bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerial Accumulation and Partitioning of Nutrients by Corn
Authors: Karlen D. L. , Flannery R. L. , Sadler E. J.
Published: July 2010

Amounts and rates of dry matter and nutrient accumulation for very high‐yielding corn (Zea mays L.) were unknown, but were needed to develop a base for future research and on‐farm maximum economic yield demonstration programs. Aerial whole plant samples, collected from a maximum yield research experiment that resulted in a 19.3 Mg ha−1 grain yield on a Typic Hapludult soil (Freehold sandy loam) near Adelphia, NJ, were used to provide that information. Samples were collected at growth stages V4, V8, V12, VT, R1, R2, R5, and R6; separated into lower leaves, upper leaves, stem and tassel, and ear and shank fractions; and analyzed to determine N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn concentrations. Accumulation curves for each plant fraction were computed using those data and described mathematically using compound cubic polynomial equations. Dry matter and nutrient accumulation rates were computed by differentiating the equations. Total accumulation at physiological maturity was approximately 31 800, 386, 70, 370, 59, 44, 40, 0.13, 0.14, 1.9, 0.9, and 0.8 kg ha−1 for dry matter, N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn, respectively. Distribution among the four plant fractions, as well as rates of accumulation, are discussed. Diagnosis and recommendation integrated system indices were calculated using leaf concentration data. Nutrient balance was very good, although fertilizer recovery was not optimum. Amounts and rates of accumulation measured in this study can provide general guidelines for very high corn yields when more economical practices are used.
Grass Seedling Emergence, Morphology, and Establishment as Affected by Planting Depth
Authors: Newman P. R. , Moser L. E.
Published: July 2010

The seeding depth of grasses affects emergence and adventitious root development. Seedling root morphology and development should be considered when determining planting depth for forage grasses. A field study was conducted on a Kennebec silt loam (fine‐silty, mixed, mesic Cumulic Hapludolls) during June to August 1985 and 1986 to investigate the effect of planting depth on seedling emergence, morphology, and establishment of smooth bromegrass (Bromus inermis Leyss.), big bluestem (Andropogon gerardii var. gerardii Vitman), indiangrass [Sorghastrum nutans (L.) Nash], and switchgrass (Panicum virgatum L.). Seeds were planted by hand to insure seeding depths of 1.5, 3.0, 4.5, and 6.0 cm. Emergence percentage decreased with increased planting depth for all grasses except switchgrass, which had similar percentages at the 1.5‐ and 3.0‐cm planting depths. Coleoptile length and seedling crown depth were positively correlated with actual planting depth in smooth bromegrass, while subcoleoptile internode length was positively correlated with actual planting depth in big bluestem, indiangrass, and switchgrass. Indiangrass differed from big bluestem and switchgrass, since its coleoptile length was positively correlated with actual planting depth. Smooth bromegrass may have the potential of increased adventitious root development due to deep placement of the seedling crown in the soil. Big bluestem, indiangrass, and switchgrass do not have the potential of increased adventitious root development as seeding depth increases, since there was no correlation of seedling crown depth with actual planting depth. Rapid increase in adventitious root number of big bluestem, indiangrass, and switchgrass was noted after three or more consecutive days of rainfall after 4 wk from planting.
Effect of Water Deficit at Different Growth Phases of Peanut. II. Response to Drought During Preflowering Phase
Authors: Rao R. C. Nageswara , Williams J. H. , Sivakumar M. V. K. , Wadia K. D. R.
Published: July 2010

Water deficits can affect peanut yields differentially depending on time of occurrence and intensity. Previous reports have shown that moderate water deficit during the preflowering phase increases pod yields by 13 to 19% relative to the fully irrigated control. This paper describes, in a more quantitative way, crop physiological factors that contribute to these increased yields. In the 1980 to 1981 and 1981 to 1982 postrainy seasons, a study was conducted on a medium deep Alfisol at the International Crop Research Institute for the Semi‐Arid Tropics (ICRISAT) in central India, to examine the responses of peanut (Arachis hypogaea L.), cv. Robut 33‐1, under three levels of soil water deficits during preflowering phase relative to an adequately irrigated control. Three intensities of drought were created (from 10–50 d after sowing [DAS]) using‐line source sprinkler irrigation, while the control was irrigated at 10‐d intervals. Moderate water deficits during the preflowering phase increased subsequent crop growth and pod growth rates in 1980 to 1981 but not in 1981 to 1982. Differences in flowering and total pod numbers between treatments were relatively small when compared to the subsequent differences in pod setting and maturity. In both seasons, greater synchrony of pod set in the moderately stressed plots resulted in a greater proportion of mature pods at final harvest. The most severely stressed plot had lower yields despite adequate irrigation subsequent to the preflowering water deficits.
Irrigation Water Management for Guar Seed Production
Authors: Alexander W. L. , Bucks D. A. , Backhaus R. A.
Published: July 2010

