The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Jack Dekker - One of the best experts on this subject based on the ideXlab platform.
-
weedy adaptation in Setaria spp ix effects of salinity temperature light and seed dormancy on Setaria faberi seed germination
Journal of Life Sciences, 2014Co-Authors: Jack Dekker, J GilbertAbstract:Life in salty habitats is a function of tolerance to those chemicals at all critical phases of a plant’s life history. The ability to withstand salt as an established plant may require different mechanisms and plant traits than those needed to germinate in salty soils. Seeds establishing themselves in high salt content may respond differently depending on the light conditions and seed germinability at the time of salty water imbibition. S. faberi seed (and S. viridis and S. pumila) plants were discovered thriving along the seacoasts of Southern Japan.. These plants possess the ability to after-ripen, germinate, emerge and establish themselves, grow and reproduce in the salty soils and salt-laden atmospheres present in these windy habitats. The objectives of this paper are to determine the effect of salt (NaCl) in water imbibed by S. faberi seed during after-ripening and germination, as well temperature and light. Observations made also provide insights on the possible relationship between salt and drought tolerance. Seed germination of all phenotypes inhibited by 2% or more of NaCl. The effects of lesser amounts of NaCl on each of the three phenotypes was highly dependent on the specific temperature and light conditions. Regardless of non-isogenic germplasm used, the three test phenotypes encompassed complete range of seed germination in a wide range of temperatures (15-35oC) and light conditions (+, -) in water: dormant, 4%; after-ripened, 26%; nondomrant, 90%. The provided a good range to detect responses to salinity over a wide range of germination phenotype expressions. The set of dormant, after-ripened and non-dormant S. faberi populations and phenotypes observed in these experiments provided an ideal group of seeds with which to compare the effects of salt, temperature and light over a wide range of germinability responses (0-98.3%). This full range of germinability states and responses represented the full range observable in seeds in natural soil seed pools, allowing the observation of both stimulatory and inhibitory responses.
-
weedy adaptation in Setaria spp ix effects of salinity temperature light and seed dormancy on Setaria faberi seed germination
arXiv: Populations and Evolution, 2014Co-Authors: Jack Dekker, J GilbertAbstract:Life in salty habitats is a function of tolerance to those chemicals at all critical phases of a plant's life history. The ability to withstand salt as an established plant may require different mechanisms and plant traits than those needed to germinate in salty soils. Seeds establishing themselves in high salt content may respond differently depending on the light conditions and seed germinability at the time of salty water imbibition. S. faberi seed (and S. viridis and S. pumila) plants were discovered thriving along the seacoasts of Southern Japan. These plants possess the ability to after-ripen, germinate, emerge and establish themselves, grow and reproduce in the salty soils and salt-laden atmospheres present in these windy habitats. The objectives of this paper are to determine the effect of salt (NaCl) in water imbibed by S. faberi seed during after-ripening and germination, as well temperature and light. Observations made also provide insights on the possible relationship between salt and drought tolerance. Seed germination of all phenotypes inhibited by two percent or more of NaCl. The effects of lesser amounts of NaCl on each of the three phenotypes was highly dependent on the specific temperature and light conditions. The three test phenotypes provided a good range to detect responses to salinity, allowing the observation of both stimulatory and inhibitory responses.
-
weedy adaptation in Setaria spp viii structure of Setaria faberi seed caryopsis and embryo germination
arXiv: Quantitative Methods, 2014Co-Authors: Milt Haar, Adriaan Van Aelst, Jack DekkerAbstract:Giant foxtail (Setaria faberi) seeds differ in requirements for germination. Variable germinability arises during seed development under the influence of genotype, environment and parent plant. Giant foxtail seed germination has been shown to be regulated by independent asynchronous or dependent synchronous action of seed structures. To gain better insight into the process, germination was divided into axis specific embryo growth categories or states. Three states were defined for each embryonic axis. The degree of embryo growth (germination state) after eight to twelve days under germination conditions is believed to reveal the germinability state (potential for germination) possessed by the seed before germination. The embryo axes behave independently, which allows any combination of germination states to occur. In general, the greater the difference in germination between the axes, the less likely the combination of states will occur. Photographic evidence of each germination state is shown for caryopses and seed. Seed with a variety of germinability states is a strategy for surviving variable environments.
