bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Economy of Pulse Crop Production in the Northern Great Plains
Authors: Walley Fran L. , Clayton George W. , Miller Perry R. , Carr Patrick M. , Lafond Guy P.
Published: November 2007

Previously published data were used to examine the N economy of pulse crops typically grown on the Northern Great Plains with the goal of assessing the potential contribution of field pea (Pisum sativum L.), lentil (Lens culinaris Medik.), chickpea (Cicer arietinum L.), common bean (Phaseolus vulgaris L.), and faba bean (Vicia faba L.) to soil N accretion. Incremental changes in soil N associated with the pulse crops (i.e., the nitrogen increment, Ninc), were strongly correlated to N2 fixation and were highly variable. Data suggest that crops that can achieve relatively high levels of N2 fixation, such as faba bean, field pea, and lentil are more likely to contribute positively to the overall N economy, particularly when a cropping system is evaluated over a long term. In contrast, pulse crops that typically achieve only modest levels of N2 fixation such as desi and kabuli chickpea and common bean are more likely to be either N neutral or contribute to a soil N deficit. Because of extreme variability in levels of N2 fixation achieved, presumably reflecting variability in soil productivity as well as variations in local climate and weather, the Ninc of pulse crops likewise is highly variable. Thus, the N contribution to a subsequent crop is difficult to predict with any certainty, particularly on a yearly or short‐term basis.
Can Pulse Crops Play a Role in Mitigating Greenhouse Gases from North American Agriculture?
Authors: Lemke R. L. , Zhong Z. , Campbell C. A. , Zentner R.
Published: November 2007

The atmospheric buildup of greenhouse gases (GHGs) is a serious environmental issue. Globally, agricultural activities are an important source of anthropogenic GHGs, contributing ∼20% of the annual atmospheric increase. Management choices largely determine if agricultural soils will be a source, a sink, or will be neutral with respect to GHG net flux. The proportion of agricultural land that is seeded to pulse crops in the Northern Great Plains (NGP) region of North America has been increasing rapidly over the past decade. Introducing pulses into cereal‐based cropping systems could influence the net GHG balance of those systems because pulse crops are thought to stimulate soil‐emitted N2O, have different pesticide and fertilizer requirements, and the quality and quantity of their residues vary substantially compared with cereal crops. In this paper we briefly review the available literature, and discuss the potential impact of pulse crops on the net flux of CO2, N2O, and CH4 from soils, and the CO2 emissions associated with energy inputs for cropping systems in the NGP. We also calculate net GHG balances for two example sites. Estimating the final GHG outcome of introducing pulses into cereal‐based cropping systems is still uncertain, but current information suggests that replacing a cereal with a pulse crop will likely result in no change or a small but positive net GHG benefit (lower emissions to the atmosphere) for crop rotations in the NGP region.
Spectral Reflectance Properties of Winter Cover Crops in the Southeastern Coastal Plain
Authors: Sullivan D.G. , Shaw J.N. , Price A. , van Santen E.
Published: November 2007

Conservation tillage is a commonly adopted best management practice for reducing runoff and erosion, and increasing infiltration. Yet current methodologies in place to monitor conservation tillage adoption are largely inappropriate for regional or national assessments. A major goal of this study was to evaluate the spectral response properties of four alternative winter cover crops using remotely derived crop residue cover indices. Experimental plots were located in east‐central Alabama on a coarse‐loamy siliceous, subactive, thermic Plinthic Paleudult. The experiment was a randomized complete block design having four replications of each of the following treatments: one fallow conventional tillage treatment and four no‐tillage treatments with black oat (Avena strigosa Schreb.), crimson clover (Trifolium incarnatum L.), turnip (Brassica rapa L. subsp.rapa), or rye (Secale cereale L.) cover crops. Remotely sensed data were acquired three times using a ∼14 d sampling interval beginning near planting and using a handheld multispectral radiometer (485–1650 nm) in 2005 and 2006. Three crop residue cover indices using combinations of middle‐infrared and visible spectra were compared and evaluated. Rye, clover, and black oat were spectrally similar, having an overall spectral response ranging from 8 to 45% (440–1650 nm). Increasing soil water content between remotely sensed data acquisitions was evidenced by as much as a 24% decline in middle‐infrared reflectance. Despite this variability, a normalized difference ratio of middle‐infrared (1650 nm) and blue (445 nm) spectra (Crop Residue Cover Index) provided the most consistent differentiation between tillage systems, varying within 8% of benchmark conditions (low soil water and low canopy cover). Considering the impact that conservation tillage may have on soil and water resources, rapid, watershed scale assessments of conservation tillage adoption may facilitate natural resource inventories, carbon sequestration estimates, and improved agricultural water management regimes.
Seeding Rate and Nitrogen Management Effects on Spring Wheat Yield and Yield Components
Authors: Otteson Brian N. , Mergoum Mohamed , Ransom Joel K.
Published: November 2007

