scholarly journals Adaptability of Pecan as a Species

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1175-1189 ◽  
Author(s):  
Darrell Sparks
Keyword(s):  
Seed Germination ◽  
Nutrient Uptake ◽  
Soil Profile ◽  
Growing Season ◽  
Freeze Tolerance ◽  
The United States ◽  
Sympatric Species ◽  
Southern Limit ◽  
Geographical Regions ◽  
Selection For

Pecan [Carya illinoinensis (Wangenh.) C. Koch] is indigenous to the Mississippi River drainage system of the United States. Climate in the native pecan region ranges from humid to semiarid and from mild to harsh winters. Rainfall is bimodal with peaks in March to April and in August to September. Pecan is site specific and is the climax tree species on loamy, well drained, first bottom river land with a relatively high water table. Detrimental effects from pecan's shade intolerance from its more vigorous, sympatric species are minimized as these species are specific to differ sites. Pecan's deep and phreatophytic rooting habit ensures soil moisture during drought periods and facilitates pecan's survival in semiarid regions. Root development in the humus-surface layer ensures nutrient uptake from the most nutrient rich layer of the soil and, when the lower soil profile is saturated, aeration for the roots and water and nutrient uptake. The bimodal rain pattern replenishes soil profile moisture and its timing ensures seed germination, stand establishment, well-developed seed, and minimal drought stress. Natural selection for freeze tolerance and for minimum fruit development time allows survival in areas with harsh winters and short growing seasons. Regulation of seed germination and budbreak by heating and chilling results in pecan being native in cold and warm climates, greatly increasing the native range. The northern limit for pecan is dictated by heat units; the southern limit is restricted by lack of bimodal rains and vivipary. Reproductive stress is caused by the high lipid content of seed, but is counteracted by a long juvenile growth period of the seedling, by a small nut size and low percentage kernel, and by “off” production years of the tree. Nut and percentage kernel decrease as the growing season decreases which contributes to species survival in geographical regions with a short growing season. Selection for small nuts with low percentage kernel is enhanced by predators. Tree reserves are depleted by heavy production during “on” years and are replenished during “off”years. Perpetuation of pecan forests is apparently from sib/half sib seedlings following predator satiation while dissemination into new areas may be mainly by predators. Pecan and its pests successfully co-exist. Major defense against fruit feeders is escape in time, leaf feeders by biological associations and accommodation, and leaf diseases by confrontation. Heterozygous progenies from cross-pollination provide ample genetic diversity for continuous pecan selection to endure pressures imposed throughout a wide climatic range. Ecological adaptions within native pecan forests should be used in developing and maintaining commercial pecan orchards.

Evaluation of Factors That Influence Benghal Dayflower (Commelina benghalensis) Seed Germination and Emergence

Weed Science ◽  
2012 ◽  
Vol 60 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Mercy H. Sabila ◽  
Timothy L. Grey ◽  
Theodore M. Webster ◽  
William K. Vencill ◽  
Donn G. Shilling
Keyword(s):  
Seed Germination ◽  
Soil Profile ◽  
The United States ◽  
Response To Treatment ◽  
Effect Of Temperature ◽  
Physical Dormancy ◽  
Planting Depth ◽  
Commelina Benghalensis ◽  
Primary Means ◽  
Benghal Dayflower

A perennial species in its native range of Asia and Africa, Benghal dayflower in North America establishes annually from seed. This species has the unique ability to produce aerial and subterranean flowers and seeds. Information on how various environmental factors affect Benghal dayflower aerial and subterranean seed germination and emergence in the United States is lacking. Studies were conducted to determine the effect of temperature, planting depth, salt concentration, and pre-emergence herbicides on germination or emergence of aerial and subterranean Benghal dayflower seed. Maximum aerial seed germination occurred at 30 C, whereas maximum subterranean seed germination occurred at 30 and 35 C. Germination at 40 C was delayed relative to optimum temperatures. The seed coats in this study were mechanically disrupted to evaluate the response of seeds to temperature in the absence of physical dormancy. The physical dormancy imposed by the seed coat could require additional study. Benghal dayflower was not tolerant to ≥ 10 mM NaCl, indicating that this exotic species is not likely to become problematic in brackish marshes and wetlands of coastal plain regions. There was an inverse linear response of Benghal dayflower emergence and planting depth, with no emergence occurring at a planting depth of 12 cm. A field survey of Benghal dayflower emergence revealed that 42% of plants established from a depth of 1 cm in the soil profile, with 7 cm being the maximum depth from which seedlings plants could emerge. This suggests that PRE herbicides must remain in the relatively shallow depths of the soil profile to maximize control of germinating seedlings. Subterranean seeds were less sensitive than aerial seeds toS-metolachlor, the primary means of controlling this species in cotton. There were no differences between the germination of aerial and subterranean seed in response to treatment with diclosulam.

scholarly journals Using a Buckwheat Cover Crop for Maximum Weed Suppression after Early Vegetables

