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- Competition (4)
- Growth analysis (4)
- Functional equilibrium (3)
- Abutilon theophrasti (2)
- Biomass partitioning (2)
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- Duration of weed interference (2)
- Helianthus annuus (2)
- Integrated weed management (2)
- Interplant competition (2)
- Leaf area index (2)
- Ontogenetic drift (2)
- Optimal partitioning theory (2)
- Phenology (2)
- Resource acquisition (2)
- Soil organic matter (2)
- <i>Zea mays </i>LA new maize (<i>Zea mays</i> L.) simulation model (1)
- ABUTH (1)
- AMARE (1)
- AMATA (1)
- AMBTR (1)
- Amaranthus retroflexus (1)
- Amaranthus rudis (1)
- Ambrosia trifida (1)
- Angular dispersion (1)
- Application timing (1)
- Atrazine (1)
- Bioeconomic model (1)
- Chlorophyll (1)
- Common lambsquarters (1)
- Competitive index (1)
Articles 1 - 28 of 28
Full-Text Articles in Life Sciences
Maize Radiation Use Efficiency Under Optimal Growth Conditions, John L. Lindquist, Timothy J. Arkebauer, Daniel T. Walters, Kenneth G. Cassman, Achim Dobermann
Maize Radiation Use Efficiency Under Optimal Growth Conditions, John L. Lindquist, Timothy J. Arkebauer, Daniel T. Walters, Kenneth G. Cassman, Achim Dobermann
John L. Lindquist
Accurate measurement of crop growth and radiation use efficiency (RUE) under optimal growth conditions is required to predict plant dry matter accumulation and grain yield near the genetic growth potential. Research was conducted to quantify the biomass and leaf area index (LAI) accumulation, extinction coefficient, and RUE of maize (Zea mays L.) under conditions of optimal growth. Maize was grown in two environments over five growing seasons (1998–2002). Total aboveground biomass at maturity ranged from 2257 g m-2 in 1998 to 2916 g m-2 in 2001; values that are considerably greater than the biomass achieved in most previous studies on …
Comparative Ecophysiology Of Grain Sorghum And Abutilon Theophrasti In Monoculture And In Mixture, Samba Traoré, John L. Lindquist, Stephen Mason, Alex Martin, D. A. Mortensen
Comparative Ecophysiology Of Grain Sorghum And Abutilon Theophrasti In Monoculture And In Mixture, Samba Traoré, John L. Lindquist, Stephen Mason, Alex Martin, D. A. Mortensen
John L. Lindquist
Selection of crop genotypes that are more competitive with weeds for light interception may improve crop yield stability in the presence of weeds. The effects of interference on ecophysiological characteristics of Abutilon theophrasti Medic. and three morphologically diverse grain sorghum hybrids was evaluated to determine the relative tolerance and suppressive ability of the three hybrids and specific traits that may contribute to those differences. A tall hybrid was more tolerant to A. theophrasti interference than two medium stature hybrids. Early leaf area growth of two medium-stature sorghum hybrids was reduced by A. theophrasti interference, whereas early growth of a tall …
Common Lambsquarters (Chenopodium Album) Interference With Corn Across The North-Central United States, David W. Fischer, R. Gordon Harvey, Thomas T. Bauman, Sam Phillips, Stephen E. Hart, Gregg A. Johnson, James J. Kells, Philip Westra, John L. Lindquist
Common Lambsquarters (Chenopodium Album) Interference With Corn Across The North-Central United States, David W. Fischer, R. Gordon Harvey, Thomas T. Bauman, Sam Phillips, Stephen E. Hart, Gregg A. Johnson, James J. Kells, Philip Westra, John L. Lindquist
John L. Lindquist
Variation in crop–weed interference relationships has been shown for a number of crop–weed mixtures and may have an important influence on weed management decision-making. Field experiments were conducted at seven locations over 2 yr to evaluate variation in common lambsquarters interference in field corn and whether a single set of model parameters could be used to estimate corn grain yield loss throughout the north-central United States.