-
weedy adaptation in Setaria spp vii seed germination heteroblasty in Setaria faberi
arXiv: Quantitative Methods, 2014Co-Authors: Milton J Haar, Jack DekkerAbstract:The dormancy status of S. faberi seed at abscission was assessed with reference to tiller and panicle development. Seed from a single genetic line were grown under field, greenhouse and controlled environment growth chamber conditions. At abscission, a small fraction (<10%) of S. faberi seed germinated under favorable conditions. Seed were dissected and germination of caryopses and embryos also tested. Removal of seed structures exterior to the embryo increased percentage germination. As the seed rain progressed mean percentage germination and variation among samples increased. Changes in germination were correlated with tiller development and relative time of seed maturity within a panicle. Seed produced on tillers that developed earlier were more likely to be dormant than seed from later-developing tillers. Seed that matured later on a panicle were more likely to germinate than seed that matured earlier on the same panicle. A consistent trend toward later maturing seed having less dormancy was found for seed grown under different environments which implies an inherent or parental source for variation in giant foxtail seed dormancy. The variation in percentage germination at abscission and following stratification treatments indicates that the S. faberi seed rain consists of individual seeds, possibly each with a different degree of dormancy.
-
Setaria faberi seed heteroblasty blueprints seedling recruitment iii seedling recruitment behavior
Planta, 2012Co-Authors: Kari Jovaag, Jack Dekker, Brad AtchisonAbstract:Seedling recruit ment of heterogeneous Setaria faberi seed entering the soil post-abscission is elucidated herein. This is the third in a series of three articles providing evidence that weedy Setaria seedling recruit ment behavior is predicated on dormancy state heterogeneity at abscission (seed heteroblasty), as modulated by environmental signals. Co mplex oscillating patterns of seedling emergence were observed during the first half of the growing season in all 503 soil burial cores of the 39 populations studied. These patterns were attributed to six distinct dormancy phenotype cohorts arising fro m inherent somatic poly morphis m in seed dormancy states (canalized phenotypes). Early season cohorts were formalized using a mixtu re model consisting of four normal distributions. Two, numerically low, late season cohorts were also observed. Variation in emergence patterns among Setaria populations revealed a fine scale adaptation to local conditions. Seedling recruit ment patterns were influenced by both parental-genotypic (time of embryogenesis) and environmental (year, co mmon nursery location, seed age in the soil) parameters. The influence of seed heteroblasty on recruitment behavior was apparent in that S. faberi populations with higher dormancy at the time of dispersal had lower emergence numbers the follo wing spring, and in many instances occurred later, co mpared to those less dormant. Heteroblasty was thus the first determinant of behavior, most apparent in recruit ment nu mber, less so in pattern. Environ ment modulated seedling numbers, but mo re strongly influenced pattern. The resulting pattern of emergence revealed the actual "hedge-bet" structure for Setaria seedling recruit ment investment, its realized niche, an adaptation to the predictable mortality risks caused by agricultural production and interactions with neighbors. These comp lex patterns in seedling recru it ment behavior support the conjecture that the inherent dormancy capacities of S. faberi seeds provides a germinability 'memory' of successful historical exp loitation of local opportunity, the inherent starting condition that interacts in both a determin istic and plastic manner with environ mental signals to define the consequential heterogeneous life history trajectories.
Matt Liebman - One of the best experts on this subject based on the ideXlab platform.
-
Fates of Setaria faberi and Abutilon theophrasti seeds in three crop rotation systems
Weed Research, 2014Co-Authors: Matt Liebman, Adam S. Davis, Zach J. Miller, Carol L. Williams, Paula R. Westerman, Philip M. Dixon, A Heggenstaller, Fabian D. Menalled, David N. SundbergAbstract:Summary Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2-, 3- and 4-year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3- and 4-year rotation systems than in the 2-year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life-history processes associated with soil seedbanks.
