Screening And Evaluation Of Some Genotypes Of Maize (Zea Mays L.) And Their F1 Hybrids For Tolerance To Drought And Striga Hermonthica (Del.) Benth

ABSTRACT 

Drought stress and striga parasitism are major constraints to maize (Zea mays L.) production in Northern Ghana. Two experiments were conducted to screen some genotypes of maize for tolerance to drought and Striga hermonthica at Nyankpala in the Guinea Savanna agro ecological zone of Ghana. In Experiment 1, seeds were planted in pots of 0.01 m3 volume arranged in rows on a platform in a screen house at Nyankpala. Genotypes were replicated three times in a completely randomized design. In another experiment (Experiment II), genotypes were evaluated in the field on single-row plots in three replicates using randomized complete block design. Results of screening from these two experiments showed that three of the genotypes; GUMA03-OB, KOBN03-OB and SISF03-OB were highly tolerant to drought, whilst another three genotypes, namely TAIS03, DT-STR-W-C2 and IWD-C3-SYN-F2 were highly tolerant to Striga hermonthica. The six genotypes stated above were crossed in complete diallel fashion to generate 30 F1 hybrids in Experiment III. The parents and their F1 hybrids were evaluated in Experiment IV for tolerance to drought and striga in two locations, that is, Nyankpala and Golinga under field conditions using randomized complete block design. Results on yield and other agronomic traits from field evaluation showed that highly negative significant (P < 0.001) GCA effect for the parent populations was observed in TAIS03, KOBN03-OB, DT-STR-W-C2 and IWD-C3-SYN-F2.  For the F1 hybrid populations, KOBN03 x DT, DT x TAIS03, TAIS03 x KOBN03, IWD x GUMA03, GUMA03 x DT, GUMA03 x SISF03 and SISF03 x TAIS03 gave the highest negative significant SCA effect for majority of the traits. Genomic DNA was extracted as reported in Experiment V with the CTAB method and polymerase chain reaction (PCR) was performed based on the common method for microsatellite markers. The PCR products were separated using 6% polyacrylamide denaturing gel. An amount of 17 microsatellites were then used to screen the parents and their F1 progenies for tolerance to drought and Striga hermonthica. The results of  the study indicated that the following F1 hybrid populations: IWD x TAIS03, IWD x GUMA03, DT x KOBN03, TAIS03 x IWD, TAIS03 x DT, TAIS03 x SISF03, SISF03 x TAIS03, SISF03 x GUMA03, GUMA03 x IWD, GUMA03 x DT and GUMA03 x KOBN03 contained the quantitative traits responsible for both drought and Striga hermonthica tolerance. The results of the molecular studies confirmed those from the field evaluation (Experiment IV). Therefore in drought-prone or striga-infested geographical areas like Northern Ghana, hybrid populations such as KOBN03 x DT, DT x TAIS03, IWD x GUMA03, GUMA03 x DT, GUMA03 x SISF03 and SISF03 x TAIS03 can be used for increased grain yield.