Trends in broad-sense heritability and predicted selection gains for the coastal short cycle breeding sugarcane programmes in South Africa

Abstract

Coastal short cycle breeding programmes develop early maturing sugarcane cultivars adapted to harvesting at 12 months under rainfed conditions. Genotypes progressed to the advanced cultivar stage from these programmes are merged and evaluated concurrently in multi-environment trials across the region. The objective of this study was to determine the magnitude and trends of broad-sense heritability and predicted selection gains for the coastal short cycle breeding programmes. Data were collected on plant, first and second ratoon crops from five advanced breeding populations planted from 2002 to 2006 at Empangeni and Gingindlovu. Broad-sense heritability for yield and agronomic traits decreased on post-1997 breeding populations, highlighting reduced selection response for these traits. Among quality traits, fiber% cane and dry matter% cane showed the largest broad-sense heritability (>0.9) across the series, indicating that a considerable proportion of the observed phenotype was heritable. There were no considerable improvements on the magnitude of predicted gains for yield and quality traits across the series, suggesting limited potential of these programmes to deliver better gains. Agronomic traits showed diminishing predicted selection gains over time. There was a non-significant (p < 0.05) correlation between broad-sense heritability and predicted selection gains of most traits.