Low temperature induced metabolic regulation in maize crop is coupled to nitrification and denitrification processes

Maize is an important cereal crops however, its growth is retarded in response to environmental stimuli although the mechanism is not clarified. In this respect, plants (Zea mays L.) were grown in plastic pots and were given low temperature (4~8 oC) for 24h, 48h and 72h in cold chamber. In response to low temperature for 24h, the amount of protein was increased (34.72%) compared to control plants kept in ambient temperature. Similarly, the amount of protein was increased by 64.68% and 16.28% for 48h and 72h respectively however, the effects were pronounced at 48h of treatment. Low temperature was shown to enhance PPO activity by 291.52% and 79.79% respectively after 24h and 48h while the effects were assumed to be reduced after 72h. H2O2 plays the potential role on signaling of diverse molecules and is regulated by low temperature stress. In separate studies, plants were exposed to cold for 24h, 48h and 72h periods and the accumulation of H2O2 in the extract was determined. H2O2 was exaggerated by 19.59%, 15.54% and 62.16% respectively compared to respective controls. It is assumed that the above findings are coupled to nitrification and denitrification process. Therefore, we also examined the effect of low temperature on nitrate content in maize tissue extract. Nitrate accumulation in response to low temperature was increased by 23.41% and 25.30% respectively after 24h and 48h. Similarly, accumulation of nitrate after 72h was recorded as 21.97% when compared to respective controls. Nitrate accumulation and degradation are consecutive processes. The results show clearly that H2O2 induced biological processes in seedlings are coupled to internal nitrification and denitrification processes. published by the Journal of Biodiversity and Environmental Sciences | JBES