International Crops Research Institute for the Semi-Arid Tropics
Abstract
This is a guide to the techniques required to produce pure and vigorous seed from varieties of this cross-pollinated crop. Multiplication rates, through sequential breeder, foundation, and certified seed stages, are high:3 kg of seed are adequate for sowing 1 ha, subsequently producing 1 tonne of clean seed. Nucleus seed plots (stage 0), sown for regeneration once every 4 years, should be effectively is o- lated . They should be between 0,1 and 0.2 ha in size, and contain at least 3000 plants. Plots of breeder seed(stage1)should similarly be well isolated, and rigorously inspected and rogued, and not more than 1% of off - types should be permit tedatfinal inspection. Plot sizes are normally between 0.1 and 0.5 ha, according to how much certified seed is required, using a conservative multiplication factor of X200. At the end of the foundation seed stage (stage 2), through protective perimeter planting, inspection, and rogueing, off-types should be less than 2%. At the final certified seed stage(3), the permitted level of off-types is 5%. Six points of guidance are given for extension staff to pass on to farmers who(as may be expected) at tempt to multiply their own improved seed