Bio-ethanol production potential of sweet sorghum (Sorghum bicolor) cultivars under different spacing and harvest stages

In a field experiment conducted at Kathalagere, Karnataka during kharif 2007 and 2008, three sweet sorghum [Sorghum bicolor (L.) Monech] cultivars (‘Madhura’, ‘SSV-84’ and ‘RSSV-9’) were evaluated for ethanol production potential under two spacing (45 cm X 10 cm) and two stages of harvest (50% flowering and at physiological maturity). Among the cultivars tested ‘Madhura’ produced significantly higher ethanol yield (556.7 l/ha and 571.7 l/ha) when compared with ‘SSV-84’ (378.5 l/ha and 405.2 l/ha) and ‘RSSV-9’ (368.4 l/ha and 425.9 l/ha). ‘Madhura’ harvested at physiological maturity showed significantly higher ethanol yield 929.7 l/ha and 958.3 l/ha when compared with that harvested at 50% flowering (183.7 l/ha and 185.2 l/ha). Similarly ‘Madhura’ cultivar recorded significantly higher brix (degrees) (13.6 and 14.0), pol percent in juice (7.3 and 6.4%) and reducing sugar per cent (3.1 and 3.7%), when compared with ‘SSV-84’ and ‘RSSV-9’. The highest benefit cost ratio was recorded with ‘Madhura’ (1.88 and 1.73) when sown at spacing of 45 cm X 15 cm and 45 cm X 10 cm and harvested at physiological maturity.