Varietal improvement and agronomic studies of irrigated rice at Maha Illuppallama [Sri Lanka]

agricultura de regadio agricultural chemicals agricultural development agronomic characters arroz arroz irrigado asia asie breeding breeding methods cereales cereals cosecha cropping systems crops cultivos cultivos de grano economic plants engrais essai fertilizantes nitrogenados fertilizers grain crops harvesting induced mutation irrigated farming irrigated rice mechanization methode methods nitrogen fertilizers plantas plante plante de culture plants productividad productivity produit agrochimique profitability pruebas recherche rendement rendimiento rentabilidad research rice riz sistemas de cultivo sri lanka trials yields