Influence Of Nitrogen And Duration Of Weed Interference On Corn Growth And Development, Sean P. Evans, Stevan Z. Knezevic, John L. Lindquist, Charles A. Shapiro
Influence Of Nitrogen And Duration Of Weed Interference On Corn Growth And Development, Sean P. Evans, Stevan Z. Knezevic, John L. Lindquist, Charles A. Shapiro
John L. Lindquist
An improved understanding of the effects of nitrogen (N) on crop–weed interactions is needed for the development of integrated weed management systems where responsible use of N fertilizers is considered. Field experiments conducted in 1999 and 2000 at two locations in eastern Nebraska quantify the effects of N and increasing duration of weed interference on corn growth and development. A naturally occurring population of weeds was allowed to compete with the corn crop for increasing lengths of time and at three rates of N application (0, 60, and 120 kg N ha-1). Weed interference and withholding applied N increased the …
Simulated Insect Defoliation And Duration Of Weed Interference Affected Soybean Growth, Travis C. Gustafson, Stevan Z. Knezevic, Thomas E. Hunt, John L. Lindquist
Simulated Insect Defoliation And Duration Of Weed Interference Affected Soybean Growth, Travis C. Gustafson, Stevan Z. Knezevic, Thomas E. Hunt, John L. Lindquist
John L. Lindquist
An improved understanding of crop stress from multiple pests is needed for better implementation of integrated pest management (IPM) strategies. Field studies were conducted in 2003 and 2004 at two locations in eastern Nebraska to describe the effects of simulated early-season insect defoliation of soybean and duration of weed interference on soybean growth. Three levels of simulated defoliation (undefoliated, 30, and 60%) and seven durations of weed interference (weedy and weed free; weed removal at V2, V4, V6, R3, and R5) were evaluated in a split-plot design. Defoliation significantly reduced soybean leaf-area index (LAI), total dry matter (TDM), and crop …
Light-Saturated Co2 Assimilation Rates Of Corn And Velvetleaf In Response To Leaf Nitrogen And Development Stage, John L. Lindquist
Light-Saturated Co2 Assimilation Rates Of Corn And Velvetleaf In Response To Leaf Nitrogen And Development Stage, John L. Lindquist
John L. Lindquist
Single-leaf CO2 assimilation rate under saturating light (CA) varies as a function of leaf nitrogen content per unit leaf area (NL). Measured CA for many crop species also declines with developmental stage. Because these relationships may have strong implications for crop–weed competition, a field experiment was conducted to quantify corn and velvetleaf CA as influenced by leaf NL and stage of development. Crop and weed CA were measured on the most recent fully expanded leaves of plants grown in four nitrogen (N) application treatments. Both corn and velvetleaf CA increased …
Hybrid-Maize—A Maize Simulation Model That Combines Two Crop Modeling Approaches, H. S. Yang, A. Dobermann, John L. Lindquist, Daniel T. Walters, Timothy J. Arkebauer, Kenneth G. Cassman
Hybrid-Maize—A Maize Simulation Model That Combines Two Crop Modeling Approaches, H. S. Yang, A. Dobermann, John L. Lindquist, Daniel T. Walters, Timothy J. Arkebauer, Kenneth G. Cassman
John L. Lindquist
A new maize (Zea mays L.) simulation model, Hybrid-Maize, was developed by combining the strengths of two modeling approaches: the growth and development functions in maize-specific models represented by CERES- Maize, and the mechanistic formulation of photosynthesis and respiration in generic crop models such as INTERCOM and WOFOST. It features temperature-driven maize phenological development, vertical canopy integration of photosynthesis, organ-specific growth respiration, and temperature-sensitive maintenance respiration. The inclusion of gross assimilation, growth respiration and maintenance respiration makes the Hybrid- Maize model potentially more responsive to changes in environmental conditions than models such as CERES-Maize. Hybrid-Maize also requires fewer genotype-specific …
A Simulation Approach For Evaluating Maize Yield Potential In Different Environments, Haishun S. Yang, Achim R. Dobermann, Kenneth G. Cassman, Daniel T. Walters, John L. Lindquist
