bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive Abscission and Yield Response of Soybean to Root and Canopy Competition
Authors: Marvel J. N. , Beyrouty C. A. , Gbur E. E. 
Published: July 2010

AbstractInterplant competition has been shown to influence plant architecture and seed yield. However, the influence of individual root or canopy competition on soybean [Glycine max (L.) Merr.] yield has not been identified. Field studies were conducted to determine the effects of root and canopy competition on abscission of reproductive structures and seed yield of the soybean cultivar Forrest. Plots were established on a Captina silt loam (fine‐silty mixed mesic Typic Fragiudults). Treatments were (i) no competition (ii) root competition only (iii) canopy competition only and (iv) both root and canopy (combined) competition. There was no difference among no, root, and canopy competition in the total number of reproductive structures produced and retained in 1985. However, in 1986 root and canopy competition resulted in an average of 281 and 166 reproductive structures produced and retained, respectively. In both years, combined competition caused the greatest reduction in the number of reproductive structures produced and retained. Combined competition resulted in 52 and 58% abscission in 1985 and 1986, respectively. In 1985, no, root, and canopy competition had similar effects on pod number per plant with an average of 387 pods, while combined competition resulted in only 99. In 1986, however, no competition resulted in the largest number of pods (310), combined competition resulted in the smallest number of pods (34), and root and canopy competition were intermediate with an average of 184 pods per plant. Subjecting plants to root competition decreased total seed weight and total seed number per plant by 44 and 42%, respectively, while canopy competition reduced total seed weight and number by 78%.
Growth and Development of Uniculm and Conventional‐Tillering Barley Lines
Authors: Dofing S. M. , Karlsson M. G. 
Published: July 2010

AbstractBarley (Hordeum vulgare L.) producers in northern regions require genotypes that develop and mature rapidly. Although the phenological development of barley has been studied extensively, the effect of the uniculm character on rate of growth and development has not been investigated. The objective of this study was to compare the growth and development of uniculm and conventional‐tillering near‐isogenic barley lines. Three pairs of near‐isogenic lines that differed by the presence of the uc2 (uniculm) gene were evaluated at Palmer and Fairbanks, AK during the 1990 and 1991 growing seasons. Averaged over four environments, uniculm genotypes required more growing degree days (GDD) to reach double ridge formation, but there were no differences for GDD to terminal spikelet formation (P < 0.01). Uniculm genotypes had 0.3 more leaves per main culm, required 12 fewer GDD to reach full flag leaf extension, and had a leaf appearance rate that was 0.12 leaves (100 GDD)−1 faster than conventional genotypes (P < 0.01). Uniculm genotypes matured 23 GDD earlier and were 10.9 cm taller than their conventional counterparts (P < 0.01). The restriction of a single culm per plant decreased kernels per spike by 2.2 kernels and increased kernel weight by 8.4 mg (P < 0.01). Our results suggest that the uniculm phenotype results in several favorable modifications of phenological development, which may be of practical value in regions where early maturity is important.
Comparison of Foliar and Preplant Applied Nitrogen Fertilizer for Sugar Beet
Authors: Lamb J. A. , Moraghan J. T. 
Published: July 2010

AbstractLeaf canopies of sugar beet (Beta vulgaris L.) grown in the Red River Valley of Minnesota and North Dakota sometimes display midseason (July) symptoms of N deficiency. The influence of in‐season foliar N applications on sugar beet grown under non‐irrigated conditions on a Wheatville loam (coarse silty over clayey, frigid Aeric Calciaquoll) with low and medium levels of soil N fertility was studied for 3 yr. A combination of eight soil and foliar treatments were investigated. The soil treatments were (i) soil NO−3 −N in the 0– to 60– cm depth of soil in the previous autumn (45 kg ha−1 in the 1986 and 1987 experiments, and 78 kg ha−1 in the 1988 experiment), and (ii) the above soil NO−3 −N levels plus sufficient fall‐applied urea‐N to give the equivalent of 157 kg N ha−1. In‐season foliar‐N treatments, using an urea‐NH4NO3 solution (28‐0‐0), were applied in 22 kg N−1 increments on 1 July, 15 July, and 1 August to give total foliar‐N treatments of 0, 22, 44, and 66 kg N ha−1 at both levels of soil‐N fertility. Overall, the use of foliar N application did not effect root yield and extractable sugar per hectare in 2 of the 3 yr. In one year, 1986, it did increase root yield by 5.2 Mg ha−1 and extractable sugar by 0.9 Mg ha‐t under N deficient conditions with no differences occurring under adequate N nutritional levels. There was a significant increase in both root yield and extractable sugar per hectare in 1986 and 1987 as a result of fall applied fertilizer N but not in 1988. If soil moisture conditions are favorable for plant growth such as in 1986, the use of a mid season foliar N application may be beneficial in N deficient situations.
Management and Environment Effects on Dry Matter Yields of Three Brassica Species
Authors: Wiedenhoeft M. Hagemann 
Published: July 2010

