Nitrate uptake by excised roots of plant and ratoon crop of sugarcane

Nitrate (NO⁻₃) uptake by excised roots of sugarcane cultivars was studied by the method of depletion of NO⁻₃ from the nutrient medium. Excised roots oflate maturing sugarcane cultivar CoS767 took up about 50% higher NO⁻₃ as compared to that of early maturing cv. CoJ64 during formative phase and 20% higher during grand growth phase of plant crop. Excised roots of ratoon crop of cv. CoS767 and CoJ64 showed 39% and 20% lower NO⁻₃ uptake rate respectively than similar roots of plant crop. Tissue NO⁻₃ content in top visible dewlap leaf of plant crop was marginally higher in late maturing cultivar (CoS767) as compared to that in early maturing type (CoJ64). The difference in tissue NO⁻₃ content vanished during grand growth phase of plant crop and was not observed during either stage in ratoon crop of the two cultivars. The difference in NO⁻₃ uptake rate and tissue NO⁻₃ content is discussed with respect to growth and maturity of sugarcane crop.