bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Sodium Chloride on Cynodon Turfgrasses1
Authors: Dudeck A. E. , Singh S. , Giordano C. E. , Nell T. A. , McConnell D. B.
Published: July 2010

Increased need for salt tolerant turfgrasses continues due to increased restrictions on water resources and to salt water intrusion into ground water. This is especially critical along coastal areas. Bermudagrass (Cynodon spp.) cultivars are widely used throughout the South on golf courses, home lawns, and sports turf facilities. Information on tolerance of warm‐season turfgrass cultivars to salinity is limited. The purpose of these studies was to document the glasshouse response of eight bermudagrass cultivars to solution cultures differentially salinized with NaCl. Salt was added to a basic nutrient solution to provide five initial salinity levels ranging from 2.7 to 9.9 dS m−1, but no cultivar differences were found in duplicate studies. Overall, top growth decreased 22%, but root growth increased 270% at the highest salt level. When salt levels ranged from 2.4 to 32.5 dS m−1 in a third study, cultivars differed in their response. ‘Tifdwarf’ and ‘Tifgreen’ were most tolerant while ‘common’ and ‘Ormond’ were most sensitive. Based on regression analyses within cultivars, Na increased and K decreased while total Na plus K in top growth was unaffected by salt concentration. Tissue levels of total Na plus K differed among cultivars.
Emergence and Yield of Fungicide‐Treated Soybean Seed Differing in Quality1
Authors: Wall M. T. , McGee D. C. , Burris J. S.
Published: July 2010

Current recommendations that soybean (Glycine max L. Merr.) seeds be treated with fungicides if they are of poor quality or to be planted in cool, wet soils, are too vague for the grower to be sure when treatment is warranted in the upper Midwest. This paper evaluates the effects of fungicide treatments on seeds with different quality characteristics under more precisely‐defined soil conditions than in previously reported studies. Seedlots of ‘Cumberland’, ‘Wells’, and ‘Williams’ with inferior quality due to age, damage, small size, or infection by Phomopsis spp. were treated with captan {N(trichloromethyl)‐thio]‐4 cyclohexene‐1,2‐dicarboximide}, carboxin‐thiram (5,6‐dihydro‐2‐methyl‐1, 4 oxathiin‐3‐carboxanilide, 17%; tetramethylthiuram disulfide, 17%), metalaxylN‐(2,6‐dimethylphenyl)‐N‐(methoxyacetyl) alanine methyl ester) or untreated. These were tested for emergence and yield in the field on two soil types [a poorly drained Webster silty clay loam (fine‐loamy, mixed, mesic, Typic Haplaquolls), and a well drained Clarion loam (fine‐loamy, mixed, mesic, Typic Hapludolls)] at three different planting times in both 1980 and 1981. Captan and carboxin‐thiram seed treatments were equally effective in increasing emergence in the laboratory and field of soybean seedlots with more than 15% Phomopsis spp. infection, but metalaxyl did not. No seed treatment consistently improved field emergence of seeds with reduced quality because of mechanical damage, age, or size. There were no obvious differences in fungicide performance in relation to planting dates or soil types. Increased yield in response to fungicide seed treatment was detected only in the 50% Phomopsis‐infected seedlot. We conclude that fungicide seed treatment cannot be justified on seeds of low quality for reasons other than disease under most of the soil conditions likely to occur in the upper Midwest. These results suggest that performance of seedlots with Phomopsis spp. infection exceeding 15% will be improved by fungicide seed treatment.
Aluminum Toxicity and DNA Synthesis in Wheat Roots1
Authors: Wallace S. U. , Anderson I. C.
Published: July 2010

Aluminum toxicity is a deterrant to the growth of plants in acid soil. Little is known of the initial site or sites of Al injury in plant roots nor of the sequence of events that characterize Al toxicity. The objective of this study was to document some effects of short‐term exposure to Al in two wheat (Triticum aestivumL.) cultivars, Eagle and Atlas 66. Root elongation in Eagle was much more susceptible to concentrations of 0.02 to 1.85 mMAl than was root elongation in Atlas 66. A 2‐h exposure to 0.19 mMAl drastically inhibited root elongation in Eagle, whereas a 48‐h treatment with 0.19 mMAl had little effect on root elongation in Atlas 66. Exposures of Eagle seedlings to 0.19 mMAl for 4 h caused a 32% inhibition in subsequent incorporation of 3H‐thymidine into DNA, with the degree of inhibition increasing with duration of exposure to Al. In Atlas 66, there was a 10% reduction in incorporation of radioactivity into the DNA fraction for all the Al pretreatments, ranging from 2 to 48 h. Exposure of Eagle roots to AI for 2 h showed this same 10% reduction in incorporation of radioactivity into DNA. For both cultivars, there usually was a 10 to 20% decrease in 3H‐thymidine uptake by whole roots after 0.19 mMAl pretreatment periods of 2 to 12 h as compared with control plants not receiving AI. The extent of inhibition was fairly constant and was not correlated with duration of Al pretreatment for either cultivar. There was a similar depression of 3H‐thymidine uptake in root tips of Eagle after 4 to 12 h of Al pretreatment. The reduction of 3H‐thymidine uptake in both cultivars resembled the depression of 3H‐thymidine incorporation into DNA in Atlas 66 but not in Eagle. This work suggests that Al has two effects on susceptible cultivars: a rapid inhibition of root elongation followed by an inhibition of DNA synthesis. Another effect of AI on both the tolerant and the susceptible cultivar, that of depression of 3H‐thymidine uptake, also was seen.
Turfgrass Evapotranspiration. 11. Responses to Deficit Irrigation1
Authors: Feldhake C. M. , Danielson R. E. , Butler J. D.
Published: July 2010

