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Corn (Zea Mays L.) Yield Response To Nitrogen Fertilizer In Conventional And Alternative Rotations, M. M. Harbur, M. Ghaffarzadeh, R. M. Cruse
Corn (Zea Mays L.) Yield Response To Nitrogen Fertilizer In Conventional And Alternative Rotations, M. M. Harbur, M. Ghaffarzadeh, R. M. Cruse
Journal of the Iowa Academy of Science: JIAS
Nitrogen (N) fertilization recommendations are not available for corn in rotation with small grains or forages despite the possibility that the N response may differ from that of more conventional corn-soybean rotations. Rotations of corn with soybean (CS), corn with soybean and oat (CSO) and corn with soybean and an oat/berseem clover intercrop (CSOB) were established in 1991 and studied from 1993 through 1998 to determine the optimal N fertilization level for corn produced in each rotation. Corn in each rotation received NH4N03 applied at the rates of 0, 56, 112, or 168 kg N ha-1. Significant differences …
Higher Population And Twin Row Configuration Does Not Benefit Strip Intercropped Corn, M. M. Harbur, R. M. Cruse
Higher Population And Twin Row Configuration Does Not Benefit Strip Intercropped Corn, M. M. Harbur, R. M. Cruse
Journal of the Iowa Academy of Science: JIAS
Increased corn (Zea mays L.) grain yield with strip intercropping, made possible because of increased edge effects, makes this soil-conserving crop production system appealing to farmers. The objective of this study was to determine the population and row configuration needed to optimize the additional yield potential in each outside corn row. Treatments 'included: 74, 99, and 124 thousand plants ha-1 were grown in twin rows and 74 thousand plants ha-1 grown in single rows. Single rows or twin row centers were spaced 0.76 m. The experiment was conducted at four central Iowa sites during 1996 and 1997. Grain …
Inheritance And Number Of Genes Affecting Quantitative Traits Within F2 Maize Populations, D. H. Schmidt, A. R. Hallauer
Inheritance And Number Of Genes Affecting Quantitative Traits Within F2 Maize Populations, D. H. Schmidt, A. R. Hallauer
Journal of the Iowa Academy of Science: JIAS
Populations derived from crosses of elite genotypes are commonly used in plant breeding programs. Knowledge of the genetic variation among individuals and their progenies within F2 populations is essential for effective selection of important traits. The genetic variation and number of effective factors affecting the expression of quantitative traits within 30 F2 maize (Zea mays L.) populations were determined by different methods suggested for study of F2 populations. Estimates of heritability and number of effective factors varied among F2 populations for each trait, primarily because of the differences in trait expression between parents of crosses and the environmental effects upon …
Genetic Variation Among And Within S1 Progenies Of Maize, R. J. Getschman, A. R. Hallauer
Genetic Variation Among And Within S1 Progenies Of Maize, R. J. Getschman, A. R. Hallauer
Journal of the Iowa Academy of Science: JIAS
Inbred line development consumes a great portion of the breeder's time and resources in maize (Zea mays L.) breeding programs. Source populations for line development often are developed by selfing F2 populations developed from elite line crosses. Visual selection is practiced among and within selfed progenies during the selection process for one or two generations before evaluated in testcrosses for combining ability. Effective discrimination among and within inbred and testcross progenies depends on the amount of genetic variation present. The objective of this study was to determine the effectiveness of selection among and within S1 progenies developed from crosses …
Anatomical Characterization Of Western Corn Rootworm Damage In Adventitious Roots Of Maize, Walter E. Riedell, Alice Y. Kim
Anatomical Characterization Of Western Corn Rootworm Damage In Adventitious Roots Of Maize, Walter E. Riedell, Alice Y. Kim
Journal of the Iowa Academy of Science: JIAS
Corn rootworms are one of the most economically damaging insect pests of maize, yet little is known about the feeding behavior of the larvae. This study was conducted to determine which tissues of the adventitious roots of maize are damaged by western corn rootworm (Diabrotica virgifera virgifera LeConte) larval feeding. Root axes (10 cm long) were removed from the fifth node of greenhouse-grown maize plants. Root segments 2 cm long, excised 4 or 6 cm from the root tip, were infested with second or third stage larvae, respectively, (0, 1, 3, or 6 larvae per segment) for a period of …
Estimates Of Genetic Variability In F2 Maize Populations, Geng-Chen Han, A. R. Hallauer
Estimates Of Genetic Variability In F2 Maize Populations, Geng-Chen Han, A. R. Hallauer
Journal of the Iowa Academy of Science: JIAS
Maize (Zea mays L.) breeders emphasize selection within F2 populations derived from crosses of inbred lines: Studies of the inheritance of quantitative traits in maize have been conducted primarily for generically broad-based populations. Objectives of our study were to estimate the generic variability in F2 populations developed from crosses of related and unrelated lines and to determine the effects of five generations of random intermating of plants within F2 populations on the estimates of genetic variability. Estimates of additive genetic variability were greater in the unrelated line crosses, but the estimates were not significantly different before and …