Agricultural crops with low water requirements and drought tolerance are needed for semiarid irrigation regions. Guar [Cyamopsis tetragonoloba (L.) Taub.] is promising as a crop for producing food‐thickening agents and fluid additives for the oil drilling industry. The effects of irrigation timing, cultivar, and plant population on water use, growth, and yield of guar were investigated at Maricopa, AZ, on a Mohall sandy loam soil (fine‐loamy, mixed, hyperthermic Typic Haplargid) with a water salinity of 1.1 dS m−1 total dissolved salts over a 2‐yr period. Variables were: six irrigation levels (one to four irrigations based on physiological plant growth stages), three cultivars (‘Kinman’, ‘Santa Cruz’, and ‘Lewis’), and three populations (78, 26, and 13 plants m−2). Three post‐establishment irrigations—one before flowering, one during initial pod development, and one at mid‐pod filling—were optimal. Four irrigations maximized vegetative growth but reduced seed production per unit of water use; two irrigations lowered growth, seed yield, and water use efficiency. Seed yields averaged 1567, 1650, and 1830 kg ha−1 for Kinman, Santa Cruz, and Lewis, respectively. Seasonal evapotranspiration was 400 mm on the optimal seed production treatments, and water use efficiencies were as high as 0.64 kg seed m−3 in 1983, and 0.41 kg seed m−3 in 1984. The newer Lewis has the potential for higher yields, in addition to being an attractive, low water‐use summer crop for the southwestern United States.
Efficiency of Maize Dry Matter Production During Periods of Complete Leaf Area Expansion
Authors: Tollenaar M. , Bruulsema T. W.
Published: July 2010

Crop dry matter production, in the absence of other limiting factors, is determined by the absorption of photosynthetically active radiation (PAR) by a crop canopy and the efficiency with which absorbed PAR is converted into dry matter. This study was conducted to investigate the effects of plant density and phase of development on PAR absorption and conversion efficiency of two maize (Zea mays L.) hybrids. The maize hybrids Pioneer 3851 and Pioneer 3925 were grown in 1984 and 1985 at plant densities of 3.9, 6, and 10 plants m−2 in irrigated field experiments near Elora, Ontario, on a London loam (Aquic Hapludalf) soil that had been systematically tile drained. Conversion efficiency was estimated from rates of aboveground dry matter accumulation and PAR absorption from approximately 2 wk before to 6 wk after silking. PAR absorption was estimated from continuous measurements of incident PAR, PAR reflectance and PAR transmittance. Crop growth rates declined during the phase of development under study due to a decline in incident PAR and a decline in conversion efficiency from 5.8 to 3.5%; PAR absorptance was approximately 89% and remained fairly stable. Leaf area index among density‐hybrid treatments ranged from 2.0 to 4.8, and PAR absorption of the latter was 9% higher than that of the former. Although crop growth rates of the plant densities were not different during the grain‐filling period, differences in PAR absorption were too small to show a significant effect of plant density on conversion efficiency. Photosynthetic conversion efficiency appears to be influenced by phase of development, but the effects of plant density on efficiency appear to be small.
Long‐Term Tillage and Rotation Effects on Corn Growth and Yield on High and Low Organic Matter, Poorly Drained Soils
Authors: Griffith D. R. , Kladivko E. J. , Mannering J. V. , West T. D. , Parsons S. D.
Published: July 2010

Little information is available that evaluates long‐term use of a range of tillage systems and different cropping sequences on poorly drained soils. This study relates corn (Zea mays L.) growth and yield to several reduced tillage systems used with continuous cropping and a corn‐soybean (Glycine max L.) rotation. Experiments were conducted on Chalmers silty clay loam (fine‐silty, mixed, mesic Typic Haplaquoll) with 40 g kg−1 organic matter for 12 yr, and Clermont silt loam (fine‐silty, mixed, mesic Typic Ochraqualf) with 10 g kg−1 organic matter for 7 yr. Both soils are nearly level and poorly drained. Tillage systems compared included moldboard plowing, chisel plowing, ridge planting, and no‐till planting. Shallow disking (10 cm) was also included at the Clermont site. On the high organic matter Chalmers soil, continuous no‐till corn was 25 cm shorter at 8 wk, 2% wetter at harvest, and 9.2% lower in yield compared to plowing. Data for chisel and ridge systems were intermediate between plowing and no‐till. No‐till yields were consistently lower than those for plowing after the first 4 yr. When following soybean, no‐till corn was 7 cm shorter at 8 wk, 1% wetter at harvest, and 2.6% lower in yield than corn under moldboard plowing. Corn growth and yield from chisel and ridge treatments were equal to those with plowing when in rotation. On the low organic matter soil in continuous notill corn, plant growth and yields were reduced for the first 3 yr, but were equal or better, compared to plowed corn, for the final 4 yr. In rotation, no‐till corn was equal to plowed corn the first 3 yr and significantly better in 3 of the last 4 yr. Yields with intermediate tillage were similar to plowed yields for continuous and rotational cropping. The relative advantage for no‐till planting with time on the low organic matter soil is attributed to improved soil physical properties.
Response of Kernel Weight of Sorghum to Environment Early and Late in Grain Filling
Authors: Kiniry J. R. , Musser R. L.
Published: July 2010

Sorghum [Sorghum bicolor (L.) Moench] is grown in a wide range of moisture and temperature environments because it is drought and heat resistant and has a relatively high yield potential. Describing the influence of reduced photosynthesis and increased temperature during grain filling on mean kernel weight (KWT) is a prerequisite to understanding the control of productivity in sorghum. Objectives of this study were to determine if decreased available assimilate due to reduced photosynthetic photon flux density (PPFD) during early grain filling reduces KWT by reducing the number of endosperm cells, and to investigate the effect of temperature on KWT and number of starch granules after endosperm cell division is complete. Plants of a single‐seeded hybrid (Hl) and a twin‐seeded hybrid (H2) were grown until heading in a greenhouse. From heading until 10 to 12 d after anthesis, plants were in growth chambers with PPFD of either 300 or 595 μmol m−2 s−1. Thereafter, plants were in chambers at 15, 22.5 or 30 °C until maturity. Measurements included seed volume and number of endosperm cells at the end of the PPFD treatments, and number of starch granules and KWT after maturity. Low PPFD early in grain filling did not decrease KWT of either hybrid although it reduced number of endosperm cells of H1 by 47%. The 30 °C treatment reduced KWT by 29% for both hybrids relative to the 22.5 °C treatment. Likewise, the 30 °C temperature reduced number of starch granules at maturity, It appeared that reduced production of starch granules contributed directly to reduced KWT at 30 °C.
Growth, Water‐Use Efficiency, and Digestibility of Crested, Intermediate, and Western Wheatgrass
Authors: Frank A. B. , Karn J. F.
Published: July 2010