Seeding rate, N level, and N application timing are key management factors for spring wheat (Triticum aestivum L.) production in North Dakota. Experiments were conducted under dryland (Casselton, ND) and irrigated (Carrington, ND) conditions in 2003 to 2005 to determine the optimum combination of seeding rate and N management to maximize yield of hard red spring wheat (HRSW). Treatments consisted of a factorial combination of HRSW genotypes (‘Briggs’, ‘Alsen’, ‘Granite’, and ND 740), seeding rates (2.9 and 4.2 million seeds ha−1), N levels (140 and 224 kg ha−1 for the dryland site; 168 and 280 kg ha−1 for the irrigated site), and N application timing (preplant, two‐split, and three‐split). Nitrogen level, N timing, and seeding rate showed no significant effect on grain yield across environments. However, genotype significantly influenced grain yield. Increasing seeding rate failed to increase grain yield of the three cultivars, but ND 740 was most productive at the lowest seeding rate. Increasing the level of N significantly increased grain protein content (GPC) over all environments. Grain volume weight (GVW) and thousand kernel weight (TKW) decreased with increasing N level and were influenced by genotype. Increased seeding rate significantly increased plant stand and tiller number while increasing N levels significantly increased head count. These data indicate that although genotype was the primary factor in determining grain yield, GPC, and agronomic traits, individual genotypes responded differently to varying seeding rates and N management practices.
An Economic Analysis of Alfalfa Harvest Methods When Infested with Verticillium Wilt
Authors: Sedman James N. , Bastian Christopher T. , Held Larry J. , Gray Fred A. , Koch David W.
Published: November 2007

Verticillium wilt is a disease that negatively affects alfalfa fields throughout the northern United States. This disease is caused by the fungus Verticillium albo‐atrum that, once introduced into alfalfa fields, spreads rapidly, becomes difficult to control, and causes substantial plant yield loss. This disease can be extremely costly for alfalfa hay producers, especially for producers where cool temperatures and relatively humid conditions exist. Little research has been conducted regarding the most economically viable management practices associated with infestation of this disease. This article analyzes the economic returns associated with different harvest practices (two cuttings, two cuttings plus fall grazing, three cuttings, and three cuttings plus fall grazing) given the presence of the disease within a stand. This study utilizes yield data from a study performed by the University of Wyoming Plant Sciences Department. Returns are evaluated using a net present value analysis. Results indicate the most economically viable practice is the two cuttings plus fall grazing.
Application of Different Organic Wastes on Soil Properties and Wheat Yield
Authors: Tejada M. , Gonzalez J. L.
Published: November 2007

Fresh and composted organic wastes [beet vinasse (BV), sewage sludge (SS), and a cotton gin crushed compost (CCGC)], were applied for 4 yr to a Typic Xerofluvent in dryland conditions near Seville, Spain. Organic wastes were applied at rates of 5, 7.5, and 10 Mg organic matter ha−1, respectively. The effect on the soil's physical properties, soil microbial biomass, and six soil enzymatic activities (dehydrogenase, urease, protease, β‐glucosidase, arylsulfatase, and alkaline phosphatase activities) and the yield parameters of wheat (Triticum aestivum cv. Cajeme) were ascertained. The application of CCGC compost improved the soil's physical (structural stability, bulk density), chemical (exchangeable sodium percentage, ESP), and biological properties (microbial biomass, soil respiration, and enzymatic activities) and the wheat yield parameters; however, the application of SS adversely affected the soil biological properties and reduced the wheat yield, probably because high of amounts of heavy metals. The application of fresh BV also adversely affected the soil's physical, chemical, and biological properties and the wheat yield, probably because high amounts of Na and fulvic acids were introduced into the soil by the vinasse, which destabilized its structure. Wheat yield decreased 22.5% in BV with respect to CCGC‐amended soil, 13.6% in SS with respect to CCGC‐amended soil, and 7.9% in BV with respect to SS‐amended soil. These results suggest that the chemical composition of the three organic wastes notably influenced the soil properties and therefore the wheat yield parameters. Of the three organic wastes studied, alone the application of CCGC originated a positive effect in the soil and in the wheat yield parameters, while the application of BV and SS originated a negative effect in the soil properties and therefore in the wheat yield parameters.
Weather, Fertilizer, Previous Year Yield, and Fertilizer Levels Affect Ensuing Year Fertilizer Response of Wheat
Authors: Girma Kefyalew , Holtz Starr L. , Arnall Daryl B. , Fultz Lisa M. , Hanks Travis L. , Lawles Kyle D. , Mack Clinton J. , Owen Kevin W. , Reed Stewart D. , Santillano Jesus , Walsh Olga , White Michael J. , Raun W.R.
Published: November 2007

Response to fertilizer is a function of several factors including weather, soil condition, previous year yield level, and the actual amount of fertilizer applied. The main objectives of this paper were to evaluate if cumulative precipitation (PPT), growing degree days (GDD), soil moisture (SM) and fertilizer can explain variability in long‐term grain yield and fertilizer response index (RI); to assess if demand for N fertilizer is greater the ensuing year given low or high yield levels in the previous year; and to evaluate if rainfall distribution coupled with the previous year grain yield level and RI of winter wheat (Triticum aestivum L.) improves the predictability of ensuing year RI. Data from two long‐term experiments located at Stillwater and Lahoma, OK were used in this report. The experimental design was a randomized complete block with four replications. Twelve (Stillwater) and thirteen (Lahoma) treatments that consisted of annual application of N, P and K inorganic fertilizers were included although selected treatments were used to address the objectives. Soil moisture at 75 cm depth was a better predictor of both grain yield (R2 = 0.35) and RI (R2 = 0.66) at Stillwater while SM at the 60 cm depth was significantly correlated to grain yield (R2 = 0.39) at Lahoma. For years where the previous year yield was low, the ensuing year had a low RI while in many years where the previous yield was high; the ensuing year had a high RI in both experiments. The practical significance of these findings is that producers could theoretically adjust preplant or in‐season topdress N fertilizer rates by considering the previous year yield level and the degree of response to N.
Distribution of Arsenic and Other Minerals in Rice Plants Affected by Natural Straighthead
Authors: Belefant‐Miller Helen , Beaty Tony
Published: November 2007

