bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Nitrogen Fertility on Water Potential of Irrigated Cotton
Authors: Radin J. W. , Mauney J.R. , Kerridge P.C.
Published: July 2010

Cotton (Gossypium hirsutum L.) grown in controlled environments responds to N deficiency with decreased hydraulic conductance and midday leaf water potential (Ψw). Experiments were initiated to determine whether N deficiency similarly affects plant water relations in the field. Cotton was grown for 4 yr with adequate N or a mild N deficiency. Nitrogen fertility had little effect on Ψw (determined with a pressure chamber) early in the season, but beginning in midseason the Ψw of N‐deficient plants was 0.2 to 0.4 MPa higher than that of the fertilized plants. This difference was seen both before N had affected leaf area, and after canopy closure had occurred at both N levels. Stomatal conductances and transpiration rates of recently matured sunlit leaves (determined by steady‐state porometry) remained unaffected by N. This evidence indicates that N deficiency increased plant hydraulic conductance in the field, contrary to its effect in controlled environments. However, in regressions of transpiration rate on leaf Ψw from dawn to midday, N had no consistent effects on the slopes (a putative measure of hydraulic conductance). These discrepancies have not been resolved. Nonetheless, N deficiency clearly does not decrease hydraulic conductance of cotton in the field in Arizona as it does in controlled environments.
Morphological Development of Crested and Western Wheatgrass Following Grazing
Authors: Frank A. B.
Published: July 2010

Stage of morphological development during spring growth of perennial forage grasses can be predicted reliably from accumulated growing degree‐days (GDD) (GDID), but information is lacking on the relationship between morphological development and GDD accumulated following grazing. A study was conducted in a rainout shelter at Mandan, ND during 1987 and 1988 to determine the GDD required for morphological development of initial and regrowth forage of crested wheatgrass [Agropyron desertorum (Fisch. ex. Link) Schult.] and western wheatgrass [Pascopyrum smithii Rydb, (Löve)] Crested wheatgrass was grazed twice each year and western wheatgrass three times each year by sheep (Ovis aries L.). Water was applied weekly to provide treatments receiving 50, 100, and 150% of the long term 1 April to 1 November rainfall received at Mandan ND. Plant development following the first grazing for both species was linearly related to GDD but plant development following subsequent grazing for both species was curvilinear. The deviation from linearity became greater after the first regrowth phase for both species and occurred during periods of decreasing photoperiods. Plan development for both species was similar at all three water treatments. This information should be useful for predicting stage of plant development and, when considered with other management information, would have utility in managing grazing systems utilizing several grazing cycles.
Reductions in Soybean Yield and Quality from Corn Earworm Flower Feeding
Authors: Eckel Craig S. , Bradley J. R. , Van Duyn John W.
Published: July 2010

Soybean, Glycine max (L.) Merr., defoliation and pod feeding by corn earworm, Helicoverpa zea (Boddie), are often considered types of injury that lead to yield and quality reductions. When infestations coincide with the flowering period, however, density of H. zea larvae is higher on flowers than on other plant parts. Experiments were conducted to assess yield reductions relative to H. zea feeding on flowers, foliage, and pods. Populations of H. zea were manipulated with insecticides at two locations in 1983 and 1984 to achieve varying densities in soybean. Flower numbers, leaf area, and pod numbers were reduced in treatments with larger populations of corn earworm larvae. In addition, fewer flowers were shed from plants with large H. zea populations, and in one trial, pod shed was also decreased. Flower removal by H. zea larvae resulted in a delay in pod set. At harvest, the number of seeds per pod was reduced in three trials that had the largest H. zea populations. Seed weight was increased or decreased by H. zea injury. Injury by H. zea sometimes increased percent soybean seed protein and sometimes reduced harvestable yield. Flower feeding contributed to yield losses by delaying pod set.
Aluminum and Calcium Constraints to Continuous Crop Production in a Brazilian Amazon Oxisol
Authors: Smyth T. J. , Cravo M. S.
Published: July 2010

Acidity constraints in Oxisols of the Amazon may entail both Al toxicity and Ca deficiency. A field study was conducted in a Xanthic Hapludox near Manaus, Brazil, to evaluate lime and Ca requirements for corn (Zea mays L.), cowpea (Vigna unguiculata L.), soybean [Glycine max (L.) Merr.], and peanut (Arachis hypogea L.) during five consecutive years. Calcitic lime was applied once at rates of 0, 0.6, 1.2, 2.3, and 4.6 t of CaCO3 equivalent per hectare. The effects of 1 t ha−1 of gypsum, applied to four crops, were evaluated with lime rates of 0, 1.2 and 2.3 t ha−1. During the two initial years, maximum yields of corn and soybean occurred with 1.2 t of lime ha−1. In subsequent years, maximum corn yields occurred to 4.6 t of lime ha−1. Liming only increased cowpea yields in the third year. Peanut yields increased with liming to the highest lime rate in the fourth and fifth year. Gypsum increased yields for all crops to which it was applied. When averaged across time gypsum increased exchangeable Ca and reduced exchangeable Al by 0.41 and 0.20 cmolc kg−1, respectively. Increased peanut shelling percent and peanut and cowpea leaf Ca concentrations with lime, gypsum, or both were indicative of improved soil Ca supply. Maximum corn and soybean yields occurred at 27% Al saturation, whereas the critical level for peanut was 54%. Regressions of relative yield for all lime and gypsum treatments on the exchangeable Ca:Al ratio gave R2 values equal to those achieved with Al or Ca saturation. Critical Ca:Al ratio values would provide a useful index to ensure that lime recommendations based on Al saturation provide an adequate Ca supply.
Effects of Previous Cropping Systems on Soil Nitrogen and Grain Sorghum Yield
Authors: Bagayoko M. , Mason S. C. , Sabata R. J.
Published: July 2010