Relationships between dry matter distribution among plant components, growth rates, in vitro digestible organic matter (IVDOM), and water‐use efficiency (WUE) have not been defined for cool‐season wheatgrass species grown on the Northern Great Plains. Three cultivars each of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.], intermediate wheatgrass [Elyfrigia intermedia (Host) Nevsk: Syn: A. infermedium (Host) Beauv.], and western wheatgrass (Pascopyrum smithii (Rhdb.) Love Syn: A. smithii Rydb.] were field grown and sampled over a 3‐yr period to define these relationships. The soil was a Parshall fine sandy loam (coarse‐loamy, mixed Pachic Haploboroll). Forage was harvested at three dates to measure IVDOM, WUE, forage yield, leaf area index (LAI), and leaf and stem dry matter. Significant differences were mainly present among cultivars of western wheatgrass compared to those of crested and intermediate wheatgrass. ‘Rodan’ western wheatgrass partitioned more dry matter into stems than leaves, which resulted in lower LAI, leaf/stem ratio (LSR), and IVDOM. However, Rodan had higher WUE and forage yield than did ‘Flintlock’ and ‘Rosana’ western wheatgrass. Although forage yield and IVDOM differed among western wheatgrass cultivars, there were no differences in total digestible organic matter. Growth analysis showed Rodan western wheatgrass to be more efficient than Flintlock and Rosana in accumulation of dry matter per unit of photosynthesizing leaf surface. These results suggest that partitioning of dry matter into leaves and stems is a primary factor in determining WUE and digestibility, especially for western wheatgrass.
Injury and Yield Responses of Differentially Irrigated Cotton to Ozone
Authors: Temple P. J. , Kupper R. S. , Lennox R. W. , Rohr K.
Published: July 2010

The hypothesis that plants subjected to drought stress should be less susceptible to air pollution than well‐watered plants has not been adequately tested in the field. This study was conducted to determine the influence of drought stress on foliar injury and yield responses of field‐grown cotton (Gossypium hirsutum L. cv. Acala SJ‐2) to O3. Cotton grown on Hanford coarse sandy loam (coarse‐loamy, mixed, non‐acidic, thermic Typic Xerorthents) at three levels of soil water in open‐top chambers was exposed to seasonal 12‐h (0900‐2100 h) O3 concentrations of 0.015, 0.074, 0.094 and 0.111 μL L−1 in Riverside, CA. At ambient O3 concentrations (0.074 μL L−1) severely drought‐stressed (SS) cotton averaged 25% foliar injury, while moderately stressed (SO) plants averaged 56%, and optimally watered (OW) plants averaged 68% foliar injury. Lint and seed yields were significantly reduced by O3 in OW and SO plots, while SS cotton showed no yield reductions, except at 0.111 μL L−1. Yield reductions were primarily attributable to fewer numbers of bolls. Regression equations for lint yield in relation to seasonal 12‐h O3 means and total seasonal irrigation predicted yield losses at ambient O3 concentrations relative to a background O3 level of 0.025 μL L−1 of 26.2% for OW, 19.8% for SO, and 4.7% for SS cotton. The relative similarity in responses of OW and SO cotton was attributed to adaptation to drought stress by SO plants, which maintained the sensitivity of moderately stressed cotton to O3. These results suggest that low or moderate drought stress would have relatively little effect on the response of irrigated cotton to O3.
Field Evaluation of Two Urease Inhibitors with Transplanted Lowland Rice
Authors: Buresh R. J. , De Datta S. K. , Padilla J. L. , Samson M. I.
Published: July 2010

The amendment of urea with a urease inhibitor has been proposed as a strategy to increase yield of lowland rice (Oryza sativa L.) through the reduction of N loss by ammonia volatilization. Field studies were conducted at two locations in the Philippines to determine the effects of two urease inhibitors, phenyl phosphorodiamidate (PPD) and N‐(n‐butyl) thiophosphoric triamide (NBPT), on N uptake and yield of rice. Urea was split applied at 16 to 18 d after transplanting (DT) and at 5 to 10 d after panicle initiation (DAPI). On a silty clay soil (Vertic Tropaquept) at Muñoz, the amendment of urea with PPD or NBFT significantly increased grain yield relative to conventional urea (P = 0.05). Agronomic efficiency for 35 kg N ha‐' increased from 43 kg grain kg−1 fertilizer‐N for urea to 51 and 52 kg grain kg−1 fertilizer‐N for urea + 20 g PPD kg−1 and urea + 9 g NBPT kg−1, respectively. Both PPD and NBPT increased grain N, averaged for four non‐zero N rates, by 5.7 and 7.8 kg ha−1, respectively. The increased uptake of N with the inhibitors occurred prior to 35 DT; subsequent N uptake was not affected. On a clay soil (Andaqueptic Haplaquoll) at Pila, the addition of inhibitors failed to give significantly greater grain yields than unamended urea in each of the three experiments. However, the quadratic response models for urea and urea + PPD obtained from combined results for the three Pila experiments were significantly different (P = 0.01). Amendment of urea with PPD increased agronomic efficiency by 4 kg grain kg−1 urea‐N. Physiological efficiency (kg grain kg−1 N uptake) was not significantly affected by the inhibitors, which suggests that an increase in N uptake with the inhibitors resulted in a corresponding yield increase. This study indicates that urease inhibitors can increase grain yield of lowland rice, but the yield increases with inhibitors might be small.
Temperature and Photoperiod Interactions with the Phenological Development of Sunflower
Authors: Goyne Philip J. , Schneiter A. A.
Published: July 2010