Because of the inconsistency and unpredictability of naturally occurring straighthead, arsenical herbicides are sometimes used to induce straighthead‐like symptoms to study this sterility disorder. In 2005, an outbreak of naturally occurring (nonchemically induced) straighthead in rice (Oryza sativa L.) study fields in Stuttgart, AR provided an opportunity to examine the role of minerals in this generally unpredictable disorder. The outbreak affected areas of yield and N rate tests thus permitting examination of the effect of N levels on straighthead. It was found that at the higher N levels, straighthead symptoms were reduced. Since several minerals, including As, have been associated with straighthead, samples of the soil and plants from three of the affected cultivars were analyzed for their levels of several minerals. Straighthead‐affected and nonstraighthead‐affected plants of each cultivar were separated into roots, stems, leaves, and seeds. Each plant part was analyzed for its level of macro‐ and micronutrients plus As, from which a relative (straighthead/nonstraighthead) mineral level for each cultivar was calculated. Relative levels of As did not show a consistent pattern among the plant parts. Magnesium may play a role in natural straighthead; only its relative concentrations were consistent across the three cultivars in the soil, stems (and its subsection, stem internodes), leaves, seeds (and its subsection, seed hulls); though not in the roots, brown rice, or stem nodes. The data provide a description of nutrient levels in the rice plant from a rare occurrence and so may provide comparisons for other studies of natural and induced straighthead.
Temporal Yield Variability under Conventional and Alternative Management Systems
Authors: Smith Richard G. , Menalled Fabian D. , Robertson G. P.
Published: November 2007

Year to year variation in yield is an inherent risk associated with crop production and many growers rely on intensive mechanical or chemical inputs to preserve crop yield in the face of fluctuating environmental conditions. However, as interest grows in alternative crop management systems which depend less on external inputs, determining the degree to which management systems can impact the temporal yield variability will help the development of sustainable agroecosystems. This study assessed average crop yields and temporal yield variability over a 12‐yr period in four agricultural management systems that are part of a long‐term cropping systems experiment at the W.K. Kellogg Biological Station (KBS) Long Term Ecological Research (LTER) site in southwestern Michigan. The four systems follow a corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and winter wheat (Triticum aestivum L.) 3‐yr rotation under conventional (CT), no‐till (NT), low‐input (LI), or organic (ORG) management, and each crop phase was present in the rotation four times from 1993 to 2004. Yields were measured each year and crop yield variability was estimated using the coefficient of variation calculated separately for each crop phase. Averaged over the study period, yields in the CT and NT systems were similar across all crop phases of the rotation and of higher magnitude than the LI system only in the winter wheat phase of the rotation. Compared to the other three management systems, yields in the ORG system were lower in the corn and winter wheat phases of the rotation. Yields in the soybean phase were similar across the four management systems. Temporal yield variability differed among management systems and rotation phases and was highest in the ORG system during the soybean (CV = 48%) and winter wheat (CV = 33%) phases of the rotation. Compared to the CT system, yield variability was 40% lower in the LI (corn phase), 33% lower in the NT (soybean phase) and similar in the NT (corn and winter wheat phases) systems. Results of this study suggest that yield and temporal yield variability under alternative management systems such as no‐till and low‐input can be comparable to that in conventional systems. However, temporal yield variability can be as high or higher in organic cropping systems without external inputs of manure or compost.
Seed‐Applied Insecticides Inconsistently Affect Corn Forage in Continuous Corn
Authors: Cox W. J. , Shields E. , Cherney D. J. R. , Cherney J. H.
Published: November 2007

Western corn rootworm (Diabrotica virgifera virgifera Le Conte) is the major insect pest in the corn phase of a corn (Zea mays L.) silage–perennial forage rotation. Dairy producers may prefer seed‐applied instead of soil‐applied insecticides for rootworm control because of ease of use and additional control of some other soil insect pests. The objective of the 2‐yr NY field study was to evaluate clothianidin [(E)1‐(2‐chloro‐1,3‐thiazol‐5‐ymethyl)‐3‐methyl‐2 nitroguanidine] and thiamethoxam (3‐[(2‐chloro‐5‐thiazolyl)methyl]tetrahydro‐5‐methyl‐N‐nitro‐4H‐1,3,5‐oxadiazin‐4‐imine) at the 1.25 mg a.i. kernel−1 rate for rootworm control, dry matter (DM) accumulation, DM yield, and silage quality. The control had moderately severe (1.40‐node injury scale), whereas clothianidin (0.18) and thiamethoxam (0.39) had acceptable rootworm damage ratings. Clothianidin had greater DM accumulation at the 12th leaf stage (384 g m−2) compared with thiamethoxam and the control (324 g m−2), greater DM accumulation 3 wk after silking (1491 g m−2), and greater DM yield (18.5 Mg ha−1) compared with the control (1245 g m−2 and 17.0 Mg ha−1, respectively). Thiamethoxam had similar DM yield (17.4 Mg ha−1) but greater milk Mg−1 (1559 kg Mg−1) compared with clothianidin (1475 kg Mg−1). Clothianidin had greater calculated milk yield (27,301 Mg ha−1) compared with the control (25,411 Mg ha−1) but similar to thiamethoxam (27,192 Mg ha−1). Clothianidin and thiamethoxam provided acceptable rootworm control in this study but more research is required to determine if these results are consistent across different environments in the Northeast United States.
Winter Wheat and Maize Response to Urea Ammonium Nitrate and a New Urea Formaldehyde Polymer Fertilizer
Authors: Cahill Sheri , Osmond Deanna , Crozier Carl , Israel Daniel , Weisz Randy
Published: November 2007

