bluuebunny/crossref_metadata_2025 huggingface dataset:
Manipulation of Sorghum Growth and Development with Gibberellic Acid1
Authors: Morgan Page W. , Miller F. R. , Quinby J. R.
Published: July 2010

This study is the initial step in an effort to understand the nature of the hormone involvement in the genetic control of height, date of flowering, and tillering in Sorghum bicolor L. Moench. The objective of these experiments was to characterize the response of sorghum genotypes varying in dwarfing genes to gibberellic acid. Since height influences commercial production, better understanding of its control may have practical and scientific value. Solutions of GA3 were applied in the whorl of vegetative plants and the growth and development of treated plants compared to controls. Sorghum grown in the field on Norwood fine sandy loam (Typic Udifluvente) soil exhibited a range of responses to gibberellic acid (GA3). Plant height of seedlings was universally promoted, but higher GA3 levels were required to increase final stem height. At concentrations up to 10−3 M GA3, stem height of members of the milo and kafir groups was promoted to a major degree and the Redlan varieties were promoted to a slight extent while hegaris were not changed. GA3 applied over a period of several weeks drastically reduced tillering and adventitious root development. Early termination of GA3 application resulted in subsequent promotion of tillering. It was possible to separate the effect of GA3 on tillering from its effect on stem height. At higher concentrations both processes are modified while at lower treatment rates GA3 reduced tillering without promoting stem height. The treatments employed did not significantly shift the date of anthesis. Several of these results were verified by experiments in a greenhouse and in the field at a different location on Hollister clay loam (Pachic Paleustoll) soil. The results support the conclusion that gibberellins function in the control of height and tillering in the genotypes studied.
Effect of Herbicides on Production and Protein Levels in Pasture Grasses1
Authors: Baur J. R. , Bovey R. W. , Holt E. C.
Published: July 2010

Field studies were conducted to evaluate the effects of spring application of picloram (4‐amino‐3,5,6‐trichloropicolinic acid), tebuthiuron (N‐[5‐(1,l‐dimethylethyl)‐1,3, 4‐thiadiazol‐2‐yl] ‐N,N′‐dimethylurea), 2,4‐D (isopropyl amine of (2,4‐dichlorophenoxy)acetic acid), and glypho‐ sate (N‐[phosphonomethyl]glycine) on five grasses. The grasses were Common and ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.), kleingrass (Panicum coloratum L.), buffelgrass (Cenchrus ciliaris L.) and an F1 apomictic buffel × birdwood (Cenchrus setigerus Vahl.) hybrid. Grasses were grown in soils classified as either a vertic albaqualf (bermudagrasses) or vertic haplustoll (klein‐ grass, buffelgrass, buffel × birdwood hybrid). All grasses tolerated (with regard to productivity) rates up to 2.2 kg/ha of 2,4‐D applied at all dates, and March applications of glyphosate. Common bermudagrass and klein‐ grass were tolerant to March and April applications of tebuthiuron, with later applications (June) causing reduced production. Coastal bermudagrass was tolerant to tebuthiuron applied in March but not April or June. The only adverse effects of picloram were noted for March applications to Common bermudagrass and all dates for Coastal bermudagrass. The herbicides used had little effect on protein concentration in Coastal bermudagrass. Picloram, tebuthiuron and 2,4‐D reduced protein concentrations in the buffel × birdwood hybrid. Glyphosate caused increases in protein levels in buffelgrass and kleingrass.
Growth and Yield of Spring Wheat as Influenced by Shelter and Soil Water1
Authors: Frank A. B. , Harris D. G. , Willis W. O.
Published: July 2010

In the Northern Great Plains, windbreaks have historically been used to protect crops and soils from winds, but data on the effects of windbreaks on growth and yield of small grains is limited. ‘Waldron’ wheat (Triticum aestivum L.) was grown on Parshall fine sandy loam (Pachic Haploboroll) with and without shelter (slat‐fence enclosures), both with and without irrigation, to determine the effects of soil water and shelter on wheat growth and yield. In 1973 and 1974, plant height, tiller production, leaf area index (LAI), specific leaf weight (SLW), and dry matter were measured at tillering, heading, and grain‐filling growth stages. Also, grain yield, kernel weight, number of heads, straw yield, and plant height were measured at crop maturity. The combination of shelter and irrigation resulted in greater dry matter production, higher LAI, lower SLW, more tillers per plant and taller plants than irrigation alone. Shelter for dryland (nonirrigated) wheat did not increase vegetative growth, other than plant height early in the growing season. With irrigation, sheltered wheat yields increased 6.4 q/ha or 21.8% over the exposed wheat. Dryland sheltered wheat yield was 3.8 q/ha or 19.4% less than that for the exposed crop. Number of heads and straw production for each treatment responded the same to soil water and shelter as did grain yield. Results of this study show that growth and yield of spring wheat in the Northern Great Plains is increased significantly when grown under sheltered vs. exposed conditions provided soil water supply is adequate.
Plant Water Relationships of Spring Wheat as Influenced by Shelter and Soil Water1
Authors: Frank A. B. , Harris D. G. , Willis W. O.
Published: July 2010

Field windbreaks have been planted primarily for soil erosion control; subsequently, research has shown that windbreaks have an effect on microclimate and on growth and yield of crops. Other research has shown that plant water relations respond to changes in microclimate. The present work was undertaken to determine the effect of microclimate changes induced by a slat‐fence windbreak on the plant water relations of field‐grown wheat (Triticum aestivum L.). Slat‐fence barriers were used as windbreaks for studying effects of shelter‐modified microclimte on plant water relations of ‘Waldron’ spring wheat, grown on Parshall fine sandy loam (Pachic Haploboroll), under irrigated and dryland soil water regimes. Data were collected on leaf water potential (Ψl), xylem water potential (Ψx), stomatal diffusion resistance (rs), canopy temperature (Tc), soil water potential (Ψs), soil water extraction, and grain yield.

