bluuebunny/crossref_metadata_2025 huggingface dataset:
Turfgrass Establishment after Application of Preemergence Herbicides1
Authors: Bingham S. Wayne , Schmidt Richard E.
Published: July 2010

Annual grasses create serious problems during turfgrass establishment from sod and from seed. Field studies were conducted to determine tbe effects of the preemergence herbicides oxadiazon [2‐tert‐butyl‐4(2,4‐dichloro‐5‐isopropoxyphenyl)‐Δ2‐1,3,4‐oxadiazolin‐5‐one], prosulfalin [N‐[[4‐(dipropylamino)‐3,5 dinitropheny]]sulfonyl]‐S,S‐dimethylsulfilimine], and siduron [1‐(2 methylclyclohexyl)‐3‐phenylurea] on the establishment of three bermudagrasses [Cynodon dactylon (L.) pers. ‘Midron’, and ‘Tufcote’ and Cynodon transvaalenis × Cynodon dactylon ‘Tifway’] from sod and perennial ryegrass (Lolium perenne L. ‘Manhattan’] from seed. Sod was placed on tilled silt loam soil (Typic Hapludults), allowed 28 days for root development, and lifted vertically using force required as a measure of root development. Excellent root growth occurred from sod of the three bermudagrasses immediately after application of oxadiazon at 3.4 kg ha−1 (1× or normal use rate). Root development of bermudagrasses was reduced at 6.7 kg ha−1 of oxadiazon; however, satisfactory root growth was still apparent. Prosulfalin at 3.4 kg ha−1 and siduron at 11.2 kg ha−1 (1× or normal use rates) severely inhibited rooting of the three bermudagrasses from sod. Perennial ryegrass establishment in the fall was inhibited when seeded within 5 weeks after oxadiazon application at 4.5 kg ha−1. Both oxadiazon or prosulfalin at 3.4 kg ha−1 reduced perennial ryegrass seedling establishment when the application was within 1 week prior to seeding. Normal seedling development occurred when perennial ryegrass was seeded at 10 weeks after prosulfalin or oxadiazon applications. Siduron had no effect on perennial ryegrass seedling growth and development.
Heat Stress Effects on Protein Synthesis and Exosmosis of Cell Solutes in Three Turfgrass Species1
Authors: Wehner D. J. , Watschke T. L.
Published: July 2010

Kentucky bluegrass (Poa pratensisL.), annual bluegrass (Poaannua L.), and perennial ryegrass (Lolium perenneL.) differ in their heat tolerance as determined by plant dry weight 2 weeks after exposure to heat stress. The status of the plants at that time depends on the degree of injury that occurs during the stress treatment and the repair or tolerance of that injury. The purpose of this research was to evaluate species differences in the degree of initial injury due to heat stress. The incorporation of radio‐labeled leucine as an indicator of the net rate of protein synthesis and the efflux of cell solutes from plant tissue sections into distilled water were evaluated immediately after turfgrass shoots or tissue sections were exposed to temperatures in the range of 43 to 51 °C for 30 min. Net protein synthesis in the grasses was very heat labile. Incorporation of radiolabeled leucine declined an average of 69% in plants previously heated at 43 °C compared to plants held at 27 °C. Efflux of cell solutes from the tissue sections did not increase in plants that had been heated to 43, 45, 47, or 49 °C compared to plants held at 25 °C. No significant differences were found between the grasses for the parameters tested. Either disruption of some other physiological process or differential repair or tolerance of the heat stress injury accounted for the heat tolerance rankings of the grasses. Also, the results of this study indicate that indirect rather than direct heat injury is responsible for the behavior of the grasses stressed at the temperatures and exposure periods used in this study.
Planting Date and Cultivar Effect on Winter Rape Production1
Authors: Auld D. L. , Bettis B. L. , Dial M. J.
Published: July 2010

The optimum planting date of six cultivars of winter rape (Brassica napusL.) was determined at Moscow, Idaho on a Palouse silt loam (fine‐silty, mixed, mesic pachic, Ultic Haploxeroll). The cultivars were seeded in early August, mid‐August, late August, and mid‐September of 1978, 1979, and 1980. Data were taken on winter survival, seed yield, oil content, nodes to fist flower, reproductive nodes, and plant height. Optimum planting dates for winter rape were early to mid‐August. Both winter survival and seed yield declined when the cultivars were established in mid‐September. A significant cultivar ✕ planting date interaction for both seed yield and winter survival occurred only in the 1978–1979 trial in which plants were exposed to a minimum temperature of −30°C. Seed yield at the late planting date of this trial was closely associated to winter survival (r = 0.93**; df = 14). Oil content, nodes to first flower, reproductive nodes and plant height were not highly sensitive to planting date. The utilization of cultivars with high levels of cold tolerance could probably improve performance of late seeded rape fields. Average seed yields of 3376, 3866, and 4682 kg ha−1were observed in the 1978 to 1979,1979 to 1980, and 1980 to 1981 trials, respectively. Average oil content of individual cultivars ranged from 406 to 490 g kg−1. Based on the results of this study it appears that cultivars of winter rape recently introduced from northern Europe have excellent potential as oilseed crops in the Pacific Northwest.
Nitrogen Utilization by Wheat from Residual Sugarbeet Fertilizer and Soil Incorporated Sugarbeet Tops1
Authors: Abshahi A. , Hills F. J. , Broadbent F. E.
Published: July 2010