The synchronization of anthesis of sunflower (Helianthus annuus L.) genotypes to be crossed is important for seed production. Little information is available concerning the interaction of temperature with photoperiod on the phenological development of sunflower. Research was conducted in growth chambers to determine the influence of variations in temperature, photoperiod, and light quantity on the phenological development of 16 sunflower genotypes. The sunflower genotypes were subjected to light treatments of: (i) 12‐h fluorescent and incandescent light, (ii) 14‐h fluorescent and incandescent light, and (iii) 12‐h fluorescent and incandescent light followed by 2‐h exposure to incandescent lights only. The fluorescent‐incandescent light combination provided a photosynthetic photon flux density (PPFD) of about 430 μmol m−2 s−1 in the chambers, whereas that for the incandescent lights alone was 5 μmol m−2 s−1. All light treatments were imposed under day/night temperature regimes of 18/15 and 28/22°C. The light X temperature X genotype interaction was not significant. Light X genotype and temperature X genotype interactions were highly significant for number of days from emergence (VE) to bud visible (R1) and number of leaves at R1. Other significant interactions were temperature X genotype for number of leaves and plant height at R1, and light X genotype for plant height. Some of the genotypes exhibited substantial delay in reaching R1 under the 12‐h light treatment, confirming prior observations in greenhouse plantings. Differences in light energy levels had little influence on genotype photoperiodic behavior.
Decreased Rates of Nitrate Uptake During Pod Fill by Cowpea, Green Gram, and Soybean
Authors: Imsande John , Edwards D. G.
Published: July 2010

Grain legumes derive their seed‐N from soil‐N uptake, remobilization of plant‐N, and N2 fixation. To establish the profile of nitrate uptake and the contribution made by soil‐N uptake during pod fill, non‐nodulated plants were grown in solution culture, and net rates of nitrate‐N uptake were measured throughout the plant growth cycle. Green gram [Vigna radiata (L.) Wilzek cv. Berken], cowpea [Vigna unguiculata (L.) Walp. cv. Ife Brown], and soybean [Glycine max (L.) Merr. cvs. Bragg and Harosoy] were utilized in these studies. At physiological maturity, plants were harvested and dry weight and N content were measured. For the determinate legumes, green gram and Bragg soybean, seeds represented approximately 25% of the total plant dry weight and contained approximately 45% of the total plant‐N. For the indeterminate cowpea and Harosoy soybean, seeds accounted for approximately 35 to 40% of the total plant dry matter and contained approximately 50 and 70%, respectively, of the total plant‐N. The fraction of nitrate‐N taken up after the onset of pod fill ranged from approximately 20% for the determinate to 30% for the indeterminate cultivars. Thus, it can be calculated that a maximum of approximately 50% of the total seed‐N for each of the four cultivars was derived directly from nitrate‐N uptake during pod fill, and the remaining 50% came from mobilization of N in vegetative tissue.
Methodology for Evaluating Nitrogen Utilization Efficiency by Rice Genotypes
Authors: De Datta S. K. , Broadbent F. E.
Published: July 2010

Low prices for rice (Oryza sativa L.) have placed farmers all over the world in a cost‐price squeeze. There is an urgent need for cultivars and production technology that will help increase yield at lower monetary costs. A method is proposed for evaluating N utilization efficiency among rice genotypes by various combinations of plant parameters, and to rank their performance in the field. From field experiments on an Andaqueptic Haplaquoll soil in six consecutive seasons, a ranking procedure was devised that does not require the use of isotopically labeled fertilizer, which makes it less expensive and more widely applicable than a similar procedure described previously. The criteria for ranking genotypes were based on differences in several plant parameters in six seasons, in three of which 33 genotypes were grown and in three when 24 genotypes were grown. Statistically significant differences among genotypes were found in 52 out of a possible 60 instances involving five selected parameters over six seasons in nonfertilized and fertilized plots. From among these five parameters, grain yield (Y) and panicle weight per total N uptake (WP/Nt) were selected by analysis of data for 12 genotypes common to all six seasons of the experiment. Genotypes such as IR21912–56–3–1–2–2 and IR15323–78–1–3–1 had consistently high rankings with and without fertilizer N and in both wet and dry seasons. Growth duration of genotypes was a factor in the differences among genotypes. Most of the high‐ranking genotypes were of medium or long duration. A satisfactory evaluation of N utilization efficiency can be obtained without the use of isotopically labeled fertilizer. Advanced breeding lines can be routinely screened for their N utilization efficiency, a valuable trait of rice for resource‐poor farmers.
Phosphorus Stress Effects on Growth and Seed Yield Responses of Nonnodulated Soybean to Elevated Carbon Dioxide
Authors: Cure Jennifer D. , Rufty Thomas W. , Israel Daniel W.
Published: July 2010