abstract

In the arid west, deficit irrigation has contributed significantly to efficient utilization of water resources. In order to understand possible benefits of deficit irrigation in turfgrass management, yield must be defined in terms of gain from water expended. Turfgrass quality influences the aesthetic appeal and physical comfort of urban environments. The effect of deficit irrigation on turfgrass quality was studied using small lysimeters where root systems were confined and evapotranspiration (ET) was limited to the amount of irrigation. In most cases there was a sharp change in slope of the quality vs. ET relationship for turfgrass. Kentucky bluegrass (Poa pratensis L. var. 'Merion') decreased about 10% in quality with an irrigation schedule providing up to a 279% ET deficit. Larger deficits resulted in greater relative decreases in quality. When ET was maintained at greater than 30% deficits, the quality rating of Kentucky bluegrass was lower if mowed at 2 cm than when mowed at 5 cm. When N fertility was low, maximum ET and maximum quality were decreased, but the response of quality to irrigation deficits greater than 27% was similar. The response of tall fescue (Festuca arundinaceaSchreb. var. 'Rebel') to deficit irrigation was similar to that of Kentucky bluegrass. Buffalograss [Buchloe dutyloides(Nutt.) Engem.], however, responded with notable differences. Decreasing ET also had an effect on microclimate. Turfgrass canopy temperature increased 1.7°C for each 10% decrease in irrigation up to 70% decrease suggesting that, during summer months, if irrigation is limited, the effect on urban climate may become a concern.
Water Table Depth Interaction with Nitrogen Rates on Subirrigated Corn1
Authors: Woodruff J. R. , Ligon J. T. , Smith B. R.
Published: July 2010

Water table control for both drainage and subirrigation holds potential benefit to crop production on many soils with imperfect drainage. Losses of soil NO‐3‐N may occur through denitrification under partial anaerobic conditions such as would be encountered near a water table. In this 3‐year field study, four N rates were superimposed over three water table depths to test the effect of water table depth on corn (Zea maysL.) response to N in a Chewacla silt loam (fine‐loamy, mixed, thermic Fluvaquentic Dystrochrepts). Water table depths were 0.35,0.70, and 1.00 m and N rates were 0,112,224, and 336 kg ha−1. The effects of N fertilization depended on the water table depth. For the 3‐year means, quadratic regressions described the relationship between N rate and ear yield or leaf N for each water table depth except 1.00 m ear yield for which no response to N fertilizer was obtained. The N rate required for maximum ear yield or leaf N increased with decreasing water table depth. There were positive linear regressions of stover yields and soil NO‐3‐N on N rate for each water table depth. With the 1.00 m water table, the N response slope was less for stover yield and greater for soil NO‐3‐N than over the shallower water table depths. The lowest ear and stover yields were associated with deficient leaf N concentrations (< 27.5 g kg−1) where no N was added over the 0.35 and 0.70 m water table depths. The results suggest that soils with water tables within 0.70 m depth require more N fertilization to reach maximum corn yields than soils with deeper water tables.
Forage Production and Weed Control in a Double‐Cropping Program1
Authors: Okoli Paul S. O. , Drolsom P. N. , Scholl J. M.
Published: July 2010

To make more intensive use of increasingly‐scarce and expensive farmland, farmers in the North‐Central region of the United States are developing considerable interest in double‐cropping systems involving feed production. Therefore, forage production and quality were evaluated in double‐cropping systems involving corn (Zea maysL.), soybeans [Glycine max(L.) Merr.], and grain sorghum [Sorghum bicolor(L.) Moench] no‐till planted following conventionally‐planted spring oats (Avena sativaL.) for forage. The 2‐year field studies were undertaken on two soil types, Plano silt loam [fine‐silty, mixed, mesic Typic Argiudoll (Exp. I)] and Fayette silt loam [fine‐silty, mixed, mesic Typic Hapludalf (Exp. II)] at two separate locations in Wisconsin. The effects of irrigation and weed control practices (chemical and cultural) on the second crops were investigated. The 2‐year average forage yields of corn, soybeans, and grain sorghum were 5820, 2660, and 3890 kg ha−1, respectively.

