Search Results

You are looking at 11 - 20 of 175 items for :

  • Refine by Access: All x
Clear All
Free access

S. Brauner, R.L. Murphy, J.G. Walling, J. Przyborowski, and N.F. Weeden

DNA primers for 37 genes have been developed in pea (Pisum sativum L.). Two-thirds of these primers also amplify orthologous sequences in lentil (Lens culinaris). The primers were designed to be complementary to highly conserved sequences in exons of known genes. In addition, most of the priming sequences were selected to be 1000 to 3000 bp distant on the genomic DNA and to amplify a fragment that contained at least one intron. Segregating sequence polymorphism in mapping populations of recombinant inbred lines (RILs) derived from wide crosses in Pisum was observed by restriction of the amplified fragment with endonucleases recognizing four-base restriction sites. Successful mapping of 36 of these genes in pea demonstrated the utility of these primers for mapping, and it appears likely that the primers should have general utility for comparative mapping in legumes.

Free access

Charles J. Simon and Richard M. Hannan

Core subsets have been selected for the USDA chickpea (Cicer arietinum), lentil (Lens culinaris), and pea (Pisum sativum) germplasm collections. These subsets are specifically intended to increase the efficiency of the utilization of the entire collections of these taxa. The cores consist of 13% of the 3873 chickpeas, 12% of the 2390 lentils, and 17.5% of the 2886 pea accessions. They were selected by a proportional logarithmic model, and also contain additional accessions based upon documented concentrations of diversity. Each core has been screened for disease reactions, and results suggest that the cores can effectively direct germplasm users toward portions of the entire collections that contain resistant germplasm. These cores have also been useful for those interested in assessing the adaptation potential of these crops in new environments, because the entire range of adaptation is represented. Although cores may not always enhance access to germplasm with unique or extremely rare characteristics, the legume cores have been very useful for directing users toward desirable germplasm from defined geographic areas, and assisting users at the preliminary stages of germplasm evaluation.

Free access

Michael Dana, Ricky Kemery, Rosie Lerner, Clark Throssell, Philip Carpenter, Michael Kerper, and Melody Putnam

Damage caused by misapplication of herbicides in landscape management or drift from agricultural fields on to nearby landscape plantings is often difficult to diagnose. Symptoms may vary with herbicide, species that is damaged, and other factors. To address this need, a photo CD-ROM has been developed to help plant damage diagnosticians determine if damage has been caused by herbicides. Fourteen herbicides or herbicide combinations commonly used in turfgrass, landscape, or field crop production applications were applied to 21 taxa of landscape trees, shrubs, groundcovers, or herbaceous perennials. More than 800 photographic transparencies of damage symptoms (representing all 21 taxa and 12 herbicides) were taken, and 457 were selected for storage in the digitized photo CD format for rapid retrieval. In all cases, as damage symptoms were observed, they were photographically recorded using a Nikon FM camera with a 55-mm micro-NIKKOR lens and Fujichrome Velvia transparency film under ambient, sunlit conditions. Species and plant taxa lists are displayed and the CD-ROM is demonstrated.

Free access

Steven C. Wiest

Digitized photographic images of turf plots composed of bermudagrass, buffalo grass, tall fescue, and zoysiagrass were taken at a height of about 150 cm with a 28-mm lens. Fast Fourier transforms of these images were performed, and a radial plot of the power spectrum was obtained from each image. Hurst plots (log frequency vs. log intensity) were used to subtract “background” from the power spectra, so peaks would be more evident. The peak of the power spectrum occurs at the average spacing between leaves (more precisely, between areas of the canopy that reflects a significant amount of light) and defines the characteristic dimension. Zoysiagrass had the lowest characteristic dimension, while tall fescue had the highest. The width of the power spectrum is indicative of the variability of the characteristic dimension within the canopy. The minimum characteristic dimension (occurring at the highest frequency) was less than 1.7 cm, whereas all the other species had about the same minimum characteristic dimension of ≈1.9 cm. The maximum characteristic dimension was greatest for fescue (6.9 cm), followed by buffalo grass (3.8 cm), bermudagrass (3.3 cm), and zoysiagrass (2.8 cm). These results indicate that the characteristic dimension can be a useful tool for discriminating between turfgrass species in digitized images.