Plant water status of the wheat crop was strongly affected by shelter and soil water content. The treatment combination of shelter plus irrigation produced a higher Ψl and lower Tc and, overall, was the most beneficial treatment in creating a favorable plant water status. The dryland treatments were under considerable water stress from early heading to maturity. The presence of the shelter did not alleviate the water stress on the dryland‐grown plants. Water‐use efficiency was significantly higher for the irrigated‐sheltered as compared with the irrigated‐exposed treatments. Water‐use efficiency of the dryland treatments was lower than the irrigated treatments, but the dryland treatments did not differ from each other. The results of our study indicated that windbreaks will be most beneficial to a wheat crop only if soil water is adequate for good crop growth throughout the growing season. Because soil water varies considerably from year to year in the northern Great Plains, crop responses to windbreaks can also be expected to vary considerably.
Tillage Effects on Winter Wheat Production where the Irrigated and Dryland Crops are Alternated1
Authors: Unger Paul W.
Published: July 2010

While adequately irrigated winter wheat (Triticum aestivum L.) yields are relatively high, drylamd wheat yields in the southern Great Plains are only about 700 kg/ha with continuous cropping and about 1,000 kg/ha on a harvested‐area basis after fallow. This study was conducted to determine if yields could be increased where irrigated and dryland wheat crops are alternated on the same plots. Tillage effects were also studied.

In this study, continuous winter wheat production was evaluated with respect to grain and residue yields and soil water storage, use, and use‐efficiency. Wheat crops were alternately grown on Pullman clay loam [fine, mixed, thermic family of Torrertic Paleustolls (Mollisols)] with or without irrigation on disk, sweep, or no‐tillage plots, and continuously on dryland and irrigated plots with sweep and disk tillage, respectively. Dryland wheat with sweep tillage yielded 2,250 kg/ha where the irrigated and dryland crops were alternated and 2,080 kg/ha on continuous dryland plots, a significant yield increase. For irrigated wheat with disk tillage, yields were similar where irrigated and dryland crops were alternated or where continuously irrigated.

For the tillage evaluations, dryland wheat yields with sweep and disk tillage were similar, averaging 2,250 and 2,330 kg/ha, respectively. Yields for both were significantly higher than the 2,120‐kg/ha no‐tillage average. Irrigated wheat yielded 4,650 with sweep, 4,390 with disk, and 4,220 kg/ha with no‐tillage in the tillage evaluation. The differences were significant. By comparisons, dryland wheat yielded significantly more grain with sweep or disk tillage in the irrigated and dryland system than in the continuous dryland system (with sweep tillage). With irrigation, wheat yielded significantly more with sweep tillage in the alternate system than with disk tillage in the continuous and alternate systems.

Considering the combined system and tillage effects, the best treatments were sweep tillage for irrigated wheat and disk or sweep tillage for dryland wheat. Using sweep and disk tillage for irrigated and dryland wheat, respectively, where the crops are alternated increased average grain yields 10.3% over the average for the continuous irrigated and continuous dryland treatments. The greater grain yield occurred with 8.4% more soil water use, but only 2.3% more total water use. Wateruse efficiency was 8.5% greater where irrigated and dryland crops were alternated than where irrigated and dry]and crops were grown continuously. The irrigated and dryland alternate system offers a potential for greater and more water‐efficient grain production than that possible where equal areas are continuously cropped to irrigated or dryland wheat.
Portland Cement as a Soil Amendent for Corn and Soybeans1
Authors: Stivers R. K. , Swartzendruber D. , Nyquist W. E.
Published: July 2010

In the corn belt there are many areas of imperfectly drained soils, often adjacent to well‐drained soils in the same fields. Tile drainage of these imperfectly drained soils helps remove excess water within the profile. Slow movement of water into and through the Ap horizon of these soils is thought to contribute to reduced crop yields in wet years. Since application of Portland cement (the binding material in concrete) to soil in a laboratory experiment increased water‐stable soil aggregate size as well as hydraulic conductivity of a soil, it was assumed that cement would act similarly in the field and increased crop yields, particularly under wet conditions.