Cultivation generally resulted in better weed control than herbicides. Irrigation increased forage yields of corn, soybeans, and grain sorghum by 31, 38, and 32%, respectively. Soybeans produced the highest crude protein (CP) ha−1but the lowest quantity of digestible dry matter (DM), estimated by the in vitro dry matter digestibility (IVDMD) technique. Corn produced the highest amount of digestible DM ha−1but had the lowest CP percentage. Grain sorghum had thelowest IVDMD and produced the lowest CP ha−1. Based on 2‐year averages, the oats‐corn double‐cropping system produced the most forage, CP and digestible DM. Double‐cropping yields show considerable promise, when compared with present yields under a one crop system.
Nitrogen Fertility Effects on Accumulation, Remobilization, and Partitioning of N and Dry Matter in Corn Genotypes Differing in Prolificacy1
Authors: Anderson E. L. , Kamprath E. J. , Moll R. H.
Published: July 2010

Results from previous studies have shown that more prolific corn (Zea maysL.) genotypes produce more grain per plant than less prolific genotypes. The objectives of this field study were to determine the effect of N fertility on dry matter (DM) and N accumulation, partitioning, and remobilization in genotypes which differ in prolificacy (ear number per plant). Two N rates were used, 56 and 224 kg N ha−1on a Typic Plinthic Paleudult. Eight genotypes were grown in 1978 and three in 1979. Leaves, stalks, and ears were sampled at various times during grain fill and N content was determined. Leaf dry weight did not change during grain fill at either of the N rates. Stalk dry weight increased initially during grain fill and then decreased at the low N rate, for all genotypes, but at the high N rate, only the nonprolific genotype showed the initial increase. The rate of increase in ear dry weight was constant throughout the grainfilling period at low N, but decreased after 30 days at high N. Leaf N decreased linearly during grain fill at both N rates. The decrease in stalk N was curvilinear at both N rates with most of the decrease occurring in the first 30 days after silking. Ear N accumulated at a linear rate for the first 30 days during grain fill and then proceeded at a slower rate. Grain yield per plant was associated with the number of ears per plant. Increasing the N rate tended to increase the number of ears per plant of the more prolific genotypes. Genotypes with a greater average ear number were more efficient in using accumulated N in producing grain and partitioned more of the total plant N and DM to grain production.
Stability of Soybean Harvest Index1
Authors: Spaeth S. C. , Randall H. C. , Sinclair T. R. , Vendeland J. S.
Published: July 2010

Previous work had indicated that the harvest index within cultivars of soybeans [Glycine max(L.) Merr.] might be fairly stable. Such stability of harvest index would greatly simplify the conceptualization of the influence of seed growth processes on yield. In the studies reported here harvest index of field‐grown soybean plants was measured in response to four types of environmental influence: interplant competition, extended photoperiod, timing of drought stress, and degrees of drought stress (line source irrigation). The experiments included both indeterminate and determinate cultivars, and included both a northern (Ithaca, N.Y.) and southern location (Gainesville, Fla). These experimental conditions resulted in considerable variability in plant sizes within a cultivar but the harvest index (ratio of seed mass to mass of mature plant without fallen leaves and petioles) was stable. Total masses of individual mature ‘Chippewa 64’ and ‘Bragg’ plants varied substantially in response to interplant competition, but harvest index was essentially constant (0.54 and 0.50 for Chippewa 64 and Bragg, respectively) across most of the range of plant sizes. Harvest index of smaller plants was less than for larger plants, but these smaller plants have little influence on total crop yield and harvest index. Extending the photoperiod to 14.5 h throughout the life cycle of six cultivars increasingly delayed ontogenic events as the distance from the photoperiod lamps decreased. However, no influence on harvest index was observed except at the position nearest the lamps where the standard errors of the harvest indices were increased. Harvest index did not respond to differences in the timing of severe drought stress. When rain was withheld from ‘Wilkin’ plants during vegetative growth, flowering, or seed setting, harvest index of individual plants was essentially 0.60. Only those plants stressed late in pod filling had lower harvest index and increased variability in harvest index. Seed yields (Chippewa 64, Wilkin, and ‘Evans’ for three planting dates) decreased substantially as degree of drought stress, induced by increasing distance from a line source irrigation system, increased yet, harvest index changed negligibly with distance from the line source. Thus, we conclude that harvest index is a conservative characteristic within each soybean cultivar.
A Trend Toward a Longer Grain‐Filling Period for Corn: A Case Study in Indiana1
Authors: McGarrahan J. P. , Dale R. F.
Published: July 2010

In assessing the effect of weather on crop growth and yield it is necessary to consider the stage of crop development. In most states since 1951 the USDA Statistical Reporting Service (SRS) has collected and summarized reports of crop progress during each season. For corn (Zea mays L.) and crop reporting districts (CRD) in Indiana, dates by which 50% of the corn acreage had been planted, silked, and matured were used to examine the trends in length of the corn vegetative and grain‐filling periods, measured in both days and thermal units from 1951 to 1980. It was found that there has been little change in the length of the period from planting to silking, but that the period from silking to maturity has increased from less than 50 days before 1961 to near 60 days in 1980. Although a climatic cooling trend may have contributed to this longer period of grain filling, the modified (10 to 30°C cutoff base) growing degree days required during the corn grain−filling period (silking to maturity) also increased, from less than 550 before 1961 to near 700 in 1980.
Drought Response of Grain Legumes Under Irrigation Gradient: II. Plant Water Status and Canopy Temperature1
Authors: Pandey R. K. , Herrera W. A. T. , Pendleton J. W.
Published: July 2010