A Simulation Approach For Evaluating Maize Yield Potential In Different Environments, Haishun S. Yang, Achim R. Dobermann, Kenneth G. Cassman, Daniel T. Walters, John L. Lindquist
John L. Lindquist
What is yield potential? To achieve yield potential of an environment: Why yield potential important? Objectives: Nebraska (NE): To estimate yield potential across NE requires: How to estimate yield potential across NE? Choice of model: Hybrid-Maize Simulation of best yields under current practices Current practices: best yields Current practices: variation of best yields To achieving full yield potential: Optimal management: gain in season length Optimal management: gain in yield Optimal management: temporal (mean=14 y) variation of yields Conclusions
Performance Of Weedsoft For Predicting Soybean Yield Loss, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
Performance Of Weedsoft For Predicting Soybean Yield Loss, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
John L. Lindquist
Decision support systems (DSSs) have been developed to assist producers and consultants with weed management decisions. WeedSOFT is a DSS currently used in several states in the northcentral region of the United States. Accurate estimates of crop yield loss due to weed interference are required for cost-effective weed management recommendations. WeedSOFT uses competitive indices (CIs) to predict crop yield loss under multiple weed species, weed densities, and relative times of weed emergence. Performance of several WeedSOFT versions to predict soybean yield loss from weed competition was evaluated using CI values in WeedSOFT version 9.0 compared to new CI values calculated …
The Influence Of Plant Population Spatial Arrangement On Individual Plant Yield, John L. Lindquist, D. Rhode, K. J. Puettmann, B. D. Maxwell
The Influence Of Plant Population Spatial Arrangement On Individual Plant Yield, John L. Lindquist, D. Rhode, K. J. Puettmann, B. D. Maxwell
John L. Lindquist
Two greenhouse experiments were conducted to evaluate the performance of individual oat (Avena sativa) target plants as influenced by neighbor oat plants with different spatial arrangements. Crop spatial arrangement was separated into three com- ponents: (I) population density, (2) distance between plants (distance dispersion, DD), and (3) angular arrangement of plants about one another (angular dispersion, AD). Distance dispersion was quantified using a weighted mean distance from a target individual to its neighbors. Angular dispersion of neighbors around the target was quantified using a measure of circular variance. DD and AD were combined to create a dispersion index (DI). At …
Critical Period For Weed Control: The Concept And Data Analysis, Stevan Z. Knezevic, Sean P. Evans, Erin E. Blankenship, Rene C. Van Acker, John L. Lindquist
Critical Period For Weed Control: The Concept And Data Analysis, Stevan Z. Knezevic, Sean P. Evans, Erin E. Blankenship, Rene C. Van Acker, John L. Lindquist
John L. Lindquist
The critical period for weed control (CPWC) is a period in the crop growth cycle during which weeds must be controlled to prevent yield losses. Knowing the CPWC is useful in making decisions on the need for and timing of weed control and in achieving efficient herbicide use from both biological and economic perspectives. An increase in the use of herbicide-tolerant crops, especially soybean resistant to glyphosate, has stimulated interest in the concept of CPWC. Recently, several studies examined this concept in glyphosate-resistant corn and soybean across the midwestern United States. However, these studies presented various methods for data analysis …
Influence Of Planting Date And Weed Interference On Sweet Corn Growth And Development, Martin M. Williams Ii, John L. Lindquist
Influence Of Planting Date And Weed Interference On Sweet Corn Growth And Development, Martin M. Williams Ii, John L. Lindquist
John L. Lindquist