Two experiments were conducted to determine whether the application of portland cement (the binding material in concrete) would increase crop yields or change selected chemical and physical properties of soil. The first experiment was on two silt loam soils—a fine silty, mixed mesic Typic Hapludalf (Russell) and a fine silty mixed mesic Aquiac Arqiudall (Raub) in 1970. Cement was incorporated at 0, 560, 1,120, 2,240, and 4,480 kg/ha in a randomized complete block design with four replications per soil. At the end of the 1970 cropping year each plot was split, and the same rates were again applied on one of the two subunits. Corn (Zea mays L.) was grown in 1970 and 1971, and soybeans (Glycine max L. Merr.) in 1972 and 1973. The second experiment was on two other silt loam soils, a fine illitic mesic Typic Hapludalf (Morley) and a fine illitic mesic, Aerie Ochraqualf (Blount), at a different location. Cement was incorporated in 1971, at 0, 3,920, and 19,600 kg/ ha, each rate with 0 and 122 kg/ha of P, with three replications per soil. Corn was grown in 1971 and 1972, and soybeans in 1973. Corn yield increased H.9%, mean weight diameter (MWD) of water‐stable soil aggregates increased 54.5%, and soil pH increased 24.6%, with the 19,600 kg/ha rate on Blount soil in 1971. Multiple regression analyses for that soil showed an influence of cement on corn yield not accounted for by MWD and/ or pH, either singly or together. There were no other crop‐yield increases related to cement application, but there were increases in Ca and decreases in z concentration in corn or soybean leaves in selected years. In summary, crop yield increases occurred in one out of six applications of cement and were not economical when they did occur.
Uptake and Losses of 15N Applied to Annual Grass and Clover in Lysimeters1
Authors: Jones M. B. , Delwiche C. C. , Williams W. A.
Published: July 2010

The California annual grasslands comprise about one‐third of the state, and they play a large role in the hydrology of most watersheds in central and northern California. Apparent recovery of applied N has been low, and a large percentage has been unaccounted for in N balance studies. The present experiment was done with 15N to determine the fate of applied N, especially that leached and that volatilized (by difference).

Ammonium sulfate labeled with 15N ammonium chloride was applied to pure stands of soft chess (Bromus mollis L.) and subclover (Trilolium subterraneum L.) growing in lysimeters in a climate with mild, rainy winters and hot, dry summers. Uptake and leaching of N were measured on single and repeated applications for 3 years (mean annual rainfall 1,100 mm). After 3 years of annual fertilization in February (100 kg N/ha) 59% of N applied to grass was removed in forage, 24% remained in the soil and roots, 3% leached, and 14% was not detected (presumed gaseous loss); for clover 49% was removed in the forage, 33% remained in the soil and roots, 9% leached, and 9% was not accounted for. October fertilization at the same rate produced in both species about the same total growth, markedly decreased plant uptake, increased soil‐plus‐root retention, increased leaching, and reduced unaccounted for N from fertilizer. An October application of 500 kg N/ha resulted in greater gaseous losses of N, and more was lost from clover than grass.

Conclusions: There was modest leaching loss but essentially no gaseous loss from moderate rates of N applied to grass in October; there was almost negligible leaching loss but modest gaseous loss from moderate rates of N applied to grass in February; recovery of fertilizer by clover was poor; and a single large application (500 kg N/ha) resulted in a substantial leaching and gaseous losses under both grass and clover.
Use of Hardwood Bark Mulch for Highway Slope Stabilization1
Authors: Osborne D. J. , Gilbert W. B.
Published: July 2010

Many studies have indicated the utility of mulching of bare roadbanks to enhance cover production and reduce runoff and erosion. The objective of this study was to determine the suitability of shredded hardwood bark as a replacement for the conventional straw‐asphalt mulch. Bark mulch was used for seeding tall fescue (Festuca arundinacea L.) during “off season” summer months; in addition, plots were mulched with bark in the summer and left unseeded until fall when they were hydroseeded with tall fescue and fertilizer. Field plot tests were conducted in each physiographic province of the state on Porters loam (fine‐loamy, mixed, mesic Humic Hapludults), Cecil and Mayodan sandy loam (clayey, kaolinitic, thermic Typic Hapludults), and Norfolk sandy loam (fine‐loamy, siliceous, thermic Typic Paleudults). Plots were prepared with conventional tillage equipment to meet state specifications. Shredded hardwood bark mulch was applied with a modified mulch blower at 66 m3/ha. Stand density of tall fescue tillers per square decimeter was evaluated by quadrat counts. Results indicate that in general, the more favorable the environment for tall fescue production, the better the stand density with any one treatment. Under cool temperature and frequent rainfall, no differences were noted. These experiments demonstrated that highway slopes may be mulched with shredded hardwood bark and left unseeded until optimum fall seeding date with adequate erosion control, obviating the need for recultivation currently used to establish permanent cover after a “temporary seeding” during the summer.
Residual Effects of N Fertilization on Dryland Spring Wheat in the Northern Plains. II. Fate of Fertilizer N1
Authors: Alessi J. , Power J. F.
Published: July 2010

Residual effects of fertilizer application on the fate of fertilizer N applied to crops in semiarid regions are largely unknown. Objectives of this study were to provide information on the recovery of fertilizer N during the fertilization and residual periods and to develop an N balance sheet for a continuous spring wheat (Triticum aestivum L.) cropping system.

