Variability and Breeding Behavior in Big Bluestem Populations from Eastern South Dakota

Three spaced-plant big bluestem (Andropogon gerardii Vit.) nurseries at Brookings, South Dakota were analyzed for their genetic variability and agronomic potential. Unselected native collections, the 1972 nursery, was comprised of 34 strains each representing a site collection from the eastern edge of South Dakota. The first cycle recurrent selection nursery, established in 1977, was comprised of progeny of 19 plants from the 1972 nursery that were exceptional seed producers in the drought year 1976. The second cycle recurrent selection nursery, established in 1976, was comprised of progeny of 33 agronomically desirable plants from open-pollinated nurseries established from difference southeastern South Dakota collections. These collections were from selected plants in relict colonies in southeastern South Dakota. The objectives of this study were to describe the variation in the populations studied, to estimate heritabilities of the agronomically desirable characteristic and to determine the most efficient breeding methods to produce a superior variety. Higher significant differences for seed yield, vigor, leafiness and plant height were found among strains in the 1972 nursery and among half-sib families in the 1976 and 1977 nurseries. Highly significant differences for seed weight were found among families in the 1976 and 1977 nurseries. Broad sense heritability estimates for strains were high plant height, heading date and pollination date in the 1972 nursery. Narrow sense heritability estimates based on one year’s data were extremely high for seed weight, plant height, vigor, leafiness, number of flowering culms and seed yield in the 1977 nursery. Positive assortative mating (like to like) must have been responsible for inflationary effects on the heritability estimates. Narrow sense heritability estimates based on two years’ data were moderately high for vigor, leafiness and plant height in the 1976 nursery. Estimates based on one year’s data were moderately high for seed yield and fertility index and very high for seed weight. Phenotypic and genetic correlations between agronomic characters in the 1976 and 1977 nurseries were generally positive, indicating that simultaneous multitrait selection for forage and seed characters would be profitable. Multiple regression and path coefficient analysis of seed yield components in the 1977 nursery indicated that number of flowering culms, size and/or number of racemes per culm and fertility index all contributed directly to seed yield. Number of flowering was the most important while size and/or number of racemes per culm and fertility index were both considerably more important than seed weight in determining seed yield. A composite made from open-pollinated seed of plants with heavy seeds (means 100 seed weight = .26g) from the 1976 nursery produced significantly taller seedlings than a composite comprised of plants selected for forage and seed yield (mean 100 seed weight = .20g) from the same nursery. A seed weight is highly heritable, mass selection for heavy seed should enhance seedling vigor. Mass selection should be extremely effective for seed weight and plant height and moderately effective for seed yield, vigor, leafiness, fertility index and number of flowering culms. More precision in selection, however, for these characters would be possible based on progeny test data. No sizable negative genetic correlations between characters were observed, consequently simultaneous multitrait selection should be effective

Life History Studies, Host Records, and Morphological Description of Genitalia of Eurytoma tylodermatis Ashm. (Hymenoptera : Eurytomidae) from South Dakota

Eurytoma tylodermatis Ashm. was found to be parasitic on Acanthoscelides perforatus (Horn) in seed pods of Canada milk- vetch {Astragalus canadensis L.). Observations on larval behavior and frequency of parasitism are discussed. Male and female genitalia of E. tylodermatis are illustrated

A new Bruchophagus from Glycyrrhiza lepidota pursh in the Northern Great Plains (Hymenoptera : chalcidoidea : eurytomidae)

A new species, Bruchophagus grisselli McDaniel and Boe, which infests seeds of Glycyrrhiza lepidota Pursh (American licorice), is described and illustrated. It\u27s known from South Dakota and North Dakota in the USA. A field study at 8 sites showed that B. grisselli has a wide distribution throughout the Dakotas

Native Grass and Legume Biology and Establishment

https://openprairie.sdstate.edu/oak-lake_presentations/1000/thumbnail.jp

Fates of Ovules in Groundplum Milk-Vetch (Astragalus crassicarpus Nutt.) in South Dakota

Groundplum milk-vetch (Astragalus crassicarpus Nutt.) is a native legume found on gravelly to sandy prairie uplands throughout central North America. The large and fleshy fruits, or pods, of this species were consumed by indigenous people and European settlers, and are cached by rodents. Our previous research on native legumes of the northern Great Plains indicated seed predation by insects, notably bruchid beetles belonging to the genus Acanthoscelides Schilsky, was a dominant factor determining viable seed production in natural and artificial plant assemblages. However, although we have studied the reproductive biology of several species of Astragalus L., none had fleshy pods. Therefore, the objective of this study was to quantify the factors influencing viable seed production in natural populations of GPMV in South Dakota. Mature pods were collected from two natural populations on the South Dakota State University Oak Lake Field Station during July 2000 and from one natural population on the Grand River National Grassland near Lodgepole, SD, in July 2003. Pods were dissected and number of ovules that: 1) produced viable seed, 2) were unfertilized, 3) produced aborted seed, and 4) produced seeds that were predated by larvae of the bruchid beetle Acanthoscelides fraterculus (Horn) (Coleoptera: Chrysomelidae: Bruchinae) were recorded for each of the two valves of individual pods. Our results indicated average seed set, i.e., percent of ovules that produced viable seed not predated, was about 55%, averaged across populations. Unfertilized ovules were 42% of the total. Predation by the bruchid beetle occurred in about 2% of the developed seeds, with aborted seed making up the rest of the ovule total. About 35% of pods infested contained larvae, or adults that were immured within the pod while attempting to exit, presumably due to the thick and leathery layers of the ovary wall. Predispersal seed predation was a relatively minor factor in the reduction of viable seed set in GPMV in South Dakota

When to Neuter: The Controversy

In this day of pet overpopulation, many alternatives are being sought to control the reproduction of domestic canines and felines. One alternative discussed often is that of early spaying and early castration. Early, in this case, is any time before the usually suggested six to eight months (before the first heat cycle in the females). In the summer of 1993 in Minneapolis, the AVMA voted to endorse the concept of early-age spaying/ neutering. The topic of early spay/neuter always brings up the possible problems associated with this practice. Safe anesthesia in these juvenile patients is always a big concern, as is ease or ability to do the actual surgery. These concerns in kittens will be discussed in the following paragraphs. For the purpose of this discussion, a small, semi-scientific study was done