Assessment of ratooning ability and genetic variability of promising sugarcane varieties under middle Egypt conditions

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Poor ratooning ability was a major cause for rejection of sugarcane varieties in the breeding program because of the decline in cane yield associating the advance in the crop cycle. Seven sugarcane-promising varieties (G.2010–26, G.2011–82, G.84–47, G.2003–47, G.2006-6, G.99–103, and G.2010-7) along with one check commercial cultivar (G.T.54-9) were evaluated for ratooning ability (RA) and genetic variability. The experiment was planted in the randomized complete block design with three replications in a crop cycle included plant cane (PC), 1st ratoon (FR), and 2nd ratoon (SR) during 2016–2019 growing seasons at Mallawi Agricultural Research Station, El-Minya Governorate, Egypt (latitude of 28° 10 ’N, longitude of 30° 75 ’E and altitude of 55m above sea level). Varieties x crop cycles interaction showed highly significant effects on all traits except for purity %, indicating that variety performed differently among cane crops within the crop cycle. The evaluated varieties showed significant differences in RA% for all studied traits. Sugarcane G.2003–47 and G.2010-7 varieties exhibited higher ratooning ability recording higher cane and sugar yields in SR, compared to G.2011–82 and G.2010–26, which had poor performance concerning the same traits in SR. The overall mean of cane and sugar yields for the tested varieties significantly decreased by 3.38 and 0.59 tons in FR, being 13.9 and 1.7 tons in SR, respectively, compared to PC. Highest genotypic and phenotypic coefficients of variation were exhibited by single stalk weight, sugar yield and cane yield in both plant and ratoon crops. High heritability and genetic advance % estimates across crops were recorded for single cane weight (85.27% and 34.97%), cane yield (96.93% and 36.44%), Brix %(89.82% and 28.08%) and sugar yield (94.81% and 41.76%). These results suggest that a simple selection for these traits would be effective. In addition, selection in ratoon crops should be based on yield contributing traits having high PCV, GCV, heritability and genetic advance along with mean value.