Ammonium nitrate was applied to spring wheat at 0 to 540 kg N/ha rate either (i) all in 1 year, (ii) one‐third in each of 3 years, or (iii) one‐sixth in each of 6 years to evaluate the availability and fate of fertilizer N in a dryland cropping system. Only grain was removed during harvest, and straw was plowed under each spring. Grain N uptake accounted for 31 to 46% of the total fertilizer N applied at 270 and 540 kg N/ha rate for various timing frequency. Fertilizer N uptake in straw and root biomass at the end of the experiment averaged 5 and 26 kg/ha, respectively. Movement of NO3‐N below the 90‐ cm depth (leaching) was detected for the 270 kg N/ha treatment, whether this total amount was applied all in 1 year, or 90 kg N/ha was applied in each for 3 years. However, with an annual application of 45 kg N/ha for 6 continuous years very little leaching of NO3‐N occurred. The amount of fertilizer N that moved beyond the root zone was greater at 540 than at 270 kg N/ha. Leaching of fertilizer N below 90 cm accounted for 4 to 37% of the total fertilizer applied, with greatest leaching occurring For the 1‐year treatment and least for the 6‐year treatment. Loss of N by runoff was negligible. The percent fertilizer N accounted for [(total fertilizer accountable ÷ total fertilizer applied) × 100] averaged 62, 64, and 66 for 1, 3, and 6‐year treatments, respectively. Unaccounted for fertilizer N possibly consisted of that portion of fertilizer N immobilized in soil organic fractions resistant to decomposition and that lost by volatilization. Results showed that if the N rate is adequate for maximum crop production, fertilizer efficiency is greatest when N is applied annually rather than at higher rates less frequently.
Comparative Toxicity of Nitrapyrin and 6‐Chloropicolinic Acid to Radish and Cucumber under Different N Nutrition Regimes1
Authors: Sander Diane J. , Barker A. V.
Published: July 2010

Nitrapyrin, 2‐chloro‐6‐(trichloromethyl)pyridine, is a nitrification inhibitor used to maintain fertilizer N in the ammonium form in order to reduce leaching and denitrification losses of N from soil. Nitrapyrin and its metabolite, 6‐chloropicolinic acid, are phytotoxic, and ammonium injury to plants is frequently greater when nitrapyrin is added to the soil. The objectives of this study were to investigate the phytotoxicity of nitrapyrin and 6‐ chloropicolinic acid under different N nutrition regimes (15 meq/liter of NO3‐N. NH4‐N, or NH4‐N with pH buffering to 7 with CaCO3) and to see if either compound affected the phytotoxicity of ammonium ions. Radish (Raphanus sativus L. ‘Cherry Belle’), and cucumber (Cumumis sativus L. ‘SMR‐18’), were grown in sand culture in a greenhouse. Plant nutrients and the inhibitors (10 ppm) were supplied in solution, and CaCO3 was mixed with the sand. Radishes were uninjured by nitrapyrin or 6‐chloropicolinic acid. Ammonium‐N (15 meq NH4‐N/liter) nutrition produced toxicity symptoms in radish and decreased root yields. Buffering of pH partially corrected the ammonium toxicity to roots and fully corrected it for shoots. Nitrapyrin and 6‐chloropicolinic acid restricted cucumber growth. Visible symptoms of nitrapyrin toxicity appeared as constricted zones on the stem base and as white areas on petioles of first true leaves. Toxicity of 6‐chloropicolinic acid appeared as curling on younger leaves and marginal burn on older ones. Cucumber growth was restricted by ammonium‐N nutrition. Buffering of pH corrected the toxicity of ammonium‐N and picolinic acid but not that of nitrapyrin.
A Mechanized Washing System for Generating Soil‐Less Sod1
Authors: Turgeon A. J. , Berns Frank , Warren Ben
Published: July 2010

Washed, soil‐less sod was developed to provide lightweight planting material that does not impose a foreign soil layer on the growing medium at the transplant site. The purpose of this study was to determine the feasibility of a mechanized sod washing technique. A sod‐washing apparatus consisting of motorized conveyors, high‐pressure water jets, rubber scrapers, and spring‐biased rollers is described. Strips of ‘A‐20’ Kentucky bluegrass (Poa protensis L.) and ‘Toronto’ creeping bentgrass (Agrostis palustris Huds.) sod were machine washed prior to measuring sod strength. The ‘Toronto’ sod began shredding apart after the first washing, but the ‘A‐20’ sod maintained adequate strength after four washings. The loss of sod strength in 'A‐20' from washing was attributed to the addition of moisture to the sod, and not to the removal of soil.
Check‐Wire System for Plot Planters1
Authors: Clark R. C. , Fehr W. R. , Freed J. C.
Published: July 2010

A check‐wire system was developed to eliminate the need for marking the beginning and end of plots for planting. Use of the system can save several hours in planting a field. The system was designed for planters that are tripped by hand and is a modification of the system used with planters tripped electronically.