Free access

Steven J. Guldan, Charles A. Martin, Jose Cueto-Wong, and Robert L. Steiner

Five legumes [hairy vetch (Vicia villosa Roth.), barrel medic (Medicago truncatula Gaerth.), alfalfa (Medicago sativa L.), black lentil (Lens culinaris Medik.), and red clover (Trifolium pratense L.)] were interseeded into sweet corn (Zea mays L.) at last cultivation when sweet corn was at about the V9 (early) or blister (late) stage. The effect of legume interseeding on sweet corn yield, and late-season dry-matter and N yields of aboveground portions of the legumes was determined. Sweet corn yield was not affected by legume interseeding. In 1993, legume dry-matter yields were 1420 kg·ha–1 interseeded early and 852 kg·ha–1 interseeded late. Nitrogen yields were 49 kg·ha–1 interseeded early and 33 kg·ha–1 interseeded late. In 1994, dry-matter yields were 2760 kg·ha–1 interseeded early and 1600 kg·ha–1 interseeded late. Nitrogen yields were 83 kg·ha–1 interseeded early and 50 kg·ha–1 interseeded late. In 1993, barrel medic was the highest-yielding legume with dry matter at 2420 kg·ha–1 and N at 72 kg·ha–1 interseeded early, while red clover yielded the lowest with dry matter at 340 kg·ha–1 and N at 12 kg·ha–1 interseeded late. In 1994, dry-matter and N yields ranged from 4500 and 131 kg·ha–1, respectively, for early interseeded barrel medic to 594 kg·ha–1 and 16 kg·ha–1, respectively, for late interseeded red clover.

Full access

Steven J. Guldan, Charles A. Martin, William C. Lindemann, Jose Cueto-Wong, and Robert L. Steiner

Hairy vetch (Vicia villosa Roth.), barrel medic (Medicago truncatula Gaerth.), and black lentil (Lens culinaris Medik.) were interseeded into `New Mexico 6-4' chile pepper (Capsicum annuum L.) when plants were 8 to 12 inches tall or 12 to 16 inches tall in 1993 and 1994. Hairy vetch overwintered well both years, whereas barrel medic and black lentil did not. Spring aboveground dry mass yields of hairy vetch averaged 2.11 and 2.57 tons per acre in 1994 and 1995, respectively, while N accumulation averaged 138 and 145 pounds per acre in 1994 and 1995, respectively. Forage sorghum [Sorghum bicolor (L.) Moench] dry mass yield and N accumulation were significantly higher following hairy vetch than following the other legumes or no-legume control. There was no significant difference between forage sorghum yields following barrel medic, black lentil, or the no-legume control. Fertilizer replacement values (FRV) for the legumes were calculated from regression equations for forage sorghum dry mass yield as a function of N fertilizer rate. FRV for hairy vetch were at least 7-times higher than for either barrel medic or black lentil. Hairy vetch interseeded into chile pepper and managed as a winter annual can significantly increase the yield of a following crop compared to a nonfertilized control.

Full access

C.H. Blazquez, H.N. Nigg, L.E. Hedley, L.E. Ramos, and S.E. Simpson

Spectral reflectance measurements were taken from immature and mature leaves of `Rio Red' grapefruit `McCarty' grapefruit `Minneola' tangelo, `Satsuma' mandarin, `Dancy' tangerine, `Nagami' oval kumquat, and `Valencia' orange from 1330 to 1530 hr 1 day at the Florida Citrus Arboretum, Division of Plant Industry, Winter Haven, Fla. A PS-1000 spectrometer was used with fiber optic cables and a lens source (visible range of the spectrum 400-800 sun) coupled with a tungsten halogen light source. A data acquisition card was connected to a notebook computer with a SpectraScope computer program for processing and data storage. Immature and mature leaves of `Minneola' tangelo had greater percentage reflectance in the 500-800 sun range than the other cultivars and leaf ages measured. More detailed information was obtained with the PS-1000 than with conventional spectrometers. The slope of the citrus spectral curves in the 800 nm range was not as sharp as conventional spectrometers, but had a much higher reflectance value than those obtained with a different spectrometer. The system used here was convenient to transport and use in the field and produced clear, interpretable data.

Free access

Steven C. Wiest

A system for the digital analysis of photographic prints of turfgrass plots is being developed. The 3-year-old turfgrass plots included Meyer zoysiagrass, Midlawn bermudagrass, Prairie buffalograss and Mustang tall fescue. The plots were photographed by a camera with a small dual bubble level on the camera back and a 28-mm-wide angle lens. Photographs were digitized with flatbed scanners. The images can then be analyzed in a variety of ways. For example, a series of photographs were taken from mid-Sept. through late Oct 1995 and spectral analysis of the resultant digital images were made. The initial RGB (red-greenblue) format of the images was converted to HSI (hue-saturation-intensity) for analysis. The results indicate, obviously, that hue changed from 104 (i.e., green) to 75.7 degrees (i.e., brownish) between the beginning and end of Oct. 1995. Similarly, intensity changed from ≈0.12 to ≈0.16 during the same time period, indicating that the images became darker over time. These phenomena were observed in all four species examined. However, the saturation value evoked a significant species * date interaction. The three warm-season species showed a decrease in saturation, while Mustang had no significant decrease during Oct. Spectral as well as textural analysis are likely the two most useful techniques in the digital analysis of turfgrass plots. Examples of both will be presented.

