Performance of intermediate maturing maize cultivars in drought-stressed and non-stressed environments in Ghana

Drought stress is a major production constraint of maize (Zea mays L.) in the lowland tropics. A study was conducted.to determine the yield potential and stability of five maize hybrids, three improved composites, and one local maize variety in favourable and drought-stressed maize production· environments in Ghana. The nine genotypes were evaluated at a total of 20 sites in the major agro-ecologicalzones of Ghana from 1995 to 1997. The 20 sites were divided into two environments (stress and non-stress) of 10 sites each, based on rainfall data during the growing season. Effects due to genotype (0" location (L), and G x L interactionwere highly significant (P<O.O I) for mid-silk, plant height, ear·acceptability, lodging, and grain yield in the stressed and non-stressed envi~onments. Grain yields averaged 3.58 Mg ha" in the stressed environmentand 6.67 Mg ha" in the non-stressed environment. On the average, the hybrids out-yielded the improved composites by 17.3 per cent and the local variety by 50.7 per cent in the stressed environment. In the non-stressed environment, the hybrids had an overall yield advantage of 11.6 and 60.2 per cent over the improved composites and the local variety, respectively. Estimates of Eberhart and Russel's stability parameters across both environmentsfor grain yield were b = 1.07, s' = 0.006 for the hybrids; b = 1.00, s' = 0.006 for the improved composites; and b = 0.61, s' = 0.008 for the looal variety. It was concluded from the study that the hybrids were more productive than the improved composites in the favourable as well as in the stressed environments, the hybrids were as stable as the improved composites across these diverse environments, and that the local variety showed low yield potentials in both environments. RESUME OBENo-ANTwI, K. , SALLAH, P. Y. K. & FiuMPoNo-MANSO, P. P.: Performance des varietes de mals de la maturite intermediaire dans les environnements de tension de secheresse el de non-tension au Ghana. La tension de secheresse est une contrainte majeure de la production de mars (Zea mays L.) dans les tropiques de la plaine. Une etude se deroulait pour determiner Ie potentiel de rendement et la stabilite de cinq hybrides de mals, trois composees ameliorees et une variete de maIs local dans les environnements favorables et tendus de secheresse pour la productionde mars au Ghana. Les neuf genotypes etaient evalues a 20 sites au total dans les zones agroeeologiquesmajeures du Ghana de 1995 a 1997. Les 20 sites etaient divises en deux environnements (tension et non-tension) de 10 sites chacun, base sur les donnees de pluie pendant la peri ode de pousse. Les effets dll au genotype (G), emplacement (E), et l'interaction G x E etaient hautement considerables (P< 0.01) pour mi-soies, taiIle de plante, acceptabilit6d'6pi, la verse et Ie rendement de grain dans les environnements de tension et de nontension. Les rendementsde grain ewent 3.58 Mg ha" de moyenne dans l'environnement de tension ct 6.67 Mg ha-' dans l'environIlement de non-tension. En moyenne, les hybrides surrendaient les composees ameliorees par 17.3 pour cent et la vari6te locale par 50.7 pour cent dans I'environnement de tension. Dans l'environnement de non-tension, les hybrides avaient un avantage de rendement total de 11.6 et 60.2 pour cent respectivement sur les composees ameliorees et la variet6 locale. Les estimationsdes parametres de stabilit6 d'Eberhart et Russel a travers les deux environnoments pour Ie rendoment de grain ewent b = 1.07, 8' = 0.006 pour les hybrides; b = 1.00, s' = 0.006 pour les composees ameliorees; et b = 0.61, s' = 0.008 pour la vari6t6 locale. La conclusion 6tait tir6e de l'6tudeque: les hybrides6taientplus productifs que les composCes am6lior6es dans l'environnement favorableainsique daDsoeluide tenlIion; leahybridesewent aussi stables que "lescomposeea am6lior6es a travers ces Original scientific paper. Received 23 Dee 99; revised 28