-
over winter predation of abutilon theophrasti and Setaria faberi seeds in arable land
Weed Research, 2009Co-Authors: Carol L. Williams, Matt Liebman, Paula R. Westerman, David N. Sundberg, Jaclyn K Borza, Brent J DanielsonAbstract:Summary To improve understanding of over-winter weed seed predation in arable fields, we used data from winter exclosure trials to determine the amount of predation and the influence of crop habitats on predation of Abutilon theophrasti and Setaria faberi seed in 2-year (maize/soyabean) and 4-year (maize/soyabean/small grain+lucerne/lucerne) crop rotation systems between 2005 and 2008. Crop habitat influenced seed predation, and had similar impacts on the two weed species. Mean A. theophrasti predation ranged from 31% in the 2-year soyabean habitat to 99% in the 4-year lucerne habitat. Mean S. faberi predation ranged from 31% in the 2-year soyabean habitat to 97% in the 4-year lucerne habitat. Results suggest that a combination or interaction of cover and substrate may have affected crop habitat preference by seed predators. Future research should further examine the influence of physical habitat on seed predation to determine characteristics of cropping systems that encourage predation, particularly during over-winter periods, so as to routinely incorporate seed predators into long-term weed management strategies.
-
comparing estimates of seed viability in three foxtail Setaria species using the imbibed seed crush test with and without additional tetrazolium testing
Weed Technology, 2007Co-Authors: Jaclyn K Borza, P R Westerman, Matt LiebmanAbstract:Estimates of seed viability using the imbibed seed crush test, a method performed by applying pressure to imbibed seeds, were compared with estimates obtained from using the imbibed seed crush test supplemented with tetrazolium staining. The seeds of three weed species, giant foxtail, green foxtail, and yellow foxtail, were collected from three different crops and tested by each method. The results from the two approaches were strongly and significantly correlated. The imbibed seed crush test requires considerably less skill and time to perform and is a reasonable alternative to tetrazolium staining to test the seed viability of newly produced foxtail seeds. Nomenclature: Tetrazolium, 2,3,5 triphenyl tetrazolium chloride; giant foxtail, Setaria faberi Herrm. SETFA; green foxtail, Setaria viridis (L.) Beauv. SETVI; yellow foxtail, Setaria glauca (L.) Beauv. SETLU. Seed viability is a critical measure in plant demographics and population dynamics research. Conducting seed-bank surveys and monitoring fluctuations in seed populations require intensive sampling and testing for seed viability on a large scale (Buhler and Hartzler 2001; Menalled et al. 2005; Nurse and DiTommaso 2005). Nonetheless, viability testing for weed seeds has proven especially difficult on account of the small size, the high number of seeds produced from each plant, and the long dormancy times that weed seeds can exhibit.
-
seasonal patterns in post dispersal seed predation of abutilon theophrasti and Setaria faberi in three cropping systems
Journal of Applied Ecology, 2006Co-Authors: A Heggenstaller, Matt Liebman, Fabian D. Menalled, Paula R. WestermanAbstract:Summary 1 Post-dispersal seed predation is an important source of mortality for arable weed populations that can potentially contribute to ecologically based management strategies. The extent to which cropping practices influence rates of seed predation is not well established. 2 Removal of Abutilon theophrasti and Setaria faberi seeds by predators was measured in 2-year (maize/soyabean), 3-year (maize/soyabean/triticale + red clover) and 4-year (maize/soyabean/triticale + lucerne/lucerne) crop rotations in Iowa, USA, during 27 48-h sampling periods conducted during the 2003 and 2004 cropping seasons. 3 Predation of S. faberi seeds was equal (eight sampling periods) or greater (19 sampling periods) than predation of A. theophrasti seeds, but the influence of crops on seasonal predation patterns was generally similar for the two weeds. 4 Seasonal patterns in seed predation were crop-specific and complementary. In maize and soyabean, seed predation was low in spring, high in summer and low in autumn. In triticale–legume intercrops, seed predation was high in spring, low in summer and moderate in autumn. In lucerne, seed predation fluctuated from high to low, matching the periodic harvest and regrowth cycle of the crop. 5 Measurements of crop canopy light interception taken in 2004 were positively correlated with rates of seed removal for both A. theophrasti (r = 0·54, P < 0·001) and S. faberi (r = 0·25, P < 0·001), suggesting that vegetative cover promotes weed seed predation. 6 Synthesis and applications. The results indicate that crop vegetation can be managed to promote weed seed predation. Diversified farming systems that include a range of phenologically dissimilar crop species are likely to provide the greatest opportunities for weed seed destruction by predators.
