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  • Author or Editor: Daniel M. Schaaf x
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Studies were conducted to evaluate the effect of stratification and seed age on percent seedling emergence of Penstemon. Emergence differences occurred between the eight Penstemon selections, as well as between seed stratification treatments and seed age. Seed stratification significantly increased emergence. Emergence varied from 0% with 1-year-old seed of Penstemon digitalis with no stratification, to 72.8% emergence with 2-year-old seed of P. angustifolius with 10 weeks of stratification. Seedlings from 3- to 4-year-old seed generally emerged as well as or better than with 1- and 2-year-old seed. Percent emergence varied significantly with stratification, seed age, and species. Some emergence occurred with species from seed up to 10 years old.

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Documenting the successful interspecific crosses in a genus is a valuable tool in making decisions in developing strategies for plant breeding activities. However, summarizing the breeding and hybridization can be confusing because of incomplete or lost breeding records and the failure to register the parentage of new cultivar names. A summary of interspecific crosses in the genus Penstemon at the University of Nebraska–Lincoln West Central Research and Extension Center over 10 years provides insight into both successful and unsuccessful crosses. The results, based on seed production and percent of successful crosses, would suggest that interspecific crosses are more likely to be successful when the parent species are more closely related.

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Severity of rust (Uromyces appendiculatus) and yield of dry edible beans (Phaseolus vulgaris L.) were recorded for 9 years in west-central Nebraska in fungicidal efficacy trials. A weighted analysis of covariance was used to estimate yield loss due to rust. The model fit the data well (R2 =0.94), and the slope over all years had a 19 kg.ha−1 decrease in yield for each 1% increase in severity of rust. Yield response within years occurred only through reduction of rust for most fungicide treatments.

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