2013 ◽  
Vol 23 (5) ◽  
pp. 575-580 ◽  
Author(s):  
Thomas Björkman ◽  
Joseph W. Shail
Keyword(s):  
United States ◽  
Cover Crop ◽  
Field Experiments ◽  
Growing Season ◽  
The United States ◽  
Weed Suppression ◽  
Optimal Timing ◽  
Northeastern United States ◽  
Geographical Regions ◽  
Short Growing Season

Establishment of a weed-suppressive cover crop after vegetables harvested early in the season is important in the northeastern United States because of the short growing season. Buckwheat (Fagopyrum esculentum) is an effective cover crop in vegetable production because of its short growing season, ability to outcompete many weeds, resistance to damage by insects and disease, and requirement for only moderate soil fertility. In two separate 3-year field experiments, we determined the best tillage techniques and the optimal timing for use of buckwheat as a cover crop after early vegetables in the northeastern United States. Incorporating crop residue with a disk was necessary and provided sufficient tillage to obtain a weed-suppressive buckwheat stand. Buckwheat growth was stunted when direct seeded with a no-till drill immediately after pea (Pisum sativum) harvest because of poor soil penetration by buckwheat roots. Planting buckwheat after incorporating the pea crop was successful; waiting 1 week to plant was optimal, whereas a 2-week wait produced a weaker stand. We determined that optimal timing for sowing buckwheat in central New York was late June to early August. Generalizing to other geographical regions in the United States, we calculated that a minimum accumulation of 700 growing degree days is necessary to reach 1 to 1.5 tons/acre of buckwheat dry matter at the appropriate growth stage for incorporation (6 weeks after sowing).

Pre-conceptual sex selection

2014 ◽  
Vol 155 (46) ◽  
pp. 1815-1819
Author(s):  
Máté Julesz
Keyword(s):  
Catholic Church ◽  
The United States ◽  
Criminal Code ◽  
Sex Selection ◽  
Reproductive Justice ◽  
Medically Assisted Procreation ◽  
Family Balancing ◽  
European Health ◽  
Selection For ◽  
The Catholic Church

According to Article 14 of the Oviedo Convention on Human Rights and Biomedicine of the Council of Europe, the use of techniques of medically assisted procreation shall not be allowed for the purpose of choosing a future child’s sex, unless serious hereditary sex-related disease is to be avoided. In Israel and the United States of America, pre-conceptual sex selection for the purpose of family balancing is legal. The European health culture does not take reproductive justice for part of social justice. From this aspect, the situation is very similar in China and India. Reproductive liberty is opposed by the Catholic Church, too. According to the Catholic Church, medical grounds may not justify pre-conceptual sex selection, though being bioethically less harmful than family balancing for social reasons. In Hungary, according to Section 170 of the Criminal Code, pre-conceptual sex selection for the purpose of family balancing constitutes a crime. At present, the Hungarian legislation is in full harmony with the Oviedo Convention, enacted in Hungary in 2002 (Act No. 6 of 2002). Orv. Hetil., 2014, 155(46), 1815–1819.

Dormancy-breaking Studies on Echinacea angustifolia

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 456f-457 ◽  
Author(s):  
Ali O. Sari ◽  
Mario R. Morales ◽  
James E. Simon
Keyword(s):  
Native Americans ◽  
Seed Germination ◽  
Tap Water ◽  
The United States ◽  
Market Demand ◽  
Dormancy Breaking ◽  
Echinacea Angustifolia ◽  
Native Populations ◽  
Percent Germination ◽  
Dry Heating

Echinacea is a medicinal plant native to North America. It was used extensively by native Americans in the treatment of their ailments. It is presently one of the most popular medicinal plants in the United States. Its popularity has created a large market demand for the roots and foliage of the plant. The gathering of echinacea from the wild is leading to the reduction of native populations and the destruction of its genetic diversity. Cultivation of medicinal echinaceas is hindered by a low seed germination. Dormancy breaking studies were done on freshly harvested seeds of Echinacea angustifolia. Seed lots were placed under light at a constant temperature of 25 °C and at alternate temperatures of 25/15 °C for 14/10 h, respectively. Germination was more rapid and uniform and percent germination higher at 25 °C than at 25/15 °C. Seed tap-water soaking, dry heating, and sharp heating alteration did not increase germination. The application of 1.0 mM ethephon (2-chloroethylphosphoric acid) increased seed germination to 94% at 25 °C and 86% at 25/15 °C. Untreated seeds gave 65% germination at 25 °C and 11% at 25/15 °C. The application of 2500 mg·L–1 and 3500 mg·L–1 of GA to dry seeds and 2500 mg·L–1 to seeds that have been soaked under tap water and then dried increased germination to 82%, 83%, and 83% at 25 °C and 64%, 78%, and 64% at 25/15 °C, respectively.

scholarly journals Prevalence of single and coinfections of human pathogens in Ixodes ticks from five geographical regions in the United States, 2013–2019