-
demography of abutilon theoprasti and Setaria faberi in three crop rotation systems
Weed Research, 2006Co-Authors: A Heggenstaller, Matt LiebmanAbstract:Summary Field experiments were conducted to characterize the demography of Abutilon theophrasti and Setaria faberi in a conventionally managed 2-year (maize/soya bean) rotation, and in 3-year (maize/soya bean/triticale + red clover) and 4-year (maize/soya bean/triticale + lucerne/ lucerne) rotations managed with 72% and 79% lower herbicide inputs respectively. Rates of weed seedling recruitment, seedling survival and adult plant fecundity were determined for populations in each phase of each rotation and used to calculate annual rates of weed population change, D. In both years of the study, D for A. theophrasti populations declined or remained stable in all three rotation systems. Despite greater rates of seedling survival and fecundity in maize and soya bean in the 3- and 4-year rotations, increases in D for A. theophrasti populations were prevented in these systems because of low fecundity in triticale and low seedling survival and fecundity in lucerne. For Setaria faberi populations, D remained stable in the 2-year rotation, increased in the 3-year rotation in both years, and increased in the 4-year rotation in 1 year. The results of this study indicate that when herbicide use is reduced, rotations that include triticale and lucerne can facilitate the suppression of A. theophrasti. Rotations that include lucerne can contribute to restraining S. faberi population growth, given adequate levels of seedling mortality in this crop.
Paula R. Westerman - One of the best experts on this subject based on the ideXlab platform.
-
Fates of Setaria faberi and Abutilon theophrasti seeds in three crop rotation systems
Weed Research, 2014Co-Authors: Matt Liebman, Adam S. Davis, Zach J. Miller, Carol L. Williams, Paula R. Westerman, Philip M. Dixon, A Heggenstaller, Fabian D. Menalled, David N. SundbergAbstract:Summary Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2-, 3- and 4-year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3- and 4-year rotation systems than in the 2-year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life-history processes associated with soil seedbanks.
-
over winter predation of abutilon theophrasti and Setaria faberi seeds in arable land
Weed Research, 2009Co-Authors: Carol L. Williams, Matt Liebman, Paula R. Westerman, David N. Sundberg, Jaclyn K Borza, Brent J DanielsonAbstract:Summary To improve understanding of over-winter weed seed predation in arable fields, we used data from winter exclosure trials to determine the amount of predation and the influence of crop habitats on predation of Abutilon theophrasti and Setaria faberi seed in 2-year (maize/soyabean) and 4-year (maize/soyabean/small grain+lucerne/lucerne) crop rotation systems between 2005 and 2008. Crop habitat influenced seed predation, and had similar impacts on the two weed species. Mean A. theophrasti predation ranged from 31% in the 2-year soyabean habitat to 99% in the 4-year lucerne habitat. Mean S. faberi predation ranged from 31% in the 2-year soyabean habitat to 97% in the 4-year lucerne habitat. Results suggest that a combination or interaction of cover and substrate may have affected crop habitat preference by seed predators. Future research should further examine the influence of physical habitat on seed predation to determine characteristics of cropping systems that encourage predation, particularly during over-winter periods, so as to routinely incorporate seed predators into long-term weed management strategies.
