Agronomic characters and eating qualities of special maize types arising from different gene combinations

Special maize types are becoming an important vegetable in the Philippines and their increasing demand in the urban centers is reflected in expansion in nearby production areas. Most of the cultivars available in the market are composed of only single mutant recessive genes for sweetness and/or flavor: shrunken(shsh), brittle(btbt), sugary(susu) and waxy(wxwx). The general objective of the study was to determine the effect of different gene combinations on the eating quality and agronomic characters of special maize types which could lead to novel and enhanced taste quality. The test of the four single genes and their five possible combinations were done in College, Laguna and Tayug, Pangasinan [Philippines] last summer of 2006. Results showed that combinations of sugary, shrunken and brittle genes enhanced the sugar level, flavor and other quality traits of the endosperm. The double mutant susubtbt and susushsh exhibit far superior eating quality than their parental single mutants. The general significant GxE interaction for the quality traits was due more to the change in magnitude of differences between entries rather than reversal in rank. This indicates consistency in quality performance across the environments tested. The yield of single mutant lines was also found to be higher than that of double mutant entries. There were significant positive correlations between yield and plant height, ear length, ear width and number of marketable ears. Most of the quality attributes evaluated in this study were found to be positively correlated with each other. Yield showed negative insignificant correlation with sweetness and % Brix, suggesting that improving the flavor especially for sweetness need not have a negative effect on yield. The study has shown, at the inbred level, the feasibility of double mutant types in the sweetcorn materials available in the Philippine market. The logical sequel is to incorporate such quality traits in heterotic inbreds for development of commercial hybrids.