Abstract:
Agrochemical industries are faced with inadequate supply of molasses that is the main
raw material for ethanol production creating a need to develop an alternative feedstock. The use of sweet sorghum will alleviate the problem. Three sweet sorghum (Sorghum bicolor L. Moench) genotypes, EUSS10, EUSS11, and EUSS17 were tested against five controls, SS21, SS17, SS14, ACFC003/12 and SS04 to evaluate their ethanol yield potential, stability, and adaptability in Busia, Siaya and Kisumu Counties of Kenya. The genotypes were from ICRISAT. A Randomized Complete Block Design (RCBD) experiment with three replications was carried out at Sinyanya and Masumbi in Siaya County and Mundika in Busia County during the first season and Nyahera and Sagam in Kisumu County and Mundika during the second growing season in 2014. Seeds were planted at the onset of rainy season in each location in plots measuring 2.5 m by 4 m each consisting of four rows of sorghum. Days to 50% heading and plant height was taken in the field. Plant height was recorded for 3 plants per plot and two central rows harvested for juice extraction. Juice was fermented and distilled to obtain ethanol. Juice samples were taken for Brix and sugar quality analysis. All data on agronomic traits and yields were subjected to analysis of variance using SAS version 9.1 and means separated using Least Significant Differences. Adaptability and stability analysis was carried out using Genstat version 15.1. The results showed high variability on all measured attributes among genotypes except juice extractability and bagasse moisture. Genotypes by
environment interactions were also high for cane and juice yield. Overall, genotypic
correlations showed a linear positive correlation of ethanol yield with plant height, juice
volume and cane yield. The genotypes that performed above the environmental mean for cane yield were: EUSS10, ACFC003/12, SS14, SS17 and EUSS11 and juice yield were SS14, EUSS11, EUSS10, and ACFC003/12. For ethanol yield, the best performing genotypes were EUSS10, ACFC003/12, SS14 and SS04. The stable genotype that performed well across environments for cane, juice and ethanol yield was SS14. Therefore, SS14 is recommended for cultivation in all tested environments. EUSS10 and SS14 were adapted to lower midland (LM)1, LM2, and LM3. Genotypes EUS11, ACFC003/12, and EUSS17 are suitable for cultivation in LM1 and LM3 agro-ecological zones (AEZ). EUSS10 and SS14 would be highly recommended for rainfed conditions at LM1, LM2, and LM3 AEZs.
