Corn competition alters the germinability of velvetleaf (Abutilon theophrasti) seeds

Weed Science ◽  
2005 ◽  
Vol 53 (4) ◽  
pp. 479-488 ◽  
Author(s):  
Robert E. Nurse ◽  
Antonio DiTommaso
Keyword(s):  
Seed Production ◽  
Seed Coat ◽  
Cropping Systems ◽  
The United States ◽  
Planting Dates ◽  
Competitive Environments ◽  
Soil Seedbank ◽  
Growing Environment ◽  
Term Management

Velvetleaf is a troublesome annual weed in many cropping systems of the United States and Canada. Differences in the growing environment of parent plants can influence the number, structure, germinability, and viability of seeds produced. Thus, the effects across a range of competitive environments and corn planting dates on velvetleaf seed production, germination, and seed coat weight were examined under field conditions. Seed production of velvetleaf increased with increasing biomass. Total velvetleaf reproductive output was reduced in competition with corn compared with monoculture stands. Corn planting date had no effect on the dormancy status of seeds, but increased competition from corn resulted in up to a 30% decrease in the proportion of seeds that were dormant. Seed and seed coat weights also decreased for plants of velvetleaf grown in competition with corn compared with those grown in monoculture. These findings suggest that velvetleaf plants growing in relatively noncompetitive environments, such as along field edges or in field areas with poor crop stands, are likely not only to produce a greater number of seeds but also a greater proportion of seeds that are dormant. This alteration in the dormancy status of velvetleaf seeds in the absence or presence of a crop provides unique opportunities for effective long-term management of the soil seedbank in this species, especially for velvetleaf individuals bordering fields or growing in fallow areas that might require more stringent control because of increased seed dormancy.

Effect of tillage on timing ofSetariaspp. emergence and growth

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 563-570 ◽  
Author(s):  
Lizabeth A. B. Stahl ◽  
Gregg A. Johnson ◽  
Ronald L. Wyse ◽  
Douglas D. Buhler ◽  
Jeffrey L. Gunsolus
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Cropping Systems ◽  
Field Research ◽  
Herbicide Application ◽  
Tillage Systems ◽  
Early Application ◽  
Setaria Faberi ◽  
Tillage System ◽  
Soil Seedbank

Weed management can be a significant challenge in cropping systems, partly because the effects of tillage systems on weed seedbank and seedling population dynamics are not well understood. Field research was conducted from 1994 to 1996 in established tillage plots consisting of moldboard plow (MP), chisel plow (CP), and no-tillage (NT). The objectives were to determine the effects of long-term tillage systems on the timing and duration ofSetariaspp. emergence and percentage cumulative emergence from the soil seedbank and to investigate the effect of tillage onSetariaspp. density and seed production following glyphosate application atSetariaspp. heights of 5, 10, and 15 cm. NT contained a greater number ofSetariaspp. seed in the 0- to 1-, 1- to 3-, and 3- to 6-cm depths than MP or CP systems. There was little difference between the three tillage systems at depths greater than 6 cm.Setariaspp. emergence was greater in NT than in MP or CP in 1994 and 1996 and greater than in MP in 1995. There was a substantial increase inSetariaspp. emergence in NT between 3 and 4 weeks after planting (WAP) in 1994 and between 5 and 6 WAP in 1995 and 1996. Significant emergence did not occur past 5 to 6 WAP in 1994 and 1995 but continued over a longer period of time in 1996.Setariaspp. plants consistently reached targeted herbicide application heights 4 to 9 d earlier in NT than in CP and MP. In 1994, finalSetariaspp. density was greater in NT compared to CP and MP at the 5- and 10-cm herbicide application timings. When glyphosate was applied to 15-cm-tallSetaria, very few weeds were present following application across all tillage systems. In 1995, NT resulted in greaterSetariaspp. density than MP or CP across all application timings. There was no difference in finalSetariaspp. density between MP and CP across all glyphosate timings in 1994 and 1995. Seed production was negligible in MP and CP, regardless of glyphosate timing. In NT, however, significant seed production occurred, especially with early application. Results indicate that the effectiveness of nonresidual herbicides forSetaria faberiHerrm. control is influenced by tillage system and the timing of application.