Slow release N fertilizers have potential to improve yield and nitrogen use efficiency (NUE) in winter wheat (Triticum aestivum L.) and maize (Zea mays L.). A slow release urea formaldehyde polymer (UFP) was compared with aqueous urea ammonium nitrate (UAN) [(NH2)2CO, NH4NO3] during a 2‐yr field experiment in North Carolina. Crops were grown on Candor (sandy, siliceous, thermic Grossarenic Kandiudults), Portsmouth (fine‐loamy over sandy or sandy‐skeletal, mixed, semiactive, thermic Typic Umbraquults), and Cape Fear (fine, mixed, semiactive, thermic Typic Umbraquults) soils. Treatments were N source (UFP and UAN) and N rate (0, 50, 78, 106, 134, 162, and 190 kg N ha−1 for wheat and 0, 39, 78, 118, 157, 196, and 235 kg N ha−1 for maize). Both sources were band applied as a split application for wheat, whereas maize received UFP at planting and split application of UAN, which is the current standard practice. Based on years of research, NC producers' apply less than one‐third of UAN at planting, with the remainder applied before the end of tillering (wheat) or at V4–6 (corn). For both crops and both sites, grain yield and NUE with UAN were statistically similar to or better than UFP. Laboratory incubations suggested UFP release of urea and urea hydrolysis were complete in less than 2 wk. Hence, UFP release was limited to a time scale of days, considered insignificant for summer crop (corn) growth conditions. Since the UFP did not significantly improve yield, UFP may only be economical if priced similar to UAN.
Corn Stover to Sustain Soil Organic Carbon Further Constrains Biomass Supply
Authors: Wilhelm W. W. , Johnson Jane M. F. , Karlen Douglas L. , Lightle David T.
Published: November 2007

Sustainable aboveground crop biomass harvest estimates for cellulosic ethanol production, to date, have been limited by the need for residue to control erosion. Recently, estimates of the amount of corn (Zea mays L.) stover needed to maintain soil carbon, which is responsible for favorable soil properties, were reported (5.25–12.50 Mg ha−1). These estimates indicate stover needed to maintain soil organic carbon, and thus productivity, are a greater constraint to environmentally sustainable cellulosic feedstock harvest than that needed to control water and wind erosion. An extensive effort is needed to develop advanced cropping systems that greatly expand biomass production to sustainably supply cellulosic feedstock without undermining crop and soil productivity.
Corn and Soybean Mapping in the United States Using MODIS Time‐Series Data Sets
Authors: Chang Jiyul , Hansen Matthew C. , Pittman Kyle , Carroll Mark , DiMiceli Charlene
Published: November 2007

Monitoring and mapping of U.S. croplands has long been a primary goal of many users of earth observation satellite data. The advantages of using low spatial and high temporal resolution data are (i) increased ability to monitor the phenological change of crop plants, and (ii) the possibility of generating consistent large area crop cover maps. This study investigates the potential of 500‐m MODIS (MODerate Resolution Imaging Spectroradiometer) data in estimating corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] area for the dominant production areas of the USA. To avoid cloud cover, MODIS 32‐day composites for all land bands, normalized difference vegetation index (NDVI), and land surface temperature (LST), were used covering March 2002 to February 2003. These time‐sequential images were further composited to produce 279 annual time‐integrated metrics. Using USDA‐NASS Cropland Data Layers (CDL) as subpixel training data, percentage soybean and corn cover per 500‐m pixel was calculated and accuracy was assessed at national, state, and county scales using data from the 2002 NASS Census of Agriculture. When these estimates were compared with the NASS Census, r2 values for corn, soybean, and combined corn and soybean areas were 0.957, 0.949, and 0.984 at the state level, respectively. At the national scale, MODIS estimates of corn and soybean cover differed by 6 and 4%, respectively. Results indicate a robust potential for using MODIS in crop type monitoring applications.
Identification of Quantitative Trait Loci in Rice for Yield, Yield Components, and Agronomic Traits across Years and Locations
Authors: Cho Yong‐Gu , Kang Hyeon‐Jung , Lee Jeom‐Sig , Lee Young‐Tae , Lim Sang‐Jong , Gauch Hugh , Eun Moo‐Young , McCouch Susan R.
Published: November 2007

A population of 164 recombinant inbred lines (RILs) of rice (Oryza sativa L.) derived from a cross between Milyang23 and Gihobyeo was evaluated for nine phenotypic characters over three years and two regions in Korea. The population had been previously mapped using 414 molecular markers. Genotype × environment (G × E) interaction was analyzed for six grain yield‐related traits and three agronomic traits across years and locations using the AMMI model. The quantitative trait loci (QTLs) were detected by interval mapping and composite interval mapping. A total of 75 QTLs were identified for the nine traits across five environments and they were categorized as (i) 29 QTLs with main effect, (ii) 18 QTLs with minor effect, (iii) 13 QTLs with G × E interaction effect, (iv) six QTLs with both main effect and G × E interaction effect, and (v) nine potential QTLs with low log of the odds (LOD) scores. The AMMI model explained from 68.6% to 84.7% of the interaction effect and 19 QTLs were significantly associated with G × E interaction. Culm length had the least G × E, while the maximum G × E interaction was exhibited for spikelets per panicle (39.7%) and percent ripened grain (35.3%). Markers closely linked to main effect QTLs will be most useful for marker‐assisted breeding.
Nutrient Uptake Responses and Inorganic Ion Contribution to Solute Potential under Salinity Stress in Halophytic Seashore Paspalums
Authors: Lee Geung‐Joo , Duncan Ronny R. , Carrow Robert N.
Published: November 2007

