Stability and Reliability Analysis of Lowland Tropical Quality Protein Maize (Zea mays) Three-way and Single-cross Hybrids

Quality protein maize (QPM) contains the opaque-2 mutation, which increases the concentration of lysine and tryptophan in the grain endosperm and roughly doubles the biological value of maize protein (Bressani, 1992), as well as additional modifier genetic systems to maintain tryptophan and lysine content in the endosperm and to make the endosperm vitreous and similar to that of normal maize (Figure 1). Developed by CIMMYT and partners, QPM can improve the diets of the poor in areas where maize is a staple crop and also serves as a low-cost, high-quality animal feed. A primary goal of CIMMYT is to identify maize cultivars that perform well under marginal agronomic environments managed by resource poor farmers, as well as under optimal conditions. Such yield stability can be evaluated by running yield trials at multi-locations. This study was carried out to determine the yield performances and yield stability of 43 white-grained tropical lowland QPM hybrids across 8 locations in the 2004B growing season. Single parameter estimates of stability for individual genotypes and spatial modeling of stability reactions were made using four different analyses. Materials and Methods The experiment was laid out in an alpha-lattice design with two replications at each location. The locations were: (1) Agua Fría