Producers who grow soybean [Glycine max (L.) Merr.] in 3 to and 4‐yr rotations with grain sorghum [Sorghum bicolor (L.) Moench] or other grain crops lack information about the duration of grain yield and soil mineral N benefits of soybean in crop rotations. To determine the 1‐, 2‐, and 3‐yr effects of soybean in crop rotations, an experiment with 8 yr of continuous soybean and grain sorghum, and soybean‐grain sorghum and grain sorghum‐soybean rotations combined with fertility treatments of control, N (45 kg ha−1 on soybean and 90 kg ha−1 on grain sorghum) and manure (16 Mg ha−1 dry‐matter containing 160 to 250 kg available N ha−1) was terminated in 1987. In 1988 and 1989 grain sorghum was grown on all plots without fertilizer to determine the residual effects of previous cropping system and fertilizer regime on soil mineral N, sorghum grain, and stover yield. The experiment was conducted near Mead, NE on a Sharpsburg silty clay loam soil (fine montomorillinitic, mesic, Typic Arqiudoll). Early in the 1988 season plots with soybean as the previous crop had 44 to 50 kg ha−1 more NO3 ‐N in the 150‐cm soil profile than did plots with continous grain sorghum. Early in the 1989 season, plots where soybean had been grown 2 yr previously had 17 to 23 kg ha−1 more soil NO3‐N than did continous grain sorghum plots, while plots 3 yr after soybean had only 3 to 8 kg ha−1 more soil NO3‐N. The yield of grain sorghum in the first, second, and third year following soybean was 2 to 3, 0.4 to 1.4, and 0.1 Mg ha−1, respectively, greater than the yield of continous grain sorghum. This study indicated that soybean in a crop rotation can contribute to soil NO3‐N and consequently increase sorghum grain yield for 2 yrs if fertilizer N is limiting.
Concentration Dependency and Stage of Crop Growth in Alfalfa Autotoxicity
Authors: Hegde Ramesh S. , Miller D. A.
Published: July 2010

Shoots of alfalfa (Medicago sativa L.) contain water‐soluble chemical compounds which are autotoxic, i.e., inhibit the growth of alfalfa itself. The objectives of this study were to (i) determine the inhibition threshold of the water‐soluble chemical compounds (autotoxic principle), and (ii) demonstrate that the inhibition of seed germination on early seedling growth of alfalfa is due to autotoxinic compounds from alfalfa shoots and not from microbes. A farmer must make a decision on whether or not it would be advisable to replant alfalfa based on the level of alfalfa residue still growing in the field. Laboratory and greenhouse studies were conducted to determine if autotoxicity in alfalfa due to water‐soluble compounds is concentration dependent. Filter‐sterilized and non‐filter‐sterilized shoot aqueous extracts from vegetative and reproductive stages of ‘WL‐316’ alfalfa were assayed at 20, 40, 60, and 80 g L−1 (fresh shoot weight basis) for their effect on seed germination and root and shoot elongation of seedlings of WL‐316 alfalfa in a growth chamber. Compared with the control, root length, shoot length, and germination were inhibited beyond 20 g L−1 concentration. Shoot extract from the reproductive stage was more inhibitory than from the vegetative stage under laboratory conditions. In the greenhouse, incorporation of 4‐wk‐old green herbage from vegetative stage beyond 48 shoots per square meter level resulted in severe reductions in seedling emergence and plant fresh weight per unit area. Among the several phenolic compounds assayed for their phytotoxicity on root and shoot growth of alfalfa, coumarin and transcinnamic acid at 60 ± 10 μg mL−1 were the most inhibitory. Mixtures of five or more phenolic acids were more phytotoxic than their respective individual components except in the case of trans‐cinnamic acid and coumarin. Autotoxicity in alfalfa may be caused by an interaction of many, yet uncharacterized chemical compounds present in shoots.
Yield Response of Bermudgrass and Bahiagrass to Applied Nitrogen and Overseeded Clover
Authors: Overman A. R. , Wilkinson S. R. , Evers G. W.
Published: July 2010

Models can be used to describe yield response of grasses to applied N and other management factors. This analysis was performed to show interactions between applied N and overseeded clover on dry matter yield, and to estimate equivalent N supplied by clover. Data from three locations were used. At Watkinsville, GA both ‘Coastal’ and common bermudagrass [Cynodon dactylon (L.) Pers.] were overseeded with crimson clover (Trifolium incarnatum L.). At Eagle Lake, TX, both Coastal bermudagrass and ‘Pensacola’ bahiagrass (Paspalum notatum Flugge) were overseeded with ‘Yuchi’ arrowleaf (Trifolium vesiculosum Savi) and 'Mt. Barker* subterranean (Trifolium subterranean L.) clovers. At Jay, FL both Coastal bermudagrass and Pensacola bahiagrass were overseeded with crimson clover. The logistic model described dry matter response to applied N and contained three parameters (A, b, c). It was shown that the presence of clover affected only the b coefficient, which related to yield at zero applied N. It was also shown that overseeded clover provided equivalent N of approximately 120 kg ha−1 for bermudagrass and 90 to 220 kg ha−1 for bahiagrass. Most of the increased yield of the bermudagrass‐clover combination over bermudagrass without clover was due to the clover production; only about 25 kg ha−1 of equivalent N was carried over to the bermudagrass under conditions where top growth of clover was removed. The model allows quantitative estimates of equivalent N supplied by clover.
No‐Till Corn Production as Affected by Mulch, Potassium Placement, and Soil Exchangeable Potassium
Authors: Yibirin H. , Johnson J. W. , Eckert D. J.
Published: July 2010

