Development of Nitrogen‐Efficient Prolific Hybrids of Maize1

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Abstract
Selection was conducted to develop single‐cross hybrids of maize (Zea mays L.) with high grain yield, high levels of prolificacy, and high values for the components of N‐use efficiency. Hybrid and S1 progenies were developed from reciprocal crosses and self‐pollinations of paired plants of the improved ‘Jarvis’ and ‘Indian Chief’ populations, JR10 and IRI0. Selection among hybrid S0 ✕ S0 progenies for high yield at high N and selection for two ears per plant in the parental lines was effective in increasing the number of ears per plant and N uptake, but it resulted in no increase in yield over the population hybrid, JR10 ✕ IR10. Subsequently, selection carried out among remaining hybrid S1 ✕ S1 progenies for five criteria (N‐use efficiency averaged over two levels of N supply, three components of N‐use efficiency, and ears per plant) was effective in improving yield at high N supply as well as N‐use efficiency, N‐uptake efficiency, and efficiency of utilization of accumulated N. Nitrogen‐use efficiency averaged over levels of N supply was the most effective selection criterion. In the selected prolific hybrids, both major components of yield (ears per plant and weight per ear) were highly correlated with grain yield. Of the six superior hybrids, five showed significant positive correlations between ears per plant and weight per ear.