Components of the system include a check‐wire and a commercial check‐head assembly. The check‐head, modified by adding a hammer and bell, can be mounted on the tractor or the planter. As the planter passes through the field, a bolt on the check‐wire trips a fork on the check‐head assembly. The hammer on the fork strikes the bell to signal the operator that the planter should be tripped to plant the next plot. Procedures for using the check‐wire system are described.
Manganese Availability of Calcareous Soils of Lebanon1
Authors: Khan M. I. A. , Ryan J.
Published: July 2010

Major agricultural areas of Lebanon were surveyed to determine Mn availability of soils and Mn content of crops grown on these soils. All soils sampled were calcareous and contained variable amounts of organic matter. Though a large number of crop species were sampled, no Mn deficiency symptoms were apparent, while Mn contents, which varied with the crop, were considered adequate by accepted criteria. A relatively small percentage of the soils extracted with NH4OAC, NH4H2PO4, and MgCl2 were considered deficient while none were deficient according to criteria for the DTPA extract. All availability indices showed Mn to increase with O.M. content but decrease with CaCO3 content. Availability was lowest in the drier Beka's Valley where O.M. was low and CaCO3 high. Inclusion of pH and CaCO3 in multiple regression analysis generally improved prediction of Mn uptake for all tests.
Utilization of Labelled Urea and Ammonium Sulfate by Lowland Rice1
Authors: Reddy K. R. , Patrick W. H.
Published: July 2010

Urea and ammonium sulfate are the most common fertilizer N sources used to topdress rice (Oryza saliva L.). The high cost of N fertilizer and the possible environmental impact of excess N make it important to obtain good utilization of the fertilizer applied to the crop. The objective of the present investigation was to compare labelled ammonium sulfate and urea in their effect on yield and N utilization in field microplots on Crowley silt loam (typic albaqualf). Nitrogen was applied as an early season topdressing or as a midseason topdressing and the grain and straw yield and recovery of labelled and native N in the grain straw, and soil were measured.

No significant differences in grain and straw yields were observed for the two sources and two times of N application. Ammonium sulfate and urea did not differ significantly in N utilization by the crop. For both sources the recovery of labelled N in the soil‐plant system was highest (34 to 55 kg N/ha) in the plots receiving midseason topdressing as compared to the plots receiving early season topdressing (30 to 38 kg N/ha). More native soil N was taken up by the plants during 1976 as compared to the 1975 season.
Selection for Drought Avoidance in Sorghum Using Aerial Infrared Photography1
Authors: Blum A. , Schertz K. F. , Toler R. W. , Welch R. I. , Rosenow D. T. , Johnson J. W. , Clark L. E.
Published: July 2010

In previous research, genetic variation in sorghum(Sorghum bicolor L. Moench) drought avoidance (maintenance of relatively high leaf water potential under conditions of soil moisture stress) was revealed. Practical screening for drought avoidance requires a fast field method. The response of near infrared reflectance from plant leaves to leaf water status stimulated the development of such a method, based on infrared photographic imagery of water‐stressed sorghum breeding nurseries.

Aerial infrared photography was performed from several altitudes over water‐stressed and non‐stressed sorghum nurseries at Lubbock, Halfway, and Chillicothe, Texas. Noontime leaf water potentials, as a measure of drought avoidance, were determined in selected strains at each nursery. Total leaf chlorophyll content of the respective strains was determined at Lubbock and Chillicothe. Strain canopy color densities in the resulting infrared color transparencies were analyzed by three methods: l) Scanning densitometry; 2) measurement of integrated light transmittance by manual photometry; 3) visual rating of color density.

Over all locations, the best correlations between canopy color density and leaf water potential across strains were obtained with the photometric method. The poorest correlations were obtained with scanning densitometry. For all methods of color density measurement, the correlations with leaf water potential across strains were the best at Halfway. At this location, plant canopies were dense, ground cover was almost complete, and film exposure and development were optimal. Leaf chloroFhyll content in the various strains was not correlated with canopy color density, although one strain presented a consistent exception. The method and some guidelines for its utilization are discussed.
Improved Technique for Marking and Sampling Band‐Applied Fertilizers and Pesticides1
Authors: Hendrickson L. L. , Keeney D. R. , Lesczynski D. B. , Walsh L. M.
Published: July 2010

One of the most difficult problems in field studies of the fate of band‐applied fertilizers and pesticides is obtaining a valid sample of the application zone. During the course of investigations to estimate the rate of nitrification and the recovery of N from banded fertilizers treated with a nitrification inhibitor, improved techniques for marking and sampling the band were developed. The band was marked by applying prilled elemental S at the point of fertilizer release. With this approach the band was easily detected many months after fertilizer application. The sampler was constructed of stainless steel and was 15 ✕ 15 ✕ 40 cm long. It was inserted into the soil above the previously located band and then removed and disassembled, and the soil subsectioned for a vertical profile of constituents in the band. The expanded dimensions of the sampler reduced sample variability, yet still allowed sufficient sampling efficiency to obtain adequate replication. These techniques provided more accurate estimates of nitrification and recovery of applied N and should find application in monitoring other fertilizers or pesticides on easily penetrated soils devoid of rocks.
Sugarbeet Genotype, N, and Soil Moisture Availability Interactions in Components of Beet Yield and Quality1
Authors: James D. W. , Doney D. L. , Theurer J. C. , Hurst R. L.
Published: July 2010

The effect of soil N on sugarbeet (Beta vulgaris L.) yield and quality has been studied extensively. However, comparatively few soil water (W) studies have been made on sugarbeet. Genotype (V) ✕ (N) interactions have been reported occasionally in one or a combination of the following parameters: root yield, sucrose percent, gross sugar, and impurity index. The interactions are very inconsistent from report to report. Most studies have involved a very narrow genetic base of two to three adapted sugarbeet hybrids.

