stiff stalk synthetic u00d7 a634 was made at dayton iowa s0 generation seed from the harvested ears was bulked seed of the s0 generation cross was sent to homestead fla for self pollination all harvested ears were returned to dayton iowa shelled and the s1 generation seed bulked the s1 generation seed was planted at dayton iowa in a single row and the plants were self pollinated three self pollinated ears s2 generation seed were harvested shelled separately and the s2 seed maintained separately s2 generation seed of ear number one of three harvested was planted at homestead fla in a five row block and the plants self pollinated five self pollinated ears were harvested and returned to dayton iowa seed of each ear was shelled separately and the s3 generation seed maintained separately s3 generation seed of ear number three of the five harvested was planted at dayton iowa in a two row block and the plants self pollinated four self pollinated ears were harvested shelled separately and the s4 generation seed maintained separately s4 generation seed of ear number four of the four harvested was planted at homestead fla in a single row and the plants self pollinated one self pollinated ear was harvested and returned to dayton iowa and the s5 generation seed shelled and maintained s5 generation seed from the single ear was planted at.