Early assessment of sweet sorghum as an agro-industrial crop. I. Varietal evaluation

Abstract

Thirty-seven sweet sorghum (Sorghum bicolor) cultivars were evaluated for sugar, solubles, grain, fibre and leaf production in first and ratoon crops under irrigation at Ayr, North Queensland, over the winter-summer period. Highest sugar yields were from cv. Rio, which produced 3.6 and 1.6 t ha-1 over 145 and 79 days from first and ratoon crops, respectively. Highest solubles (brix) yields of 7.6 and 4.8 t ha-1 were produced by cv. Italian over 141 and 81 days. The highest grain yield was 5.7 t dry matter ha-1 in the first crop by cv. FS26. Stem fibre yields of about 9 t dry matter ha-1 were realised from the higher yielding cultivars. In the first crop, sugar and solubles yields were found to be negatively correlated with grain yield, early development rate and fibre yield. They were positively correlated with time to maturity, plant leaf area and leaf area index at anthesis, a low position of the largest leaf on the stem, dry matter yield of plant fractions, high stem-juice extraction rates, and degree days and accumulated radiation received. In the ratoon crop, age and environmental variables showed a weaker association with yields. Productivity of fermentables appeared to be comparable with that of sugar cane for the region.