Optimizing the yield of no‐till corn (Zea mays L.) requires an understanding of corn response to K fertilization practices in no‐tillage systems. This study was conducted to determine the effects of mulch rate, K‐fertilizer placement method, and soil exchangeable K (SEK) concentration on corn grain yield, ear leaf K concentration (ELKC), and root SEK distribution in a no‐tillage system. There were five initial SEK concentrations (54, 59, 78, 95, and 122 mg K kg−1), three mulch rates (zero, normal, and double), and two methods of K‐fertilizer placement, broadcast and banded, at a rate of 46 kg K ha−1.. A Crosby silt loam soil (fine, mixed, mesic Aeric Ochraqualf) was used. Increasing mulch rate increased ELKC at all SEK concentrations and yield at SEK below 90 mg K kg−1. Increasing SEK increased yield in the zero and normal mulch treatments but not in the double mulch treatments. Banding K increased ELKC and yield only at low SEK concentrations; the effect of banding on yield was observed only in the zero mulch treatments. The lack of yield increase with banding in the mulched treatments was attributed to greater root growth in the 0‐ to 5‐cm depth, which may have allowed for more efficient use of broadcast K fertilizer. The SEK concentration decreased with depth and distance from the row in all treatments. Results indicate that the yield benefit of banding K, increasing SEK concentration, or both decreases with increasing rate of mulch.
Within‐Season Calibration of Modeled Wheat Growth Using Remote Sensing and Field Sampling
Authors: Maas Stephan J.
Published: July 2010

Within‐season calibration using observations of growth and phenology provides an objective means for crop simulation models to be self‐correcting. Estimating crop growth and phenology for a large number of fields by traditional ground‐based sampling methods can be undesirably time‐consuming. Certain aspects of crop growth can be estimated more quickly for a large number of fields using remote sensing. A study was conducted to compare the results of calibrating a crop simulation model using within‐season observations of leaf area index (LAI) obtained either from field sampling or remote sensing. Winter wheat (Triticum aestivum L.) yields at three locations in the U.S. Great Plains for 2 yr were modeled more accurately using remotely sensed LAI observations, than using field‐sampled LAI observations. This difference in accuracy appeared to result from the apparent ability of the remotely sensed LAI observations to better represent the photosynthetically active plant area in the crop canopy. Results of the study indicate that remote sensing may be an effective source of field observations for within‐season calibration of crop simulation models.
Nitrogen and Planting Date Effects on Low‐Protein Spring Barley
Authors: Weston Dale T. , Horsley Richard D. , Schwarz Paul B. , Goos Robert J.
Published: July 2010

Grain protein of barley (Hordeum vulgare L.) produced for malting often is greater than the industry's acceptable standards of 135 and 130 g kg−1 for six‐rowed and two‐rowed barley, respectively. Environmental conditions such as low rainfall and high temperatures after anthesis often cause increased grain protein. This study was conducted at four dryland environments in North Dakota over 2 yr to compare the effects of N fertilization and planting date on agronomic and malt quality traits of two experimental barley genotypes inherently low in grain protein with two barley cultivars currently grown in the U.S. Midwest. Agronomic traits evaluated were grain protein, grain yield, kernel weight, and kernel plumpness. Malt quality traits evaluated were fine‐grind extract, soluble wort protein, diastatic power (DP), and ɑ‐amylase activity. Nitrogen rates ranged from 0 to 200 kg ha−1. Nitrogen significantly increased grain protein, grain yield, soluble wort N, DP, and ɑ‐amylase activity, and decreased kernel weight, kernel plumpness, and fine‐grind malt extract. Significant genotypes differences were observed for all traits. The N × genotype interaction was significant for all agronomic traits, soluble wort N, and DP. The standard cultivars had greater than the acceptable grain protein when fertilized with 150 or 200 kg N ha−1. Delaying planting significantly decreased grain yield and fine‐grind malt extract. Grain protein of the low‐protein genotypes was within the limit desired by the malting and brewing industry at all N rates and planting dates. Thus, protein levels acceptable to maltsters can be obtained for low‐protein barley genotypes when excessive N is available and growing conditions are unfavorable.
Grazing Initiation Date and Stocking Rate Effects on Pasture Productivity
Authors: Bryan William B. , Prigge Edward C.
Published: July 2010

Date of grazing initiation in spring and stocking rate have large effects on both animal and pasture productivity. A grazing experiment with yearling steers (Bos taurus L.; average 320 kg) was conducted in the growing season of three years to compare two dates of grazing initiation (differing by 2 wk) at three stocking rates (3, 4, and 5 steers ha−1) on set‐stocked naturalized pasture in the AppalachiaUn USA. Pasture botanical composition, herbage mass and accumulation, and animal liveweight changes were measured. Early grazing initiation increased percentage grass in the pasture compared with late initiation. Crude protein concentration was higher, and acid‐ and neutral‐detergent fiber were lower in pastures on which grazing was initiated earlier. Herbage mass was >33% more at the later grazing initiation date compared with the early initiation date. Earlier grazing initiation did not affect pasture dry matter accumulation or average daily gain but animal gain per hectare was almost 20% higher with earlier grazing. Stocking rate the previous year had no effect on botanical composition or herbage mass at initiation of grazing. A verage daily gain was highest at 4 steers ha−1 (0.81 kg) and lowest at 5 steers h−1 (0.62 kg). Animal production per hectare was almost 50% greater at 4 steers ha−1 (358 kg) than at 3 steers h−1 (246 kg). We conclude that naturalized pasture in Appalachia can be grazed early without detrimental effects.
Dry Matter Partitioning and Forage Nutritive Value of Soybean Plant Components
Authors: Hintz Rodney W. , Albrecht Kenneth A.
Published: July 2010