A great need exists in semiarid or tropical areas to include food legumes in rice (Oryza sativa L.) based cropping systems during the post monsoon or dry season. The seed of these legumes provide needed protein for the prevalent high starch diets. Mungbean (Vigna radiata L.), cowpea (Vigna unguiculata L.), soybean (Glycine max L.), and peanut (Arachis hypogeae L.) are four short‐season legumes receiving attention. The purpose of this research was to compare their drought responses on a medium‐deep Tropudalf soil by using a line‐source sprinkler irrigation system. This paper presents findings on plant water status and canopy temperature and their relationships to yield. Plant water status was determined with a pressure chamber and canopy temperature with an infrared thermometer. Plants exhibited leaf water potentials between 1300 to 1400 h of −1.20 MPa in mungbean, −1.40 MPa in cowpea, −1.41 MPa in soybean, and −0.67 MPa in peanut in the dry regimes 60 days after emergence. Seasonal leaf water potential was closely related to canopy temperature in all four legumes. Increasing water stress decreased leaf water potential and increased canopy‐air temperature differences (ΔT). The seasonal cumulative leaf water potential and ∆T during crop growth were negatively correlated with yield and may be useful for selecting crop species for drought prone areas. Peanut had a higher leaf water potential and maintained a lower canopy temperature than the other species.
Influence of Grass Species on Composition, Yield, and Quality of Birdsfoot Trefoil Mixtures1
Authors: Sheaffer C. C. , Marten G. C. , Rabas D. L.
Published: July 2010

Mixtures with noncompetitive perennial grasses have been recommended to reduce weed invasion which commonly occurs in pure stands of birdsfoot trefoil (Lotus corniculatus L.). Our objective was to determine the potential of competitive vs. noncompetitive grass species in mixtures with birdsfoot trefoil to prevent weed invasion while maintaining stands with maximum birdsfoot trefoil composition and forage quality. ‘Leo’ and ‘Viking’ birdsfoot trefoil were established in monoculture and in binary mixtures with nine grass species on a Waukegan silt loam (fine‐silty over sandy, mixed, mesic Typic Hapludolls) in southeastern Minnesota. The same treatments, except one, were also established on a Cowhorn sandy loam (coarseloamy, mixed nonacid sand, frigid Aeric Haploquepts) in northcentral Minnesota. Conventional (when Leo reached first flower) and stockpiled (when Leo reached full bloom) harvest managements were applied for 2 years. Mixtures with high yielding competitive grasses (Phalaris arundinacea L., Bromus inermis Leyss., or Dactylis glomerata L.) had the least weed infestation and greatest weed‐free forage yield, but had consistently lower forage quality than the birdsfoot trefoil monoculture or mixtures with noncompetitive grasses (Phleum pratense L., K2‐106; Lolium perenne L.; or Poa pratensis L.) at the southeastern location. Competitive grasses also maximized birdsfoot trefoil persistence in southeastern Minnesota, while noncompetitive grasses and the birdsfoot trefoil monoculture maximized birdsfoot trefoil persistence in northcentral Minnesota. Relative mixture differences in weed infestation, forage quality, and yield were generally not affected by harvest management (stockpiled vs conventional). Stockpiled forage had lower quality than did conventionally harvested forage at both locations, and greater yields at the southeastern location. Stockpiled mixtures containing Leo had a greater final birdsfoot trefoil composition than did mixtures containing Viking only at the southeastern location. Birdsfoot trefoil cultivar selection did not affect final composition when mixtures were conventionally managed at either location. Because competitive vs noncompetitive grasses led to differing birdsfoot trefoil persistence depending on location, noncompetitive companion grasses may maximize birdsfoot trefoil persistence in mixtures in some environments, whereas competitive grasses may ultimately maximize birdsfoot trefoil in others. If forage quality is the primary concern, noncompetitive grasses should be used; if total weed‐free forage yield is the primary concern, competitive grasses may be advisable.
Response of Sorghum and Wheat to Different K+/Na+ Ratios at Varying Osmotic Potentials1
Authors: Devitt D. , Stolzy L. H. , Jarrell W. M.
Published: July 2010

Plants growing in saline‐sodic conditions must confront not only osmotic stress but the relative toxicity of the Na ion. The impact of these two factors on the physiology and morphology of the plant will often determine the plant growth in saline‐sodic soils. The objective of this experiment was to investigate the impact of low K+/Na+ ratios at given osmotic potentials in the solution phase on cation composition in the plant tissue, stomatal response, and root growth and development. The experiment was conducted in outdoor solution culture tanks. Wheat (Triticum aestivum) and sorghum [Sorghum bicolor (L.) Moench] were grown for 6 weeks in nutrient solution to which a range of polyethylene glycol 6000 and/or NaCl additions were made (MPa = −0.070, −0.076, −0.193, −0.340, −0.493 and K+ mmol L−1/Na+ mmol L−1 = 1/0,1/1,1/10,1/25,1/60,1/100). Porometry measurements were taken twice weekly at 830 and 1230 h. Leaf xylem water potentials were measured at 1230 h. Root length extension, root volume solution displacement and solution samples were taken weekly over the 6 week experimental periods. At harvest, fresh and dry weights were measured and the plants were subdivided into roots, shoots, stalks, and leaves for eventual analysis of Na, K, Ca, and Mg. Diffusive resistances generally increased with decreasing osmotic potential for both sorghum and wheat; however, measurement variability prevented clear separation between all osmotic and K+/Na+ treatments. The highest diffusive resistances were measured in plants grown in the −0.493 MPa, K+/Na+ = 1/100 solution. Interpolated Na+ concentrations in the plant tissue from estimated growth and Na uptake curves suggested translocation of Na to the upper leaves coincident with the stomatal response. The Ca concentration in the upper leaves decreased as Na increased. The combination of high Na and low Ca concentrations in the leaves, even when K concentrations appeared to be adequate, apparently decreased effective regulation of the stomata in the sorghum treatment. Root mass decreased as the osmotic potential of the solution decreased, while root elongation was primarily dictated by the Na concentration in solution. Sorghum root elongation decreased while wheat root elongation increased as the Na concentration increased within each osmotic level. Sodium was primarily confined to the root system in sorghum but translocation to the tops increased as the Na concentration increased. With wheat, Na was not restricted to the root system. An excellent exponential relationship for sorghum was found between the coefficient of root elongation and the concentration of Na in the plant. Root elongation of both wheat and sorghum under saline‐sodic conditions is controlled to a great extent by the degree of Na saturation of the root tissue.
Yield and Quality of a Warm‐Season Grass Mixture Treated with N, P, and Atrazine1
Authors: Rehm G. W.
Published: July 2010