AbstractBrassica crops have potential use as a forage during summer, fall, and early winter months. The influence of planting date and harvest date on the initial and regrowth herbage yields for three Brassica species: rape (B. napus L., ‘Winfred’ in 1987 and ‘Emerald’ in 1988 and 1989), turnip (B. rapa L., ‘Purple Top’), and a turnip hybrid (B. rapa × B. pekinensis L., ‘Tyfon’) were investigated. The species were planted in late May to early June, late June to early July, and late July to early August in 1987, 1988, and 1989. Herbage yields before grazing were taken 64, 76, or 85 d after planting. The remaining herbage was allowed to regrow for 60, 70, or 80 d and then harvested. Averaged over planting dates, harvest dates, and species, initial and regrowth herbage dry matter yields were 3.4 and 1.2 Mg haha−1, respectively. The turnip hybrid produced the greatest amount of total herbage yield, 4.5 Mg haha−1, followed by the rape species, 4.1 Mg haha−1. The total herbage yield, 2.7 Mg ha−1, for the turnip species was low because there was little regrowth. The herbage yields for 1987 and 1988 were not significantly different; 1989 yields were much lower, probably due to the wet climate conditions and high weed population. The earliest planting date produced the greatest herbage yields, followed by the mid‐summer planting date. Because of cold temperatures and short days no regrowth herbage was produced from the late summer plantings. Forage Brassica crops could provide adequate herbage yields during the late summer months and well into early winter months, thereby reducing the need for purchased feed.
Water Use, Intercepted Radiation, and Soil Temperature of Skip‐Row and Equidistant‐Row Barley
Authors: Sharratt B. S. 
Published: July 2010

AbstractCropping systems are sought in the subarctic that improve the plant growing environment for sustained and diversified production of crops. This study assessed whether microclimate and water use of barley (Hordeum vulgare L.) could be altered in the subarctic by crop row configuration and fertilizer placement. Treatments established at Fairbanks, AK, included equidistant‐row planting (0.18‐m equidistant rows) with N banded between alternate rows or broadcast, and skiprow planting (skipping every third row of equidistant rows) with N banded between the closely spaced rows or broadcast. Crop water use, net and reflected radiation, interception of photon flux density (PFD), and soil temperatures were monitored during 1987 through 1989. Banding N resulted in a higher water‐use efficiency (WUE) than did broadcasting N in 1989 but not 1988. Seasonal water use was equal among treatments, although higher leaf area index (LAI) for equidistant‐ row barley suggested less evaporation and greater transpiration than for skip‐row barley. Equidistant‐row barley intercepted 5% more PFD at heading, resulting in part from higher canopy reflectance. Skip‐row barley, however, intercepted more PFD per unit leaf area. Midday net radiation was 3% higher and midday soil temperatures at 0.01 m in the interrow were as much as 5 °C higher for skip‐row barley. In this subarctic environment, barley grown in equidistant rows appeared to utilize water more effectively in transpirational processes and to intercept more PFD for improving production efficiency compared to skip‐row planting.
An Inexpensive Thermocouple Multiplexing Device
Authors: Kvien C. K. , Hook J. E. , Thomson S. J. , Smith M. C. 
Published: July 2010

AbstractThe expense of monitoring large numbers of thermocouples has constrained many research and development projects. We developed an inexpensive multiplexing device which allows 640 or more thermocouples to be accessed from a microcomputer. The multiplexing unit is connected to a microcomputer expansion box equipped with a 16‐channel digital input/output (I/O) board and a preamp connected to an analog‐to‐digital (A/D) converter with cold junction compensation. A BASIC program controls the sequencing of each of the 640 channels and storage of information on the microcomputer's disk system. Temperatures measured through the system were accurate to ± 1 °C when channel switching intervals of 1 s or more were used. Temperature at the thermocouple junctions within the multiplexing unit does not significantly affect the observations. We found the device suitable for monitoring temperatures by thermocouples, and the programming gave us complete flexibility over timing and selection of thermocouples read. The multiplexing capability reduced the amount of expensive thermocouple wire needed for sensing at remote sites.
White Clover Response to Grazing Method
Authors: Brink G. E. , Pederson G. A. 
Published: July 2010