Soybean [Glycine max (L.) Merr.] can be a high‐quality alternative forage, but little is known about the influence of management practices on partitioning and composition of soybean plant components, and therefore on whole‐plant forage quality. Cultivar, row spacing, planting rate, and harvest maturity effects on the dry matter partitioning and nutritive value of soybean plant parts were determined in a 2‐yr field study. The cultivars Corsoy 79, Pella, and Williams 82 were grown in 20‐ and 76‐cm row spacings at planting rates of 280 000 and 890 000 seeds ha−1. Plants were harvested at R1, R3, R5, and R7 stages of development. Harvest maturity had the greatest effect on dry matter partitioning and nutritive value of soybean plant parts. The leaf dry matter fraction decreased continually as plants were harvested at later reproductive growth stages, declining from 708 g kg−1 at R1 to 168 g kg−1 at R7. The stem fraction of total plant mass increased from 292 g kg−1 at R1 to 383 g kg−1 at R5 and then declined to 283 g kg−1 at R7. The pod fraction increased from 105 g kg−1 at R5 to 549 g kg−1 at R7. As plants matured, neutral‐detergent fiber (NDF), acid‐detergent fiber (ADF), and acid‐detergent lignin (ADL) concentrations increased; crude protein (CP) concentration decreased for leaf and stem components. The greatest change occurred as plants matured from Stage R5 to R7. The pod component showed an opposite trend, with NDF, ADF, and ADL concentrations decreasing and CP concentration increasing between Stages R5 and R7. Row spacing, planting rate, and cultivar had little effect on dry matter partitioning and nutritive value of soybean plant parts.
Interrow Cultivation to Reduce Herbicide Use in Corn following Alfalfa without Tillage
Authors: Buhler Douglas D. , Doll Jerry D. , Proost Richard T. , Visocky Mark R.
Published: July 2010

Information on integrated weed management systems for conservation tillage systems is needed so that producers can minimize the environmental impacts of crop production without sacrificing profitability. Our objective was to evaluate reduced levels of preemergence herbicides in combination with interrow cultivation for weed control in corn (Zea mays L.) planted into an untilled, deteriorated alfalfa stand treated with glyphosate [N‐(phosphonomethyl)glycine] the previous fall. Fall application of glyphosate controlled 97% of the perennial vegetation without additional treatment the following spring. Atrazine [6‐chloro‐N‐ethyl‐N'‐(l‐methylethyl)‐l,3,5‐triazine‐2,4‐diamine] at 1.1 kg a.i. ha−1 or cyanazine (2‐[[4‐chloro‐6‐(ethylamino)‐ 1,3,5‐triazin‐2‐yl]amino]‐2‐methylpropanenitrile) at 2.2 kg a.i. ha−1 applied within 1 d after corn planting greatly reduced weed densities compared with no herbicide use, but did not control annual weeds as well as a standard treatment (atrazine at 2.2 kg ha−1 plus 2.8 kg a.i. ha−1 metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐ 1‐methylethyl)acetamide]). In most cases, one or two interrow cultivations following atrazine or cyanazine increased control of annual weeds to > 90%, which was similar to the standard treatment. Corn grain yields were affected by varying environmental conditions during the three years of research, but in the two years without drought, integrating cultivation and reduced levels of herbicide resulted in corn yields equal to the standard herbicide treatment. This research indicates that integrating interrow cultivation with reduced levels of herbicide is a sound weed management option for com planted into untilled, fall‐controlled alfalfa stands infested with perennial weeds.
Spring Lamb Production on Alfalfa, Sainfoin, and Wheatgrass Pastures
Authors: Karnezos T. P. , Matches A. G. , Brown C. P.
Published: July 2010

Lamb (Ovis aries) weight gains from wheatgrass‐sainfoin (Agropyron and Thinopyron spp.‐Onobrychis viciifolia Scop.) mixtures suggest that grazing sainfoin monocultures offers advantages over mixtures. Our objective was to determine levels of spring lamb production from irrigated ‘Renumex’ sainfoin, ‘Cimmaron’ alfalfa (Medicago sativa L.), ‘Luna’ pubescent wheatgrass [T. intermedium subsp. barbulatum (Schur) Barkw. & D.R. Dewey], and pubescent wheatgrass‐sainfoin pastures. Replicated pastures grown on a fine, mixed, thermic Torrertic Paleustoll were rotationally stocked (herbage dry matter [DM] allowance of 6.5% of body wt. d−1) by weaned Rambouillet ✕ Suffolk wether lambs for an average of 88 d in spring of 1991 and 1992. Across years, cumulative weight gain (CWG) ranged between 7.9 kg lamb−1 for wheatgrass and 16.4 kg lamb−1 for alfalfa. In 1991 (avg. 16.1 kg lamb−1) and 1992 (avg. 12.3 kg lamb−1) CWG for alfalfa and sainfoin was similar. Lamb production per hectare (PROD) was greatest for legumes (808 kg lamb ha‐1) and least for wheatgrass (533 kg lamb ha−1). Including sainfoin with wheatgrass increased PROD by 23% over wheatgrass, whereas sainfoin alone increased PROD by 25% over the mixture. Intake of sainfoin herbage (1.5 kg DM lamb‐unit‐1 d‐1) was 29% greater than of alfalfa, wheatgrass, or wheatgrass‐sainfoin (1.2 kg DM lamb‐unit−1 d−1, where 1 lamb‐unit is a 35‐kg lamb). Herbage crude protein concentrations (pregrazing) were highest for alfalfa (253 g kg−1) and lowest for wheatgrass (159 g kg−1). Sainfoin had the lowest organic matter digestibility (641 g kg−1), which did not reflect the high CWG or PROD obtained. Alfalfa or sainfoin offer greater opportunities for spring lamb production than wheatgrass or wheatgrass‐sainfoin pastures.
Phosphorus and Temperature Effects on Magnesium, Calcium, and Potassium in Wheat and Tall Fescue Leaves
Authors: Reinbott T. M. , Blevins D. G.
Published: July 2010