The influence of P availability on plant responses to elevated atmospheric CO2 concentrations has received limited research attention. Therefore, an experiment was conducted to examine the effect of a wide range of P availabilities on plant response to enriched atmospheric CO2. Nonnodulating soybean [Glycine max (L.) Merr., ‘Lee’] plants were grown from germination to maturity in controlled environment chambers at 350 or 700 μL L−1 CO2 and supplied with a complete nutrient solution containing either 0.005, 0.10, 0.25, 0.50, or 1.00 mM P. Growth and seed yield were maximized at the 0.25 and 0.50 mM P concentrations at 350 and 700 μL L−1 CO2, respectively. Growth and yield were significantly increased by CO2 enrichment at all except the lowest P concentration. The stimulation of growth at high CO2 was consistently associated with increased leaf area, net assimilation rate, P uptake, and P utilization efficiency in the production of dry matter. When averaged over the four highest P levels, total root mass was increased 63% by CO2 enrichment, but P uptake efficiency per unit root mass was decreased 22%. The yield enhancement of 23 to 57% at high CO2 was associated with increases in the number and size of seed. Carbon dioxide enrichment had no significant effect on harvest index. The results indicate that CO2 enrichment can result in stimulation of growth and yield of nonnodulated, NO−3‐fed soybean plants, even at concentrations of P that limit plant growth at ambient CO2 concentrations.
Optimizing Soil and Fertilizer Nitrogen Use by Intensively Managed Winter Wheat. I. Crop Nitrogen Uptake
Authors: Baethgen W. E. , Alley M. M.
Published: July 2010

Information is lacking on the N uptake pattern of intensively managed soft red winter wheat (Triticum aesrivum L.) in the mid‐Atlantic region of the United States. Such information would facilitate decision making for N fertilizer management, increase the precision of simulation models used in research, and delineate crop growth stages for use as indicators of plant N needs. Field experiments were conducted in the Atlantic Coastal Plain region of Virginia during the 1981–1982 through 1984–1985 winter wheat growing seasons to describe the winter wheat N uptake pattern and measure responses to N fertilization. The treatments in these experiments consisted of single or split spring N applications at Zadoks growth stages 25 (GS 25) and 30 (GS 30) totaling 0, 90, or 135 kg N/ha. Total dry matter production and total N concentration were measured in the aboveground plant material and in leaves, stems, and heads. These measurements were made shortly after dormancy, at GS 30,45, and 58, and at harvest to assess the effects of the N fertilizer rates and climatic conditions on crop N uptake. Maximum daily N uptake rates were obtained in the period immediately after GS 30, suggesting that this is when the highest efficiency of N fertilizer use could be expected. Crop N uptake at GS 30 also appeared as a potentially good indicator of the plant N requirement. Total amounts of N found in leaves and stems decreased with time during the spring, while spike N increased from the early stages of head development until harvest. Climatic conditions in the different growing seasons affected plant N uptake. Variations in residual soil N and temperatures in early spring probably determined the differences in amounts and patterns of N uptake by whole plants and by the various plant fractions.
A Continuous Two‐Variable Design Using the Line‐Source Concept
Authors: Magnusson D. A. , Asher J. Ben , De Malach Y.
Published: July 2010

Multivariable experiments involving different water salinities are usually conducted using drip irrigation. Preparing the irrigation system to apply these different treatments requires a considerable investment of labor and materials. This study was conducted to examine an alternative irrigation system that is relatively simple and inexpensive, yet produces gradients of two variables. A variation of the line‐source irrigation system was tested using water salinity and N levels as variables. The middle line of a triple line‐source irrigated using saline water (7.0 dS m−1)> while the two parallel outside lines irrigated using nonsaline water (1.0 dS m−1). A second triple line‐source using only nonsaline water was superimposed perpendicularly on the first set. Ammonium nitrate was injected into the middle line. This layout produced linear gradients for both variables (r2=0.99) perpendicular to their source and provided every possible combination of saline water concentrations (7.0−1.0 dS m−1) and N levels (8.1−0.0 mmol L−1). It proved to be a simple yet highly informative system.
Flurprimidol Effect on the Emergence and Growth of Annual Bluegrass and Creeping Bentgrass
Authors: Haley J. E. , Fermanian T. W.
Published: July 2010

Annual bluegrass [Pou annua (L.)) and creeping bentgrass (Agrostis palustris Huds.) are major components of golf course turf. The application of the growth regulating compound flurprimidol [α‐(methylethyl)‐ α‐[4‐trifluoromethoxy)phenyl]‐5‐pyrimidinemethanol] might interfere with the emergence and early growth of creeping bentgrass used in overseeding programs, or cause sudden reductions in either species population. Greenhouse experiments were conducted in the summer and winter of 1985 to determine the effects of flurprimidol on germinating seeds and young seedlings of annual bluegrass [P. annua ssp. annua (L.) Timm.] and creeping bentgrass (A. palustis Huds. ‘Penneagle’). Seeds of each species were sown in pots filled with sterilized Flanigan silt loam (fine, montmorillonitic, mesic Aquic Argiudolls) soil. Flurprimidol (0.6, 0.8, 1.1, and 2.3 kg ai. ha−1) was applied preemergence or postemergence to plants 3 to 6 cm in height. Verdure collected 6 wk following treatment showed a significant decrease in yield (25 to 94% of the weight of untreated seedlings) of seedlings of both species treated with flurprimidol prior to or after emergence regardless of rate. Correlation between verdure and flurprimidol rate were significant (0.51 to 0.71) for both species and application timings in both experiments. Injury to both species observed 6 wk following treatment was similar based on visual estimates of color with severe injury (>6) occurring at rates greater than 1.1 kg a.i. ha−1 in the summer experiment. Similar injury was observed in the winter experiment for both species when flurprimidol was applied postemergent. While the effect of flurprimidol at tested application rates was prominent, similar results have yet to be verified through field testing. Thus, turfgrass managers are cautioned to be aware of potential adverse effects of flurprimidol to creeping bentgrass when overseeding.
Boron Effect on Mineral Nutrients of Maize
Authors: Mozafar A.
Published: July 2010