2021 ◽  
Vol 12 (2) ◽  
pp. 101637
Author(s):  
Aine Lehane ◽  
Sarah E. Maes ◽  
Christine B. Graham ◽  
Emma Jones ◽  
Mark Delorey ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Human Pathogens ◽  
Geographical Regions ◽  
Ixodes Ticks

scholarly journals Relation of therapies for ankylosing spondylitis and psoriatic arthritis to risk of myocardial infarction: a nested case control study

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Rachael Stovall ◽  
Christine Peloquin ◽  
David Felson ◽  
Tuhina Neogi ◽  
Maureen Dubreuil
Keyword(s):  
Myocardial Infarction ◽  
Psoriatic Arthritis ◽  
Ankylosing Spondylitis ◽  
Case Control Study ◽  
Tumor Necrosis Factor Inhibitor ◽  
The United States ◽  
Case Control ◽  
Geographical Regions ◽  
Nested Case Control ◽  
Control Study

Abstract Background Risk of myocardial infarction (MI) is elevated in ankylosing spondylitis and psoriatic arthritis (AS/PsA) compared to the general population. We evaluated the risk of MI related to the use of tumor necrosis factor inhibitor (TNFi) and other therapies in AS/PsA. Methods We conducted a nested case-control study using 1994–2018 data from OptumLabs® Data Warehouse, which includes de-identified medical and pharmacy claims, laboratory results, and enrollment records for commercial and Medicare Advantage enrollees. The database contains longitudinal health information on enrollees and patients, representing a diverse mixture of ages, ethnicities and geographical regions across the United States. Assessing AS/PsA separately, MI cases were matched to 4 controls by sex, age, diagnosis year and insurance type. We evaluated treatment within 6 months prior to MI including NSAIDs (AS referent), disease-modifying anti-rheumatic drug (DMARDs; PsA referent) and TNFi alone or in combinations. We evaluated the relation of treatment categories to MI risk using conditional logistical regression adjusting for confounders. Results Among 26,648 AS subjects, there were 237 MI cases and 894 matched controls. Among 43,734 PsA subjects, there were 404 cases and 1596 controls. In AS, relative to NSAID use, the adjusted odds ratio (aOR) for MI among TNFi only users was 0.85 (95% CI 0.39–1.85) and for DMARD only users was 1.04 (95% CI 0.65–1.68). In PsA, relative to DMARD use, the aOR among TNFi only was 1.09 (95% CI 0.74–1.60). Combination therapies also had no effect. Conclusions Among AS/PsA, no combination of therapies appeared to be protective or harmful with regards to MI. Future studies should capture more AS and PsA patients and include longer term follow up to further investigate this question.

Market, timber pricing, and forest management

2010 ◽  
Vol 86 (5) ◽  
pp. 580-588 ◽  
Author(s):  
Shashi Kant
Keyword(s):  
Forest Management ◽  
Economic Efficiency ◽  
Sustainable Forest Management ◽  
The United States ◽  
Residual Value ◽  
Market Economic ◽  
Geographical Regions ◽  
Optimal Mix ◽  
Optimal Resource ◽  
Social Optimality

Some resource economists and policy-makers believe that market mechanisms in general and timber pricing through auctions specifically are the only solutions for forest management in Canada. In this paper, simple economic concepts of market, economic efficiency, and social optimality are discussed, and the specific features of forest resources and sustainable forest management and their implications for optimal resource allocation through the market are highlighted. Economic theory behind competitive timber pricing in two geographical regions is presented to demonstrate that in a competitive setting, the prices of timber need not be the same in the two regions. Timber pricing mechanisms used by different countries are summarized, and auctions, their limitations, and some important outcomes of timber auctions by the United States Forest Service are discussed. Market performances of residual value and auction-based timber pricing are compared. On the basis of these discussions, it is inferred that sustainable forest management cannot be achieved either by the market or by government-controlled mechanisms only. An optimal-mix of the market and government-controlled mechanisms is the only answer to achieve sustainable forest management. Key words: auction, Canada, economic efficiency, market, residual value, social optimality, sustainable forest management, timber pricing

Site Selection Bias in Program Evaluation *

2015 ◽  
Vol 130 (3) ◽  
pp. 1117-1165 ◽  
Author(s):  
Hunt Allcott
Keyword(s):  
United States ◽  
Selection Bias ◽  
Site Selection ◽  
The United States ◽  
Randomized Control Trials ◽  
Program Evaluations ◽  
Out Of Sample ◽  
Target Treatment ◽  
Randomized Control ◽  
Selection For

Abstract “Site selection bias” can occur when the probability that a program is adopted or evaluated is correlated with its impacts. I test for site selection bias in the context of the Opower energy conservation programs, using 111 randomized control trials involving 8.6 million households across the United States. Predictions based on rich microdata from the first 10 replications substantially overstate efficacy in the next 101 sites. Several mechanisms caused this positive selection. For example, utilities in more environmentalist areas are more likely to adopt the program, and their customers are more responsive to the treatment. Also, because utilities initially target treatment at higher-usage consumer subpopulations, efficacy drops as the program is later expanded. The results illustrate how program evaluations can still give systematically biased out-of-sample predictions, even after many replications.

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