High K fertilization often reduces leaf Mg and Ca concentration, increasing the incidence of grass tetany, while increased P treatment increases uptake and leaf concentrations of Mg and Ca in winter wheat (Triticum aestivum L.). Since P availability and uptake are often reduced at low soil temperatures, the effects of P and K nutrition on mineral element composition of wheat at two root‐zone temperatures were determined. The effects of P and NPK + Mg fertilization on leaf elemental concentrations of tall fescue (Festuca arundinacea Schreb.) grown in the field near Mt. Vernon, MO, on a Creldon silty clay loam (fine, mixed, mesic Mollic Fragiudalf) were determined. Concentration of Mg in wheat shoots was 20% higher when treated with 400 μM P than 50 μM P, and only 9% higher when root‐zone temperature was 25°C rather than 15°C. Similarly, shoot Ca concentration was 11% higher with the high P treatment. Total plant Mg uptake was 60% greater and total Ca uptake was 51% greater with high P. The higher root‐zone temperature increased total plant Mg uptake 38% and total plant Ca uptake 36%. Increasing K treatment from 400 to 800 μM decreased shoot Mg concentration 13% and shoot Ca concentration 7%. In the field, at soil temperatures <15°C, treatments of 20 or 28 kg ha−1 P increased both Mg and Ca leaf concentration of tall fescue. When leaf Mg and Ca concentrations in control plots were below 2.0 and 4.0 g mg−1 respectively, P fertilization increased Mg and Ca concentration above those thresholds considered likely to cause grass tetany. Fertilization with Mg increased leaf Mg concentration only when P fertilizer was added, but caused a decrease in leaf Ca concentration when no P fertilizer was applied. Leaf concentration and total plant uptake of Mg and Ca were more dependent on P nutrition than root temperature.
Defoliation Effects on Agronomic Performance of Seeded Pennisetum Hexaploid Hybrids
Authors: Spitaleri R. F. , Sollenberger L. E. , Schank S. C. , Staples C. R.
Published: July 2010

Interspecific Pennisetum hybrids between pearl millet [P. glaucum (L.) R.Br.] and elephantgrass (P. purpureum Schum.) have been developed that are seed propagated, productive, and high in nutritive value, but defoliation effects on hybrid agronomic performance have not been assessed. A field experiment was conducted on an Adamsville soil (hyperthermic, uncoated Aquic Quartzipsamment) in 1991 and 1992 to determine the effect of three clipping treatments (every 6 or 12 wk to 15 cm and every 6 wk to 30 cm) on dry matter (DM) yield, nutritive value, and persistence of 10 seeded hybrids and ‘Mott’ elephantgrass. In the first year of defoliation, Mott and the hybrids had similar yields when harvested at 6‐wk intervals (9.7 vs. 9.2 Mg ha−1 yr−1), but hybrids had greater yields than Mott when harvested at 12‐wk intervals (17.9 vs. 13.0 Mg ha−1 yr−1). Yields were greater for Mott than hybrids in the second year, regardless of clipping treatment. In 1991, crude protein (CP) concentration was not different when cut every 6 wk (139 g kg−1 DM), but Mott had higher CP than the hybrids when clipped every 12 wk (112 vs. 95 g kg−1). Across clipping treatments, in vitro digestible organic matter (IVDOM) was greater for Mott than for the hybrids (638 vs. 602 g kg−1 OM) in 1991. In 1992 there were no differences in CP or IVDOM between Mott and hybrids. After 1 yr of defoliation, winter survival of hybrid plants was 18%, while Mott survival was 100%. Comparison of reserve status of hybrids and Mott showed that hybrids had lower rhizome mass (0.46 vs. 1.1 kg m−2), total nonstructural carbohydrate (TNC) concentration (115 vs. 276 g kg−1 DM), and TNC pool (56 vs. 304 g m−2). These data indicate that seeded hybrids are productive and high in nutritive value. Their potential for use in the U.S. Gulf Coast, however, depends on development of lines that are more persistent under defoliation.
Tillage, Seed Size, and Seed Density Effects on Performance of Soft White Winter Wheat
Authors: Douglas C. L. , Wilkins D. E. , Churchill D. B.
Published: July 2010

