Field experiment was conducted to determine the optimum maturity of the major sugarcane varieties (Saccharium officinarium L.) with high sucrose content and sugar yield. Six levels of harvest ages (10, 12, 14, 16, 18 and 20 months) and four major varieties N-14, NCO-334, CO-680 and B52-298 which cover 90% of the area were used in a completely randomized block design with 6x4x3 factorial treatment arrangements. All data's were collected at the end of each level of harvest ages. Analysis of

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... ce (ANOVA) showed that harvest age significantly influenced quality parameters (brix, pol, purity and ERS) and yield parameters (plant height, cane yield and sugar yield) (P<0.001). The important parameters of maximizing sugar yield and net revenue in relation to harvest date and crop age is expressed by t/ha/month as an index of time value of sugarcane crop. Considering the time value, increase in harvest age showed a negative impact on brix, pol, estimated recoverable sucrose, cane yield and sugar yield in the tropical area of Ethiopia. As a result high sugar yield was recorded at the early harvesting ages 12 and 14 months. However, optimum sugar yield was recorded on 12 months harvest age with economically acceptable marginal rates of return 178.13%. Therefore, adjusting harvest age to 12 months for the major sugarcane varieties was economically recommended to obtain optimum sugar yield with efficient time use at the tropical areas of Tendaho.