There is increasing interest in superior halophytes for use on saline turfgrass, forage, and land reclamations sites. We investigated halophytic seashore paspalum (Paspalum vaginatum Swartz) ecotype responses for inorganic ion uptake in shoot tissues and to identify total and individual inorganic ion contributions to total solute potential (Ψs) adjustment under increasing salinity. In a greenhouse study, nine ecotypes varying substantially in salinity tolerance were grown in nutrient/sand culture with six salinity levels up to 49.7 dS m−1 Increasing salinity reduced uptake of K, Ca, and Mg, with Mg most affected. Sodium tissue content increased with salinity, but Cl increased and then declined as salinity increased. The least salt‐ tolerant ecotype, ‘Adalayd’, exhibited lower Cl uptake at high salinity compared to the most salt‐tolerant types (SI 93‐2, HI 101). Shoot and root growth were positively correlated to K tissue content and K was the primary ion for solute potential (Ψs) adjustment. Inorganic ions contributed 57 to 97% to Ψs adjustment with salt‐tolerant ecotypes exhibiting less dependence on inorganic ions for Ψs adjustment apparently due to their ability to maintain synthesis of organic osmolytes under high salinity. In terms of physiological traits adapted for salt‐screening protocols the following were not useful: tissue nutrient/element content; K/Na and Ca/Na tissue content ratios; and K or other ion contributions to total Ψs in percent or MPa units. Shoot tissue content relationships of K, Mg, and Ca to increasing salinity indicate the importance of nutritional programs for these nutrients on salt‐affected sites.
Genetic Engineering of Maize with theArabidopsisDREB1A/CBF3Gene Using Split‐Seed Explants
Authors: Al‐Abed Diaa , Madasamy Parani , Talla Reddy , Goldman Stephen , Rudrabhatla Sairam
Published: November 2007

Transformation of maize (Zea maysL.) split‐seed explants from inbred line R23 was performed following particle bombardment with a construct carrying theArabidopsistranscriptional factorCBF3under the control of the inducible promoterrd29Aand the selectable marker hygromycin phosphotransferase. OverexpressingCBF3has been shown to enhance cold, drought, and salt tolerance inArabidopsis, tobacco (Nicotiana tabacumL.), and wheat (Triticum aestivumL.). TheCBF3gene was detected in 18 lines by polymerase chain reaction (PCR), and stable integration of multiple copies ofCBF3was confirmed by Southern blot analysis in three selected lines. Reverse transcription PCR detected expression ofCBF3in the transgenic lines under unstressed conditions despite the use of the stress‐induciblerd29Apromoter. This constitutive expression was associated with growth retardation and sterility in most of the transgenic lines. Transmission of the gene in a Mendelian fashion to T1and T2generations was confirmed in one line by Southern blot analysis. Plants of this line showed stress‐inducible expression of theCBF3gene and hardly detectable expression under unstressed conditions along with significant tolerance to cold, drought, and salinity compared with wild‐type plants. These results demonstrate that stress‐inducible overexpression ofCBF3has the potential to enhance abiotic stress tolerance in corn.
Carbon Dioxide Enhancement Effects in Container‐ versus Ground‐Grown Soybean at Equal Planting Densities
Authors: Fiscus Edwin L. , Booker Fitzgerald L. , Dubois Jean‐Jacques B. , Rufty Thomas W. , Burton Joseph W. , Pursley Walter A.
Published: November 2007

Prior work showed that CO2 enhancement ratios (ER) were similar for plants grown in open‐top chambers (OTCs) whether grown in the ground or in insulated containers aboveground. Per plant comparisons were suspect since the ground‐grown plants were cultivated in rows at normal densities making it difficult to separate the effects of plant competition from the variables of interest. Soybean [Glycine max (L.) Merr. cv. Essex] was grown in the ground and in aboveground containers in OTCs in ambient and elevated CO2 at equal planting densities. The hypothesis was that at equal densities, container‐ and ground‐grown plants would exhibit both equivalent ERs and equivalent per plant yields. Although the only differences in net photosynthetic rate (An:μmol m−2 s−1) and conductance to water vapor (gs:mol m−2 s−1) were due to CO2 and container‐ and ground‐grown plants had similar ERs (mean = 20%), per plant yields were still less in the container‐grown plants at both levels of CO2 (mean = −17%). Reproductive measures, except mass per seed, as well as total stem biomass were significantly reduced in the containers. High CO2 increased seed oil concentration and the level of fatty acid saturation. The only observed environmental difference was higher daytime root zone temperatures in containers (2–6°C). The robust ERs suggest that neither above‐ nor below‐ground resource limitations was the cause of the yield discrepancies.
Selection for Nutritional Function and Agronomic Performance in Oat
Authors: Chernyshova A. A. , White P. J. , Scott M. P. , Jannink J.‐L.
Published: November 2007