Conservation tillage systems, which leave residues on or near the soil surface, can suppress soft white winter wheat (Triticum aestivum L.) emergence, early development of seedlings, and grain yield. This field study evaluated effects of tillage, seed size, and seed density on the above parameters. Commercially processed, untreated ‘Stephens’ winter wheat grains, separated into size‐density combinations of large‐dense, largelight, small‐dense, small‐light, and unsorted, were seeded into tilled and nontilled soil in the fall of 1990 and 1991. In 1990, when seed zone soil moisture was adequate, tillage significantly decreased seminal root intercepts at 3 cm (16%) and 5 cm (24%) below the seed. There was no significant effect of seed size‐density. When seed zone soil moisture was marginal in 1991, tillage significantly increased emergence (15%), number of main stem leaves (11%), seminal roots (4%), root intercepts (3 and 5 cm > 100%), straw yield (17%), and grain yield (12%). The only significant effect of seed size and density on aboveground parameters was on main stem leaf number, seedling weight, and number of heads. Small‐light seed had significantly more 3‐cm (53%) and 5‐cm (39%) root intercepts and 26% fewer disease‐pruned roots than other size‐density treatments. Seed size and density did not significantly affect grain yield in either year. Therefore, there is not sufficient justification to change the current seed processing procedure by use of a gravity table.
From Cell Growth to Leaf Growth: I. Coupling Cell Division and Cell Expansion
Authors: Arkebauer Timothy J. , Norman John M.
Published: July 2010

An area of plant growth modeling that appears to have been neglected is incorporation of current knowledge regarding cell expansion and cell division into the growth models. The objective of this research was to incorporate this knowledge into a quantitative description of plant growth. A general cell growth module is described that combines known aspects of cell expansion and cell division. Cell expansion is governed by water flux equations. The cells start at a fixed minimum volume and expand to a final (fixed) volume. The wall extensibility of a cell is considered to be a function of its volume. Cell division is described through use of a daughter ratio vs. time function that categorizes the cells resulting from a division as either proliferative or nonproliferative. Temperature is coupled to the water flow equations through its influence on cell cycle time. The daughter ratio vs. time function is of paramount importance. The influence of a number of daughter ratio functions on the rate of cell production and the rate of total cell volume accumulation are considered. Exponential, linear, and sigmoidal increases in both cell numbers and total cellular volume are shown to result from the various daughter ratios examined. A comparison was made of simulations using a constant wall extensibility to those made using the wall extensibility vs. volume function. The difference between these two cases was much less than the differences obtained by varying the daughter ratio function.
STABLE: A BASIC Program for Calculating Stability and Yield‐Stability Statistics
Authors: Kang Manjit S. , Magari Robert
Published: July 2010

There is a worldwide interest among plant breeders, geneticists, and production agronomists in genotype × environment (GE) interaction. A stability analysis is often conducted to estimate and interpret GE interaction. From a practical standpoint, stability statistics and genotype performance (yield) need to be integrated. A DOS‐version computer program (STABLE) was developed that calculates Shukla's stability‐variance statistic (σ2i) and Kang's yield‐stability statistic (YSi) that combines yield and stability of performance into a single selection criterion. STABLE operates on IBM‐PCs or compatible microcomputers with a BASIC, GWBASIC, or QBASIC interpreter. Input of data and other information is menu‐driven. Output consists of (i) a table showing an analysis of variance, (ii) a table showing genotype means, σ2i, s2i (a stability‐variance statistic computed from residual GE interaction after removal of heterogeneity due to a covariate), and Wricke's ecovalence (Wi), and (iii) a table showing various statistics and information, such as σ2i, YSi, and genotypes selected on the basis of YSi. This program should be useful for selecting high‐yielding, stable genotypes.
Intercropped Oat and Fababean in Alaska: Dry Matter Production, Dinitrogen Fixation, Nitrogen Transfer, and Nitrogen Fertilizer Response
Authors: Cochran Verlan L. , Schlentner Sharon F.
Published: July 2010

There are conflicting reports on the amount of N transferred from legumes to intercropped nonlegumes and on the need for N fertilizer to obtain high total dry matter yields on soil with low N availability. This study evaluates (i) the ability of fababean (Vicia faba L.) to meet its N requirements from biological N2 fixation: (ii) the amount of N transferred to intercropped oat (Avena sativa L.); and (iii) N fertilizer management to maximize dry matter production and N2 fixation in a cold soil. A randomized complete block experimental design with four replications was used with two rows of fababean alternating with two rows of oat. Urea was applied in bands between fababean or oat rows at 90 kg N ha−1 to get the following treatments: (i) oat with added N (+N), fababean +N, inoculated with Rhizobium leguminosarum bv. viceae (+I); (ii) oat +N, fababean without added N, inoculated (−N, +I); (iii) oat −N, fababean −N,+I; (iv) oat −N, fababean +N,−I; and (v) oat −N, fababean −N, + I. A second study compared uptake of 15N‐depleted fertilizer by oat and fababean, where the fertilizer was broadcast over the plot or band‐applied between rows of oat and fababean planted in alternate rows. Less than 1% of the uninoculated fababean plants nodulated in either experiment; thus, they were a good check for estimating N2 fixation using the difference method. Nitrogen fertilizer increased dry matter production of fababean in some years, but did not increase N uptake. There was little evidence of N transfer from fababean to oat. Oat depended on N fertilizer for maximum dry matter production 3 of the 4 yr. Maximum total dry matter production was achieved by fertilizing the oat and not the fababean in 3 of the 4 yr. The amount of N2 fixed by fababean averaged 50 kg N ha−1. Fababean plants obtained >50% of their N from broadcast urea, but <10% when urea was banded between oat and fababean rows. Configuring a commercial drill to band fertilizer between pairs of oat rows alternating with fababean is a practical way to maximize both N2 fixation and total dry matter production.
Seasonal Nitrogen and Carbohydrate Partitioning in Forage Brassicas
Authors: Guillard Karl , Pietrzyk Stephen W. , Allinson Derek W. , Cassida Kimberly A. , Wiedenhoeft Mary Hagemann , Hough Robert L. , Barton Barbara A.
Published: July 2010