AbstractGrazing management is a major factor influencing white clover (Trifolium repens L.) growth. Our objective was to determine the response of white clover cultivars differing in leaf size to grazing method (continuous vs. rotational stocking) using cattle (Bos spp.). In each of 2 yr, a predominantly tall fescue (Festuca arundinacea Schreb.) sod on a Savannah fine sandy loam (fine‐loamy siliceous, thermic Typic Fragiudult) was oversown in September with ‘Grasslands Huia’ (medium‐small leaf), ‘Louisiana S‐1’ (medium‐large leaf), and ‘Regal’ (large leaf) white clover. From March to August of the following year, plots of each cultivar were stocked continuously (3‐ to 5‐cm stubble) on rotationally (grazed to 5‐cm stubble every 35 to 38 d). Clover growth was measured prior to rotational grazing and stolon survival was determined in November. When precipitation during the grazing season was 59% above normal, grazing method had no influence on mean single leaf area, stolon dry weight, and stolon growing point density of white clover. In contrast, continuous stocking reduced these responses when precipitation was 32% below normal the following year. Cultivar ranking for mean single leaf area was generally the same as that for leaf size category: Grasslands Huia < Louisiana S‐1 < Regal. Although stolon length and growing point density were frequently greatest for Grasslands Huia, stolon survival of Grasslands Huia was no greater than that of the larger‐leafed cultivars. Despite varying effects of grazing method on growth and morphology, stolon survival of white clover was always greater under rotational stocking.
Relationships among Maximum Hypocotyl Length, Seed Weight, and Emergence in Sericea Lespedeza
Authors: Qui J. , Mosjidis J. A. 
Published: July 2010

AbstractPoor seedling emergence is a major limitation in establishing sericea lespedeza [Lespedeza cuneata (Dumont de Courset) G. Don]. A series of controlled‐environment and field experiments were conducted to determine relationships among maximum hypocotyl length (MHL), seed weight, and percentage and rate of emergence in sericea lespedeza and to define criteria for selecting sericea lespedeza with good field emergence. The best time to distinguish MHL among sericea lespedeza genotypes was 9 d after emergence at alternating temperature of 26/22 °C (13/11 h). Seed weight and MHL were positively correlated, and both were positively correlated with field emergence. Selection for heavier‐seeded genotypes, which should tend to increase MHL, is easy. However, direct selection for greater MHL is required if the advantages of MHL especially when planting deep, are to be fully exploited.
Soil‐Applied Atrazine Alters Blue Grama Physiology and Indirectly Influences Soil Nitrogen
Authors: Knight W. G. , Morgan J. A. , Guenzi W. D. , Shoop M. C. 
Published: July 2010

AbstractAtrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] applied at sublethal concentrations to rangelands, has resulted in herbage production and/or enhanced plant N concentration of desirable warm‐season grasses beyond that expected from weed control alone. This investigation was conducted to determine whether this is a metabolically regulated plant response, the result of enhanced soil N availability via microbially mediated processes, or both. Aerobic and anaerobic laboratory incubation studies with an atrazine‐amended, rangeland soil indicated no direct effect of atrazine on soil‐mediated N transformations. Applications of atrazine to the same soil type in column‐lysimeters containing blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] plants resulted in temporarily elevated soil NO3 concentrations and reduced NH4 concentrations in proportion to the different rates of atrazine applied (0, 0.5, 1.0, and 2.0 mg column−1). Applications of atrazine to soil containing blue grama plants initially inhibited photosynthesis and plant growth, and resulted in temporarily elevated soil NO5 concentrations and reduced NH4 concentrations. A strong inverse relationship was observed across the four atrazine treatments between soil available N and shoot N content, strongly suggesting that the dominant plant‐mediated effect of atrazine on soil N pools was elicited through atrazine's initial inhibitory effect on plant growth. A strong negative correlation between leaf photosynthesis rate and tissue NO3 levels across all four atrazine rates suggests that in addition to its negative effects on blue grama photosynthesis and growth, atrazine also impairs blue grama's ability to reduce NO3, enhancing the accumulation of plant tissue NO5 levels. We conclude that temporary changes in soil NO3 and NH4 concentrations from atrazine resulted indirectly from changes in plant growth and metabolism, and not from alterations in soil microbiological processes.
Accumulation and Redistribution of Dry Matter and Nitrogen by Spring Barley
Authors: Bulman Patrick , Smith Donald L. 
Published: July 2010

