Formation of quality protein maize hybrids: lysine, tryptophan and quality index

At CEVAMEX (Chapingo, Mexico) it was developed experimental hybrids of quality protein maize with six lines (L-1 to L-6) derived from CML176 opaco2 source (CIMMYT), and their 15 single crosses. Lysine, tryptophan, quantity and quality of protein and genetic gains of the crosses were determined from the parent's average and the best of them. A completely randomized design with two replications (100 seeds) was performed. A variance analysis, means test (Tukey, 0.05), linear correlation between the variables, and the genetic advances were performed and analyzed with the "t" test. It was detected L-2, L-3, and L-6 as quality protein maize. L-2 x L-6 was the best cross (alpha=0.01) for their genetic gain of protein (2.3%) and quality index (-0.5%) in parent's average, and in genetic advance for the best parent through all parameters, as well, their increases in protein and amino acids corresponded with the protein quality index. Also L-1 x L-4, and L-4 X L-5 showed acceptable genetic advances both in tryptophan and lysine; furthermore their amount of amino acids impacted the protein quality, unlike the crosses L-2 X L-4, L-3 X L-6, and L-4 X L-6 with favorable gain in parent's average in lysine, tryptophan, and total protein. The protein quality index did not correlate with protein but it did with tryptophan (r=0.9) and lysine (r=0.7). In some crosses remained the quality protein of L-2, L-3, and L-6 lines.