Line x tester analysis in sugarcane (Saccharum officinarum)

Combining ability variances and effects were estimated for important agronomic and biochemical traits in sugarcane using line x tester mating design. Five commercially grown varieties and one line from germplasm collection were involved in this study of which three were used as females (lines) and three as males (testers). The six agronomic characters studied were number of millable stalk per stool, stalk diameter, stalk height, weight of millable stalk, refroctometre brix and plant volume. The five bio-chemical characters studied include polatronic reading (pol), fibre, purity, brix and pure obtainable cane-sugar (POCS). Among the lines, Aiwa and Mana and among the testers Vatu and Mentor were found to be the best general combiners for most of the agronomic and bio-chemical characters. Four out of nine crosses namely Aiwa x Mentor, Kaba x Vatu, Kaba x Yasawa and Mana x Yasawa were found to be the best crosses. Analysis of Variance for bio-chemical characters showed that only one character ( % fibre) was significant. The line x tester interaction was not significant for any of the characters studied. Estimates of variance due to gca and sca and their ratio revealed predominantly non-additive gene action for these characters. Non-additive gene action can be exploited in F1 generation. Development of new hybrid varieties with improved agronomic and bio-chemical characters is therefore suggested.