Crop planting date and canopy density influence interactions between weeds and sweet corn (Zea mays L.); however, little is known about sweet corn growth response to weed interference. Field studies were conducted in 2004 and 2005 near Urbana, IL, to quantify the influence of planting date and weed interference on growth of sweet corn height, leaf area, aboveground biomass, and phenological development. Crop growth response to weed interference (presence or absence) was determined for sweet corn planted early May (EARLY) and late June (LATE). Dominant weed species included barnyard-grass [Echinochloa crus-galli (L.) Beauv.], common lambsquarters (Chenopodium album L.), common purslane …
Comparison And Hybridization Of Two Approaches For Maize Simulation, Haishun Yang, Kenneth G. Cassman, Achim R. Dobermann, Daniel T. Walters, John L.. Lindquist, Timothy J. Arkebauer
Comparison And Hybridization Of Two Approaches For Maize Simulation, Haishun Yang, Kenneth G. Cassman, Achim R. Dobermann, Daniel T. Walters, John L.. Lindquist, Timothy J. Arkebauer
John L. Lindquist
Two approaches dominate simulation modeling of maize growth: (1) a generic approach, represented by the family of crop models developed by Dutch scientists at the Wageningen University, e.g. SUCROS (Spitters et al, 1989), WOFOST (Diepen et al, 1989) and INTERCOM (Kropff and van Laar, 1993), and (2) a maize-specific approach, represented by CERES-Maize (Jones and Kiniry, 1986) and its derivatives such as the maize module in DSSAT, and the MSB model developed by Muchow et al. (Muchow et al, 1990). These two approaches differ in three aspects. First, maize development in generic models is driven primarily by availability of assimilate …
Effect Of Cultivation And Within-Field Differences In Soil Conditions On Feral Helianthus Annuus Growth In Ridge-Tillage Maize, Michael G. Burton, David A. Mortensen, John L. Lindquist
Effect Of Cultivation And Within-Field Differences In Soil Conditions On Feral Helianthus Annuus Growth In Ridge-Tillage Maize, Michael G. Burton, David A. Mortensen, John L. Lindquist
John L. Lindquist
Differences in weed population dynamics with respect to within-field heterogeneity are not well documented despite increasing interest in site-specific management of agro-ecosystems. The focus of this study was to determine if mechanical weed management (cultivation) and/or soil factors help to explain observed within-field distributions of feral common sunflower ( Helianthus annuus L.). The ridges and furrows created by the ridge–tillage system adds additional microsites to existing spatial heterogeneity for soil characteristics such as soil organic carbon (SOC) concentration. Experimental areas were selected on the basis of naturally high or low SOC concentration. Cultivation resulted in 100% mortality of H. annuus …
Soybean Row Spacing And Weed Emergence Time Influence Weed Competitiveness And Competitive Indices, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
Soybean Row Spacing And Weed Emergence Time Influence Weed Competitiveness And Competitive Indices, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
John L. Lindquist
Weed competitiveness can be quantified with the concept of competitive index (CI), a relative scale of weed competitiveness. Field studies were conducted in 2002 and 2003 in northeastern and southeastern Nebraska to evaluate the influence of soybean row spacing and relative weed emergence time on the competitiveness of major weed species in soybean. Ten weed species were seeded in soybean spaced 19 and 76 cm apart at the planting, emergence, and first trifoliate leaf stages of soybean. Total weed dry matter (TDM), weed plant volume, and percent soybean yield loss were arbitrarily selected as a base for determining the CI …
Effect Of Nitrogen Addition And Weed Interference On Soil Nitrogen And Corn Nitrogen Nutrition, John L. Lindquist, Sean P. Evans, Charles A. Shapiro, Stevan Z. Knezevic
Effect Of Nitrogen Addition And Weed Interference On Soil Nitrogen And Corn Nitrogen Nutrition, John L. Lindquist, Sean P. Evans, Charles A. Shapiro, Stevan Z. Knezevic
John L. Lindquist
