Effect of Storage Temperatures on Phenotypic and Gene Expression of Maize (Zea mays L.) Genotypes

Introduction: Maize is an important cereal grown globally across wide range of altitude and latitude. Temperature is one of the factors that affect the viability of maize under storage conditions.

Aim: This study, therefore, assessed the effect of different temperature storage levels on the morphological characters and molecular variability of maize genotypes.

Materials and Methods: The seeds of maize genotypes: TZLCOMP4C3, EVDT-W200STRCO, POP66SR/ACR94, POOL18SR QPM, TZM 132, TZM 1291, EVDT- Y2008 STR and TZM 1326 obtained from the National Centre for Genetic Resources and Biotechnology (NACGRAB) Ibadan were stored at different temperature conditions of -80°C, -20°C, 5°C, 50°C, and 25°C for 6 hours. The stored maize was sown in perforated polythene bags containing 7 kg of soil and replicated thrice in a complete randomized design. The molecular variability was also investigated on the maize genotypes stored under the varying temperatures. The effect of storage temperature was significantly higher at 50°C for all growth characters but was not significant at -80°C.

Results: The genotypic effect on the growth characters was significantly (p< 0.05) higher in TZM 132 with plant height (99.09 cm), leaf length (46.54 cm), leaf width (3.05 cm), number of leaves (6.25) and stem length (50.12 cm). The contribution of principal component axis (PCA) showed that PC 1 had the height variation with a proportion of 47.17% and eigen value of 2.83 across the growth characters. Molecular evaluation showed that EVDT-W200STRCO had the highest DNA concentration of 4885.7 ng/μl at storage temperature of 25°C, while EVDT-W200STCO at -20°C recorded the least DNA concentration of 26.60 ng/μl. The highest DNA concentration across the maize varieties were recorded at -20°C (POOL18SR QPM, TZM 132 and TZM 1326), 5°C (TZLCOMP4C3), 25°C (EVDT-W200STRCO and EVDT- Y2008 STR) and 50°C (POP66SR/ACR94 and TZM 1291). OPB 10 had the highest allelic no, gene diversity and polymorphic information content of 15, 0.97 and 97.0% respectively. The genetic distance matrix established relationship among the stored maize genotypes.

Conclusion: Maize seeds can therefore be stored at temperature range of -20°C to 50°C depending on the variety, without losing its viability and molecular constituents.