Boron deficiency affects the uptake of several elements by plants. Information on the effect of B on yield and nutrient uptake by maize (Zea mays L.) is limited. This sand‐culture study was conducted to acquire information on the long‐term effects of B and interruption of its supply on yield, and the concentrations of 12 elements in earleaf and root of two maize hybrids, Mutin and Carlos Semu 201 (CS 201). Hybrids differed significantly in the concentrations of 11 elements in the earleaves and eight elements in the roots. Increase in solution B concentration increased the concentration of B in the earleaf and root and changed the concentrations of N, P, Mn, Fe, Zn, and Mo in the earleaf and Ca, Mg, Mn, Fe, Zn, Cu, and Mo in the root. Interruption of B supply from tasseling to maturity significantly reduced ear and total yield, decreased B concentration, and altered the concentrations of several other elements in earleaf and root. Significant interactions between B concentration and interruption of B supply, and hybrids with yield and concentrations of several earleaf and root nutrients were observed. Earleaf concentrations of N, K, Ca, Mg, Na, Cu, Mn, and Mo in Mutin, and K, Ca, Cu, and Mo in CS 201 showed significant correlation with earleaf B. Root concentrations of Ca, Fe, and Na in Mutin and Ca, Fe, Mn, and Mo in CS 201 showed correlation with root B. These observations indicate that B, depending on its concentration in the rooting medium, the element under study, and the hybrid, may change the uptake and transport of several other elements in maize. This effect of B, presumed to be due to changes in the membrane transport properties, supports similar findings in other plants. The relationships between the concentrations of K, Ca, Cu, and Mo with the B in the earleaves of both maize hybrids, if proved to hold true under field conditions, indicate that in studies on the uptake of these elements by maize the availability of B in the growth substrate needs also to be taken into account. The confounding effect of B in the rooting medium on the concentration of other elements in the earleaves and in the roots, which could be different for the same element in different hybrids or for different elements in the same hybrid, may partly explain the inconsistency observed by different workers in the yield response of maize to B fertilization.
Forage Preservation Method Influences on Tannin Concentration, Intake, and Digestibility of Sericea Lespedeza by Sheep
Authors: Terrill T. H. , Windham W. R. , Hoveland C. S. , Amos H. E.
Published: July 2010

Livestock do not like to graze high‐tannin (HT) sericea lespedeza [Lespedeza cuneata (Dum‐Cours) G. Don], but readily consume it as hay. Intake and digestibility of fresh‐frozen (FF) and field‐dried (FD) HT and low‐tannin (LT) sericea were studied in a feeding trial with sheep (Ovis spp.) in a 2 ✕ 2 factorial with a 4 ✕ 4 Latin square arrangement of treatments. Tannin concentrations were 181,87,31, and 44 g kg‐1 for HT‐FF, LT‐FF, HT‐FD, and LT‐FD sericea, respectively. There was no difference in digestibility due to preservation method, but HT‐FF was less digestible than LT‐FF [forage ✕ preservation method (P < 0.05)]. Digestibility of neutral detergent fiber, acid detergent fiber, hemicellulose, cellulose, lignin, N, neutral detergent insoluble N, acid detergent insoluble N (ADIN), and intake of HT‐FF sericea were lower than LT‐FF or the FD forages. Decreased intake and digestibility of HT‐FF sericea were related to the high tannin concentration. Elevated fecal recovery of lignin and ADIN in sheep fed HT‐FF forage resulted in negative digestibilities and may be related to formation of insoluble tannin‐protein complexes in the digestive tract. Field drying decreased analyzable tannin concentration in HT sericea.
Cover Crop Management and Nitrogen Rate in Relation to Growth and Yield of No‐Till Corn
Authors: Wagger M. G.
Published: July 2010

Cover crop management in no‐tillage systems prior to planting the principal crop can be an important tool in maximizing the beneficial effects of the cover crop on the principal crop. A field experiment was conducted in 1984 and 1985 to examine timing effects of cover crop desiccation relative to corn planting [early desiccation/early plant (EE), early desiccation/late plant (EL), and late desiccation/ late plant (LL)] and fertilizer N (0, 100, and 200 kg ha−1) on corn growth and yield. These management schemes were evaluated for fallow, rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), and hairy vetch (Vicia villosa Roth.) cover crop systems. Corn dry matter production and N uptake, monitored in all 0 kg N ha−1 treatments, were significantly affected by cover crop management and varied according to stage of development and climatic conditions. Cover crop type had a pronounced effect on corn growth, with corn dry matter production in a rye cover crop lower than in legume cover crops. Grain yield response to applied N was greatest in a rye cover crop system. In contrast, a grain yield response up to the first increment of fertilizer N (100 kg ha−1) in legume cover crop systems was observed only in 1984. Corn recovery of legume N was estimated at 40 to 45 kg N ha−1 (2‐yr avg.), representing approximately 36 and 30% of the total N content of crimson clover and hairy vetch, respectively. These data indicate that winter annual legume cover crops are capable of providing a substantial portion of the N required by corn. Additionally, cover crop management should insure that corn planting is not delayed to allow for additional legume growth and N production.
Rapid Dinitrogen Fixation During Soybean Pod Fill Enhances Net Photosynthetic Output and Seed Yield: A New Perspective
Authors: Imsande John
Published: July 2010

