Accelerated wheat production in semi-arid developing regions: economic and policy issues

agricultural chemicals agronomic characters cereales cereals clima climat climate climatic zones condiciones ambientales condition de milieu consommation consumo consumption control de malezas control de plagas costos costs crops cultivation cultivo cultivos cultivos de grano economic plants engrais environment environmental conditions environnement farming systems fertilizantes nitrogenados fertilizers grain crops herbicidas herbicide herbicides labranza lutte anti-mauvaise herbe medio ambiente methode methods nitrogen fertilizers pest control plant production plantas plante plante de culture plants policies politique politique de la recherche pratique culturale precios prices prix production production costs productividad productivity produit agrochimique profitability rendement rendimiento rentabilidad research policies site factors technologie technology tecnologia tillage travail du sol trigo weed control wheats yields zone climatique zone semi-aride