Effects ofEriochloa villosadensity and time of emergence on growth and seed production inZea mays

Weed Science ◽  
1999 ◽  
Vol 47 (6) ◽  
pp. 687-692 ◽  
Author(s):  
James A. Mickelson ◽  
R. Gordon Harvey
Keyword(s):  
Seed Production ◽  
Field Experiments ◽  
Seed Mass ◽  
Model Parameters ◽  
Growth Stages ◽  
Vegetative Biomass ◽  
Eriochloa Villosa ◽  
Term Management ◽  
Weed Emergence

Field experiments were conducted in 1997 and in 1998 to determine the effects of density and time of emergence onEriochloa villosagrowth and seed production inZea mays. E. villosawas transplanted at four densities (3, 9, 27, and 81 plants m−2) to simulate emergence at four Z.maysgrowth stages (VE, V2, V5, and V10). Compared toE. villosaplants that emerged withZ. maysplants, total above-groundE. villosabiomass at maturity of plants grown at 3 plants m−2was reduced by 54, 97, and 99% when emergence was delayed until the V2, V5, and V10 stages ofZ. mays, respectively, in 1997. In 1998, total abovegroundE. villosabiomass at maturity was reduced by 70, 87, and 99% when emergence was delayed until the V2, V5, and V10 stages ofZ. mays, respectively.E. villosaaboveground vegetative biomass per plant at maturity was linearly related to seed production per plant in each year.E. villosaseed production m−2decreased nonlinearly as density decreased and time of emergence was delayed. Based on estimated model parameters, maximum seed production was 57,100 and 12,700 seeds m−2in 1997 and 1998, respectively. Within time of emergence,E. villosadensity did not affect seed mass per seed, however, seed mass of late-emerging cohorts was less than that of early-emerging cohorts. Time of weed emergence relative to the crop was a very important factor in determining biomass and seed production. Results suggest that late-emerging plants may not be very important to long-term management ofE. villosa.

scholarly journals Natural Suppression of Rhizoctonia Bare Patch in a Long-Term No-Till Cropping Systems Experiment

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 389-394 ◽  
Author(s):  
W. F. Schillinger ◽  
T. C. Paulitz
Keyword(s):  
Pacific Northwest ◽  
Cropping Systems ◽  
Spring Barley ◽  
The United States ◽  
Carthamus Tinctorius ◽  
Bare Patch ◽  
Yellow Mustard ◽  
No Till ◽  
Mapping Software

The soilborne fungus Rhizoctonia solani AG-8 is a major concern for farmers who practice no-till in the inland Pacific Northwest of the United States. Bare patches caused by Rhizoctonia spp. first appeared in 1999 during year 3 of a 15-year no-till cropping systems experiment near Ritzville, WA (269 mm of annual precipitation). The extent and pattern of patches were mapped each year from 1999 to 2012 at the 8-ha study site with a backpack-mounted global positioning system equipped with mapping software. Bare patches appeared in winter and spring wheat (SW; Triticum aestivum), spring barley (SB; Hordeum vulgare), yellow mustard (Brassica hirta), and safflower (Carthamus tinctorius). At its peak in years 5 to 7, bare patches occupied as much as 18% of total plot area in continuous annual monoculture SW. The area of bare patches began to decline in year 8 and reached near zero levels by year 11. No measurable patches were present in years 12 to 15. Patch area was significantly greater in continuous SW compared with SW grown in a 2-year rotation with SB. Additionally, the 15-year average grain yield for SW in rotation with SB was significantly greater than for continuous SW. Russian thistle (Salsola tragus), a troublesome broadleaf weed with a fast-growing tap root, was the only plant that grew within patches. This article reports the first direct evidence of natural suppression of Rhizoctonia bare patch with long-term no-till in North America. This suppression also developed in a rotation that contained broadleaf crops (yellow mustard and safflower) in all but 5 years of the study, and the suppression was maintained when safflower was added back to the rotation.

scholarly journals Redefining Hormone Sensitive Disease in Advanced Prostate Cancer

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Xiaoyu Hou ◽  
Thomas W. Flaig
Keyword(s):  
Prostate Cancer ◽  
Hormonal Therapy ◽  
Advanced Prostate Cancer ◽  
The United States ◽  
Castration Resistant ◽  
Hormonal Resistance ◽  
Hormone Sensitive ◽  
Hormone Resistant Prostate Cancer ◽  
Term Management

Prostate cancer is the most common cancer among men in the United States. For decades, the cornerstone of medical treatment for advanced prostate cancer has been hormonal therapy, intended to lower testosterone levels, known as Androgen Deprivation Therapy (ADT). The development of hormone-resistant prostate cancer (now termed castration-resistant prostate cancer:CRPC) remains the key roadblock in successful long-term management of prostate cancer. New advancements in medical therapy for prostate cancer have added to the hormonal therapy armamentarium. These new therapeutic agents not only provide a survival benefit but also show potential for reversing hormonal resistance in metastatic CRPC, and thus redefining hormonally sensitive disease.