The soluble fiber (1→3),(1→4)‐β‐D‐glucan has been identified as an active component of oat (Avena sativa L.) that lowers serum cholesterol, reduces the risk of heart disease and colon cancer, and alleviates the symptoms of diabetes. Those beneficial effects may be caused by the ability of β‐glucan to generate viscosity in the digestive system. The objective of this study was to estimate the genetic components of variance for β‐glucan content and oat slurry viscosity in a population derived from the cross of high β‐glucan with elite agronomic oat lines. Twelve high β‐glucan inbred lines were crossed with 12 inbred lines with good agronomic performance. The F3:4 generation was evaluated in 2005 at two Iowa locations. The range in β‐glucan content was 37.1 g kg−1 to 73.5 g kg−1 A positive correlation (r2 = 0.38) was found between β‐glucan content and log‐transformed viscosity. High β‐glucan lines tended to have low grain yield and biomass. Significant variation among families and among lines within families were observable for most traits, suggesting selection for β‐glucan content, viscosity, and viscosity deviation should be feasible.
Combining Ability of Binary Mixtures of Introduced, Cool‐ and Warm‐Season Grasses and Legumes
Authors: Springer T. L. , Gillen R. L. , McNew R. W.
Published: November 2007

When two forage species are grown together they can be compatible, compete, or allelopathic with each other. We estimated the combining ability effects for introduced, cool‐ (CS) and warm‐season (WS) grasses and legumes grown in binary mixtures. Six pure stands and 15 mixtures were transplanted into field plots in a replicated randomized block design at Woodward, OK. Plots were harvested three times a year over a 2 yr period. Each harvest was analyzed as a mixed model combining ability analysis. The dependent variables were forage dry matter (DM) and crude protein (CP) yield. Specific combining ability (SCA) effects for DM yield were either zero or negative for mixtures of CS grasses or mixtures of WS grasses. For DM yield the SCA effects were either zero or positive for CS grass‐legume mixtures or zero or negative for WS grass‐legume mixtures. A few grass–grass and grass–legume mixtures produced positive SCA effects; but, their species compositions were highly skewed toward one species. When SCA effects are zero, species compete with each other. This was the case for yellow bluestem [Bothriochloa ischaemum (L.) Keng. var. ischaemum (Hack.) Celarier and Harlan]–legume mixtures. Yellow bluestem‐legume mixtures averaged 59% yellow bluestem: 41% legume DM forage across harvests. Yellow bluestem‐legume mixtures may be a suitable forage production system for the Southern Plains. Long‐term grazing studies are needed to determine the sustainability of these mixtures.
Performance of Traditional and Improved Upland Rice Cultivars under Nonfertilized and Fertilized Conditions in Northern Laos
Authors: Saito K. , Atlin G. N. , Linquist B. , Phanthaboon K. , Shiraiwa T. , Horie T.
Published: November 2007

Shortened fallows have reduced the productivity of traditional upland rice (Oryza sativa L.)‐based slash‐and‐burn systems in northern Laos. New cultivars and management methods are needed for food security in the region. To assess their potential for increasing upland rice productivity, this study compared two improved and three traditional upland rice cultivars in three fertilizer treatments: no fertilizer, nitrogen (90 kg N/ha), and N plus phosphate (50 kg P/ha), in six trials over 2 yr. The two improved cultivars had consistently higher grain yields than the traditional cultivars across all fertilizer treatments (3.9 vs. 2.1 t/ha). The improved cultivars had greater total biomass and harvest index, more panicles, and were shorter than the traditional cultivars. They were also more responsive to N without applied P than traditional cultivars. Two of three traditional cultivars gave a response that was similar to the improved cultivars when both N and P were applied. In addition, on‐farm trials were conducted at 13 locations to compare the productivity of the improved cultivars with fertilizer (N–P–K 60–26–50 kg/ha) to farmers' practice consisting of traditional cultivars without fertilizer. In these trials, the improved cultivars with fertilizer achieved much higher grain yields than farmers' practice (3.0 vs. 1.8 t/ha). Improved cultivars and moderate inorganic fertilizer application offer a new approach to increasing the productivity of upland rice in Laos.
Latitudinal and Longitudinal Adaptation of Switchgrass Populations
Authors: Casler M. D. , Vogel K. P. , Taliaferro C. M. , Ehlke N. J. , Berdahl J. D. , Brummer E. C. , Kallenbach R. L. , West C. P. , Mitchell R. B.
Published: November 2007

Switchgrass (Panicum virgatum L.) is a warm‐season native grass, used for livestock feed, bioenergy, soil and wildlife conservation, and prairie restoration in a large portion of the USA. The objective of this research was to quantify the relative importance of latitude and longitude for adaptation and agronomic performance of a diverse group of switchgrass populations. Six populations, chosen to represent remnant prairie populations on two north–south transects, were evaluated for agronomic traits at 12 locations ranging from 36 to 47°N latitude and 88 to 101°W longitude. Although the population × location interactions accounted for only 10 to 31% of the variance among population means, many significant changes in ranking and adaptive responses were observed. Ground cover was greater for northern‐origin populations evaluated in hardiness zones 3 and 4 and for southern‐origin populations evaluated in hardiness zones 5 and 6. There were no adaptive responses related to longitude (ecoregion). Switchgrass populations for use in biomass production, conservation, or restoration should not be moved more than one hardiness zone north or south from their origin, but some can be moved east or west of their original ecoregion, if results from field tests support broad longitudinal adaptation.
Assessment of Genetic Diversity among Nondormant and Semidormant Alfalfa Populations Using Sequence‐Related Amplified Polymorphisms
Authors: Ariss Jennifer J. , Vandemark George J.
Published: November 2007

