Photoperiod sensitivity in tropical maize accessions, early inbreds, and their crosses

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Mungoma, Catherine
Major Professor
Linda M. Pollak
Wilbert A. Russell
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The Department of Agronomy seeks to teach the study of the farm-field, its crops, and its science and management. It originally consisted of three sub-departments to do this: Soils, Farm-Crops, and Agricultural Engineering (which became its own department in 1907). Today, the department teaches crop sciences and breeding, soil sciences, meteorology, agroecology, and biotechnology.

The Department of Agronomy was formed in 1902. From 1917 to 1935 it was known as the Department of Farm Crops and Soils.

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  • Department of Farm Crops and Soils (1917–1935)

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Six tropical maize populations and five testers were used to characterize critical daylengths, to determine which tester reduced time to flowering when crossed to tropical populations, and to determine whether there was a population x tester interaction for genes controlling photoperiod. The six populations were: (1) Caingang (BOV 78) from Brazil; (2) Negro de Tierra Caliente (GUA 146) (NDTC-146) from Guatemala; (3) Lenha (RGS XX) from Brazil; (4) Negrito from Colombia; (5) Costeno (VEN 453) from Venezuela; and (6) Negro de Tierra Caliente (GUA 159) (NDTC-159) from Boliva. The testers were: (1) Zapalote Chico (Z. Chico), a population from Mexico; (2) B14A, an inbred of Iowa Stiff Stalk Synthetic background; (3) Oh43, an inbred of Lancaster Sure Crop background; (4) CM105, an inbred of Iowa Stiff Stalk Synthetic background; and (5) A654HT, an inbred of Reid Yellow Dent background. These plant materials were evaluated as populations and testers per se and also as testcrosses under decreasing periods of light in the growth chamber. The testcrosses were also evaluated in three field environments;Significant differences were found among populations and testers per se and among testcrosses for days to tassel emergence in the growth chamber evaluations. Days to tassel emergence for populations and testers occurred during four photoperiods, while in the testcrosses they occurred during two photoperiods. Among the tropical populations, the least photoperiod sensitive was NDTC-146, followed by Caingang, Costeno, Lenha, Negrito, and NDTC-159. The least photoperiod sensitive tester was CM105, followed by OH43, Z. Chico, B14A, and A654HT. There were significant differences among testcrosses, and populations in the combined analysis for days to pollen shed for the field environments. The testers and populations x testers interaction mean squares were not significant. Populations, therefore, performed in a similar manner in their crosses with different testers. Two testers, CM105 and A654HT, produced the earliest population crosses over all environments;Crossing tropical populations to adapted Corn Belt testers can bring the population cross to a maturity level where is can be evaluated for agronomic traits in Iowa. It was, however, not possible to determine which tester would reduce the time to flowering the most.

Fri Jan 01 00:00:00 UTC 1988