Author(s): Hadush Hagos, Walelign Worku and Abuhay Takele
Field experiment was conducted at Metahara Sugar Estate during the 2011/2012 cropping period to determine the effect of drying off period and harvest age on quality and yield of ratoon sugarcane (Saccharium officinarium L.). Major variety B52-298 was used under the four levels of drying off periods (25, 45, 65 and 85 days) and harvest ages (12, 13, 14 and 15 months) in a completely randomized block design with 4*4*3 factorial treatment arrangements. All data’s were collected at the end of each levels of drying off periods and harvest ages. Analysis of variance (ANOVA) showed that drying off period significantly influenced maturity testing parameters (sheath moisture content and handrefractometer brix), quality parameters (brix, pol, purity and CCS) and yield parameters (sugar yield) (P < 0.001). Brix, pol, juice purity, estimated recoverable sucrose and sugar yield were significantly increased when the level of drying off period was increased with a peak at 65 days. Brix, pol, juice purity, estimated recoverable sucrose and sugar yield were significantly increased with increasing level of drying off period up to 65 days. In contrast, soil moisture content, sheath moisture content, plant height and stalk diameter were reduced with increasing drying off period. Sugar yield increased by 20.97 % with extending drying off period from 25 days to 65 days with no further increase at 85 days drying off period. Effect of harvest age also significantly influenced maturity testing parameters (hand refractometer brix), quality parameters (brix, pol, purity and ERS) and yield parameters (plant height, cane yield and sugar yield) (P < 0.001). Increase in harvest age, significantly increased brix, pol, juice purity, estimated recoverable sucrose, plant height, cane yield and sugar yield. Optimum yield was recorded on 65 days drying of period and 15 months harvest age with economically acceptable marginal rates of return 2544% and 135%, respectively. Therefore, adjusting the drying off period to 65 days and the harvest age to 15 months for variety B52-298 under the tested soil condition for ratoon cane is recommended to increase sugar yield at Metahara Sugar Estate.
