Variation in sucrose concentration with crop age in primary, sucker and dead stalks in New South Wales environments

High sucrose concentration is required to maintain financial viability and so knowledge about how sucrose concentration varies is important in decision-making, especially with regard to harvest time. This paper describes the changes in sucrose concentration and dry matter content over time in one variety, TS65-28, for two first ratoon crops grown in NSW. Data are presented for three stalk classes (primary, sucker and dead) and for changes in sucrose concentration for different stalk sections. Sucker contribution to total sucrose yield was significant which suggests that harvesting of large lodged crops with lots of suckers may need to be delayed until sucrose concentration in suckers is close to that of primary stalks. Stalk sucrose concentration on a fresh weight basis (Sucrose FW), on a dry weight basis (Sucrose DW) and the stalk dry matter content (Stalk DM) reached peaks some time between 10 and 15 months, followed by a decline and then a slow increase. Patterns of distribution of Sucrose FW, Sucrose DW and Stalk DM along the stalk were quite different at 22-24 months than at 12 months, indicating either significant mobilisation of sucrose within stalks at different crop ages or that sucrose in older internodes is respired and not replaced. The implications from this study are that time of harvest management in relation to crop age and condition can enhance sucrose concentration and CCS, and that other management options, including the use of ripeners, should be evaluated.