This study was conducted to investigate the genotype ✕ soil N and genotype ✕ soil water interaction from a broad genetic base. A series of 20 genetically different genotypes differing in yield, sugar percent, and impurity index potential were field tested in 1974 at four N levels: 0, 84, 210, and 525 kg/ha. In 1975, eight genetically diverse genotypes were field tested at five N levels and four irrigation levels. The soil type was a coarse, loamy mixed mesic family of calcic haploxerolls. Analysis of data were for root yield, sucrose percent, gross sugar, and impurity index. Highly significant main effects due to N in 1974 and 1975 and water in 1975 were observed for all measured parameters. A significant genotype (V) ✕ N (N) interaction was obtained in 1974 for all parameters. There was an apparent genotype ✕ water interaction in 1975; however, unbiased statistical inferences could not be made because of the experimental design. These interactions indicate that genetic variation exists such that new cultivars may be developed that give high sugar production at low N levels or are not affected adversely in quality at a high N level; i.e., high yield—high sugar percent, rather than high yield—low sugar percent.
Effects of Environment and Management on Soybean Performance in the Tropics1
Authors: Whigham D. K. , Minor H. C. , Carmen S. G.
Published: July 2010

Yield potential of soybeans [Glycine max (L.) Merr.] in tropical areas is similar to that in temperate regions. Yield variability among sites indicates that exploitation of this potential under tropical conditions will require a better understanding of how environment and management influence yield. This study was undertaken to investigate the effects of several environmental and management variables on among site variability in yield and other plant characteristics of soybeans in the tropics. Results from 10 cultivars common to International Soybean Program (INTSOY) experiments at 25 sites 10 countries were used in the study. Agronomic variables, expressed as site means, were: yield, seed weight, pod number, number of days to flower, number of days from flowering to maturity, and plant height. Environmental variables measured were: altitude, latitude, daylength, maximum temperature, and minimum temperature. Management variables measured were: amounts of N, P, and K fertilizer applied and mean site nodule number, nodule dry weight, and plant population.

Mean site yield was not significantly correlated with any environmental variable measured. The only management variable significantly correlated with mean site yield was nodule dry weight. However, after adjustment for the environmental effects, all management variables together accounted for 56% of the variability in yield among sites. The environmental variables measured, after adjustment for management effects, accounted for only 27% of the variation in yield. Therefore, with respect to the 25 sites studied, the environmental variables were concluded to be less important than the management variables as determinants of yield.

The mean site number of days to flower was influenced more by environmental variables than by management variables. Conversely. the mean site number of days from flowering to maturity was more affected by management variables than by environmental variables. Individual variables significantly associated with days to flower were altitude, daylength, maximum temperature, and minimum temperature. Only daylength was significantly correlated with number of days from flowering to maturity.

Mean site plant height was positively correlated with latitude, daylength, nodule number, and nodule dry weight, and negatively correlated with applied K fertilizer. Environmental and management effects accounted for similar percentages of among site variability in plant height. Mean site plant height and mean site seed weight were the only agronomic characteristics significantly correlated with mean site yield.

The high grand mean yield for the 25 sites studied (2,034 kg/ha) suggest that with adequate management at least some of the cultivars among those tested may perform well in tropical environments. Because of the importance of management in explaining among site variation in yield, considerable effort must be made to train farmers in the proper management of soybeans when they are introduced as a new crop.
Effects of Soil Water Stress on Growth and Nutrient Accumulation in Corn1
Authors: Verasan V. , Phillips Ronald E.
Published: July 2010

Soil water stress affects growth and accumulation of plant nutrient ions in corn (Zea mays L.); however, the functional relationship of these are not clearly understood. The objective of this study was to more clearly delineate the effect of soil water stress on growth and accumulation of nutrient ions in corn. Corn was grown in the greenhouse in 20‐liter pots containing soil from the Ap horizon of Maury silt loam (Typic Paleudalfs) under two soil moisture treatments, stressed and non‐stressed. The relationship soil water potential and cumulative evapotranspiration with nutrient accumulation and dry matter production were more significant than the relationship of soil water potential with dry matter production and nutrient accumulation. Since water stress affects turgidity, photosynthesis, respiration, cell enlargement, and other physiological processes of the plant, it was concluded that cumulative transpiration is a better integrator of the effects of these processes on plant growth than is soil water potential.
Comparison of Root Activity in Vegetative and Reproductive Soybean Plants1
Authors: Jones C. Allan , Reeves Alvin , Scott John D. , Brown D. A.
Published: July 2010