Nitrogen is frequently the limiting nutrient in plant growth and reproduction. Nevertheless, it is widely reported that the seed yield of the nodulated soybean [Glycine max (L.) Merr.] grown on fertile soil is not N‐limited. This paper, based on new experimental evidence obtained under carefully controlled laboratory conditions, seeks to review and reevaluate this conclusion. To test this claim, inoculated soybean plants were grown hydroponically in the presence of suboptimal urea or with an excess of either nitrate or nitrate plus urea. Acetylene reduction activities (i.e., N2 fixation rates) of plants grown on suboptimal urea were approximately tenfold greater than those of plants grown on excess nitrate. At maturity, plants that had fixed N2 at a rapid rate during pod fill had a greater biomass (i.e., a greater net photosynthetic output), a higher N content, and produced larger seeds than uninoculated or poorly nodulated plants grown on excess nitrate. Likewise, published reports show that plant biomass, seed N, and mean seed weight (i.e., g/100 seeds) of nodulated plants grown in the field without added fertilizer N were significantly greater than those of nonnodulated plants grown on adjacent field plots and given a modest level of fertilizer N. Calculations show that mean seed weight of both hydroponically grown and fieldgrown plants correlated significantly (r ≥ 0.93) with seed yield. Because of this strong positive correlation and because rapid N2 fixation during pod fill significantly increases mean seed weight without lowering the number of seeds, it is concluded that elevated N2 fixation by field grown plants would increase soybean yield significantly. An increase in both total plant N and net photosynthetic output is thought to promote this increase in seed yield.
Soil Temperature and Water Content, Seeding Depth, and Simulated Rainfall Effects on Winter Wheat Emergence
Authors: Lafond G.P. , Fowler B. D.
Published: July 2010

Winter wheat (Triticum aestivum L.) can be produced on the northern edge of the North American Great Plains provided it is protected from winterkill by an insulating blanket of snow. No‐till seeding into standing stubble (stubbling‐in) has provided the most efficient means of maintaining this protective snow cover. Soil water at seeding is usually below optimum level for growth and development with this management system, and producers are often left with the dilemma of either seeding at the optimum date into a dry seedbed or delaying seeding until after a rain. The objectives of this study were to determine the effects of soil temperature, soil water, and seeding date and depth on median emergence time, development, and cold tolerance of winter wheat plants grown under controlled laboratory conditions. Median emergence time decreased by 1.3 d and emergence was more uniform for every degree increase in soil temperature in the 5 to 20°C range. Median emergence time increased as soil water potential decreased from −0.20 to −1.5 MPa. However, simulation studies demonstrated that 9.3 mm of precipitation on a dry soil was adequate to establish winter wheat seeded less than 25 mm deep. Increasing the depth of seeding from 19 to 76 mm increased median emergence time by 4.4 d for the optimum seeding date and 9.6 d if seeding was delayed 3 wk. Consequently, delayed deep seeding resulted in poorly developed plants with a reduced ability to withstand low temperatures. From a practical standpoint, this study demonstrates that in western Canada stubbled‐in winter wheat should be seeded shallow (10 to 25 mm) at the optimum date even if it means seeding into a dry seedbed.
Dicamba Injury to Soybean
Authors: Weidenhamer J. D. , Triplett G. B. , Sobotka F. E.
Published: July 2010

Dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) effectively controls many dicotyledonous weeds, but nontarget species such as soybean [Glycine max (L.) Merrill) are susceptible to spray or vapor drift. Field studies were conducted on a Canfield silt loam (fineloamy, mixed, mesic Aquic Fragiudalf) soil to determine the response of ‘Elf’ and ‘Williams’ soybean to dicamba over a wide range of applied rates, and to evaluate the use of dicamba injury symptoms to predict yield reductions. Soybean yield in response to increasing rates of dicamba was described by equations of the form y = Aexp( −bx), where y = yield, A = maximum yield (rate = 0 g ha−1), b is a constant, and x = rate of dicamba applied. Height reduction, seed number ha−1, and morphological symptoms of dicamba injury were useful in assessing yield reduction. Except for Elf soybean treated at the midbloom stage, there was no yield reduction without height reduction, regardless of foliar symptoms. Seed number ha−1 decreased with increasing rates of dicamba and was closely correlated with yield. Yield reductions greater than 10% were indicated by severe morphological symptoms of injury, such as terminal bud kill, splitting of the stem, swollen petioles, and curled, malformed pods. Other foliar symptoms, such as distinctive crinkling and cupping of the terminal leaves, occurred at rates much lower than those required to cause yield reductions.
Genotype × Environment Interaction in Maize
Authors: Kang M. S. , Gorman D. P.
Published: July 2010