Sugarbeet (Beta vulgaris L.) crops usually receive N fertilizer and sugarbeet tops are often returned to the soil following the harvest of storage roots. Residual sugarbeet fertilizer N and N in tops may reduce the amount of fertilizer N required for a subsequent crop. Field experiments at Davis, CA in 1980 and 1981 were designed to assess the contribution of these factors to a following wheat (Triticum aestivum L.) crop and to trace the partitioning of fertilizer N applied to sugarbeet, N in sugarbeet tops, and fertilizer N applied to the following wheat. The site was a Reiff loam, a deep alluvial coarse loamy soil with medium‐textured substratum (Typic xerothents, Entisols, mixed, nonacid thermic). Sugarbeet, with and without 157 kg fertilizer N ha−1 and each with and without beet tops returned to the soil, were followed by wheat receiving four rates of fertilizer N (0, 62, 124, and 186 kg ha−1). The fertilizer used for both crops was stable, isotopically labeled 15N‐depleted ammonium sulfate. Nitrogen from sugarbeet tops was traced in the wheat crop by returning sugarbeet tops containing labeled N to plots where sugarbeet had been fertilized with nonlabeled N and tops and storage roots removed. Residual sugarbeet fertilizer N was traced by additional plots of sugarbeet fertilized with more strongly labeled 15N‐enriched ammonium sulfate. Of the 157 kg N ha−1 applied to the sugarbeet crop, 43% was taken up by tops and storage roots, 45% remained in the soil, primarily as organic N, leaving 12% not accounted for. Of the 45% (71 kg N ha−1) remaining in the soil only about 10% was taken up by the wheat crop, 66% remained in the soil, mostly as organic N, and 24% was not accounted for. When beet tops were returned to the soil, wheat straw and grain yield were maximized for this site with about 62 kg fertilizer N ha−1, but when tops were not returned, 124 kg fertilizer N ha−1 were required. From these applications, fertilizer N recovery by wheat was 82 and 61%, respectively. Sugarbeet tops contained, on average, 119 kg N ha−1 of which 27% was taken up by the wheat crop, 39% remained in the soil, mostly as organic N, leaving 34% not accounted for. Sugarbeet tops supplied the equivalent of 15 kg fertilizer N Mg−1 dry tops.
Tall Fescue Response to Plant Growth Retardants and Fertilizer Sources1
Authors: McCarty L. B. , DiPaola J. M. , Lewis W. M. , Gilbert W. B.
Published: July 2010

Plant growth retardant applications have been reported to reduce mowing requirements of tall fescue (Festuca arundinacea. Schreb.), but turf response to retardants under various fertility regimes has not been adequately explored. The objective of this study was to evaluate the effects of three spring‐applied growth retardants {mefluidide, (N‐[2,4‐dimethyl‐5‐[[(trifluoromethyl)sulfonyl]amino] phenyl]acetamide), at 0.14 kg ha−1; maleic hydrayide (MH) (1,2‐dihydro‐3,6‐pyridazinedione), at 4.5 kg ha−1; and a combination of mefluidide plus flurprimidol, (α‐(1‐methylethyl)‐α‐[4(trifluoromethoxy) phenyl]‐5‐pyrimidinemethanol), at 0.3 + 0.8 kg ha−1} and fertilizer sources and rates on the color, height, seedhead suppression, root growth and stand density of ‘Kentucky 31’ tall fescue. The three fertilizer sources included: a) 2‐1‐1 ratio ammonium sulfate blend, 160 g N kg−1, b) ammonium nitrate, 330 g N kg−1, and c) an ammonium sulfate liquor, ASL, 70 g N kg−1. Each fertilizer source was applied at 39 and 78 kg N ha−1 in October 1981 and 1982. A single ASL treatment was also applied in 1981 at 78 kg N ha−1. The field plot was a Typic Hapudalt Clayey, kaolinitic, thermic (Cecil gravely sandy loam) soil. Mefluidide + flurprimidol and MH treatments reduced cumulative turf height 40% and suppressed seedhead formation up to 95% for 6 to 8 weeks. Mefluidide alone reduced turf height by 20% during this period. Fall fertilization of tall fescue improved turf color following spring growth retardant application. Interactions were not observed between fertilizer sources and growth retardant treatments, except for cumulative turf height at 7 and 9 weeks after 1983 treatment. Turf responses to fertilizer sources were equivalent, but higher rates of application improved color and increased turf height and seedhead numbers.
Alcohol Dehydrogenase and Pyruvate Decarboxylase Activities in Flood‐Tolerant and Susceptible Corn Seeds during Flooding1
Authors: Van Toai T. T. , Fausey N. R. , McDonald M. B.
Published: July 2010

Early planted corn (Zea maysL.) is frequently subjected to flooding stress, especially in poorly drained soils. This study characterizes the role of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) enzymes in the flooding susceptibility of corn seeds; PDC and ADH activities were assayed in a flood‐tolerant (A632) and a flood‐susceptible (Mo17) inbred during flooding at 10 and 25 °C. Each inbred consisted of two seed lots possessing different germination levels (95 and 75% germination). Flooding induced an increase in the activity of both enzymes. However, the increase was greater and sustained longer for ADH than PDC. The maximum level of ADH activity achieved was similar in both inbreds, but was greater in the high‐quality than in the low‐quality seeds. Since the highquality seeds survived flooding longer than the lowquality seeds, no correlation between flooding susceptibility and maximum ADH activity was observed. The two inbreds also exhibited similar ADH isoenzyme patterns. These data indicate that flooding susceptibility is not associated with PDC or ADH activities in corn seeds.
Root Control of Leaf Phosphorus and Chlorine Accumulation in Soybean under Salinity Stress1
Authors: Grattan S. R. , Maas E. V.
Published: July 2010

