郑单二号玉米,系我院1969年以塘四平头自交系作母本,获白自交系作父本培育而成的单交种。1970—72年,连续三年在全省31处试验、示范结果,春夏播均表现增产。夏播平均亩产689斤,较新单一号增产43.5%。春播平均亩产851.6斤,较新单一号增产17.3%。1973年参加河南省夏玉米联合区域试验,产量居13个杂交种首位,平均亩产788斤,较新单一号增产24.3%。1973年开始大面积推广,1975年省内种植面积已达 Zheng Dan No. 2 maize, Department of our hospital in 1969 to Tong Siping first inbred line as the female parent, white inbred line parent breed made of single cross-species. 1970 - 72 years, for three consecutive years in 31 experiments in the province, demonstration results, spring and summer sowing performance increase. Summer sowing average yield of 689 pounds, 43.5% higher than the new single number. The average yield per mu in spring was 851.6 kg, up 17.3% over the new single. In 1973, he joined the regional trial of summer maize in Henan Province, ranking the top of 13 hybrids with an average yield of 788 jin per hectare, up 24.3% from the previous single. Large-scale popularization started in 1973, and the area planted in the province reached in 1975