“哲单四”是哲盟农科所一九七三年用“哲黄五”与“海七”两个自交系杂交育成的玉米单交种。经一九七六年前后示范推广,一度颇受重视,直到一九七九年以后,不仅种植面积逐渐减少,有的种子公司甚至把它和它的亲本“海七”也做为商品粮处理掉。“哲单四”为什么在短短的几年内竟落到如此境地?据称有几种说法:一曰“哲单四”产量低;二曰“哲单四”对水肥要求高,与当前的生产水平不适应;三曰“哲单 “Zhedan Si” is a cross corn cultivar cultivated by Zhegong Agricultural Science Institute in 1973 with “Zhehuang Five” and “Sea Seven” hybrids. Demonstrated and promoted around 1976, it was valued very much. Until after 1979, not only has the area planted gradually decreased, some seed companies have even disposed of it and its parent, “Sea Seven,” as commodities . Why did Zhezheng Si fall into such a situation within a few short years? There are several allegations allegedly made: one is the low output of Zhezhe Si; the other is the high demand for water and fertilizer from Zhezhe Si, Production level does not meet; three said "Zhe single