Warm‐season grasses can be important in pasture systems in the eastern Great Plains. Currently, production from the majority of pastures which contain these grasses is quite low and improvement is needed. In previous research with warm‐season prairie grasses, the effect of fertilization as well as the influence of atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] has been investigatd in separate studies. Only limited research has been conducted to evaluate the combined effects. This study evaluated the rate and frequency of fertilizer N and P with and without use of atrazine on yield and protein content of warm‐season prairie grasses. Three management systems (annual fertilizer with no atrazine, annual fertilizer with atrazine, biennial fertilizer with atrazine) were randomized and replicated in the experimental area. The soil was a Crofton silt loam [fine‐silty, mixed (calcareous) mesic Typic Ustorthent]. Applications of N (0, 34, 67, 101, and 134 kg ha−1) and P (0, 6, 12, 18, and 24 kg ha−1) were applied to the systems involving annual fertilization. These rates were doubled when applied on alternate years (1974, 1976, 1978). Atrazine (1.12 kg ha−1) was applied in early April in 1974, 1976, and 1978. All fertilizer treatments were applied in late May. The response to P was linear in all situations. The response to N was linear where atrazine was not used and curvilinear where atrazine was applied. Atrazine effectively controlled weeds and encroachment of cool‐season species. Compared to the system where no herbicide was used, atrazine applied every 2 years resulted in higher forage production in 4 out of 6 years. Crude protein concentration of the forage increased by about 35 g kg−1with the use of fertilizer N. Neither applied P nor atrazine affected crude protein concentration.
Examination of Microorganisms and Deterioration Resistance Mechanisms Associated with Velvetleaf Seed1
Authors: Kremer R. J. , Hughes L. B. , Aldrich R. J.
Published: July 2010

Annual weed seeds persist in cultivated soils due to seed dormancy and possibly to resistance to microbial attack. The relationships between microorganisms and velvetleaf (Abutilon theophrastiMedic.) seeds were investigated to elucidate the deterioration resistance mechanisms in this species. Microorganisms were isolated from velvetleaf seeds matured on the plant and from seeds dispersed on the soil surface. An association of sporulating fungi comprised of Alternaria alternata, Cladosporium cladosporioides, Epicoccum purpurascens, and Fusariumspp. was consistently found on the seed surface. This association persisted on seeds after dispersal to the soil. Seed deterioration was infrequent despite abundant microbial growth on the seed surface. About 80% of the bacteria isolated from within seeds were antagonistic to externally seedborne fungi.

The proportion of surface‐sterilized seeds with internal fungi was 10%, indicating the seed coat acts as a barrier to most fungal invasions. When the seed coat was punctured, however, seed deterioration by the seedborne microorganisms readily occurred. Seed coat extracts contained tannin‐like compounds that inhibited in vitro growth of several bacterial and fungal isolates. Histochemical examination of seed sections revealed localization of tannin‐like compounds in the palisade layer of the seed coat and the chalazal area of the embryo. It is suggested that deterioration of velvetleaf seeds by microorganisms is limited by the dense layer of palisade cells in the seed coat, chemical compounds within the seed coat that are inhibitory to certain microorganisms outside the seed, and antagonistic bacteria located within the seed. Resistances to microbial attack may act together with seed dormancy to maintain velvetleaf seed longevity in soil.
Night Temperature Effects on Morphology, Phenology, Yield and Yield Components of Indeterminate Field‐Grown Soybean1
Authors: Seddigh Majid , Jolliff Gary D.
Published: July 2010