AbstractThe grain protein content of barley (Hordeum vulgare L.) is derived from the retranslocation of vegetative N, as well as from the continued uptake and assimilation of N during grain filling. Field trials were conducted at the E.A. Lods Agronomy Research Centre of McGill University on a a Bearbrook soil (fine, mixed, nonacid, frigid Humaquept) to study the effects of fertilizer N on grain and total plant N accumulation, vegetative N retranslocation, and post‐heading N uptake, and also to evaluate the importance of pre‐ and post‐anthesis N uptake in determining grain protein concentration (GPC). ‘Cadette’ and ‘Leger’, which are adapted feed types, and ‘Argyle’, an unadapted malting type, were grown with N rates of 0, 50, 100, 150 and 200 kg N ha−1 broadcast at seeding as NH4NO3. Two other treatments consisted of applying 100 kg N ha−1 at seeding and 50 kg N ha−1 as NH4NO3 (broadcast) or urea (foliar solution) 6 to 10 d after awn emergence. Retranslocation of vegetative N to the grain generally decreased with increased N application in 1988 and 1989, but not in 1990, when it increased. The proportion of vegetative N retranslocated to the grain decreased with increasing rates of fertilizer N in all years. Post‐heading N uptake and assimilation increased with fertilizer N, and appeared to be the major contributor of N to the grain. Cultivar differences in GPC were not related to differences in total N uptake, grain N, N harvest index, and apparent post‐heading N uptake or N retranslocation.
Estimating Spatial Variation in Analysis of Data from Yield Trials: A Comparison of Methods
Authors: Brownie Cavell , Bowman Daryl T. , Burton Joe W. 
Published: July 2010

AbstractIn large yield trials, variation in soil fertility (or, more generally, yield potential) can result in substantial heterogeneity within blocks and, thus, poor precision in treatment estimates. Precision may be improved using statistical analyses in which this spatial variation is accounted for in estimation of treatment or entry means. Three such types of spatial analysis are trend analysis, the Papadakis method, and analyses based on correlated errors models (which account for spatial variation through correlations between yields of neighboring plots). We reviewed the theory and empirical performance of these spatial analyses and compared them with the classical analyses. The classical analyses can be justified solely on the basis of randomization; spatial analyses depend on the model specified for the variation in yield potential. Performance depends on the polynomial used to describe yield potential in trend analysis, on the neighboring plots used to estimate fertility in the Papadakis analysis, and on the correlation structure in the correlated errors models. Empirical comparisons were based on data from 11 corn (Zea mays L.) yield trials and 1 soybean (Glycine max L.) trial, each showing evidence of heterogeneity within blocks. In comparison with the classical randomized blocks analysis, precision tended to be best for the trend and the trend plus correlated errors analyses, with the Papadakis method intermediate. Ranking of entries differed across analyses, because each analysis adjusts for spatial variation in a different way. Using a spatial analysis technique can improve precision, but selecting the most appropriate analysis for a given data set can be hard.
In‐Row Subsoiling and Potassium Placement Effects on Root Growth and Potassium Content of Cotton
Authors: Mullins Gregory L. , Reeves Donald W. , Burmester Charles H. , Bryant Hamilton H. 
Published: July 2010

