Agronomic performance, aflatoxin accumulation and protein quality of subtropical and tropical QPM hybrids in southern US

Development and adoption of Quality Protein Maize (QPM), at homozygous (o(2)o(2)) hard endosperm high lysine corn, would increase the nutritional value of food and feed maize products. Elite white and yellow QPM hybrids with subtropical and tropical adaptation that are competitive ill yield with commercial checks have been developed. The objectives of this study were: i. to evaluate the adaptation and agronomic performance of tropical and subtropical white and yellow QPM hybrids in southern U.S. environments; ii. to assess their response to aflatoxin accumulation; and iii. to estimate their protein and lysine content. QPM hybrids and non-QPM commercial hybrids adapted to southern USA were evaluated in replicated trials at 6 (white) and 8 (yellow) environments, and in 2 inoculated trials with Aspergillus flavus. QPM hybrids had bigger tassels, higher ear placements and longer flowering dates than non-QPM checks. QPM hybrids yielded less than non-QPM checks across locations. Avenge yield across locations for white QPM hybrids was 5.54 t ha(-1) vs. 6.44 t ha(-1) for white non-QPM checks. Sonic white QPM hybrids had similar grain yields to commercial hybrids. For yellow QPM hybrids, the average yield was 5.55 t ha(-1) as compared to 7.44 t ha(-1) For non-QPM checks. Both white and yellow QPM hybrids were significantly less susceptible to aflatoxin than non-QPM checks. All QPM hybrids had superior nutritional quality. White QPM hybrids had average lysine per protein content of 41.73 g kg(-1) vs. 34.13 g kg(-1) for commercial checks, and yellow QPM hybrids 41.91 g kg(-1) vs. 29.71 g k(-1) for non-QPM hybrids. Some QPM hybrids combined protein content similar to normal maize and high protein quality. QPM germplasm appears to be a source of aflatoxin resistance and nutritional quality. Although the agronomic performance of tropical and subtropical QPM hybrids was inferior to current commercial hybrids adapted to the area, it seems feasible to develop competitive QPM temperate hybrids with enhanced quality and nutritional value.