Variety Difference of Nitrate Nitrogen Concentration of Sorghum under a Large Amount of Nitrogen Fertilizer Application

Abstract

Difference among sorghum cultivars (Sorghum bicolor Moench, Sorghum bicolor Moench×Sorghum sudanense (Piper) Stapf) of nitrate nitrogen concentration under a large amount application of nitrogen fertilizer was investigated. The cultivars tested were NS-V, BR48 (grain type), P956 (dual purpose type), FS305, FS902 (sorgo type) and SS901 (Sudangrass types). After late internode elongation stage, the following equation could be used in all cultivars; [nitrate nitrogen concentration based on dry matter]≒[nitrate nitrogen concentration of stem based on fresh weight]×[the ratio of stem based on dry matter per the ratio of dry matter of stem]. Nitrate nitrogen concentration of FS 305 was drastically decreased after flowering stage. The decrease was analyzed by using above the equation, and it was due to the decrease of the ability to accumulate nitrate nitrogen in stem.