VARIATION AND INHERITANCE OF SUCROSE ACCUMULATION PATTERNS AND RELATED AGRONOMIC TRAITS IN SUGARCANE FAMILIES

HIGH sucrose accumulation is a desirable characteristic to compensate for sub-optimal sucrose content easly in the hawesting season in Mauritius. Furthermore, with the centralisation of milling operations, there is a need to breed for precocious high sucrose cultivars that may be harvested much earlier to extend the halvest season. Studies on sucrose accuinulation and 011 other physiological parameters were carried out on segregating seedling populations using 15 biparental crosses involving parents evaluated for their sucrose accumulation pattern. A number of quality traits were followed at the exponential growth phase (March) and at early harvest stage (July). Height of primaiy and secondary tillers was recorded on four occasions during the tillering and growth phases. Families showed highly significant genetic differences for inost quality and physiological characters at both sampling dates. Narrow-sense heritability, estimated from biparental progeny analyses, was highest in March (0.12-0.82) for most quality characters, compared to early harvest (0.06-0.30). Primary tiller height showed higher heritability estimates compared to the secondary tiller height. Pronounced male effects were evident for some cane quality traits. In general, crosses which included an early ripening parent started sucrose accumulation earlier and accumulated a higher amount at the age of seven months cornpared to those involving late ripening parents. The late x late categories of crosses generally showed lower pol percent cane at both sampling dates compared to the other groups (middlellate x early). The genetic implications of these obselvations in relation to breeding and selection strategies for developing parents and cultivars with precocious and high sucrose accumulation patterns are discussed.