U.S. Nuclear Defense Waste Program Current Development and Key Research Areas

1985 ◽  
Vol 50 ◽  
Author(s):  
Ray D. Walton ◽  
Kenneth A. Chacey
Keyword(s):  
Nuclear Waste ◽  
The United States ◽  
Management Program ◽  
Department Of Energy ◽  
Current Development ◽  
Research Areas ◽  
Develop Technology ◽  
Over 40 Years ◽  
Term Management

AbstractThe United States has been engaged in defense nuclear activities for over 40 years. The primary goal of the Defense Waste and Byproducts Management Program is to develop technology which ensures the safe, permanent disposal of all defense nuclear waste. Programs are in place at each U.S. Department of Energy site which address long-term strategy for permanent disposal of waste generated as a result of defense operations. Technology is developed for assessing the hazards, environmental impact, and cost of each long-term disposition alternative for selection and implementation. This paper addresses the key research areas and major facilities associated with the long-term management of defense nuclear waste.

Venice Mallow (Hibiscus trionum) Seed Production and Persistence in Soil in Colorado

1996 ◽  
Vol 10 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Philip Westra ◽  
Calvin H. Pearson ◽  
Randal Ristau ◽  
Frank Schweissing
Keyword(s):  
Seed Production ◽  
Seed Dormancy ◽  
Seed Coat ◽  
Crop Production ◽  
Hard Seed ◽  
Hibiscus Trionum ◽  
Soil Seedbank ◽  
Hard Seed Coat ◽  
Insight Into

This study was conducted to gain insight into the soil seedbank dynamics of Venice mallow in two irrigated Colorado soils. Venice mallow plants produced an average of 3100 seeds per plant under noncompetitive irrigated conditions. Venice mallow seeds collected from three regions of Colorado and stored at 25 C averaged 95% dormancy and less than 4% nonviable seeds 6 mo after harvesting. Percent nonviable seeds in soil remained relatively constant over 2 yr. Most seeds germinated within the first 3 mo after burial in the first crop production year. Seed dormancy decreased to an average of 40% after 3 mo of burial in cultivated soil at Fruita and Rocky Ford, and thereafter remained relatively constant for 21 mo. Fruita seeds underwent lessin situgermination than seeds from Greeley or Rocky Ford. Innate seed dormancy was lower at Fruita (27%) than at Rocky Ford (39%). Enforced dormancy remained constant over a 21-mo period and was similar for both locations (32%). Seeds buried for 2 yr at Fruita underwent greaterin situgermination (42%) than at Rocky Ford (27%). At Fruita, the level of enforced dormancy was higher and the level of innate dormancy lower at the 20-cm than the 2-cm depths. Venice mallow seed dormancy likely is due to an impermeable hard seed coat.

scholarly journals Betwixt and Between: Bridging the Gap Between Field and Repository

2018 ◽  
Vol 2 ◽  
pp. e27042
Author(s):  
Meghan Grizzle
Keyword(s):  
National Park ◽  
Field Work ◽  
The United States ◽  
Online Database ◽  
Archaeological Collections ◽  
Park Service ◽  
Set Up ◽  
Collections Care ◽  
Term Management

