A study was conducted to elucidate differential induction of nitrate reductase activity as a function of form of nitrogen in two varieties of sugarcane. These varieties (Co 1148 and Co J 64) showed differential behaviour with respect to nitrate reductase activity, chlorophyll contents, total nitrogen and dry matter production when various forms of nitrogen were applied in sand culture. The variety Co 1148 registered higher values for nitrate reductase activity than Co J 64, although the chlorophyll contents were higher in the latter. Nitrate and amide (urea) form of nitrogen enhanced the activity more than the ammoniacal form of nitrogen. The dry matter production, chlorophyll contents, total nitrogen per cent Increased when nitrate and urea were applied. On total nitrogen basis sett-roots preferred ammoniacal nitrogen in contrast with shoot-roots which preferred nitrate nitrogen.