AbstractOne method of correcting K deficiencies in cotton (Gossypium hirsutum L.) is by in‐row deep placement of K fertilizer. At present, the mechanisms involved in cotton yield response to deep placement of K have not been elucidated. A field study was conducted in 1990 and 1991 to evaluate root development and dry matter yield of cotton as affected by in‐row subsoiling and placement of K fertilizer. The experiment was located in central Alabama on a Norfolk fine sandy loam (fine‐loamy, siliceous, thermic Typic Kandiudult). Five treatments were compared: (i) check, without in‐row subsoiling; (ii) check, with in‐row subsoiling; (iii) 84 kg K ha−1 surface‐applied, without in‐row subsoiling; (iv) 84 kg K ha−1 surface‐applied, with in‐row subsoiling; and (v) 84 kg K ha−1 deep‐placed, in‐row. Penetrometer readings taken in 1991 demonstrated that the soil has a well‐developed traffic pan at a depth of approximately 15 to 38 cm. In‐row subsoiling disrupted the pan up to 25 cm away from the in‐row position. Root density measurements taken in‐row showed that root growth at depths > 20 cm was improved by in‐row subsoiling and K fertilization. Cotton root growth at depths > 20 cm was generally better for the treatment receiving the deep applied K. However, broadcast K in combination with in‐row subsoiling resulted in the highest productivity and K accumulation per plant. Results of this study suggest that, for cotton production in Alabama, deep placement of K is not superior to broadcast applications of K.
Legumes as Nitrate Catch Crops during the Dry‐to‐Wet Transition in Lowland Rice Cropping Systems
Authors: George Thomas , Ladha J. K. , Garrity Dennis P. , Buresh Roland J. 
Published: July 2010

AbstractIn tropical rice (Oryza sativa L.) lowlands, NO3‒ assimilation by plants during the transition from the dry to the wet season can preclude NO3‒ loss upon soil flooding and permit recycling of this N. In a 2‐yr field study in an Alfisol in the Philippines, we examined the role of legume crops and weeds during the dry‐to‐wet (DTW) transition in conserving and/or recycling soil NO3‒ that accumulated under varied dry‐season fallow management. During the May‐to‐July DTW transition, Sesbania rostrata (Bremek. & Oberm.), mungbean [Vigna radiata (L.) Wilczek], weedy, and weed‐free treatments were subplots in the February‐to‐May dry‐season mainplots of weedy, weed‐free, and frequently tilled fallows. Legume biological N2 fixation (BNF) was measured by 15N dilution. Depending on dry‐season management, the maximum extracted N (top 60‐cm layer) in the DTW transition ranged from 38 to 164 kg ha−1; this N was 62 to 96% NO3‒. Soil N uptake by weeds ranged from 31 to 46 kg N ha−1, that by mungbean from 29 to 80, and by S. rostrata from 46 to 125. The minimum estimates of DTW transition NO3‒ loss varied from none when plants were present to 107 kg N ha−1 in weed‐free fallows. Legume BNF partially offset NO3‒ loss, although increased soil NO3‒ decreased BNF‐N. Nitrogen fixed ranged from 37 to 63 kg N ha−1 by mungbean and 68 to 154 by S. rostrata. Harvest of mungbean caused negative BNF‐N contribution to the succeeding rice crop in a few cases. In lowland rice‐based cropping systems, weeds are effective in conserving soil N during the DTW transition, but legumes are more suitable nitrate catch crops because they allow the harvest of an economic product or the recycling of more N to a subsequent flooded rice crop.
Second‐Derivative Spectra for Estimating Crop Residue Cover
Authors: Su Haiping , Ransom Michel D. , Kanemasu Edward T. , Demetriades‐Shah Tanvir H. 
Published: July 2010

AbstractEstimating crop residue is important for soil conservation and tillage management, and such estimates are used in determining conservation compliance with the U.S. Food Security Act of 1985. This study was conducted to (i) examine the relationship between derivative spectra of reflectance and oat (Avena sativa L.) residue covers and (ii) determine if the relation can be used to estimate oat residue cover from ground‐based reflectance measurements, using broad‐band (MMR) and high‐spectral‐resolution (SE590) instruments. A simple spectral model was proposed to interpret the interaction of solar radiation and crop residue with different soil backgrounds. A spectral derivative technique was applied to the field‐measured reflectance data to minimize the soil background noise and extract information about crop residue. SE590 wavelength at 402 nm and MMR Band 1 (450–520 nm) were the most sensitive. The second‐derivative value, defined as the derivative spectral index, strongly correlated (r2 ≥ 0.85) with oat residue cover using SE590 and MMR data. Four empirical regression equations were developed from the relationship between the derivative spectral index and the oat residue cover from four different data sets. Our results suggest that derivative spectral indices can be useful for estimating fresh oat residue in a disked field. The broad‐band data also can be used to calculate the derivative spectral index for detecting oat residue.