Constant radiation use efficiency throughout the entire sugarcane crop cycle is often assumed for crop yield forecasting and management purposes. However, several examples are known where the linear relationship between cumulative intercepted radiation and biomass accumulation becomes uncoupled at some stage, with the latter declining by 21% in one reported case. This slowdown in growth is commonly referred to as the reduced growth phenomenon (RGP). In certain instances, this phenomenon appears to be related to the timing of crop initiation and harvesting. Summer-initiated sugarcane crops do not always resume expected growth rates after the transition from winter to spring, despite conditions being favourable for vigorous growth. Possible factors underlying the failure of sugarcane crops to realize full yield potential are reported and interrogated in this review. The potential involvement of lodging, flowering, and tiller mortality have been reviewed and the data suggest that, while such factors may contribute, they are unlikely to be the major causes of sugarcane RGPs. Similarly, reports indicate that temperature cannot account for reduced growth, as rates remain low despite the onset of favourable conditions in spring. In contrast, a decline in specific leaf nitrogen, potential initiation of sugar-mediated source-sink feedback inhibition of photosynthesis, and increased rates of maintenance respiration that occur during sugarcane development and maturation appear to be likely factors contributing to RGPs. An evaluation of areas of sugarcane biology and agronomy that would benefit from further research towards overcoming yield restriction imposed by reduced growth phenomena is provided.
The development of recommendations for drying-off management in sugarcane is
difficult due to climatic variability and lack of knowledge of the sensitivity
of changes in sucrose content and cane yield to severity of water deficit.
Relative cane biomass targets were developed for drying-off irrigated
sugarcane before harvest based on derived relationships between cane yield,
cane dry weight, and sucrose concentration, using pooled data from previous
field studies. These targets were then linked to a crop–soil model and
long-term climate data to determine the economically optimum duration of
drying-off, and its variability from season to season for 2 locations in
Australia and one location in South Africa, for a range of harvest dates and
soil types. The crop–soil model was validated on yields measured in 37
drying-off treatments conducted in South Africa and Australia. The simulation
results show that the required drying-off duration can be highly variable,
although the level of variability is not necessarily correlated with rainfall
per se. There were interactions between soil type and
harvest date, but not at every location.
The systems approach outlined here can be useful in developing recommendations
for drying-off where experience is limited, such as in expanding areas of
sugar industries, for districts in which the practice of irrigation is
increasing, or for harvest dates outside the current harvesting season.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.