Increasing stalk sucrose in sugarcorn (Zea mays L.): genetic analysis and preliminary breeding

The generation of biofuels from biomass such as corn (Zea mays L.) stalks may be improved by increasing the concentration of available sugar. Understanding the inheritance of high stalk sugar traits is important for the development of new hybrids adapted for this purpose. The genetics associated with high stalk sugar (measured as sucrose equivalents) concentration was investigated by conducting a diallel analysis of six adapted inbred lines varying in stalk sucrose concentration, and a generation mean analysis using high and low sucrose inbred lines as parents tested in multiple years. Changes in stalk sucrose concentrations for six families with repeated cycles of selfing and selection over seven generations was also investigated. Results of the diallel and the generation means analysis of stalk sugar traits revealed that both additive [general combining ability (GCA)] and non-additive gene effects [specific combining ability (SCA)] were important for the inheritance of these traits and their expression was influenced by environment. Additive gene actions were more important than non-additive gene actions for controlling these traits. The study also demonstrated that the hybrid combinations of C103 with 73353 for stalk sucrose and with CO384 for stalk juice may be the best candidates for increasing stalk sugar as these inbreds had high means for these traits with favourable SCA estimates and at least one inbred had high GCA. Substantial increase in stalk sucrose in six different families over seven generations using a pedigree breeding method showed that selection gains could be made following this procedure.