DETERMINATION OF THE OPTIMUM TIME FOR WITHHOLDING IRRIGATION WATER BEFORE HARVESTING OF SUGARCANE (Saccharum spp. Hybrid) AT KURAZ SUGAR DEVELOPMENT PROJECT, ETHIOPIA

Abstract

Study was carried out to determine optimum time of withholding irrigation period before harvesting of sugarcane at Omo Kuraz Sugar Development Project, Ethiopia. Experiments on two varieties, N Co 334 and B 52 298 planted in adjacent fields characterized with clay soil during 2014. The experiment was designated with two sugarcane varieties (N Co 334 and B 52 298) and five withholding irrigation periods (WIPs) treatments for 20, 30, 40 50 and 60 days and the treatment was laid out in randomized complete block design (RCBD) with four replications. The data on soil moisture content, cane height, cane weight, cane diameter, number of internodes, number of millable canes, moisture percent cane, fiber percent, cane yield, cane yield per month, top to bottom ratio brix in cane juice, Brix %, Pol %, purity, reducing sugars, estimated recoverable sugar, estimated sugar yield, and estimated sugar yield per month were analyzed using SAS package. Error variances for most characters were found to be homogeneous and the data were subjected for analysis of variance. The soil moisture percent differed at five different WIPs with lowest at WIP for 60 days. Variation in soil moisture was caused by occurrence of rain during WIPs for 30, 40 and 50 days. Cane height, cane weight and number of internodes per stalk increased significantly at the subsequent WIPs with maximum at 50 to 60 days. Millable canes in plots at the five WIPs were on par. Moisture and fibre percent in cane decreased and increased significantly at subsequent WIPs, respectively. Quality characters, top to bottom ratio of Brix in juice, Brix, pol or sucrose and purity percent in composite juice, and sugar recovery percent cane differed at five WIPs. Above quality characters increased significantly at subsequence WIPs being highest at WIPs for 50 and 60 days. Reducing sugars percent juice declined significantly with increase in days for WIPs with lowest at WIP for 60 days. Cane yield and cane yield per month were on par at WIPs. Estimated sugar yield and sugar yield per month tons per hectare increased significantly at subsequent WIPs with maximum at WIP for 50 and 60 days. The results revealed that optimum period for withholding irrigation was 50 to 60 days for obtaining maximum Pol or sucrose in cane. Therefore, it was suggestive that irrigation to sugarcane should be withheld for at least 50 to 60 days for enhancing sugar accumulation in cane before harvesting in the month of May under the conditions of South Omo Kuraz Sugar Development Project.