The CGIAR centers have published a number of resources, all of them OER. For example, the International Center for Agricultural Research in Dry Areas (ICARDA) has developed course modules on hybridization techniques in the faba bean and the chickpea, on experimental design and data analysis, and on biological nitrogen fixation, to name a few. The World Agroforestry Center has also developed modules. You must register to participate in some courses, but it is free of charge.