Synthetic populations of alfalfa (Medicago sativa L.) consist of genetically heterogeneous mixtures of plants, which may complicate use of molecular markers for examining genetic relationships among populations. Molecular marker techniques combined with bulked DNA from multiple plants provides perhaps the best combination of accuracy and high throughput for characterization and differentiation of alfalfa populations. Using 20‐plant bulked DNA templates we assessed how sequence‐related amplified polymorphisms (SRAPs) would estimate genetic similarity among 29 nondormant and semidormant alfalfa populations representing diverse genetic backgrounds and the nine historically recognized U.S. germplasm sources. Cluster analysis based on estimates of genetic similarity showed separation of populations in fall dormancy classes 6 to 8 (semidormant) from fall dormancy classes 9 to 11 (nondormant) and in many examples, DNA bulks of the same population clustered together. A single SRAP marker was identified that was present only in bulks of fall dormancy classes 6 and 7, and another marker was identified that was detected only in bulks of fall dormancy class 8. This study demonstrates that the amplification of SRAP markers from DNA extracted from bulked plant samples is an efficient method for estimating genetic similarity both within and between a large numbers of populations. The SRAPs may also be useful for indirectly classifying relative fall dormancies of uncharacterized populations.
Genetic Diversity, Plant Adaptation Regions, and Gene Pools for Switchgrass
Authors: Casler Michael D. , Stendal Chad A. , Kapich Ludmila , Vogel Kenneth P.
Published: November 2007

Switchgrass (Panicum virgatumL.) is a perennial grass native to the North American tallgrass prairie and broadly adapted to the central and eastern USA. Transfer of germplasm throughout this region creates the potential of contaminating local gene pools with genes that are not native to a locale. The objective of this study was to identify structural patterns and spatial variation for molecular markers of switchgrass populations from the northern and central USA. Forty‐six prairie‐remnant populations and 11 cultivars were analyzed for random amplified polymorphic DNA (RAPD) markers. Although there was significant population differentiation, little of this variation was associated with geographic regions. A small amount of population differentiation was associated with hardiness zones and ecoregions, suggesting that a recent proposal to use these two criteria for defining plant adaptation regions has merit for defining gene pools and seed‐transfer zones of switchgrass. Cultivars of switchgrass cannot be differentiated from prairie‐remnant populations in the northern and central USA on the basis of RAPD markers, indicating that they are still highly representative of natural germplasm. Seed sources of switchgrass can be moved considerable distance within hardiness zones and ecoregions without causing significant contamination, pollution, swamping, or erosion of local gene pools.
Little Heterosis between Alfalfa Populations Derived from the Midwestern and Southwestern United States
Authors: Şakiroğlu Muhammet , Brummer E. Charles
Published: November 2007

Increasing the yield of alfalfa (Medicago sativa L.) is a desirable breeding goal. The objective of this experiment was to test the hypothesis that hybrids between nondormant‐derived alfalfa germplasm selected for winter hardiness and semidormant germplasm will express heterosis for yield. Four semidormant cultivars and four nondormant‐derived populations were handcrossed in a half‐diallel mating design to form population hybrids. Both seeded and transplanted trials were grown in Iowa between 2003 and 2005. Total biomass yield was measured at four harvests each year. The nondormant‐derived germplasm produced lower yields than the semidormant cultivars. The hybrids between groups were intermediate to the parents with little evidence of heterosis in any environment or for any harvest during the year. Although particular crosses produced high yields in certain environments, no general heterotic pattern was observed between the two proposed groups. A Gardner and Eberhart Analysis III indicated the presence of variation for both general combining ability and specific combining ability effects of approximately equal magnitude among these eight populations. The nondormant germplasm sources used here do not form a new heterotic group for midwestern U.S. alfalfa breeding programs.
The Effect of Clothianidin Seed Treatments on Corn Growth following Soybean
Authors: Cox W. J. , Shields E. , Cherney J. H.
Published: November 2007

Cool soil conditions after planting frequently delay corn (Zea mays L.) emergence in the northeastern United States, which contributes to occasional early‐season soil insect damage. Two corn hybrids with three seed‐applied insecticide treatments, which included a control, 0.25 mg a.i. seed−1 clothianidin [(E) 1‐(2‐chloro‐1, 3‐thiazolyl‐5‐ymethyl)‐3‐methyl‐2‐nitroguanidine], and 1.25 mg a.i. seed−1 clothianidin were evaluated in 2004 and 2005 in New York to determine how clothianidin affects corn growth and yield in an environment with low incidence of soil insect pests. Both clothianidin treatments had greater leaf area index (LAI) values (∼2.60) at the 10th to 11th leaf stage (V10–11) compared with the control (2.45). The 0.25 mg a.i. rate had a greater LAI (4.46) than the 1.25 mg a.i. rate (4.28) at the silking stage (R1) and a greater mean crop growth rate from the V10–11 to R1 stage (36.5 and 32.7 g m−2 d−1, respectively). The control had a greater harvest index (0.54) than the 1.25 mg a.i. rate (0.50), but all three treatments had similar grain yield (9.7–10.3 Mg ha−1). Results from this study indicate that clothianidin seed treatments do not have phytotoxic effects on corn growth and yield in an environment with low incidence of soil insect pests. Nevertheless, we do not recommend clothianidin seed treatment as inexpensive insurance against early‐season soil insect damage when corn follows soybean [Glycine max (L.) Merr.] in the northeastern United States.
Trait Associations at the Xgwm 261 and Rht‐B1 Loci in Two Winter Wheat Recombinant Inbred Line Populations
Authors: Clayshulte Sally R. , Haley Scott D. , Byrne Patrick F. , Shan Xueyan
Published: November 2007

