Diallel Analysis and Evaluation of Parents and F<sub>1</sub> Progenies of Maize (<i>Zea mays</i> L.) for Tolerance to Drought and <i>Striga hermonthica</i> (Del.) Benth in the Guinea Savanna Agro-Ecological Zone of Ghana

Abstract

Field studies were conducted to evaluate 6 parents and 30 F1 hybrids of maize for tolerance to drought and Striga hermonthica in Nyankpala, Ghana during the 2014 and 2015 cropping seasons. These genotypes were evaluated for two years on single-row plots of three replicates, in a randomized complete block design. The control plants were planted in July each year which is the normal and usual time of planting of maize in the study area, whilst the water-stressed plants were planted six weeks later to ensure that their growth period coincides with the drought period. The Striga hermonthica infested plants were also planted at the normal time of planting maize in the study area. Results showed that highly negative significant GCA effect for the parent populations was observed in TAIS03, KOBN03-OB, DT-STR-W-C2 and IWD-C3-SYN-F2 for majority of the traits. The four parents were good general combiners for majority of the traits observed. For the F1 hybrids, KOBN03 × DT, DT × TAIS03, TAIS03 × KOBN03, IWD × GUMA03, GUMA03 × DT, GUMA03 × SISF03 and SISF03 × TAIS03 gave the highest negative significant SCA effect for most of the traits studied and are good specific combiners for the traits observed. The highly significant negative GCA and SCA effects of parents and F1 hybrids for majority of observed traits showed that those genotypes were highly tolerant to drought and/or Striga hermonthica. Drought rating, leaf-rolling rating, striga rating, striga count and Anthesis-Silking Interval (ASI) had been reduced significantly when plants were watered throughout the experimental period (control) as compared to the water-stressed and striga-infested plants. However, grain yield, hundred-grain weight, number of ears harvested, plant height, ear height, days to 50% anthesis, days to 50% pollen shed and days to 50% silking were significantly higher (p<0.05) for the normal (control) plants as compared to the water-stress and striga-infested plants. In drought-prevalent or striga-infested geographical areas like Northern Ghana, parent and F1 hybrid populations such as (TAIS03, KOBN03-OB, DT-STR-W-C2 and IWD-C3-SYN-F2) and (KOBN03 × DT, DT × TAIS03, TAIS03 × KOBN03, IWD × GUMA03, GUMA03 × DT, GUMA03 × SISF03 and SISF03 × TAIS03) respectively, can be used for increased grain yield.