Sugarcane Yield and Juice Quality as Affected by Harvest Age and Chemical Ripeners in Central Rift Valley of Ethiopia

Chemical ripening is a promising technology at Metahara and Kessem sugarcane plantations where conditions are not optimal for natural ripening in the early and late period of sugarcane processing. However, the harvest age at which sucrose yield could be maximized with application of ripeners has not been established. Thus, field experiments were conducted to determine the effects of harvest age and chemical ripeners on yield and juice quality of sugarcane. The experiments were conducted in the late period (June) harvesting at Metahara, and in the early (October) and late period (June) harvesting at Kessem. A split plot design with three replications was used where the main plot treatments were two sugarcane varieties, viz. B52-298 and SP70-1284, and the sub-plot treatment consisted of combinations of four harvest ages (10, 12, 14 and 16 months) and two ripener treatments [Moddus™ at 250 g ai ha⁻¹ + Fusilade Forte™ (M + FF) at 25.6 g ai ha⁻¹ combination sequentially sprayed and unsprayed control]. The results showed significant difference between the varieties for stalk height and stalk weight in early period study at Kessem with variety SP70-1284 being superior as compared to variety B52-298. Furthermore, harvest age and ripener combination significantly affected all yield and quality parameters, while there was a significant cane and sucrose yield response at Kessem at both sites and seasons. The highest cane yield was recorded in the unsprayed 16-month harvest age treatment, while the highest sucrose yield was recorded in the M + FF ripener combination 12-month harvest age treatment in all the studies. The economic analysis showed the highest marginal rate of return and net revenue in the M + FF ripener combination 12-month harvest age treatment and represents the best cane quality management practice for varieties B52-298 and SP70-1284 at these plantations.