Weeds cause crop loss indirectly by reducing the quantity of resources available for growth. Quantifying the effects of weed interference on nitrogen (N) supply, crop growth, and N nutrition may assist in making both N and weed management decisions. Experiments were conducted to quantify the effect of N addition and weed interference on soil nitrate-N (NO3- N) over time and the dependence of corn growth on NO3-N availability, determine the corn N nutrition index (NNI) at anthesis, and evaluate if relative chlorophyll content can be utilized as a reliable predictor of NNI. Urea was applied at 0, 60, …
Effect Of Nitrogen Addition On The Comparative Productivity Of Corn And Velvetleaf (Abutilon Theophrasti), Darren C. Barker, Stevan Z. Knezevic, Alex R. Martin, Daniel T. Walters, John L. Lindquist
Effect Of Nitrogen Addition On The Comparative Productivity Of Corn And Velvetleaf (Abutilon Theophrasti), Darren C. Barker, Stevan Z. Knezevic, Alex R. Martin, Daniel T. Walters, John L. Lindquist
John L. Lindquist
Weeds that respond more to nitrogen fertilizer than crops may be more competitive under high nitrogen (N) conditions. Therefore, understanding the effects of nitrogen on crop and weed growth and competition is critical. Field experiments were conducted at two locations in 1999 and 2000 to determine the influence of varying levels of N addition on corn and velvetleaf height, leaf area, biomass accumulation, and yield. Nitrogen addition increased corn and velvetleaf height by a maximum of 15 and 68%, respectively. N addition increased corn and velvetleaf maximum leaf area index (LAI) by up to 51 and 90%. Corn and velvetleaf …
Understanding Corn Yield Potential In Different Environments, Achim R. Dobermann, Timothy J. Arkebauer, Kenneth G. Cassman, Rhae A. Drijber, John L. Lindquist, James E. Specht, Daniel T. Walters, Haishun Yang, Daniel N. Miller, Darren L. Binder, Gregory J. Teichmeier, Richard B. Ferguson, Charles S. Wortmann
Understanding Corn Yield Potential In Different Environments, Achim R. Dobermann, Timothy J. Arkebauer, Kenneth G. Cassman, Rhae A. Drijber, John L. Lindquist, James E. Specht, Daniel T. Walters, Haishun Yang, Daniel N. Miller, Darren L. Binder, Gregory J. Teichmeier, Richard B. Ferguson, Charles S. Wortmann
John L. Lindquist
The UNL research program on Ecological intensification of irrigated maize-based cropping systems aims to (i) improve understanding of the yield potential of corn and soybean and how it is affected by management, (ii) develop a scientific basis for evaluating yield potential at different locations, (iii) develop practical technologies for managing intensive cropping systems at 70-80% of the yield potential, and (iv) conduct integrated assessment of productivity, profitability, input use efficiency, soil carbon sequestration, energy and carbon budgets, and trace gas emissions. Results of this work have been reported earlier (Arkebauer et al., 2001; Dobermann et al., 2002). In this paper …
Influence Of Soybean Row Width And Velvetleaf Emergence Time On Velvetleaf (Abutilon Theophrasti), Shawn M. Hock, Stevan Z. Knezevic, Alex R. Martin, John L. Lindquist
Influence Of Soybean Row Width And Velvetleaf Emergence Time On Velvetleaf (Abutilon Theophrasti), Shawn M. Hock, Stevan Z. Knezevic, Alex R. Martin, John L. Lindquist
John L. Lindquist
Row spacing and the relative time of velvetleaf emergence affects the time of soybean canopy closure relative to velvetleaf, influencing the growth and development of velvetleaf. Field studies were conducted in northeastern Nebraska in 2002 and 2003 to describe velvetleaf growth as influenced by soybean presence or absence (velvetleaf grown with soybean or in monoculture), soybean row spacing (19 and 76 cm), and relative time of velvetleaf emergence. Velvetleaf seed production, leaf area (LA), and total dry matter (TDM) were greater in 76-cm- than in 19-cm-wide soybean rows. LA, TDM, and seed production of velvetleaf were reduced with later emergence …
Corn–Velvetleaf (Abutilon Theophrasti ) Interference Is Affected By Sublethal Doses Of Postemergence Herbicides, Brescia R. M. Terra, Alexander R. Martin, John L. Lindquist
Corn–Velvetleaf (Abutilon Theophrasti ) Interference Is Affected By Sublethal Doses Of Postemergence Herbicides, Brescia R. M. Terra, Alexander R. Martin, John L. Lindquist
John L. Lindquist
