Lodging reduces sucrose accumulation of sugarcane in the wet and dry tropics

Abstract

Previous experiments in the Australian tropics have observed a 'slowdown' in biomass accumulation in mature sugarcane crops. By installing scaffolding to prevent lodging, we eliminated the growth 'slowdown' in 3 experiments to confirm that lodging and stalk death are part of the explanation. In both the wet and dry (irrigated) tropics, lodging of sugarcane significantly decreased both fresh cane yield and commercial cane sugar content (CCS). Prevention of lodging increased cane yield by 11–15%, CCS by 3–12%, and sugar yield by 15–35% at the final harvest in August–September. The rate of increase in CCS in lodged cane was reduced following lodging, although CCS had partially recovered by harvest.

A possible component of the lodging effect is a slowdown in the growth due to the ageing of the crop. However, a younger crop (late crop treatment) grew no faster than the scaffolded treatment and so discounted this. In the dry tropics, where cane is irrigated and grows under high radiation, sugar yield was 40 t/ha with scaffolding installed. The increased yield (compared with 35 t/ha in lodged cane) was due to both the survival of an extra 0.8 stalks/m² and increased accumulation of sugar in live stalks. In 2 years in the wet tropics where sugar yield with scaffolding was 16 t/ha, the same factors, with the addition of increased biomass accumulation in live stalks, were responsible for the increase.