Attempts to delineate the factor(s) which limit soybean (Glycine max (L.) Merrill) yields suggest that one of the reasons may be the decline in new root growth, longevity, and/or metabolic activity of the root system as the plant changes from the vegetative to the reproductive stage of growth. The objective of this research was to investigate the absorption and desorption characteristics of intact soybean roots of plants in the vegetative and reproductive stages of growth. Compartmental analysis was used to determine whether the movement of 45Ca and 32P within the roots of intact soybean plants is different in the vegetative and reproductive stages. Soybeans were grown under greenhouse conditions in nutrient solution. Half the plants were induced to flower at 7 weeks of age, by reducing the day length from 16 to 12 hours. At 12, 14, 15, and 16 weeks of age both vegetative and reproductive plants were transferred to a controlled environment chamber, and 45Ca and 32P were used to characterize nutrient translocation to the tops and nutrient efflux from the root tissue to the nutrient solution. At 16 weeks of age the cation exchange capacity, mitotic activity, and oxygen consumption of the roots of the greenhouse‐grown plants were determined. The initial rate of 45Ca and 32P efflux from the cytoplasmic compartment and the initial 45Ca and 32P content of the cytoplasmic compartment of the roots of reproductive plants were twice those of vegetative plants. Oxygen consumption and mitotic activity were greater in the roots of vegetative plants. Cation exchange capacity was greater in the roots of reproductive than in vegetative plants. There was little evidence that the accumulation of 32P and 45Ca in the tops, the rate constants of 32P and 45Ca from the cytoplasmic or vacuolar compartments, or the initial rate of efflux of 32P or 45Ca from the vacuolar compartments differed significantly in vegetative and reproductive plants. The implications of the results are discussed with regard to nutrition of reproductive soybeans.
Relationship Between Soil Test and Small Grain Response to P Fertilization in Field Experiments1
Authors: Fixen P. E. , Carson P. L.
Published: July 2010

Yield data from 74 small grain field experiments over a l3‐year period were used to evaluate the relationship between various soil tests and P response. Past field studies have resulted in low correlations between P soil test value and yield response, indicating that either alternative soil tests should be evaluated or additional soil and climatic factors should be considered. The soil tests examined in this study were the Bray 1 (soil to solution ratio of 1:7, 1:10, 1:20, and 1:50), Olsen P, and P sorption index of Bache and Williams. The crop species included were Triticum aestivum L., Hordeum vulgare L., and Avena sativa L. At each location soil samples were taken and stored and yield response to P fertilizer, applied with the seed, was recorded. The highest correlation between soil test value and yield response to P fertilization was found with the Bray 1, 1:50 (r2 = 0.41). An additional 23% of the yield response variation could be explained by including six additional variables in a multiple regression analysis employing dummy variables. Borolls were generally less predictable in their response to P than were Ustolls. Ustolls responded less to P fertilization than Borols while soils of the vertic subgroup responded more to P fertilizer according to the Bray 1, 1:50 soil test. The r value between P sorption index and yield response on alkaline soils was −0.70 (the highest of the soil tests examined) but was near zero for acid soils. Differences were also noted in degree of response between parent materials and crop species. Organic matter content appeared to influence response on some soils.
An Electronic Sensor for Vapor‐Pressure Deficit of the Air1
Authors: Johnson W. C. , Davis R. G.
Published: July 2010

The parameter of vapor‐pressure deficit (VPD) is used in several methods of calculating potential evapotranspiration. This note describes an electronic sensor for measuring VPD whose principle of operation is based on wet and dry‐bulb psychrometry and utilizes thermistors and silicon diodes as wet and dry‐bulb probes. These probes produce two voltages which, when multipled together by an inexpensive, commercially available, analog multiplier, result in an output voltage proportional to VPD that can be recorded continuously on a strip chart recorder. The VPD sensor has shown good reliability in actual field tests with accuracy that would not be a limiting factor in calculating potential evapotranspiration. Detailed information on construction and operation of the sensor is available from the authors and will be mailed on request.
Factors Associated with Zn Chlorosis in Dryland Beans1
Authors: Khan Adam , Soltanpour P. N.
Published: July 2010

Dryland pinto beans (Phaseolus vulgaris L. ‘San Juan’) are grown in more than 40,000 ha in the San Juan Basin of Colorado. Chlorosis and root rot are two major problems encountered by the bean growers. This research was initiated to investigate the cause of chlorosis of beans. Paired plots, one chlorotic and the other relatively green, were selected on 18 farms in 1975 and 1976. The soils of the experimental sites belong to Ackmen, Witt, and Pulpit series of Fine‐silty, mixed, mesic family. The Ackmen series belong to the Cumulic Haplustolls. The Witt and Pulpit series belong to the Ustollic Haplargids. Yield, root rot, soil factors, and plant composition were compared for the chlorotic and the green plots. In 1976 the chlorotic plots were divided into two subplots, one receiving zinc spray to confirm the results of regression analysis that suggested zinc deficiency was the cause of chlorosis. The chlorotic plots had significantly higher mean levels of soil moisture and pH, and lower organic matter than the green plots. The chlorotic leaves had higher mean levels of P and P/Zn, and lower Zn than the green leaves. The chlorotic plants had a higher incidence of root rot than the green plants. The mean soil P and soil Zn availability indexes were not different in the chlorotic and the green plots. Soil Zn levels in all plots except one were lower than 0.5 ppm. It was observed that the chlorotic areas were situated lower on the slope than the green areas, with a marked demarcation between them. The regression analysis suggested that 72% of the variability in yield was due to leaf P/Zn ratio, root rot and their positive interaction. Other measured variables did not significantly contribute to R2. Spraying the chlorotic plants with a solution containing 1% zinc sulfate removed chlorosis and increased the yield by 18 to 92%. In general, the yield of the chlorotic plants sprayed with zinc solution did not increase to the level of the green plants. This difference was attributed to the higher root rot index of the chlorotic plants. The data suggested that higher soil moisture in low lying areas increased the P availability and thus caused a P‐induced Zn deficiency in the bean plants growing in these soils of marginal Zn availability.
Influence of Date of Harvest on Yield and Agronomic Characteristics of Meadowfoam1
Authors: Johnson J. W. , Devine M. B. , White G. A.
Published: July 2010