Some soybean cultivars [Glycine max(L.) Merr.] grown in saline (−0.34 MPa osmotic potential) solution cultures with inorganic phosphate ≥ 0.25 mM, accumulate excessive P and Cl in their leaves. Greenhouse experiments were conducted with reciprocally grafted soybean to evaluate the role of the scion and rootstock on leaf P and Cl accumulation and foliar injury. Four distinctly different genotypes were studied. ‘Lee’ and ‘Lee 74’ are described as leaf‐Cl excluders, whereas ‘Clark 63’ and ‘Jackson’ are leaf‐Cl accumulators. Clark 63 and Lee 74 accumulate excessive amounts of P in their leaves, whereas Lee and Jackson do not. Root‐scion grafts of all combinations of the four cultivars, including self‐grafts were made and tested. Visual foliar injury, its onset, severity, and symptoms, was controlled predominantly by the genotype of the rootstock and was correlated with leaf P and Cl concentration. Thus, scions of all four genotypes when grafted on rootstocks that translocate P and Cl to the shoots, were sensitive to P and Cl. Scions on Clark 63 rootstocks were killed and necrotic leaves were beige in color. Since leaf P and Cl exceeded 550 and 600 mmol kg−1dry wt (1.7% P and 2.1% Cl) we attributed this injury to combined P and Cl toxicity. Leaves of scions on Lee 74 rootstocks were severely injured and exhibited a distinctive reddish‐brown coloration indicative of P toxicity. Scions on Jackson rootstocks exhibited only moderate foliar injury. Injured leaves were chlorotic and necrotic along the margins characteristic of Cl toxicity. Scions on Lee rootstocks remained healthy during the entire experiment and leaf P and Cl were maintained below 405 and 275 mmol kg−1dry wt, respectively. Although leaf P and Cl accumulation were controlled predominantly by the genotype of the rootstock, an additional mechanism, as yet unidentified, was found in the scion of Lee and Lee 74 that reduced leaf P and Cl concentration. The contribution of the mechanism was not sufficient to delay the onset of foliar injury.
Tropical Legumes for Green Manure. II. Nematode Populations and Their Effects on Succeeding Crop Yields1
Authors: Reddy K. C. , Soffes A. R. , Prine G. M. , Dunn R. A.
Published: July 2010

The high cost of nitrogenous fertilizer and the withdrawal of many effective nematicides from the marketplace created needs that might be partially satisfied by growing nematode‐resistant legumes. Legumes resistant to prevalent nematode species could furnish N for and suppress nematode populations in succeeding crops if green manured and incorporated into the soil. The effects of tropical legumes, grown as summer green manure crops, on populations of four plant‐parasitic nematodes were compared with fallow and ‘Cracker Jack’ marigold (Tagetes erectaL.) in fumigated (with 1,2‐dibromethane) and nonfumigated plots in 1979, 1980, and 1981 on an Arrendondo fine sand (loamy, siliceous, hyperthermic, Grossarenic Paleudult). Long‐term effects of summer legume green‐manuring on nematode populations and yield of succeeding crops was determined using several cereals and legumes grown in the succeeding fall, winter, and spring seasons. One cultivar, ‘Norman’, and one line, ‘F1 81d’, of pigeonpea [Cajanus cajan(L.) Millsp.], showy crotalaria (Crotalaria spectabilisRoth.), hairy indigo (Indigofera hirsutaL.), jointvetch (Aeschynomene americanaL.), velvetbean [Mucuna deeringiana(Bort.) Merr.], and marigold reduced soil populations of root‐knot nematodes [Meloidogyne incognita(Kofoid and White) Chitwood] in each year planted; ‘PI 305070’ mungbean [Vigna radiata(L.) Wilcz.] did not. Fumigation, fallowing, and rotation with jointvetch, hairy indigo, and crotalaria reduced sting nematode (Belonolaimus longicaudatusRau.) populations. Rotation with hairy indigo or marigold consistently reduced the lesion nematodes [Pratylenchus brachyurus(Godfrey) Goodey] in all the succeeding crops. Fumigation generally reduced ring nematode (Criconemoidesspp.) populations. Root‐knot nematode and the incorporated green manure had the greatest influence on snap bean [Phaseolus vulgarisL.) cv. ‘Blue Lake Bunch’] dry matter yield.
Rice Responses to a Short‐Duration Green Manure. I. Grain Yield1
Authors: Morris R. A. , Furoc R. E. , Dizon M. A.
Published: July 2010

For many Asian farmers, inorganic N fertilizer for rice (Oryza sativaL.) is costly. Biologically fixed sources of N are being reexamined as alternatives to inorganic N fertilizer. Land that is fallow during the first 5 to 7 weeks of the wet season, before monsoon rains intensify, can be used to accumulate N in a green manure. This experiment determined quantities of N that well‐adapted tropical legumes accumulated in 20 to 45 days and rice yield responses to green manuring with legumes grown for 45 or fewer days. The experiment, repeated in 1981, 1982, 1983, and 1984, was conducted on a fine, mixed, isohyperthermic Aeric Tropaqualf at IRRI, Los Baños, Philippines. Rice was transplanted in factorial arrangements of inorganic N rates (0 and 80 kg N ha 1) and green manure growth durations. In 1981, 1982, and 1983, mungbean [Vigna rudiata(L.) Wilczek] was the green manure, and growth durations were 0 (clean fallow), 20, 30, and 40 days. In 1984, cowpea [Vigna Unguiculata(L.) Walp.] was the green manure, and durations were 0,25,35, and 45 days. Average N accumulation in the oldest green manure was 83 kg N ha 1. Mean rice yield response to 80 kg inorganic N ha 1was 1.0 Mg ha1. Mean response to the oldest green manure was 2.0 Mg ha−1. The study demonstrated that a fast‐growing tropical legume can accumulate more than 80 kg N ha−1in 45 days and that rice yield responses exceeding 2 Mg ha−1are possible from green manure incorporation.
Soil pH and Manganese Effects on Manganese Nutrition of Peanut1
Authors: Parker M. B. , Walker M. E.
Published: July 2010

