Analysis of genotype by environment interaction for grain yield of intermediate maturing drought tolerant top-cross maize hybrids under rain-fed conditions

Maize plays a crucial role in combating food insecurity in Ghana due to its high yield potential and wide adaptability. Thirty five intermediate maturing maize hybrids were evaluated at eight locations in Ghana for two years (i) to determine grain yield performance, stability and adatability, (ii) to determine the representativeness and discriminating ability of the test locations and (iii) identify core testing sites for selection of superior maize hybrids. Genotype, environment and genotype × environment interactions were significant (p < 0.01) for grain yield and most other traits measured. Grain yield of the hybrids ranged from 3.3 to 4.7 t ha−1 for in the present study. The GGE biplot analysis identified genotype M1326-17 as the most stable and high yielding hybrid followed by M1326-14 and M1326-4. Test locations were divided into three groups; Ejura and Damongo constituting the first group; Kpeve, Fumesua, Nyankpala, Pokuasi and Yendi the second and Wa standing alone as the third. Damongo was highly discriminating and representative in the first group and was identified as a core test site in that group. Fumesua and Nyankpala were identified as core test sites within group two while Wa was identified as the only test site in group three. The core testing sites identified would be used to facilitate the identification of superior maize hybrids to reduce testing cost in the country.