subcontinent, wheat is followed by rice causes delays in planting of wheat consequently resulting higher heat stress. Under field conditions, late planting (resulting in terminal heat stress) was found to

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In recent years, Helminthosporium leaf blights (HLB), caused by Bipolaris sorokiniana and Pyrenophora tritici-repentis, have emerged as serious concerns for wheat cultivation in the developing world. Due to the increasing food demand and to limited agricultural land, wheat is grown in more intensive cropping systems - an example is the rice-wheat rotation covering 12 million ha in South Asia.

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