-
seasonal patterns in post dispersal seed predation of abutilon theophrasti and Setaria faberi in three cropping systems
Journal of Applied Ecology, 2006Co-Authors: A Heggenstaller, Matt Liebman, Fabian D. Menalled, Paula R. WestermanAbstract:Summary 1 Post-dispersal seed predation is an important source of mortality for arable weed populations that can potentially contribute to ecologically based management strategies. The extent to which cropping practices influence rates of seed predation is not well established. 2 Removal of Abutilon theophrasti and Setaria faberi seeds by predators was measured in 2-year (maize/soyabean), 3-year (maize/soyabean/triticale + red clover) and 4-year (maize/soyabean/triticale + lucerne/lucerne) crop rotations in Iowa, USA, during 27 48-h sampling periods conducted during the 2003 and 2004 cropping seasons. 3 Predation of S. faberi seeds was equal (eight sampling periods) or greater (19 sampling periods) than predation of A. theophrasti seeds, but the influence of crops on seasonal predation patterns was generally similar for the two weeds. 4 Seasonal patterns in seed predation were crop-specific and complementary. In maize and soyabean, seed predation was low in spring, high in summer and low in autumn. In triticale–legume intercrops, seed predation was high in spring, low in summer and moderate in autumn. In lucerne, seed predation fluctuated from high to low, matching the periodic harvest and regrowth cycle of the crop. 5 Measurements of crop canopy light interception taken in 2004 were positively correlated with rates of seed removal for both A. theophrasti (r = 0·54, P < 0·001) and S. faberi (r = 0·25, P < 0·001), suggesting that vegetative cover promotes weed seed predation. 6 Synthesis and applications. The results indicate that crop vegetation can be managed to promote weed seed predation. Diversified farming systems that include a range of phenologically dissimilar crop species are likely to provide the greatest opportunities for weed seed destruction by predators.
Adam S. Davis - One of the best experts on this subject based on the ideXlab platform.
-
Fates of Setaria faberi and Abutilon theophrasti seeds in three crop rotation systems
Weed Research, 2014Co-Authors: Matt Liebman, Adam S. Davis, Zach J. Miller, Carol L. Williams, Paula R. Westerman, Philip M. Dixon, A Heggenstaller, Fabian D. Menalled, David N. SundbergAbstract:Summary Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2-, 3- and 4-year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3- and 4-year rotation systems than in the 2-year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life-history processes associated with soil seedbanks.
-
maternal and burial environment effects on seed mortality of velvetleaf abutilon theophrasti and giant foxtail Setaria faberi
Weed Science, 2008Co-Authors: Brian J Schutte, Karen A. Renner, Adam S. Davis, John CardinaAbstract:The primary defense against seed mortality, the seed coat, is maternally derived. Hence, weed seed mortality in the soil seedbank is likely to be influenced by the maternal environment and genetics. We hypothesized that seed accessions from contrasting maternal environments (seed lots) exhibit different rates of seed mortality and that the relative differences among seed lots remain consistent across burial environments. Velvetleaf and giant foxtail annual seed mortality rates were studied in field experiments in Hickory Corners, MI, and Wooster, OH, using seed lots collected from the same locations. Seeds enclosed within mesh bags and unenclosed seeds (‘‘seeded cores’’) exhibited similar levels of seedbank persistence (r 5 0.90, P , 0.001) and seed mortality (r 5 0.65, P 5 0.006). Annual seed mortality rates ranged from 16 to 56% and 27 to 91% for seed lots of velvetleaf and giant foxtail, respectively. Relative differences among velvetleaf seed lots were consistent across burial environments in both years, whereas giant foxtail differences were consistent in only 1 of 2 yr. The relative ranks among velvetleaf seed lots varied between years, indicating that maternal environment may have influenced seed persistence more than seed-lot genetics. Within years, variation in seed mortality was predicted by changes in soil moisture in the burial environment (R 2 5 0.47, P , 0.001 for velvetleaf; R 2 5 0.34, P 5 0.007 for giant foxtail). Accelerated seed mortality was associated with moist soils (soil water potential 52 6 kPa for velvetleaf, 27 kPa for giant foxtail). These results suggest that agronomic practices affecting the maternal environment and moisture levels in the soil seedbank may promote weed seed mortality in the soil seedbank. Nomenclature: Giant foxtail, Setaria faberi Herrm. SETFA; velvetleaf, Abutilon theophrasti Medik. ABUTH.
-
influence of seed depth and pathogens on fatal germination of velvetleaf abutilon theophrasti and giant foxtail Setaria faberi
Weed Science, 2007Co-Authors: Adam S. Davis, Karen A. RennerAbstract:Abstract Fatal germination of weed seeds occurs when a weed seed germinates, but the seedling dies before reaching the soil surface. Controlled-environment bioassays of velvetleaf and giant foxtail seed fate in Michigan field soil (Kalamazoo silt loam, 1.1% soil organic matter) were used to determine the role of pathogenic fungi and seed burial depth in fatal germination of these species. Fatal germination at 2 cm seed depth was nonexistent for giant foxtail, and rare (< 10% of seeds studied) for velvetleaf. At greater depths, fatal germination remained close to zero for giant foxtail, whereas it increased to as high as 40% for velvetleaf at a 10-cm burial depth. Cultures taken from fatally germinated velvetleaf seedlings were found to contain Pythium ultimum, a soilborne pathogen known as the causal agent for pea root rot. When samples of infected media taken from these cultures were used to inoculate field soil in pots, fatal germination of velvetleaf from depths of 4 to 6 cm increased, compared with fi...
