Evaluation of Sugarcane Germplasm for Development of Core-collections for Directional Breeding of Sugarcane (Saccharum hybrid spp.)

Abstract

Sugarcane (Saccharum hybrid spp.) is cultivated globally as a main source of raw material for production of sugar. Currently, Sri Lanka produces about six percent of the local sugar requirement, which is around 650,000 tons per annum. The present government has launched programmes as per the Mahinda Chinthana Development Frame work (2005) to achieve 40% self-sufficiency in sugar by year 2020 and 100% by year 2030. Sugarcane variety improvement plays a major role in achieving the said targets by developing new varieties with commercial attributes and selecting of varieties suitable for growing in different agro-ecological regions in the country. Selection pressure is applied to select varieties with higher cane yields and sugar contents, equitable fiber and resistance to major pests and diseases. Germplasm evaluation, parental selection in hybridization and progeny selection using appropriate methodologies increase the efficiency of the sugarcane breeding programme. Most of the local collections belong to Saccharum officinarum and there were a few hybrids which could not be recognized visually. The imported varieties and standard varieties were hybrid derivatives of early nobilization work.The present study was carried out to assess the parental worth of 217 sugarcane accessions to identify the most suitable parent clones and I nclusion of them into the proven parents system for crossings directed to high cane yield, high sugar content in juice and moderate fiber content. The specific objectives of this study were to estimate breeding values of accessions for yield components, clustering of accessions for making core-collections and estimation of association between yield components of sugarcane.

Methodology

The experiment was laid out in a completely randomized design with two replicates. A uniformly prepared land with furrows opened 1.37 m apart were divided into 1 m plots across the furrow direction and 1 m space was given between two plots. A total of 217 accessions that comprised local collections (131), imported varieties (75) and standard varieties (11) were tested in plant crop and ratoon 1 crop.

Data collected from the plant crop included plot weight (WT), stalk length (SL), stalk diameter (DM), number of stalks (ST) and, hand refractometer brix (HB). In addition, laboratory brix (BRIX), pol in juice (POL), purity (PUR), pure obtainable cane sugar (POCS) and fiber percentage (FIB) were recorded in the ratoon 1 crop. Analyses of variance for all the characteristics followed by means separation employing the unnett’s procedure against the commercial standard variety Co 775, and phenotypic correlation and cluster analysis using agglomerative hierarchical approach for the variables WT and HB for plant crop and WT and POCS ratoon 1 crop to characterize the accessions for cane yield and sugar content were done. Breeding values of the accessions were estimated as proposed by Marshall (2008) for all characteristics except FIB. The narrow-sense heritability values of the characteristics estimated by Wijesuriya et al. (2012) were used for the estimation of breeding values of the accessions.