Small changes in geography and topography can result in great differences in night temperature. Indeterminate soybeans [Glycine max(L.) Merr. ‘S09‐90’] of Maturity Group 0 were grown under field conditions in 1981 and 1982 to assess the effect of low night temperature on growth and seed yield. The soil was a Woodburn silt loam (fine‐silty, mixed, mesic Aquultic Argixerolls). Mean minimum night temperature treatments were: Check (uncontrolled, ca. 10°C), 16±1°C and 24±2°C. Elevated night temperatures were achieved by enclosing the plots at night in polyethylene‐covered chambers and increasing chamber temperature with electric heaters. The chamber covers were removed each morning to provide natural field conditions during the daylight hours. Treatments were applied from 2 weeks after crop emergence until physiological maturity. Higher night temperatures enhanced vegetative growth. However, morphological characteristics, e.g., plant height, number of nodes, and number of auxiliary branches were not significantly (P < 0.05) different among the treatments at maturity since the growth of these components also terminated earlier for plants receiving higher night temperatures. Warmer night temperatures considerably shortened the time period between plant emergence and appearance of first flower (R1) and appearance of flowers at the node immediately below the uppermost node (R2), while they had little additional effect on the subsequent reproductive development. Physiological maturity (R7), however, was hastened by higher night temperatures. Accumulated growing degree‐days appeared to be of value for the prediction of all developmental stages and were a good indicator of the time period between emergence and physiological maturity of plants within treatments. Plants with warmer nights, however, accumulated more heat units than the check for the onset of all developmental stages. Seed weight/plant increased above the check by 27 and 37% for 16°C, and 20 and 23% for the 24°C treatments in 1981 and 1982, respectively. The growth of individual seeds appeared to be most responsive to night temperatures, and increased seed size (1000‐seed weight) accounted for the seed yield increase of both treatments. Final numbers of seeds/plant and pods/plant were not significantly affected by the treatments. The number of seeds/pod for the 24°C treatment was, however, significantly greater than the check. The data indicate that the genetic potential for seed yield of indeterminate soybeans is not realized under low night temperatures. This study emphasizes the importance of night temperatures as a potential criterion for developing new soybean cultivars.
Canopy Target Dimensions for Infrared Thermometry1
Authors: O'Toole J. C. , Real J.
Published: July 2010

The increasing use of infrared thermometry in agricultural research and management obviates the necessity of users being cognizant of the instrument's target area characteristics. In this note, we illustrate the target dimensions when an infrared thermometer of specified field of view (4°, 8°, and 20°) is used to remotely sense surface temperature of a leaf, canopy, or crop surface. Knowledge of target dimensions and special characteristics related to the ellipse center and target point at various distances to and angles above the target surface should decrease error in surface temperature measurements and assist in standardization of techniques.
Increased N Efficiency from Nitrapyrin Added to Liquid Swine Manure Used as a Fertilizer for Corn1
Authors: McCormick R. A. , Nelson D. W. , Sutton A. L. , Huber D. M.
Published: July 2010

Increases in the price of N fertilizers encourage farmers to utilize alternative sources of nutrients such as sewage sludges and animal manure when the wastes are available. However, a portion of the applied N may be lost by leaching and/or denitrification after organic N and NH +4‐N in the waste is converted to NO ‐3 by ammonification and nitrification. One way to reduce leaching and denitrification losses is through the use of a nitrification inhibitor. Therefore, field experiments were conducted during three growing seasons to evaluate the effects on corn (Zea mays L.) grain yield and plant composition of mixing nitrapyrin [2‐chloro‐6(trichlormethyl)pyridine], a nitrification inhibitor, with liquid swine (Sus spp.) manure applied to a silty clay loam (fine‐silty, mixed, mesic, Typic Haplaquoll). Nitrapyrin was added to swine manure at rates of 0, 25, and 50 mg L−1, and the swine manure was soil injected in bands during the fall or spring prior to corn planting. Corn grain yields, ear leaf N levels, and grain N concentrations were measured. In 1978, the addition of nitrapyrin (at a rate of 50 mg L−1) to liquid swine manure springapplied at a rate of 49 Mg ha−1 (154 kg available N ha−1) significantly increased grain yield, but not tissue N levels when compared to plots receiving only manure. Yields obtained from plots treated with manure (49 Mg ha−1) plus nitrapyrin were similar to those from plots receiving swine manure at a rate of 110 Mg ha−1 (345 kg available N ha−1) without nitrapyrin or from 134 or 180 kg urea N ha−1. During the 1979 and 1980 growing seasons, the addition of 25 or 50 mg nitrapyrin L−1 of swine manure applied at rates of 31 to 60 and 38 to 60 Mg ha−1, respectively, in the fall significantly increased yields as compared to plots receiving waste without the inhibitor. In 1979 and 1980, addition of nitrapyrin to swine manure applied in the spring at rates of 63 and 78 Mg ha−1 (161 and 286 kg available N ha−1, respectively) had no effect upon corn yield. However, in 1980 the addition of 50 mg nitrapyrin L−1 to manure applied in the spring at a rate of 44 Mg ha−1 (159 kg available N ha−1) significantly increased yields as compared to plots receiving waste without the inhibitor. Large losses of applied N apparently occurred following fall applications of manure. Based upon yield results of manure treatments it is likely that nitrapyrin was effective in reducing losses of applied N and, thereby, increased corn yields by maintaining adequate levels of available N in the plant rooting zone throughout the growing season
Growth, Nutrition, and Water Uptake of Tomato Plants with Divided Roots Growing in Differentially Salinized Soil1
Authors: Papadopoulos I. , Rendig V. V. , Broadbent F. E
Published: July 2010

