Genetic Variability of Some Promising Sugarcane Varieties (Saccharum spp) under Harvesting Ages for Juice Quality Traits, Cane and Sugar Yield

The objective of study to estimate genetic variability of some traits in the Egyptian sugarcane breeding program under different harvesting ages (10, 11, 12 and 13 months. Four promising sugarcane verities (C57-14, C203-8, G2003-47 and G99-160) and check cultivar (GT54-9) were evaluated for yield and juice quality traits and genetic parameters were measured in plant cane and first ratoon under Upper Egypt conditions at Kom Ombo Agricultural Research Station, (latitude of 24.28°N and longitude of 32.57°E), Aswan Governorate, Egypt during 2014/2015 and 2015/ 2016 seasons. The experimental design was a split plot with three replications. Harvesting ages were arranged in the main plots, whereas; the sub-plots were devoted to the promising sugarcane varieties. The results indicated that harvest age at 13 months recorded the highest mean values of most studied traits, but harvesting age at 13 months not significantly increased cane and sugar yield compared with harvesting at 12 months. The promising sugarcane variety G2003-47 recorded the highest value of all traits compared with other varieties and the commercial variety GT 54-9 in both seasons. Results showed that high genetic variance (σ2g) relative to environmental variance for all traits under study across seasons. Moderate values of genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were coupled with high heritability for brix, sucrose, richness, sugar recovery and sugar yield. The Highest values of PCV and GCV % across seasons were observed for reducing sugar (54.310% and 47.221%) followed by sugar yield (19.846% and 19.238%), respectively. Heritability estimates across seasons exceeded 80% for all studied traits, except for purity (75.728%) and reducing sugar (75.596%). Finally, this study recommends harvesting age 12 or 13 months because there was no significant increase in cane and sugar yield (ton/fad).