Original Articles

Effect of nitrogen supply on the production and distribution of dry matter in sugarcane

Published in: South African Journal of Plant and Soil
Volume 19, issue 1, 2002 , pages: 12–16
DOI: 10.1080/02571862.2002.10634430
Author(s): J., C.S. Allison, South Africa, N.W. Pammenter, South Africa

Abstract

Sugarcane productivity is probably limited by characteristically slow early growth and, later, by progressively decreasing leaf nitrogen (N) concentration. Increasing the N supply might increase productivity by influencing these attributes. In a pot experiment on two cultivars N was supplied at either a level corresponding to normal field supply (‘low’), or a level twice this (‘high’). Plants were sampled at 173 days, and then N level supplied to the remaining plants was either maintained or decreased until a final harvest at 270 days. Stem and total dry mass at 173 days were increased by c. 20% by high N, and at 270 days by c. 60%. Dry masses at 270 days were not affected by decreasing N supply at 173 days. Crop growth rate (C) between 173 and 270 days was increased about two and a half-fold by high N, because of both greater leaf area index (L) and net assimilation rate (E); variation in E was related to leaf N concentration. Sucrose yield was increased by c. 60% by high N supply because of greater stem dry mass rather than of increased sucrose concentration. The results suggest that augmenting the N supply during the early part of the growth period should increase productivity, but results from pots should be confirmed in the field.

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