Manganese deficiency of peanut (Arachis hypogaea L.) is a common problem on some soils of the Coastal Plain region of the southern USA. Information is limited, however, on the concentration of Mn required in the peanut plant. ‘Florunner’ peanut was grown on a Pelham sand (loamy, siliceous, thermic, Arenic Paleaquult) to determine soil pH and Mn effects on Mn nutrition of peanut. Soil‐applied Mn treatments of 0, 10, 20, and 40 kg ha−1 were compared at pH levels near 5.2, 6.0, and 6.8. Manganese deficiency occurred only on plots with pH levels near 6.8 where yields were increased by applying up to 40 kg Mn ha−1. Critical Mn levels were 13, 15, 15, 15, 13, and 12 mg kg−1 in leaves collected at 7, 9, 11, 13, 15, and 17 weeks after planting, respectively. Pod yields averaged 3.41, 5.40, and 5.73, and 6.37 Mg ha−1 at pH level near 6.8 for 0, 10, 20, and 40 kg Mn ha−1 treatments, respectively. Maintaining a soil pH near 6.0 provided a desirable medium for peanut production without the need for Mn fertilizer.
Soybean Cultivar Response to Tillage Systems1
Authors: Elmore Roger W.
Published: July 2010

Modern crop cultivars were developed in cleanly tilled environments. As reduced‐ and no‐till production increases, we must study cultivar responses to these planting conditions to assist growers with cultivar selection for specific tillage situations. In addition, if certain cultivars respond better to a tillage system, this genetic variability could be useful in breeding programs. A field study was conducted to compare six soybean [Glycine max (L.) Merr.] cultivars of different maturities and growth habits in three tillage systems. A Hastings silt loam soil (fine, montmorillonitic, mesic Udic Argiustoll) was used in 1982 and 1983, and a Crete silt loam soil (fine, montmorillonitic, mesic Pachic Argiustoll) was used in 1984. Tillage treatments were double disk, single disk, and no‐till. Soil profiles were at field capacity at planting in all years. Tillage did not affect yield, and cultivars responded similarly to tillage systems; the best yielding cultivars in tilled systems were also best yielding in the no‐till system. There is no immediate need for cultivar performance testing in different tillage systems. However, in one year ‘Mead’ yielded 15% more in no‐till than in tilled systems, whereas ‘Williams 82’ yielded 8% less in no‐till than in tilled systems. This response may be related to a slight plant density difference between the two cultivars or genotypic differences. Effects of residue cover on evaporation are of less consequence when soils are at field capacity at planting. Thus, cultivar and tillage responses may be different than those reported here when soil moisture is deficient at planting.
Fertilizer Applicator/Planter for No‐till Small‐grain Research1
Authors: Westfall D. G. , Strohman R.
Published: July 2010

Subsurface placement of fertilizer under no‐till, small‐grain soil fertility research presents unique problems to researchers if minimum soil disturbance and minimum residue incorporation is desired. A fertilizer applicator/planter was built from commercially available parts and designed to allow evaluation of fertilizer rates, sources, and placements under no‐till, small‐grain production. It has been demonstrated to successfully plant through at least 3000 kg/ha of year‐old prostrate residue and through 4000 kg/ha of fresh, standing small‐grain residue. Residue levels higher than this have not been tested. Three people can fertilize/plant 50 plots/h, changing rates, placements, and sources.
Soil Water Effects on Low‐Temperature Seedling Emergence of Five Brassica Cultivars1
Authors: Rao S. C. , Dao T.H.
Published: July 2010

Identifying Brassica that are least sensitive to cool soil temperature and variable soil water availability during early spring is important to fill the forage deficit period in the southern Great Plains. A growth chamber study was conducted to determine the effect of soil water potential under low temperatures on the rate and total emergence for three Brassica spp. in Dale sandy loam (fine‐silty, mixed, thermic Pachic Haplustolls). Three turnip (Brassica rapa L.) cultivars, Purpletop, Cyclon and Tyfon, ‘Merlin’ kale (B. oleracea L.) and ‘Winfred’ rape (B. napus L.) were evaluated at a soil temperature of 7.5°C and five soil water potentials (−10, −30, −100, −250, and −500 kPa). Total emergence and rate of emergence of all cultivars were not affected by change in soil water potentials between −10 and −100 kPa. Soil water potential of −250 kPa reduced total emergence, whereas both rate and total emergence were greatly reduced with decrease in soil water potential from −250 to −500 kPa. Differences in total emergence were observed among cultivars even though seed germination potentials of all cultivars were similar. Purpletop turnip and Winfred rape were higher in total emergence and emerged in a shorter period under sub‐optimal environment conditions, comparedto other cultivars.
Tillage Systems for Wheat Production in the Southeastern Coastal Plains1
Authors: Karlen D. L. , Gooden D. T.
Published: July 2010