-
cropping system effects on giant foxtail Setaria faberi demography ii retrospective perturbation analysis
Weed Science, 2003Co-Authors: Adam S. Davis, Philip M. Dixon, Matt LiebmanAbstract:Abstract Cropping system characteristics affect weed management by altering key demographic rates of weeds, including recruitment, seedling survival, fecundity, and seed survival. To facilitate the design and improvement of cropping systems that limit weed population growth, analytical methods are needed to identify weed management “choke points” (weed life stages that vary in response to management and whose variation strongly affects weed population growth rate). The objectives of this study were to (1) determine whether wheat–red clover green manure can limit giant foxtail population growth rate (λ) in a wheat–corn–soybean crop sequence and (2) identify choke points in the giant foxtail life cycle with respect to the green manure treatment. Demographic data were used to construct a periodic matrix model of giant foxtail population growth in a wheat–corn–soybean crop sequence, with either a wheat sole crop (W) or a wheat–red clover intercrop (R) in the wheat phase. Identification of choke points was acc...
-
cropping system effects on giant foxtail Setaria faberi demography i green manure and tillage timing
Weed Science, 2003Co-Authors: Adam S. Davis, Matt LiebmanAbstract:Abstract Manipulation of cropping systems to improve weed management requires a better understanding of how crop- and soil-related factors affect weed life cycles. Our objective was to assess the impacts of timing of primary tillage and use of legume green manure on giant foxtail demography and soil properties. We measured giant foxtail seed survival and dormancy, seedling emergence and survival, and fecundity, in addition to soil phytotoxicity, chemical properties affecting soil fertility and soil water, in the transition between the wheat and corn phases of a wheat–corn–soybean crop sequence. Postdispersal predation of giant foxtail seeds was measured in all three phases of the crop sequence. Wheat was grown either as a sole crop (W) or underseeded with red clover (R), and residues from this phase were rototilled either in the fall (FT) or in spring (ST). There were strong interactions between Red clover and Tillage timing in their effects on giant foxtail recruitment and fecundity in corn. Giant foxtai...
Fabian D. Menalled - One of the best experts on this subject based on the ideXlab platform.
-
Fates of Setaria faberi and Abutilon theophrasti seeds in three crop rotation systems
Weed Research, 2014Co-Authors: Matt Liebman, Adam S. Davis, Zach J. Miller, Carol L. Williams, Paula R. Westerman, Philip M. Dixon, A Heggenstaller, Fabian D. Menalled, David N. SundbergAbstract:Summary Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2-, 3- and 4-year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3- and 4-year rotation systems than in the 2-year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life-history processes associated with soil seedbanks.
-
seasonal patterns in post dispersal seed predation of abutilon theophrasti and Setaria faberi in three cropping systems
Journal of Applied Ecology, 2006Co-Authors: A Heggenstaller, Matt Liebman, Fabian D. Menalled, Paula R. WestermanAbstract:Summary 1 Post-dispersal seed predation is an important source of mortality for arable weed populations that can potentially contribute to ecologically based management strategies. The extent to which cropping practices influence rates of seed predation is not well established. 2 Removal of Abutilon theophrasti and Setaria faberi seeds by predators was measured in 2-year (maize/soyabean), 3-year (maize/soyabean/triticale + red clover) and 4-year (maize/soyabean/triticale + lucerne/lucerne) crop rotations in Iowa, USA, during 27 48-h sampling periods conducted during the 2003 and 2004 cropping seasons. 3 Predation of S. faberi seeds was equal (eight sampling periods) or greater (19 sampling periods) than predation of A. theophrasti seeds, but the influence of crops on seasonal predation patterns was generally similar for the two weeds. 4 Seasonal patterns in seed predation were crop-specific and complementary. In maize and soyabean, seed predation was low in spring, high in summer and low in autumn. In triticale–legume intercrops, seed predation was high in spring, low in summer and moderate in autumn. In lucerne, seed predation fluctuated from high to low, matching the periodic harvest and regrowth cycle of the crop. 5 Measurements of crop canopy light interception taken in 2004 were positively correlated with rates of seed removal for both A. theophrasti (r = 0·54, P < 0·001) and S. faberi (r = 0·25, P < 0·001), suggesting that vegetative cover promotes weed seed predation. 6 Synthesis and applications. The results indicate that crop vegetation can be managed to promote weed seed predation. Diversified farming systems that include a range of phenologically dissimilar crop species are likely to provide the greatest opportunities for weed seed destruction by predators.