Tomato (Lycopersicon esculentum Mill. var. VF 145) plants were grown in the greenhouse to determine effects of uniform and nonuniform salinity distribution on root growth and on water and N uptake. The plants were grown in Reiff sandy loam (Coarse‐loamy, mixed, nonacid, thermic Mollic Xerofluvents) using a technique by which the root system was divided and each of four quadrants allowed to grow in separate compartments. Nutrient solutions differing in salinity levels (1, 4, 7, and 10 dS/m; nonuniform treatment) were applied to the four compartments, or all four received a nutrient solution otherwise similar but with a salinity of 5.5 dS/m (uniform treatment). The salinization was brought about by a mixture of NaCl and CaCI2 in a ratio of 1:1 by weight. To determine sources of N taken up, sufficient K15NO3 was added to provide 2% 15N in the solution. Yields of shoots and roots were lower for the plants grown with the uniform than the nonuniform salinization treatment. With nonuniform salt distribution, about 62 and 8% by weight of the total root system were found in the compartments irrigated with nutrient solutions having initial salinities of 1 and 10 dS/m, respectively. About 63% of the total water taken up per plant was drawn from the compartment with the lowest salinity. With the uniform salt distribution treatment, N uptake into the shoots was more severely affected than growth. With treatments in which salinity was nonuniformly distributed, the main source of N was the compartment with the lowest salinity. The contribution of this compartment, however, decreased during the growing period as its relatively greater salinity buildup favored uptake of N by roots in the other compartments, initially irrigated with the more saline solutions. Plants growing in the units with the nonuniform salinity treatment generally showed lower leaf concentrations of Ca, Na, K, and Cl, but higher leaf concentrations of Mg and P than the plants growing in the uniformly salinized units. Unlike the other elements, K and P concentrations decreased with time. Differences in S concentrations as related to salinization treatments were variable during the growth period. Higher concentrations of the “bound” organic anion fraction, but lower concentrations of the “diffusible” fraction, as determined from differences in amounts of inorganic cations and anion present, were found in leaves of plants grown with the higher salinity levels. In general, for nutrition of tomato plants grown under conditions in which different regions of the root system are exposed to differences in salinity, the least saline environment is dominant, but over time root activity shows some accommodation to the presence of salt.
Narrow Row Soybean Production in Untilled Oat Stubble1
Authors: Burnside O. C. , Moomaw R. S.
Published: July 2010

Both established and subsequently emerging weed species in ecofarming systems must be selectively controlled without tillage in order to better conserve soil and water in the semiarid region of the Great Plains. The objective of this research was to determine selective weed control methods for an oat (Avena sativa L.)‐soybean [Glycine max (L.) Merr.] ecofarming rotation in order to allow dryland soybean production to move further west in the Great Plains. Experiments were conducted at Concord, NE on a Colo silty clay loam (fine‐silty, mixed, mesic, Cumulic Haplaquoll) and at Lincoln, NE on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic, Typic Argiudoll) during 1976 through 1979. Weed control must be effective during the entire crop rotation. There are several herbicide treatments that provide ample length and spectrum of weed control after oat harvest. During the subsequent soybean year, glyphosate [N‐ (phosphonomethyl)glycine] at 0.8 kg ha−1 controlled established weeds prior to soybean planting, and there were several residual herbicide treatments that gave selective weed control in soybeans without cultivation. The low‐till farmer has several herbicide treatments available that will selectively and adequately control weeds without tillage in an oat‐soybean rotation. This low‐tillage method of growing crops in the Great Plains should improve soybean yields and yield stability while conserving soil, water, energy, and labor.
Effect of pH on Proteolysis in Ensiled Legume Forage1
Authors: McKersie B. D.
Published: July 2010

The hydrolysis of proteins is extensive in ensiled forages but the production practices which may influence the extent of proteolysis remain to be characterized. An in vitro assay system was developed to estimate the relative rates of proteolysis and was compared to a laboratory silo system as a means of estimating the relative extent of proteolysis in three forage legumes, alfalfa (Medicago sativa L. cv. Iroquois), red clover (Trifolium pratense L. cv. Arlington) and birdsfoot trefoil (Lotus corniculatus L. cv. Leo). Plants were harvested from field plots as first and second cuts at the same time and were in the early bud to 10% bloom stages, depending on species and sampling time. Leaf homogenates containing chloramphenicol as an antibiotic were used as in vitro systems to monitor changes in the level of free amino acids at pH values between 4.0 and 6.5 at incubation times up to 72 h. This method provided a more satisfactory estimate of the relative proteolysis in ensiled forage than previous attempts using azocasein as substrate. Proteolysis was more extensive in alfalfa than the other two species. The optimal pH of proteolysis was approximately 6.0 in alfalfa, but 6.5 or above in red clover and birdsfoot trefoil. Low pH inhibited proteolysis. In a second experiment, forage from the same field plots as the in vitro experiment was ensiled in laboratory silos with the addition of 1% Na2CO3, 1% formic acid, 0.7% HCl, 1% formaldehyde, or no treatment. After ensiling for 30 days, protein hydrolysis was consistently highest in the alfalfa silages. The acid additives reduced proteolysis in all species, but a significant (P≤0.01) additive ✕ species interaction was observed in the second cut. A close positive relationship between the initial pH of the forage at ensiling and proteolysis was established for each species. The amount of protein degraded to free amino acids during ensiling of these legumes appears to be dependent on the proteolytic activity in the leaves, the rate of pH decline during ensiling, and the interaction between these two factors.
Response of Sugarbeet in Europe and the USA to Cercospora beticola Infection1
Authors: Smith G. A.
Published: July 2010