Increased wheat (Triticum aestivum L.) production has raised numerous questions regarding tillage practices and N fertilizer rates for the Coastal Plain. Therefore, eight field studies conducted on Ardilla (Fragiaquic Paleudults), Dothan (Plinthic Paleudults), and Norfolk (Typic Paleudults) soils are summarized to report N fertilizer and tillage effects. Average grain yield with moldboard plowing was significantly higher (0.4 Mg ha−1) than with disking in four of five studies, but it was significantly higher than chisel plowing (3.09 vs. 2.48 Mg ha−1) only once. No‐till yield was significantly lower (0.5 Mg ha −1) than yield with disking in two of four studies. Nitrogen response was significant in five of six studies, but the tillage ✕ N interaction was significant only once. Head number and weight were increased by plowing or higher N rates. Poor soil‐seed contact presumably caused erratic stands and lower no‐till yields because seedling emergence was not reduced by the equivalent of 10 Mg ha−1 of corn (Zea mays L.) residue. Approximately 100 kg N ha−1 was sufficient for conventional tillage, but chisel or moldboard plowing should be used rather than disking. For no‐till wheat, drills must provide good soil‐seed contact and N rates may have to be increased.
Comparison of Organic and Inorganic Nitrogen Sources for Rice1
Authors: Westcott M. P. , Mikkelsen D. S.
Published: July 2010

Rice (Oryza sativa L.) responds well to green manure‐N under flooded conditions, but more quantitative data are needed for comparisons to inorganic N. This study compared the effects of vetch (Vicia benghalensis L.) and (NH4)2SO4 on patterns of N availability and plant uptake, applied‐N recovery at harvest, and grain yield in flooded rice culture. The sources were incorporated in a Clear Lake clay (Typic Pelloxerert) in factorial combination of 60 kg N/ha increments up to a maximum rate of 180 kg N/ha. Grain yields were determined in plots of 18.9 m2 while N balance was assayed in microplots (0.27 m2) treated with 15N‐labeled materials. Ammonium sulfate was more effective in raising extractable‐N concentrations early in the growing season and made a greater contribution to plant N status throughout the season. There was no evidence that vetch extended the period of N availability to plants. Grain yields were highly dependent on N uptake; they maximized at 10.1 Mg/ha with 120 kg N/ha as (NH4)2SO4 but responded linearly to vetch up to 8.4 Mg/ha with the highest rate of addition. Ammonium sulfate effected greater labeled‐N recovery (19% across rates) and apparent N recovery (55.6%) by plants than vetch (10.1 and 27.9%, respectively). More vetch‐N was recovered in the soil at harvest; total recoveries were, therefore, not significantly different between N sources. The rate of green manure‐N mineralization early in the growing season appears to be the limiting factor in comparison to inorganic N.
Damage to Barley Spikes Resulting from Impact Momentum Similar to Small Sized Hail1
Authors: Ferguson Hayden , Jones A. J. , Tsai K. J.
Published: July 2010

Hail loss assessment in small grains is based on percent kernel loss because of shatter or spike loss. This procedure does not consider losses that may occur in kernel size and weight as a result of spike bruising without accompanying shatter or spike loss. This study was conducted to determine if bruising of barley (Hordeum vulgare L.) spikes by small, low energy hailstones might cause a yield loss above that resulting from kernel shatter or spike loss. A hail simulation device was constructed that approximately duplicated the momentum of hail particles in the size range of 10 to 12 mm in diameter. Spikes of two‐ and six‐rowed barley were impacted over a period beginning when kernels were starting to form and ending when they were fully swollen. Bruising caused a significant decrease in kernel weight in both spike types. In six‐rowed cultivars, the loss was associated with a decrease in the number of plump kernels; in two‐rowed cultivars, the loss resulted from a decrease in both the weight and number of plump kernels. Thus, hail loss assessment that considers only kernel shatter or spike loss may underestimate actual loss, especially from small hail occuring during the early stages of kernel development.
Growth and Partitioning in Peanut as Influenced by Gibberellic Acid and Daminozide
Authors: Gardner F. P.
Published: July 2010

Peanut (Arachis hypogaea L.) cultivars differ in growth habit and potential for vegetative and reproductive growth modification with plant growth regulators (PGRs). Cultivars differing in growth habit were studied in light, dark, and field environments in 1982 and 1983 to assess the effects of two PGRs on apparent assimilate partitioning, and on vegetative and reproductive growth. The cultivars used were Dixie Runner (indeterminate spreading type), Florunner (somewhat determinate spreading type), and Pronto (bunch type). The PGR foliar spray treatments were gibberellic acid (GA), a growth stimulant, and daminozide (DA) (Kylar), a growth retardant. The field‐study treatments included Dixie Runner and Florunner, and GA and DA in one and two applications, beginning at pod initiation. Gibberellic acid (0.01 or 0.1 g L−1) increased stem petiole elongation in the light, dark, and field environments. Dixie Runner in most comparisons was slightly less responsive to GA than was Florunner. Daminozide (0.5 g L−1) retarded main‐stem, cotyledonary‐branch, and petiole elongation in both cultivars in light and dark environments. Response to a mixture (1:1,v/v) of GA and DA was similar to the water control in most comparisons. Darkness stimulated greater stem elongation than did GA; the two effects were additive. Daminozide decreased leaf area and shoot/root ratio, and increased chlorophyll concentration on a leaf‐area basis. Effects of PGR treatments were similar for Dixie Runner and Florunner. It is concluded that cultivars diverse in growth habit respond similarly to GA and DA, and modification of vegetative growth by PGRs to alter assimilate partitioning and fruiting appears problematic.
Fertilizer Placement Effects on Seasonal Nitrogen Accumulation and Yield of No‐Tillage and Conventional Tillage Sorghum
Authors: Locke M. A. , Hons F. M.
Published: July 2010

