应用植株快速诊断确定春小麦的追氮量

Using Quick Tissue Diagnosis to Determin the Amount of Nitrogen Topdressing for Spring Wheat

春小麦生长期间,取植株茎基部,采用二苯胺法和 NO_3^-N 快速试纸法同时测定NO_3^--N 浓度。发现拔节期 NO_3^--N 浓度、氮肥施用量和地上部干物重有较好的相关性。同时两种测试方法之间也存在极好的相关性(r=0.95)。当达到最大产量,施氮后 NO_3^--N 开始在体内累积。因此以达到最佳经济产量时体内的 NO_3^--N 浓度作为临界值较为合适。该值相当于二苯胺法测试值为2.50。当测定体内 NO_3^--N 浓度低于临界值时,则需增加氮的追肥量。

Stem bases from spring wheat were analysed for nitrate concentration by diphenylamine methed and"Merkequant"nitrate test stripe during growth.The concentration of NO_2^--N at jointing stage was related to both rates of applied nitrogen and shoot dry matter yield.There was also very good corela- tion between the two methods(r= 0.95).The NO_3^--N began to accumulate in plant when the application rate reached that for maximum yield.Therefore,the plant NO_3^--N concentration at the time when plant yield reached optimum could be taken as a critical value.It was around the nitrate scale(diphenylanine methed)2.50.The nitrogen top dressing was needed when nitrate in plant stayed below the critical value.