Injury to weeds from sublethal doses of POST herbicides may reduce the effect of weed interference on crop yield. Information on how herbicide dose influences weed mortality, growth, and seed production is needed to assess the potential benefit of applying reduced herbicide doses. Field experiments were conducted at Mead, NE, in 2001 and 2002 to quantify velvetleaf mortality, growth, and corn–velvetleaf interference in response to varying doses of three POST herbicides. Untreated velvetleaf at six densities (0, 1, 3, 6, 12, and 20 plants m-1 corn row) was grown in mixture with corn to establish a baseline corn–velvetleaf interference relationship. …
Glyphosate Efficacy On Velvetleaf Varies With Application Time Of Day, Aaron L. Waltz, Alex R. Martin, Fred W. Roeth, John L. Lindquist
Glyphosate Efficacy On Velvetleaf Varies With Application Time Of Day, Aaron L. Waltz, Alex R. Martin, Fred W. Roeth, John L. Lindquist
John L. Lindquist
Field and growth chamber experiments determined the efficacy of temporal glyphosate applications on velvetleaf. Glyphosate was applied post-emergence to velvetleaf periodically before and during light and after dark. In 1999, glyphosate at 840 g ae/ha applied before sunrise and after midday provided 54 and 100% velvetleaf control, respectively. In 2000, glyphosate at 840 g/ha applied before sunrise, midday, and after sunset provided 69, 100, and 37% velvetleaf control, respectively. In the growth chamber, glyphosate at 840 g/ha applied before or after light reduced velvetleaf biomass 15 to 20% or 32 to 47%, respectively, and reduced velvetleaf height 24% or 45 …
Factors Affecting The Realized Niche Of Common Sunflower (Helianthus Annuus) In Ridge-Tillage Corn, Michael G. Burton, David A. Mortensen, David B. Marx, John L. Lindquist
Factors Affecting The Realized Niche Of Common Sunflower (Helianthus Annuus) In Ridge-Tillage Corn, Michael G. Burton, David A. Mortensen, David B. Marx, John L. Lindquist
John L. Lindquist
Because soil characteristics and weed densities vary within agricultural landscapes, determining which subfield areas are most favorable to weed species may aid in their management. Field and greenhouse studies were conducted to determine whether subfield environments characterized by higher soil organic carbon (SOC), or ridge vs. furrow microsites, affect common sunflower seed germination after winter burial, seedling emergence, or the control afforded by a preemergence herbicide in a ridge-tillage corn production system. Among seeds buried in situ during winter months and germinated in the laboratory, no differences in common sunflower seed germination or mortality were detected between high-SOC (1.8% mean) …
Predicting Biomass Partitioning To Root Versus Shoot In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, John L. Lindquist
Predicting Biomass Partitioning To Root Versus Shoot In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, John L. Lindquist
John L. Lindquist
Knowledge of how plants will partition their new biomass will aid in understanding competition between crops and weeds. This study determined if the amount of biomass partitioned to the root versus the shoot can be predicted from tissue carbon [C] and nitrogen [N] concentrations and the daily gain in C (GC) and N (GN) for each unit shoot and root biomass, respectively. Pots measuring 28 cm diameter and 60 cm deep were embedded in the ground, and each contained one plant of either corn or velvetleaf. Each plant received one of three nitrogen treatments: 0, 1, …
An Improved Measure Of Angular Dispersion In Plant Neighborhoods, Klaus J. Puettmann, Dan Rhode, Bruce D. Maxwell, John L. Lindquist
An Improved Measure Of Angular Dispersion In Plant Neighborhoods, Klaus J. Puettmann, Dan Rhode, Bruce D. Maxwell, John L. Lindquist
John L. Lindquist
Spatial distribution is an important factor determining the intensity and outcome of plant competition. The commonly used measure of angular distributions of plants around a target plant (1 - r) is shown to be limited to unimodal distributions. We present a new index which is based on the variance of the differences between the azimuth of neighboring plants. The new index is an improvement as it characterizes the angular dispersion in both unimodal and multimodal distributions.