Little information is available concerning fertilizer placement effects on accumulation of fertilizer N in no‐tillage sorghum [Sorghum bicolor (L.) Moench]. Possible differential accumulation patterns among tillage systems could influence management practices for these systems. Fertilizer N placement effects on sorghum yield and N accumulation in 1985 and 1986 were evaluated in a field study on a Weswood silt loam soil (fine‐silty, mixed, thermic Fluventic Ustochrept) near College Station, TX. Four N rates (0, 50, 100, and 150 kg N ha−1) as NH4NO3 were surface broadcast or subsurface banded into soil managed with no‐tillage or conventional tillage. Nitrogen‐15‐depleted NH4NO3 was applied to microplots receiving the 150 kg N ha−1 rate to monitor plant fertilizer N accumulation with seasonal progression. Fertilizer and total (fertilizer plus soil) N accumulation patterns were the same for both no‐tillage and conventional tillage treatments. Total N accumulation at harvest, and grain and stover yields were higher with banded placement. Leaf N concentration at anthesis indicated better N nutrition in banded treatments. Most total and fertilizer N accumulation had occurred by anthesis both years, with most of the N allocated to stover. During grain filling, the panicle became the primary N sink. Placement influenced neither total nor fertilizer N accumulation at anthesis in 1985, but these parameters were higher for banded treatments by harvest. Fertilizer N accumulation in culms and leaves early in the 1986 season was higher in broadcast treatments. At harvest, more total N had accumulated in broadcast treatment panicles, but more fertilizer N had accumulated in banded treatment panicles. Fertilizer uptake patterns indicated subsurface band placement was the most effective method of supplying fertilizer N for both tillage treatments.
Nitrogen Needs of Sugarbeet Produced with Reduced‐Tillage System
Authors: Halvorson A. D. , Hartman G. P.
Published: July 2010

Recent studies have shown that sugarbeet (Beta vulgaris L.) can be produced with reduced‐tillage systems; however, the effects that reduced‐tillage systems may have on N requirements of sugarbeet have not been studied. Therefore, field studies were conducted on a furrow‐irrigated silty clay loam soil (Typic Argiboroll) to determine N requirements for optimum sucrose production by sugarbeet grown with reduced‐tillage systems. Tillage treatments were conventional tillage (CT), strip tillage (ST), and no‐tillage (NT). Four N rates of 0, 56, 112, and 168 kg/ha in 1980 and 1981, and 0, 84, 140, and 196 kg/ha in 1982 were imposed on each of the tillage treatments in a split‐plot design. Fertilizer N was applied prior to establishment of tillage treatments in the fall prior to spring sugarbeet planting. Sucrose yields were ST > NT = CT. Application of N significantly increased root yield as well as gross and recoverable sucrose yields, but reduced sucrose content of the sugarbeet root and clear juice purity of all tillage treatments similarly. Except for clear juice purity, tillage ✕ N interactions were not significant when averaged over 3 yr. Therefore, N recommendations formerly developed for yield and quality relationships for sugarbeet produced with conventional tillage can be used to make N recommendations for sugarbeet produced with reduce‐tillage systems.
Spacing Pattern and End‐Trimming on Solid‐Seeded Soybean Plot Comparisons
Authors: Philbrook B. D. , Oplinger E. S.
Published: July 2010

Planting soybean [Glycine max (L.) Merr.] in solid stands increases grain yields for many producers. Testing techniques that simplify plot work but separate the effects of adjacent plots in solid‐seeded soybean have not been described. This study was conducted to determine the influence of plot planting patterns and time of end‐trimming on soybean cultivar comparisons in a solid‐seeded system. The effects of three planting patterns and end‐trimming at two stages of growth on yield, yield components, and agronomic characteristics of six cultivars were investigated in field studies conducted near Arlington, WI, from 1982 through 1984. All patterns had seven 0.18‐m harvest rows plus a border row spaced 0.28 m from each of the outside harvest rows that created a tramline through the plot. Yields of cultivars were inflated 6% when the distance between border rows of adjacent plots was increased from 0.18 m in Pattern 1 to 0.48 m in Pattern 2; however, relative yield differences among cultivars were consistent. Adding an additional border row using a common cultivar (Pattern 3) increased the distance between harvest rows of adjacent plots without increasing the distance between their borders. Soybean planted using Pattern 3 performed more consistently with respect to lodging, plant height, and yield than when either of the other patterns was used. Plot yields were inflated an average of 10% when plot ends were not end‐trimmed late in the season near plant maturity, as opposed to early season end‐trimming only. Cultivars did not respond uniformly to end‐trimming in 1983. Final plant density, pods per plant, and seed weight averaged 55, 60, and 6% more in the plot ends than in the middles, while the number of seeds per pod was unchanged. Response of pods per plant to end effects was greater for ‘Hardin’ and ‘Corsoy 79’ in 1982, and ‘Hodgson 78’ in 1984 than for the other cultivars. Techniques for solid‐seeded soybean plot comparisons are improved by using additional border rows to separate plots and by end‐trimming at or near harvest maturity.
Grain Moisture Loss Rate of High‐Oil and Standard‐Oil Maize Hybrids
Authors: Mišević D. , Alexander D. E. , Dumanović J. , Kerečki B. , Ratković S.
Published: July 2010

