the Symposium on Wheats for More Tropical Environments - cimmyt

93of <strong>the</strong> plants selected from eachgeneration are subsequently discarded,due to unacceptable seedcharacteristics.As a result of many years' experience inwheat breeding, CIMMYT placesemphasis on <strong>the</strong> pedigree and modifiedbulk breeding systems and <strong>the</strong> use ofsimple and top crosses. This methodpermits rapid combination ofgermplasm and increases geneticdiversity; this is especially importantbecause of CIMMYT's mandate to breedfor diverse climates and regions withdifferent problems.To accomplish <strong>the</strong> breeding objectivesof CIMMYT's Tropical WheatImprovement Program, and to facilitateTable 1. World target environments included under CIMMYT's operational mandateAreasIrrigated AreasDryland areas,500 mm rainfallDrylands areas,500 mm rainfallAluminum toxicareasHighlands areas,above 1500 mTropical areas,23 0 N-23 0 S latitudes,excluding highlandsAreas affectedby salinityCountries and regionsGanges plains of India, IndusValley of Pakistan, Bangladesh,Tarai of Nepal, Egypt, Mexico,Zimbabwe, Lybia, SudanMediterranean North Africa,Middle East, China, Sou<strong>the</strong>rnCone countriesCentral India, parts of <strong>the</strong>Middle East, North Africa,Sou<strong>the</strong>rn Cone countriesBrazil, Central AfricanhighlandsHigh plateaus of Mexico andGuatemala, Andean countries,East AfricaCentral America, Caribbean,South and Sou<strong>the</strong>ast Asia,West AfricaCertain dryland areas of <strong>the</strong>Middle East and North Africa,PakistanImportant diseasesStem rust, leaf rust, stripe rustStem rust, leaf rust, striperust, Septaria triticiBunts, loose smutStem rust, leaf rust,Septaria tritici, Septorianodorum, Fusarium spp.,Helminthosporium spp.,Xanthomonas translucensStripe rust, BYDV,Septoria tritici, Septorianodorum, Fusarium spp.,Helminthosporium spp.,Xanthomonas translucensLeaf rust, stem rust,Fusarium spp.,Helminthosporium spp.,Xanthomonas translucensLeaf rust, stem rust