Microsatellite marker locus Xgwm 261 has been associated with reduced plant height attributed to the linked gibberellic acid (GA) sensitive Rht8c allele in wheat (Triticum aestivum L.). Our objective was to determine effects of allelic variation at the Xgwm 261 and Rht‐B1 loci in two winter wheat recombinant inbred line (RIL) populations. ‘Longhorn’/‘Akron’ and Longhorn/‘Yuma’ RIL populations were evaluated in controlled environments for GA sensitivity and coleoptile length and were grown in Colorado at five locations for 2 yr for agronomic evaluation. Microsatellite markers were used to identify alleles at the Xgwm 261 and Rht‐B1 loci. In both populations, the Rht‐B1b class showed reduced plant height (8.9% average), GA sensitivity (average 73.5%), coleoptile length (average 11.3%), and test weight (average 1.9%) relative to the Rht‐B1a class. In the Longhorn/Yuma population, Rht‐B1b and Xgwm 261 165‐bp classes were shorter than the Xgwm 261 210‐bp and Rht‐B1a classes. Increased GA sensitivity and coleoptile length of the Xgwm 261 165‐bp class were observed, although only in the Rht‐B1a background. Plant height of the Xgwm 261 165‐bp + Rht‐B1a combination was intermediate to the shorter Xgwm 261 165‐bp + Rht‐B1b and the taller Xgwm 261‐210‐bp + Rht‐B1a combinations. No negative associations attributed to the Xgwm 261 165‐bp allele were observed. Our results suggest that the Xgwm 261 165‐bp allele may provide reduced plant height, increased coleoptile length, and increased test weight when combined in a background with the Rht‐B1a allele.
Quantitative Trait Loci Linked to White Mold Resistance in Common Bean
Authors: Maxwell Judd J. , Brick Mark A. , Byrne Patrick F. , Schwartz Howard F. , Shan Xueyan , Ogg James B. , Hensen Robert A.
Published: November 2007

White mold disease (WM) of common bean (Phaseolus vulgaris L.), caused by Sclerotinia sclerotiorum (Lib.) de Bary, reduces crop yield and quality throughout the United States. The development of cultivars with resistance to WM would be facilitated by the identification and use of molecular markers linked to resistance genes. The objectives of this research were (i) to characterize WM reaction in a recombinant inbred line (RIL) population derived from a cross between resistant and susceptible germplasm, (ii) to validate the effect of a previously reported quantitative trait locus (QTL) for WM resistance, and (iii) to locate additional QTL associated with WM resistance. A RIL population that consisted of 94 lines was derived from a cross between G122 (resistant) and CO72548 (susceptible). The population was evaluated for WM reaction in three greenhouse tests and one field environment, and for molecular markers throughout the genome. Two RIL were identified with higher resistance levels (P < 0.05) than the resistant parent G122. A previously reported QTL on linkage group B7 was significant (P < 0.01) in single‐factor analysis of variance, but not with composite interval mapping. Five QTL for resistance to WM were found (likelihood odds ratio [LOD] > 2.7) on linkage groups B1, B2b, B8, and B9. The QTL were contributed from both parents and together accounted for 48% of the phenotypic variation (R2). For field resistance, one QTL (R2 = 12%) on linkage group B8 was detected. These results confirm polygenic resistance to WM in common bean.
Evaluation of the Effect of Density on Potato Yield and Tuber Size Distribution
Authors: Bussan Alvin J. , Mitchell Paul D. , Copas Michael E. , Drilias Michael J.
Published: November 2007

Potato (Solanum tuberosum) yield has been optimized for in‐row spacings ranging from 15 to 40 cm depending on region, targeted market, variety, and other factors. Production goals require optimizing tuber size to maximize crop value. Our goal was to evaluate the effect of plant, stem, and tuber density on stem and tuber set, potato yield, tuber size distribution, and other quality factors. Research plots were established within a 20‐ha commercial production field, and analysis was done with linear and nonlinear regression. Plant density decreased with increasing in‐row plant spacing. Stem density increased linearly with increasing plant density, but response differed across years. Tuber density increased to a maximum of 190 tubers m−2 in response to plant and stem density, with stem density more accurately predicting tuber set. Yield was related to plant, stem, and tuber density using nonlinear regression, more accurately predicted by stem and tuber density than by plant density. A hyperbolic model was used to predict yield with estimated maximum yield of 86 Mg ha−1 when related to stem density. Average tuber size was related to stem and tuber density using the inverse yield law and estimated maximum average tuber size of >200 g. The distribution for tuber sizes was estimated as a Weibull probability density function that predicted changes in tuber size in response to stem and tuber density. The hyperbolic model accurately predicted tuber density and yield with the added benefit that estimated parameters have biological importance, unlike polynomial or other regression models used to predict crop yield. Modeling tuber size distribution over different stem densities provides a mechanism for future economic analysis to optimize management and conduct sensitivity analysis to determine the most important factors influencing crop value.