All too often, archaeologists have viewed curation as a process that manages, rather than investigates, archaeological and natural history collections. The curation crisis can be understood as the result of a serious imbalance between the continued generation of field collections and a corresponding lack of resources and facilities devoted to accessioning, analyzing, reporting, curating and otherwise caring for these collections. Researchers mistakenly prioritize ‘interpretation at the trowel’s edge’ with emphasis on excavation and field work, without considering the problem of how and where to store the objects they excavate. While legislation, Curation of Federally Owned and Administered Archaeological Collections (36 C.F.R. Part 79), was intended to ensure the long-term management and care of these resources, the absence of funding at the institutional and federal levels, nonexistent enforcement of the legislation through the National Park Service, and lack of compliance from field archaeologists, have resulted in collections throughout the United States being at risk of loss through deterioration, mismanagement, and neglect. I will demonstrate that accessioning, inventorying, cataloguing, rehousing and conserving are meaningful generative encounters between scholars, objects and collections staff, not simply byproducts of research. The need for an online database specifically set up for archaeological collections is suggested as a way to address the curation crisis. Implementing digitization will enhance preservation by reducing damage to the artifacts caused by physical handling. Persons working within the field will gain a better understanding of collections care and the collections transition to the repository.

Physician–patient shared decision making in the treatment of primary immunodeficiency: an interview-based survey of immunologists

2018 ◽  
Vol 5 (3) ◽  
pp. 100-114 ◽  
Author(s):  
Christopher C. Lamb
Keyword(s):  
Decision Making ◽  
Shared Decision Making ◽  
Primary Immunodeficiency ◽  
Treatment Guidelines ◽  
The United States ◽  
Shared Decision ◽  
Bias Power ◽  
Patient Health ◽  
Term Management

Background: Patient–physician shared decision making (SDM) can result in better care as well as reduced treatment costs. A better understanding of the factors predicting when physicians implement SDM during the treatment of primary immunodeficiency (PID) could provide insight for making recommendations to improve outcomes and reduce healthcare costs in PID and other long-term chronic conditions. Method: This study made use of grounded theory and was based on the interview responses of 15 immunologists in the United States. It focused on their decision making in the diagnosis and treatment of PID, how they interact with patients, and the circumstances under which they encourage SDM with patients. Results: All invited immunologists took part in the interviews and were included in the study. All but one had 10 or more years of experience in treating PID. The study found that SDM is bounded/limited by “nudging” bias, power balance considerations, and consideration of patient health literacy alignment. Immunologists also reported that they were mainly responsible for coordinating care and for allowing sufficient time for consultations. Conclusion: SDM occurs between the physician and patient throughout the treatment of PID. The study also shows the ways physicians influence SDM by guiding patients through the process. Statement of novelty: Little is known about the factors that influence SDM in the long-term management of chronic diseases. The present study investigated the extent to which immunologists experienced in the treatment of patients with PID include SDM in clinical practice. Findings such of these may be of use when formulating treatment guidelines and improving the effectiveness of long-term management of PID.

scholarly journals Flowering of the Cover Crop Sunn Hemp, Crotalaria juncea L.

HortScience ◽  
2017 ◽  
Vol 52 (7) ◽  
pp. 986-990 ◽  
Author(s):  
Robert L. Meagher ◽  
Rodney N. Nagoshi ◽  
James T. Brown ◽  
Shelby J. Fleischer ◽  
John K. Westbrook ◽  
...  
Keyword(s):  
Seed Production ◽  
Cover Crop ◽  
Warm Season ◽  
The United States ◽  
Agricultural Landscapes ◽  
Seeding Rate ◽  
Planting Dates ◽  
Crotalaria Juncea ◽  
Weed Growth ◽  
Sunn Hemp

Sunn hemp, Crotalaria juncea L., is a warm-season legume that is planted before or after a vegetable cash crop to add nutrients and organic matter to the soil, for weed-growth prevention, and to suppress nematode populations. Sunn hemp flowers may also provide nectar and pollen for pollinators and enhance biological control by furnishing habitat for natural enemies. Despite these benefits, adoption in the United States has been limited because of restricted availability of seeds, particularly in temperate climates. Experiments were conducted in north-central Florida to compare flowering and seed production of domestic and foreign sunn hemp lines across different seeding rates and planting dates. Our objectives were to test whether a low seeding rate would result in the production of higher numbers of flowers and to test whether planting earlier in the season would also result in higher numbers of flowers. Our results over a 2 year period showed that the domestic cultivar AU Golden is capable of substantial flowering and seed production in the test region, confirming the compatibility of local environmental conditions. Seed costs suggest that ‘AU Golden’ is comparable with sunn hemp lines grown in foreign countries and is much less expensive than the standard cultivar Tropic Sun from Hawaii. The results demonstrate the potential economic viability of early flowering cultivars of sunn hemp as a cover crop alternative in Florida to improve soils in agricultural landscapes.

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