Ripening response of sugarcane varieties to chemical ripeners and economic benefits during the early period of harvesting at Wonji-Shoa and Metahara sugarcane plantations, Central Rift Valley of Ethiopia

Abstract

Wonji-Shoa and Metahara sugarcane plantations experience reduced sucrose content (%) during the starting period of sugarcane crushing due to the combined influence of high (>27°C) temperature and the presence of high residual soil moisture. Studies elsewhere showed the potential of chemical ripeners in boosting the sucrose content (%), where natural ripening is deterred by these challenges. Accordingly, a field experiment was conducted to evaluate the responsiveness of selected sugarcane varieties to chemical ripeners at both plantations. &e treatments consisted of a factorial combination of four sugarcane varieties (B52298, NCo334, C86-56, and SP70-1284) and six ripener treatments: (1) Ethephon™(720 g ai ha− 1), (2) Fusilade Forte™(25.6 g ai ha− 1), (3) Moddus™ (250 g ai ha− 1), (4) Ethephon™ (720 g ai ha− 1) + Fusilade Forte™ (25.6 g ai ha− 1), (5) Moddus™ (250 g ai ha− 1) + Fusilade Forte™ (25.6 g ai ha− 1), and (6) Unsprayed (control). &e experiment was laid out in a randomised complete block design in a factorial arrangement with three replications. The results showed a significant (p 0.025) and highly significant (p 0.001) variety by ripener interaction in stalk height and sucrose content, respectively, while the main effect ripener highly significantly affected stalk weight (p 0.001) and sucrose yield (p 0.003). &e variety C86-56 sprayed with combinations of Ethephon™ + Fusilade Forte™ and Moddus™ + Fusilade Forte™ had the shortest stalk heights of 1.27 and 1.29 m, respectively, compared with the control. Ethephon™ + Fusilade Forte™ combination resulted in the highest reduction of stalk weight (8.36%), while the lowest was recorded in the sole Moddus™ treatment (6.31%). From the ripener treatments, the Moddus™ + Fusilade Forte™ combination and Ethephon™ + Fusilade Forte™ combination improved sucrose yield by 1.42 and 1.34 t ha− 1, respectively, compared with the control. However, in economic terms, the Moddus™ + Fusilade Forte™ combination treatment resulted in the highest marginal rate of return of 1244%. Therefore, the Moddus™ + Fusilade Forte™ combination ripener treatment was found to be promising to be evaluated at a commercial scale on immature sugarcane varieties B52-298, NCo334, and SP70-1284.