Nitrate toxicosis is more prevalent when ruminants consume forages high in NO3 and low in readily fermentable carbohydrates. Environmental conditions vary with season and may differentially affect herbage N and total nonstructural carbohydrate (TNC) composition. Experiments were conducted to determine the concentrations and partitioning of NO3−N, total N (TN), TNC, and inorganic N in summerand autumn‐grown brassicas in CT. Kale (Brassica oleracea var. acephala DC.), rape (B. napus L.), turnip (B. rapa L.), and tyfon [B. rapa L. ✕ B. pekinensis (Lour.) Rupr.] were established in June and August of 1988 and 1990 on a Paxton fine sandy loam soil (coarse‐loamy, mixed, mesic Typic Dystrochrept). The experimental design in each season was a split‐plot, with species as main plots and sampling dates [30, 60, 90, and 120 days after seeding (DAS)] as subplots. Concentrations of NO3−N and TN decreased with time in both seasons, but the rate of decline for both constituents was generally greater during the summer than autumn. Concentrations of TNC in the whole plant and most plant parts increased with time and peaked at 90 or 120 DAS in both seasons. Inverse relationships were found between TN and TNC (except in laminae), and between NO3−N and TNC (except in roots). Concentrations of NO3−N were relatively low in the whole plant, central midrib‐petioles, stems, and roots when the concentrations of TN were <29 g kg−1, but increased linearly when TN was greater than this. Concentrations of NO3−N increased linearly in laminae only when TN concentrations were >54 g kg−1. Whole‐plant inorganic N concentrations, as a percentage of TN, were <10% at 60 DAS. The potential risk for NO3 toxicosis in ruminants is higher if animals graze brassicas before 60 DAS than if they graze brassicas after 60 DAS.
Source‐to‐Sink Manipulation Effects on Cotton Fiber Quality
Authors: Pettigrew William T.
Published: July 2010

Cotton (Gossypium hirsutum L.) fiber quality varies considerably among years and locations depending on the prevailing environmental conditions. These environmental conditions often affect the assimilate source/reproductive sink ratio of the developing crop. This study investigated the effects of various source‐sink manipulations on cotton fiber quality at various times during the growing season. In 1991 and 1992, field studies were conducted in which six source‐sink manipulation treatments (partial defruited, partial leaf pruned, reflectors, open canopy, shaded plot, and an untreated control) were imposed on the cotton genotypes ‘DES 119’, ‘DPL 5690’, and ‘Prema’. Blooms at anthesis were tagged on four dates each year, and the seed cotton was harvested when these bolls had opened. This seed cotton was then ginned, and fiber quality traits were determined. The shaded plot treatment reduced fiber strength 6% compared with the control. Fiber from the shaded plot treatment was about 2% longer than the control when the shade was applied within the first 7 d of fiber development. The micronaire value was decreased 7% from the control when the shade was applied during the period of fiber development when the fiber secondary cell wall is being deposited. The partial defruited treatment consistently produced about 8% greater micronaire than the control. Fiber from the partial leaf pruned and shaded plot treatment (low source‐to‐sink ratio) averaged 11% lower micronaire than the open canopy and partial defruited treatment (high source‐to‐sink ratio) on the first tagging date. On the third tagging date, fiber maturity, a component of micronaire, for the partial defruited treatment was 6% greater than the control. None of the treatments significantly altered fiber elongation or perimeter. These data indicate that alterations in the light intensity or carbon assimilate supply can affect the quality of cotton fiber produced, particularly fiber strength and micronaire.
Interaction of Early‐Season Herbicide Injury, Tobacco Thrips Injury, and Cultivar on Peanut
Authors: Brecke Barry J. , Funderburk Joe E. , Teare Iwan D. , Gorbet Daniel W.
Published: July 2010

Peanut (Arachis hypogaea L.) can tolerate severe early‐season injury by tobacco thrips [Frankliniella fusca (Hinds)], and controlling populations usually is not recommended in the southeastern USA. Field observations, however, indicated that injury from early‐season thrips infestation may exacerbate injury caused to peanut by early postemergence herbicide application. Studies were conducted near Jay and Marianna, FL, during 1989 and 1990 to evaluate the interaction between peanut cultivar, preplant incorporated application of vernolate (S‐propyl dipropylcarbamothioate), postemergence application of alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] plus paraquat(1,1'‐dimethyl‐4,4'‐bipyridinium ion) and thrips suppression with foliar application of acephate (O,S‐dimethyl acetylphosphoroamidothioate). ‘Southern Runner’ was more susceptible than ‘Florunner’ to early‐season stress from insect and herbicide injury. Injury from preplant incorporated herbicide alone, postemergence herbicide alone, or thrips alone usually was not sufficient to cause long‐term damage to peanut growth or to adversely affect peanut maturity or yield. When two or all of these factors impacted peanut simultaneously, however, delays in crop maturity and reduced yields (up to 11%) were often observed. Early‐season suppression of tobacco thrips often alleviated the detrimental effects to peanut. Suppression of thrips populations should receive greater consideration in future integrated pest management programs of peanut to avoid interactions with early‐season herbicide stress, especially when growing Southern Runner.
Salinity Effects on Four Sunflower Hybrids
Authors: Francois Leland E.
Published: July 2010