The interaction among cultivars and pathogen races is of particular relevance since sugarbeet (Beta vulgaris L.) cultivars developed in one geographic area may or may not be resistant in other areas. The objective of this study was to investigate the presence of pathological variability among indigenous biotypes of Cercospora beticola under field conditions as measured by cultivar ✕ location (biotype) interaction. Twelve sugarbeet cultivars developed in four different and unrelated breeding programs were evaluated for response to C. beticola in Greece, Italy, Spain, and the USA. The cultivars representing a wide range of inherent resistance were evaluated under field epidemics for 3 years. Results indicated that resistance to C. beticola was stable over the four diverse geographic locations and the 3 years, in all probability in the presence of several different biotypes of the pathogen. If pathogenic races do exist, as has been reported, their presence may be of limited consequence to germplasm development programs.
Row Spacing, Plant Population, and Water Management Effects on Corn in the Atlantic Coastal Plain1
Authors: Karlen D. L. , Camp C. R.
Published: July 2010

Lack of water because of erratic rainfall frequently limits corn (Zea mays L.) production on Typic Paleudults in the Atlantic Coastal Plain. Traditionally, wide (96 cm) row spacing and low plant population have been used to prevent water stress, but recently landowners have begun to invest in irrigation systems. Changes in row spacing, plant population, or fertilization practices may be required to achieve maximum water‐and nutrient‐use efficiency with those systems. We evaluated plant population treatments averaging 7.0 and 10.1 plants m−2 in single and twin rows on a Norfolk (fineloamy, siliceous, thermic Typic Paleudult) loamy sand during 1980, 1981, and 1982. Three water management [nonirrigated, irrigated using tensiometers (TENS) to measure soil‐water potential for scheduling, and irrigated using a computer‐based water balance (CBWB) for scheduling], and two fertilization programs were also evaluated in a four‐factor split‐plot design. Water management and plant population interacted significantly. Planting in twin rows increased grain yield an average of 0.64 Mg ha−1 (10 bu/A), but planting more than 7.1 plants m−2 significantly increased grain yield only in 1980. Irrigation increased grain yield 150, 161, and 8% in 1980, 1981, and 1982, respectively, as a result of increased kernel weight and number of kernels per ear. Increasing total N, P, and K application beyond 200, 30, and 167 kg ha−1, respectively, did not significantly influence grain yield or yield components. Yield advantages of narrow rows can be obtained on Coastal Plain soils which require subsoiling by using a twin‐row planting configuration. Irrigation can be scheduled using either tensiometers (soil‐water potential) or a computerized water balance without significantly changing corn grain yield, nutrient accumulation, or yield components.
Phosphorus Relationships in Potato Plants1
Authors: Westermann D. T. , Kleinkopf G. E.
Published: July 2010

Maximum potato (Solanum tuberosum L.) tuber yields occur when an active plant canopy is maintained until normal plant maturation. Plant nutrient concentrations and uptake rates play a major role in maintaining an active plant top. The objectives of this study were to relate the plant P concentrations to the P and dry matter balance between tuber and total plant growth needs. Growth analysis data, plant and leaf total P concentrations and content, and the petiole soluble P concentrations were obtained on a 10‐to 14‐day sampling interval from P fertilization treatments in replicated field studies. The P concentration of the plant tops was significantly related to the petiole soluble P concentration and the P concentration of the active leaves. Total plant P uptake and dry matter production rates were not adequate for the tuber growth rate when the total P concentrations of the tops and active leaves were less than 2.2 g P kg−1. Soluble P concentrations in the fourth petiole down from the growing tip were less than 1000 and 700 mg kg−1 when P uptake and dry matter production rates were not adequate for tuber growth, respectively. Final tuber yields increased from 30 to 70 Mg ha−1 as the number of growing days past tuber set increased from 10 to 60 days for which the P concentration of the tops was above 2.2 g P kg−1. The petiole soluble P concentration decreased during the growing season following a semi‐logarithmic relationship. This relationship enabled the prediction of the petiole soluble P concentration for the rest of the growing season and could be used to predict when to apply supplemental P fertilizer.
Corn Hybrids Response to Four Methods of Tillage1
Authors: Hallauer A. R. , Colvin T. S.
Published: July 2010

Conservation tillage methods are becoming more widely used in corn (Zea maysL.) production because of energy costs and soil losses due to wind and water erosion. Changes in tillage methods, however, create different environments for the germination, development, and maturation of the corn plant. The objective of our study was to determine if single‐cross corn hybrids responded differently to tillage methods. A 5‐yr continuous corn study was conducted that included 14 single‐cross hybrids and four tillage methods (fall‐plow, striptill, spring‐disk, and no‐till). The soil was a mesic Typic Hapludoll. There was no significant interaction of hybrids by tillage methods, but significant differences were detected among tillage methods for yield, stand, and grain moisture. Hybrids planted in fall‐plow or spring‐disk conditions had greater yields, better stands, and lower grain moisture than when planted in strip‐till and no‐till conditions. Hybrids performed similarly for the fall‐plow and spring‐disk treatments, but spring‐disk had significantly greater plant residue cover (54.5 vs. 7.8%). Our results suggested that it was not necessary to test hybrids for different tillage methods.