High‐oil hybrids having the same date of anthesis as normal‐oil hybrids are frequently found to have higher moisture content in the grain at harvest time. Field drying rate of maize (Zea mays L.) grain was followed in nine single‐cross hybrids differing in percent oil in the kernel and in agronomic traits. The objectives of this study were to determine the duration of the grain filling period (GFP), moisture content at physiological maturity, and grain moisture loss throughout the period after physiological maturity. Hybrids were grown in 1984 in a randomized complete‐block design with four replications at Urbana, IL, and Zemun Polje, Yugoslavia. Three ears were harvested from each plot 14 d after pollination (DAP) and at weekly intervals until 70 DAP. Percent moisture in the grain, and 100‐kernel weight were measured for each hybrid, harvest date, and location. High‐oil hybrids had higher moisture content 70 DAP than did normal‐oil hybrids. Differences in kernel moisture percent among oil groups at the beginning of GFP were not significant at Zemun Polje, but were significant at Urbana. At the time of approximate physiological maturity the 7% oil group had significantly lower moisture percent in the grain than did the normal‐ and 9% oil hybrids at both locations, and had significantly lower moisture percent in the grain than the 9% oil hybrids at Zemnn Polje only. There were no significant differences in rate of kernel water loss among oil groups throughout the GFP. However, normal‐oil hybrids were faster drying than 7 and 9% oil hybrids after physiological maturity. Differences in the drying down rate between the 7 and 9% oil groups were not significant at one (Urbana) of the two locations.
Nodule Occupancy by Introduced Bradyrhizobium japonicum in Iowa Soils
Authors: Berg R. K. , Loynachan T. E. , Zablotowicz R. M. , Lieberman M. T.
Published: July 2010

Competitive indigenous strains of Bradyrhizobium japonicum occupy many soils of the Midwest, but they are generally considered to be less efficient in fixing N2 than many strains added as inoculants. Inoculant strains will not improve N2 fixation in soybean [Glycine max (L.) Merr.], however, unless they are able to form nodules on the host plant. This research evaluated whether strains selected for competitiveness in the greenhouse could compete against indigenous bradyrhizobia in the field in forming nodules when added at rates used for commercial inoculants, and whether higher nodule occupancy resulted in improved plant growth. Plots were established in north‐central Iowa at seven sites on four representative soil series. Seven to 12 strains were introduced in two or three soils each year from 1983 to 1985 at approximately 5.8 log10 viable cells per centimeter of row as granular‐peat inoculants. Results showed that average strain recoveries ranged from 0 to 46%. Some introduced strains differed in their competitive ability among the sites tested. The most competitive strains were AN8, AN10, AN11, AN23, AN27, and AN30, which typically occupied at least 20% of the nodules at a given site. When considering all members of each serogroup tested, strains from serogroup 123 were the best competitors. Increased nodule occupancy by the introduced strains did not result in increased plant growth or yield. Nodulating and nonnodulating ‘Clark’ isolines and urea fertilizer treatments were used to evaluate contributions from N2 fixation and plant growth with added N fertilizer.
Histological and Physical Factors Affecting Digestibility of Forages
Authors: Akin D. E.
Published: July 2010

Factors that limit forage quality are complex and interactive. Structural characteristics that limit forage breakdown are primarily highly lignified support tissues like sclerenchyma and xylem. However, the presence of chemical barriers (likely the low molecular weight phenolic compounds) within “living” cell walls, such as the parenchyma bundle sheath and epidermis, prevents fiber degradation in these tissues. The presence of high proportions of these tissues in leaves of warm‐season grasses plus growth in hotter climates, which tends to speed maturity, combine to limit breakdown of warm‐season grass leaves compared to cool‐season species. Legume leaflets in warm‐ and cool‐season species can be readily degraded due to a high proportion of mesophyll. However, leaflets of certain species or cultivars with high tannin concentrations are poorly degraded, with mesophyll and vascular bundles comprising the residue. Grass stems have a more rigid structure than leaves, with the non‐digestible epidermis, sclerenchyma ring, and vascular tissue occupying about 30% of the tissues in the cross sections. In addition, mature grass stems have a poorly degraded parenchyma that contributes to a rigid structure in the residue. Parenchyma in legume stems is totally degraded, leaving a residue of a hollow cylinder surrounded by a uniformly lignified ring. Possibly, variations between structures of mature grass and legume stems contribute to observed differences in forage quality for these forage types. Rumen bacteria and fungi both physically associate with the more recalcitrant forage tissues. Fungi are better able to colonize the lignocellulosic tissues and can partially degrade the most resistant xylem tissues. Research avenues for improving forage quality are: (i) to enhance the ability of anaerobic fungi to weaken lignocellulosic barriers, (ii) to reduce the amount of non‐degradable barriers, particularly in stems, by plant breeding, and (iii) to improve by plant breeding the rate and extent of slowly or partially degraded tissues in leaves.
Aluminum Effects on Growth and Macronutrient Uptake by Annual Ryegrass
Authors: Rengel Z. , Robinson D. L.
Published: July 2010