Genotype × environment (GE) interactions are a challenge to plant breeders because they cause difficulties in selecting genotypes evaluated in diverse environments. When GE interaction is significant, its cause, nature, and implications must be carefully considered. No information is available on the contribution of weather variables and environmental index (Ȳ.j or mean yield of all cultivars in jth location minus Ȳ.. or overall mean yield for all cultivars and all locations) to GE interaction for yield in maize (Zea mays L.). The objective of this study was to determine the effect of an environmental index, maximum and minimum temperatures, rainfall for the growing season, preseason rainfall, and relative humidity (covariates) on GE interaction for yield. Seventeen hybrids grown in 12 environments (4 locations × 3 yr) were studied. The GE interaction was significiant and was partitioned into σ2i (stability variance) components assignable to each genotype (hybrid). Heterogeneity (non‐additivity) due to each covariate was removed from the GE interaction, and the remainder of the GE interaction variance was partitioned into s2i components assignable to each genotype. Environmental index accounted for 9.61% of the GE interaction sum of squares (P = 0.10). This was the largest amount of heterogeneity removed from the GE interaction by any single covariate. Rainfall during the growing season removed 1.4% of the GE interaction sum of squares and preseason rainfall removed 1.1% of the GE interaction sum of squares as heterogeneity. Minimum temperature, maximum temperature, and relative humidity removed a negligible amount of heterogeneity from the GE interaction. The 17 hybrids evaluated in this study were differentially affected more by differential fertility and/or cultural practices (environmental index) than by weather factors. Seven of the 17 hybrids had unstable performance across the 12 environments.
Vegetative Establishment of Three Warm‐Season Perennial Grasses in Late Fall and Late Winter
Authors: Chamblee D. S. , Mueller J. P. , Timothy D. H.
Published: July 2010

Too much moisture for field entry in late winter or early spring, or drought in late spring and summer create problems for vegetative establishment of warm‐season perennial grasses. Late fall planting, in drier months when the plants are dormant, offers an alternative and a possible advantage. The primary objective of this study was to determine the feasibility of late‐fall planting of ‘Coastal’ and ‘Tifton 44’ bermudagrasses [Cynodon dactylon (L.) Pers.] and ‘Carostan’ flaccidgrass (Pennisetum flaccidum Griseb.) compared with the late‐winter date commonly used for central North Carolina. Three field trials in different years were conducted on a Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudult) using the above cultivars planted in November, December, and March at two planting depths (3.8 and 7.6 cm) and two orientations (horizontal and vertical). In addition, at each planting date in the third trial, sprigs of the grasses were subjected to temperatures of 0, −3, −6, −9, −12, and −15°C in a low temperature stress simulator. Relative order of cold survival was Carostan flaccidgrass >Tifton 44 >Coastal bermudagrass. Nothing survived the −9°C or lower temperatures. Horizontal plantings of Tifton 44 bermudagrass in December to a depth of 7.6 cm produced stands in May of 79, 54, and 78% in Exp. 1, 2, and 3, respectively. For the same treatments Coastal bermudagrass produced stands of only 2, 2, and 21%, and Carostan flaccidgrass 77, 76, and 95%. Winter survival of Tifton 44 bermudagrass and Carostan flaccidgrass was markedly improved (71 vs. 32% stand in May for December planting) when placed horizontally at the 7.6‐cm depth, compared with 3.8 cm in the two more severe winters. The 7.6‐cm horizontal placement of Coastal bermudagrass in March plantings resulted in stands in May of only 36%, compared with 81% from 3.8 cm and 70% from the vertical orientation. Tifton 44 bermudagrass was less sensitive to deeper planting in March. We conclude that Carostan flaccidgrass and Tifton 44 bermudagrass may be successfully planted in the fall, particularly in areas with slightly more moderate winters than the central North Carolina area.
Corn Yield and Residual Soil Nitrate as Affected by Time and Rate of Nitrogen Application
Authors: Jokela W. E. , Randall G. W.
Published: July 2010

Efficient use of N fertilizer for corn (Zea mays L.) production is important for increasing economic return to the grower and for minimizing the potential impact on water quality. Time and rate of application are important management tools for improving N efficiency. This experiment was conducted for 3 yr on two nonirrigated southern Minnesota soils—a Mt. Carroll silt loam (fine‐silty, mixed, mesic Mollic Hapludalf) and a Webster clay loam (fine‐loamy, mixed, mesic Typic Haplaquoll)—to evaluate the effect of time and rate of N application on corn yield, N uptake, and residual soil NO−3‐N. Nitrogen as (NH4)2SO4 was applied in a factorial arrangement of N rate (low and high) and time of application (at planting (PL), eight‐leaf stage (8L), or split evenly between the two times (SP)). A zero N control and a very high N rate at PL were also included. Nitrogen rates were 75, 150, and 225 kg ha−1 on the Mt. Carroll, and 100, 200, and 300 kg ha−1 on the Webster. Grain and total dry matter (DM) yield, and plant uptake of N were increased by N application in five of six site years, in most cases up to the high N rate. Delayed N application (8L or SP vs. PL) resulted in either no effect or a slight decrease in DM and in variable effects on N uptake, depending on the year and location. Residual NO−3‐N in the 1.5 m profile ranged from 150 to 400 kg ha−1 for most treatments in the fall but was 50 to 70% lower the following spring. Residual NO−3 in the fall was consistently increased by delayed application of the high N rate from the PL to 8L stage, with most of the increase occurring in the upper 0.6 m of the profile. The decrease in residual NO−3 from fall to spring, attributed in part to leaching beyond the sampled zone, minimized the potential carryover effect for the next year's production and indicated a potential for greater environmental impact where N application was delayed. Dry matter production, N uptake, and residual NO−3‐N were affected by unusually dry periods in midsummer of all 3 yr, especially at the Webster site.