Sunflower (Helianthus annuus L.) is becoming an increasingly important source of edible vegetable oil throughout the world because of its high polyunsaturated fatty acid content and no cholesterol. The increasing demand for this oil may promote increased hectarage of sunflower in the western USA, where some soils are saline or have the potential to become so. Since there is little information concerning the response of sunflower grown under saline conditions, a 2‐yr field plot study was conducted. Six salinity treatments were imposed on a Holtville silty clay (clayey over loamy, montmorillonitic [calcareous], hyperthermic Typic Torrifluvent) by irrigating with Colorado River water artificially salinized with NaCl and CaCl2 (1:1 by weight). Electrical conductivities of the irrigation waters both years were 1.4 (control), 2.0, 3.0, 4.0, 6.0, and 8.0 dS m−1. Seed yield and oil content of the seed were measured. Relative seed yield of four hybrids was unaffected by soil salinity up to 4.8 dS m−1 (electrical conductivity of the saturation extract, ECe). Each unit increase in salinity above 4.8 dS m−1 reduced yield by 5.0%. These results indicate that sunflower is appropriately classified as moderately tolerant to salinity. Yield reduction was attributed primarily to a reduction in seeds per head. Oil concentration in the seed was relatively unaffected by increased soil salinity up to 10.2 dS m−1. Sunflower appears to be well adapted for growth under moderately saline soil conditions.
Alfalfa Establishment with Diverse Annual Ryegrass Cultivars
Authors: Sulc R. Mark , Albrecht Kenneth A.
Published: July 2010

There is limited information on forage yield and nutritional value of binary mixtures of annual ryegrass (Lolium multiflorum Lam.) with forage legumes in the north‐central USA. A diverse set of annual ryegrass cultivars in binary mixtures with alfalfa (Medicago sativa L.) was evaluated for seeding‐year forage yield and nutritional value and for forage yield and alfalfa presence the year after seeding. Annual ryegrass cultivars differing in ploidy and maturity were sown at 215 seeds m−2 with alfalfa at two locations in Wisconsin in spring 1990 and 1991. As a control, alfalfa was also sown alone. Seeding‐year forage yields of ryegrass‐alfalfa mixtures ranged from 5.00 to 10.65 Mg ha−1 in 1990 and from 7.06 to 8.96 Mg ha−1 in 1991. Mixtures of alfalfa with earlymaturing ryegrass cultivars were higher in yield and fiber fractions (neutral‐ and acid‐detergent fiber) and lower in crude protein concentration than mixtures with late‐maturing ryegrass cultivars, with greater differences observed in 1990 than 1991. The ryegrass‐alfalfa mixtures usually were higher yielding but lower in forage nutritional value than alfalfa sown alone, with greater differences observed in 1990 than 1991. Alfalfa stands were reduced by ryegrass in one site‐year, where conditions favored vigorous ryegrass development over alfalfa seedling development. In the other three environments, alfalfa was successfully established with all ryegrass cultivars, but alfalfa yields the year after seeding were highest in plots established with early‐maturing diploid cultivars. The most suitable annual ryegrass companions for alfalfa establishment in the north‐central region are early‐maturing diploid cultivars.
Root Distribution and Soil Moisture Depletion Pattern of a Drought‐Resistant Soybean Plant Introduction
Authors: Hudak Colleen M. , Patterson Robert P.
Published: July 2010

In the southeastern USA, soybean [Glycine max (L.) Merr.] yield is often limited by water availability. Breeders have explored the use of exotic germplasm as a means of developing a root system capable of exploiting soil water reserves more fully. In this study, the drought‐resistant PI 416937 was compared with ‘Forrest’ for soil moisture utilization and root distribution on a Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudults). Water treatments (well‐watered and water‐deficient) were established during R4 to late R6 with rain exclusion shelters and differential irrigation. Soil moisture utilization in row and interrow areas was monitored via neutron attenuation and tensiometry. A direct measurement of root distribution was obtained on a second site by a trench profile technique. Results suggest that PI 416937's advantage may reside in its ability to exploit upper soil horizons (above 68 cm) with a network of fibrous roots. Localized measurements of soil moisture tension indicated that PI 416937's rate of soil desiccation was slower than Forrest's, but it appeared to exploit a larger total soil volume. Trench profile results indicated that the lateral spread of PI 416937's root system was greater than that of Forrest. The usefulness of PI 416937 may lie in the opportunity it provides soybean breeders for adding diversity to the root morphology of present soybean cultivars.
Maize Nodal Root Response to Time of Soil Ridging
Authors: Thomas Andrew L. , Kaspar Thomas C.
Published: July 2010

An improved understanding of maize (Zea mays L.) nodal root response to soil ridging is needed to allow farmers to maximize the benefits of ridge‐till tillage systems. Greenhouse (three trials, 1992 to 1994) and field (two sites in Iowa, 1992 and 1993) experiments were conducted with one maize hybrid to examine the effect of time of soil ridging on nodal root development, internode elongation, shoot dry matter, and grain yield. Maize root clumps were evaluated from unridged plants and from plants ridged either at early V4 to V6) or late (V7) growth stages. Total numbers of nodal roots, numbers of roots per node, numbers of nodes developing functional roots, internode lengths, shoot dry matter, and grain yields (field study) were determined. Time of ridging significantly affected nodal root numbers and internode lengths. In two of the field trials, unridged maize plants produced 42.7 and 48.3 functional nodal roots, whereas plants ridged at growth stage V7 developed significantly more, 47.0 and 56.0 roots, respectively. Internodes 6 and 7, covered with soil during ridging, increased in length by as much as 124% in the field and 175% in the greenhouse when plants were ridged early rather than late. In one field trial, Internode 6 elongated to 44.1 mm with early ridging, but to less than 17.0 mm with either late or no ridging. Shoot dry matter and grain yields generally were not affected by ridging treatments in either field or greenhouse experiments. Later ridging tends to result in shorter internodes and more functional nodal roots which may be important to maize plants in terms of lodging resistance and recovery from corn rootworm (Diabrotica spp.) damage.