Annual ryegrass (Lolium multiflorum Lam.) is an important forage crop in the southeastern USA, often grown on acid soils with potentially high levels of soluble Al. Effects of Al on growth and nutrient relationships in ryegrass are poorly understood. In this study four ryegrass cultivars were grown in a growth chamber in nutrient solutions at 0, 37, 74, 148, 296, and 592 µmol L−1 Al. The pH was initially adjusted to 4.2 and subsequent changes were monitored daily. More Al‐tolerant cultivars induced higher nutrient solution pH than more sensitive cultivars. For more Al‐tolerant cultivars, these pH changes were positively correlated with root and shoot tolerance indexes and negatively correlated with percent inhibition of Ca, Mg, K, and Na uptake. Root (shoot) tolerance index was defined as dry weight (wt.) of roots (shoots) grown with Al/dry wt. of roots (shoots) grown without Al. Changes in nutrient solution pH were effects rather than causes of differential Al tolerance, but once induced, differences in pH intensified cultivar differences in Al tolerance. An Al concentration of 37 µmol L−1 in solution significantly increased root Al concentrations, but very little Al was translocated to shoots. Higher shoot Al concentrations were found more often in the less Al‐tolerant cultivars Wilo and Urbana than in the more tolerant cultivars Gulf and Marshall. Larger root and shoot tolerance indexes, and lower percentages of inhibition of total Ca and Mg uptake were observed more often for more Al‐tolerant cultivars Marshall and Gulf than for more sensitive cultivars Wilo and Urbana. The average net influx of Ca and Mg was decreased where Al was added. Total uptake of K (quantity factor) was decreased by Al, while net K influx (intensity factor) increased for plants grown in the nutrient solution containing up to 74 µmol L−1 Al. Short exposure to Al increased net influx and total Na uptake. Longer exposure to higher concentrations of Al (at least 74 µmol L−1) inhibited both total uptake and net influx of Na. The root tolerance index was positively correlated with net influx of Ca, Mg, K, and Na. Increasing the nutrient solution Al level to 148 µmol L−1 greatly increased K/(Ca+Mg) ratio of shoots, thus increasing the grass tetany potential of the ryegrass forage.
Soil Temperature and Moisture Stress Effects on Kernel Water Uptake and Germination of Winter Wheat
Authors: Lafond G. P. , Fowler D. B.
Published: July 2010

Direct seeding into standing stubble from a previous crop (stubbling‐in) has allowed successful production of winter wheat (Triticum aestivum L.) on the northern edge of the North American Great Plains. Soil at seeding is usually very dry with this production system, and the producer is 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 importance of soil temperature and moisture potential on kernel water uptake and germination, so that the minimum requirements for successful crop establishment could be identified. Controlled environment studies demonstrated that germination could occur at moisture contents as low as 512 g water kg−1 kernel dry weight. Therefore, differences in rate of water uptake observed for kernels placed in a Typic Haploboroll soil at −0.2, −1.0, and −1.5 MPa did not result in differences in speed of germination. Temperature differences in the 5 to 30°C range had a large influence on rate of kernel water uptake and speed of germination. As temperature increased, rate of water uptake increased and median germination time decreased from 6.9 d at 5°C to 0.9 d at 25 and 30°C. This study demonstrated that the effects of temperature on speed of germination are much larger than those of moisture, indicating that seeding of stubbled‐in winter wheat should proceed at the optimum date regardless of seedbed moisture conditions.
Efficiency of Type 2 Modified Augmented Designs in Soybean Variety Trials
Authors: Lin C. S. , Voldeng H. D.
Published: July 2010

Replicated designs are not practical when large numbers of test lines with limited seed supplies must be evaluated. Therefore modified augmented design (Type 2) was used to assess yield and other agronomic variables in a large number of soybean [Glycine max. (L). Merr.) strains in Ottawa. Thirty‐three experiments, each involving 100 to 500 test lines, were studied to determine the relative efficiency (RE) of adjusted versus unadjusted observations. There were seven groups of experiments in which the same set of test lines were used, and these were further investigated to determine RE in replicated conditions. Thus, RE was defined in two different ways; for nonreplicated (single) experiments the RE was measured by the ratio of variances between the unadjusted and the adjusted values of the subplot controls, and for the replicated experiments the RE was measured by the ratio of the mean squares of the “Replication ✕ Test line” (based on a randomized block design) between the unadjusted and the adjusted values. Adjustment was made for fertility variation by using the row and the column effects of control plots (Method 1), and the regression coefficient of the test plots on the control (Method 3). The results show that, for yield, the average RE by Method 3 was 220% for the nonreplicated and 167% for the replicated experiments, and 160 and 147% for Method 1 for the corresponding experiments. The adjustment was most effective for yield and plant height, somewhat less effective for protein and oil, and not very effective for maturity and 100‐seed weight.
Quadratic Programming Method for Determining Optimum Nitrogen Rates for Winter Wheat During Tillering
Authors: Baethgen W. E. , Taylor D. B. , Alley M. M.
Published: July 2010

The objective of this study was to determine the recommended amount of N fertilizer to be applied to winter wheat (Triticum aestivum L.) at Zadoks growth stage (GS) 25 that would optimize the use of a model previously developed to predict N required at GS 30. Quadratic programming models were developed for six experimental sites in Virginia to maximize marginal profit with N fertilizer application. First, the models were solved to determine the amounts of N necessary at GS 25 and at GS 30 to produce maximum profit. Then, four N fertilizer rates at GS 25 (N25) (0, 30,60, and 100 kg N ha−1) were evaluated by replacing the N25 value with each of these four predetermined amounts, and to again determine maximum profit. The difference (D) between the yields with maximum attainable profit (Y) without replacing N25 and the yields in which N25 was replaced With 0,30,60, and 100 kg N ha−1 (YR) was then calculated (D = Y –YR). The best N25 recommendation was selected as the one that minimized the mean value and standard deviation of D. This method was used for three N fertilizer:wheat price ratios (2.0, 4.0, and 8.0). The results indicated that the best recommendations for N25 were 50 to 60 kg N ha−1 for N fertilizer:wheat price ratios of 2.0 and 4.0, and 40 to 50 kg N ha−1 for a price ratio of 8.0.