-
composted swine manure effects on germination and early growth of crop and weed species under greenhouse conditions1
Weed Technology, 2005Co-Authors: Fabian D. Menalled, Douglas D Buhler, Matt LiebmanAbstract:Composted manure produced in deep-bedded hoop structures constitutes a source of nu- trients and organic materials that can influence crop and weed emergence, growth, competitive in- teractions, and soil physical properties. The impact of composted swine manure on corn, soybean, winter wheat, velvetleaf, giant foxtail, and common waterhemp emergence and early growth were compared at compost rates of 0, 8, 16, or 24 Mg C/ha. Compost amendment had no effect on crop emergence but did reduce weed emergence. Inhibition of seedling emergence ranged between 15 and 57% for giant foxtail, 0 and 23% for velvetleaf, and 16 and 76% for common waterhemp. Soil amendment enhanced weed growth but not crop growth. A response surface regression analysis indicated that, while large-seeded crops have constant relative growth rates, small-seeded weed spe- cies increase their relative growth rates with compost amendment (P , 0.0001, r 2 5 0.5252). Nomenclature: Common waterhemp, Amaranthus rudis Sauer # 3 AMATA; corn, Zea mays L. 'Pi- oneer 3563'; giant foxtail, Setaria faberi SETFA Herm.; soybean, Glycine max (L.) Merr. 'Pioneer 92B84'; velvetleaf, Abutilon theophrasti ABUTH Medicus; winter wheat, Triticum aestivum L. 'Arapahoe'. Additional index words: Compost amendment, relative growth rate, germination inhibition, organic amendment, seedling emergence, soil quality. Abbreviations: EI%, percentage emergence inhibition; MTE, mean time of emergence; RGR, rela- tive growth rate; VOA, volatile organic acids.
-
gryllus pennsylvanicus orthoptera gryllidae laboratory weed seed predation and within field activity density
Journal of Economic Entomology, 1999Co-Authors: Dora M Carmona, Fabian D. Menalled, D A LandisAbstract:Laboratory and field studies were conducted during the summer–fall season of 1997 to evaluate the potential of the field cricket Gryllus pennsylvanicus Burmeister as a weed seed predator in annual crops. Laboratory no-choice tests showed that both male and female G. pennsylvanicus readily accepted and consumed seeds of small and large-seeded annual weeds. In 24 h, female and male G. pennsylvanicus consumed an average of 12 and 8 velvetleaf ( Abutilon theophrasti Medic.), 26 and 9 giant foxtail ( Setaria faberi Herrm.), 87 and 69 crabgrass [ Digitaria Sanguinalis (L.) Scop.], and 223 and 90 redroot pigweed ( Amaranthus retroflexus L.) seeds, respectively. Tests of pitfall trap sampling in outdoor arenas showed that G. pennsylvanicus is susceptible to this sampling technique. Pitfall traps were subsequently used to monitor activity-density of G. pennsylvanicus in a soybean ( Glycine max L. Merr.) field and 2 adjacent perennial filter strips, one composed of switchgrass ( Panicum virgatum L.) and the other an alfalfa ( Medicago sativa L.) and timothy grass ( Pheum pratense L.) mixture. G. pennsylvanicus individuals were first captured in early August, peaked in mid-September, and decreased in October. Field cricket activity-density was greatest in switchgrass filter strip followed by legume-grass filter strip and lowest in soybean.