manihot esculenta 769 starch crops 230 cultivation 108 development 98 marketing 95 productivity 95 research 90 economics 82 production 82 variedades 82 root productivity 72 processing 69 cassava 67 cultivars 63 fitomejoramiento 62 producción 62 pests 61 cassava products 60 processed products 60 mercadeo 56 cultivation systems 51 cultivo 50 uses 50 costs 48 plant anatomy 47 productividad de raices 46 roots 46 technology 44 varieties 43 drying 41