Comparative response of some tropical maize hybrid and their parental varieties to low and high nitrogen regime.

The study was carried to investigate the differential response of some maize hybrids and their open pollinated parents to low and high nitrogen soil condition. Ten open-pollinated varieties were crossed in a partial diallel fashion to generate 45 F hybrids during the 2011 cropping season at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. The 45 F hybrids and the ten parents were evaluated in four environments at Mokwa and Zaria in August, 2012 under high and low N conditions with two different levels of nitrogen application (30kgha and 90kgha) respectively. Hybrids recorded shorter plant height under the two different nitrogen fertilizer conditions compare with open pollinated parents. Thus the hybrids are better for mechanical harvesting. Taller ear height was observed among the hybrids compare with the open pollinated parents; rate of stem and root lodging were consequently higher among the hybrids. Hybrid had better husk cover under both nitrogen fertilizer regime; that's they will be less susceptible to insect and animal attack. Mean difference of ear per plant between the maize hybrids and open pollinated parents was not significant. Significant difference was observed between maize hybrids and their parents for grain yield under low and high fertilizer regimes. That the hybrids had higher grain yield under both nitrogen fertilizer regime; indicates the tolerance of maize hybrid to low-N condition than the parental varieties. Low-N environment seemed to favor shorter day to silk for maize hybrid, however, high nitrogen soil condition appeared to increase day to silk. It is an evidence that flowering and consequently maturity time is delayed under favorable nitrogen soil environments. Days to 50% pollen shed are significantly different among the maize hybrids and their parents. The maize hybrids attained day to pollen earlier than the parents under both fertilizer regime. It is an indication that setting of maize grain occur earlier among hybrids than their open pollinated parents.