Free access

Steven J. Guldan, Charles A. Martin, Jose Cueto-Wong, and Robert L. Steiner

Three legumes [hairy vetch (Vicia villosa Roth.), barrel medic (Medicago truncatula Gaerth.), and black lentil (Lens culinaris Medik.)] were interseeded into `New Mexico 6-4' chile pepper (Capsicum annuum L.) when plants were 20–30 cm tall (3 Aug., “early” interseeding) or when plants were 30–40 cm tall (16–17 Aug., “late” interseeding) in 1993 and 1994. Our objectives were to determine the effect of legume interseeding on cumulative chile yield, and late-season dry-matter and nitrogen yields of aboveground portions of the legumes. Legumes were harvested on 8 Nov. 1993 and 15 Nov. 1994. Chile yield was not significantly affected by legume interseeding. In 1993, legumes accumulated 57% more dry matter and 55% more N when interseeded 3 Aug. vs. 16 Aug. In 1994, legumes accumulated 91% more dry matter and 86% more N when interseeded 3 Aug. vs. 17 Aug. Aboveground dry-matter yields in 1993 ranged from 1350 kg·ha–1 for black lentil interseeded late to 3370 kg·ha–1 for hairy vetch interseeded early. Nitrogen yields ranged from 52 kg·ha–1 for black lentil interseeded late to 136 kg·ha–1 for hairy vetch interseeded early. In 1994, hairy vetch was the highest yielding legume with dry matter at 1810 kg·ha–1 and N at 56 kg·ha–1 interseeded early, while black lentil yielded the lowest with dry matter at 504 kg·ha–1 and N at 17 kg·ha–1 interseeded late. In the spring following each interseeding year, we observed that hairy vetch had overwintered well, whereas barrel medic and black lentil had not, except when a few plants of barrel medic survived the winter of 1994–95. Results from this study indicate that legumes can be successfully interseeded into chile in the high-desert region of the southwestern United States without a significant decrease in chile yield.

Free access

L.J. Grauke, Bruce W. Wood, and Marvin K. Harris

Long-established native tree populations reflect local adaptations. Representation of diverse populations in accessible ex situ collections that link information on phenotypic expression to information on spatial and temporal origination is the most efficient means of preserving and exploring genetic diversity, which is the foundation of breeding and crop improvement. Throughout North America, sympatric Carya species sharing the same ploidy level tend to hybridize, permitting gene flow that contributes to regional diversity and adaptation. The topographic isolation of many fragmented populations, some of which are small, places native Carya populations of United States, Mexico, and Asia in a vulnerable position and justifies systematic collection and characterization. The characterization of indigenous Mexican pecan and other Carya populations will facilitate use for rootstocks and scion breeding and will contribute to pecan culture. The Asian species, as a group, are not only geographically isolated from North American species, but also occur in disjunct, fragmented populations isolated from other Asian species. Section Sinocarya includes the members of the genus most vulnerable to genetic loss. With all species, recognition of utility based on characterization of ex situ collections may contribute to the establishment of in situ reserves. Global Carya genetic resources should be cooperatively collected, maintained, characterized, and developed. The integration of crop wild relatives into characterization and breeding efforts represents a challenging opportunity for both domestic and international cooperation. Genomic tools used on the accessible collections of the National Collection of Genetic Resources for Pecans and Hickories (NCGR-Carya) offer great potential to elucidate genetic adaptation in relation to geographic distribution. The greatest progress will be made by integrating the disciplines of genetics, botany, pathology, entomology, ecology, and horticulture into internationally cooperative efforts. International germplasm exchange is becoming increasingly complicated by a combination of protectionist policies and legitimate phytosanitary concerns. Cooperative international evaluation of in situ autochthonous germplasm provides a valuable safeguard to unintended pathogen exchange associated with certain forms of germplasm distribution, while enabling beneficial communal exploration and directed exchange. This is threatened by the “proprietary” focus on intellectual property. The greatest risk to the productive development of the pecan industry might well be a myopic focus on pecan production through the lens of past practice. The greatest limitation to pecan culture in the western United States is reduced water quantity and quality; in the eastern United States the challenge is disease susceptibility; and insufficient cold hardiness in the northern United States. The greatest benefit for the entire industry might be achieved by tree size reduction through both improved rootstocks and scions, which will improve both nut production and tree management, impacting all areas of culture. This achievement will likely necessitate incorporation of crop wild relatives in breeding, broad cooperation in the testing leading to selection, and development of improved methods linking phenotypic expression to genomic characterization. The development of a database to appropriately house information available to a diverse research community will facilitate cooperative research. The acquisition of funds to pursue development of those tools will require the support of the pecan industry, which in the United States, is regionally fragmented and focused on marketing rather than crop development.