Nitrogen Supply Affects Root:Shoot Ratio In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, Daniel T. Walters, Kenneth G. Cassman, John L. Lindquist
Nitrogen Supply Affects Root:Shoot Ratio In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, Daniel T. Walters, Kenneth G. Cassman, John L. Lindquist
John L. Lindquist
Competitive outcome between crops and weeds is affected by partitioning of new biomass to above- and below-ground plant organs in response to nutrient supply. This study determined the fraction of biomass partitioned to roots vs. shoots in corn and velvetleaf in response to nitrogen (N) supply. Pots measuring 28 cm in diam and 60 cm deep were embedded in the ground and each contained one plant of either corn or velvetleaf. Each plant received one of three N treatments: 0, 1, or 3 g N applied as ammonium nitrate in 2001, and 0, 2, or 6 g N in 2002. …
Simulation Study Of The Competitive Ability Of Erect, Semi-Erect, And Prostrate Cowpea (Vigna Unguiculata) Genotypes, G. Wang, M. E. Mcgiffen Jr., John L. Lindquist, J. D. Ehlers, I. Sartorato
Simulation Study Of The Competitive Ability Of Erect, Semi-Erect, And Prostrate Cowpea (Vigna Unguiculata) Genotypes, G. Wang, M. E. Mcgiffen Jr., John L. Lindquist, J. D. Ehlers, I. Sartorato
John L. Lindquist
Ecophysiological simulation models provide a quantitative method to predict the effects of management practices, plant characteristics, and environmental factors on crop and weed growth and competition. The INTERCOM interplant competition model was parameterized, calibrated by monoculture data for three cowpea (Vigna unguiculata) genotypes that differed in growth habit, common sunflower (Helianthus annuus) and common purslane (Portulaca oleracea), and used to simulate competition of cowpea cover crops with sunflower or purslane. The simulation results were compared with observations from field competition experiments in 2003 and 2004. INTERCOM more accurately simulated actual field data for the competition of cowpea genotypes and sunflower …
Changes In Nitrogen Use Efficiency And Soil Quality After Five Years Of Managing For High Yield Corn And Soybean, Timothy J. Arkebauer, Achim R. Dobermann, Kenneth G. Cassman, Rhae A. Drijber, J. Lindquist, James E. Specht, Daniel T. Walters, Haishun Yang
Changes In Nitrogen Use Efficiency And Soil Quality After Five Years Of Managing For High Yield Corn And Soybean, Timothy J. Arkebauer, Achim R. Dobermann, Kenneth G. Cassman, Rhae A. Drijber, J. Lindquist, James E. Specht, Daniel T. Walters, Haishun Yang
John L. Lindquist
Average corn grain yields in the USA have increased linearly at a rate of 1.7 bu/acre over the past 35 years with a national yield average of 140 bu/acre. Corn yield contest winners and simulation models, however, indicate there is ~100 bu/a in exploitable corn yield gap. Four years (1999-2002) of plant development, grain yield and nutrient uptake were compared in intensive irrigated maize systems representing (a) recommended best management practices for a yield goal of 200 bu/acre (M1) and (b) intensive management aiming at a yield goal of 300 bu/acre (M2). For each management level, three levels of plant …
Comparative Nitrogen Uptake And Distribution In Corn And Velvetleaf (Abutilon Theophrasti), John L. Lindquist, Darren C. Barker, Stevan Z. Knezevic, Alexander R. Martin, Daniel T. Walters
Comparative Nitrogen Uptake And Distribution In Corn And Velvetleaf (Abutilon Theophrasti), John L. Lindquist, Darren C. Barker, Stevan Z. Knezevic, Alexander R. Martin, Daniel T. Walters
John L. Lindquist
Weeds compete with crops for light, soil water, and nutrients. Nitrogen (N) is the primary limiting soil nutrient. Forecasting the effects of N on growth, development, and interplant competition requires accurate prediction of N uptake and distribution within plants. Field studies were conducted in 1999 and 2000 to determine the effects of variable N addition on monoculture corn and velvetleaf N uptake, the relationship between plant N concentration ([N]) and total biomass, the fraction of N partitioned to leaves, and predicted N uptake and leaf N content. Cumulative N uptake of both species was generally greater in 2000 than in …