Improvement of Yield per se in Sugarcane - Translational Genomics for Crop Breeding: Abiotic Stress, Yield and Quality - page 213

Fig. 13.1. Current and future prospects for the sugarcane industry in Brazil (according to Arruda
2011; with kind permission from Springer Science and Business Media). For a color version of
this figure, please refer to the color plate.

(Gravois and Milligan 1992; Jackson 1994; Kang
et al. 1989). Cane DM quality can be assessed
based on its soluble and insoluble fractions. In
the soluble fraction (cane juice), DM is esti-
mated by measuring pol (sucrose content) and
brix (total soluble DM) content. The brix:pol
ratio determines the purity of industrial juice.
Combined with fiber content (insoluble DM),
this information allows for estimation of the per-
centage of sucrose content per fresh cane weight
and finally the sugar yield per unit area.
Significant increases in yield have been
obtained by classical breeding. The average
worldwide yield of fresh cane increased by 41%
over the last 50 years, from 50 tons per hectare in
1961 to 71 tons per hectare in 2010 (Figure 13.2)
(FAOSTAT 2012). This increase is the combined
result of genetic progress and improved agro-
nomic practices (irrigation, fertilization, etc.). In
terms of relative value (

that of grain crops such as maize, rice, and wheat.
However the gain in terms of absolute value
( 0.43 tons/ha/year) reveals a parallel evolu-

tion between sugarcane and sugar beet or silage
maize. In the sugar industry of Barbados (Sim-
monds 1979) and Louisiana (Edme et al. 2005),
in recent decades, an average of 1% annual
increase in yield can be attributed to genetic
progress. Genetic gain for sugarcane yield is gen-
erally explained by an increase in biomass yield
rather than an increase in sugar content (Jackson
2005; Kang et al. 1983), although some improve-
ments in sucrose content may have been made in
some areas such as Louisiana (Lingle et al. 2010;
Lingle et al. 2009). Although significant regular
increases in yield have been obtained through
conventional breeding, sugarcane still appears to
be far from achieving its theoretical agronomic
potential (Waclawovsky et al. 2010).
The demand for sugarcane for the produc-
tion of sucrose and ethanol along with all its
valuable

+

41%), the gain in sug-
arcane yield over the same period was half that of
sugar beet and silage maize and about a quarter of

+

co-products will increase with the