Limnanthes alba Benth. is a winter annual and a potential new oil crop. Effective harvesting techniques are necessary to improve the seed retention of Limnanthes before its acceptance as an agronomic crop. The influence of time of harvest on seed yield, seed weight, and oil content was determined. The use of paraquat, 1,1′‐dimethyl‐4,4′‐bi‐pyridinium ion, as a harvest aid to hasten maturity and reduce shattering was evaluated. Seed yield, seed weight, and oil content were measured in the field on two plant introductions grown on a Matapeake silt loam (fine‐loamy, mixed mesic Typic Hapludults). A 20 to 37% decrease in yield was observed when the harvest was delayed 2 weeks. Harvesting 1 week before maturity resulted in the highest yield (1,461 kg/ha). The highest oil content (26%) and seed weight were obtained by harvesting at maturity. Paraquat was unacceptable as a harvest aid because of its adverse effects on yield and oil content.
Corn Residue Management and Weed Control in Close‐Drilled Soybeans1
Authors: Moomaw R. S. , Burnside O. C.
Published: July 2010

Increased use of reduced tillage systems has contributed to larger amounts of plant residue being left on the soil surface. The purpose of this study was to determine the effects of several methods of corn (Zea mays L.) residue management on the effectiveness of herbicide applied to a succeeding soybean [Glycine max (L.) Merr.] crop. Corn residue management methods used were (a) stalks not shredded but soil disked; (b) stalks shredded and soil disked; (c) stalks shredded and soil disked and plowed. Methods of managing the prior year's corn residue did not affect performance of soybean herbicides at two locations in eastern Nebraska over a 3‐year period. Weed control and soybean yield of closedrilled soybeans did not differ significantly between herbicide rates suggested on the labels and one‐half those rates, but there was less weed control when one‐half the labelled rates of the herbicide was used.
Establishing Wheat After Soybeans in Double‐Cropping1
Authors: Sanford J. O.
Published: July 2010

A method whereby wheat (Triticum aestivum L.) can be sown earlier would be a distinct advantage in a wheatsoybean (Glycine max (L.) Merr.) double‐cropping system. ‘Abe’ wheat overseeded in standing soybeans about 1 October was compared with conventionally seeded wheat after soybean harvest (1 to 10 November). Wheat overseeded consistently outyielded the conventionally seeded wheat. The optimum seeding rate for overseeding wheat was 101 kg/ha. Overseeded wheat failed during 1 of 4 years, because the soybean canopy was only 50% closed because of late planting (15 July).

The growth regulator, 2, 3, 5‐triiodobenzoic acid (TIBA) was applied to ‘Bragg’ soybeans at different growth stages to create canopies with varying degrees of closure. Plots with these different canopies were overseeded with ‘Abe’ wheat at a rate of 134 kg/ha about 1 October (when the topmost soybean leaves began to turn yellow). Emergence and yield of wheat were significantly greater when no TIBA was applied (completely closed canopy) than when TIBA was applied and the canopy was not completely closed.

Overseeding wheat in standing soybeans in double‐cropping was found to be an acceptable method of establishing the wheat crop However, emergence and yields of wheat can be expected to be reduced when the soybean canopy is less than completely closed.
Differential Cultivar Tolerance in Soybean to Phytotoxic Levels of Soil Zn. II. Range of Zn Additions and the Uptake and Translocation of Zn, Mn, Fe, and P1
Authors: White M. C. , Chaney R. L. , Decker A. M.
Published: July 2010

This investigation was part of a general characterization of Zn tolerance among cultivars of an agriculturally important plant species. Greenhouse studies were conducted to further evaluate the effect of soil Zn additions on soybean (Glycine max L. Merr.) cultivar differences in Zn tolerance, as well as plant Zn, Mn, Fe, and P contents. Four cultivars selected from a previous Zn tolerance screening trial (‘Wye’ and ‘Hudson Manchu’, tolerant; ‘York’, sensitive; ‘Columbus’, normal) were grown for 4 weeks on a fertilized Sassafras sandy loam (Fragiudult) amended with a wide range of Zn additions at pH 5.5 (nine additions between 1 and 131 ppm Zn) and 6.5 (10 additions between 1 and 524 ppm Zn).

Leaf dry weight reductions were curvilinear across the Zn additions at each pH, with yield increases occurring at the lower Zn treatments. For all cultivars, root dry weight was unaffected by the Zn additions at the lower pH and significantly reduced at the higher pH by Zn additions greater than 262 ppm. Significant cultivar differences in leaf dry weight yields were observed at the higher Zn treatments.

Leaf and root Zn contents increased linearly with increasing soil Zn at each soil pH (root r2 > 0.92, leaf r2 > 0.93 for all cultivars). The soil pH strongly influenced plant Zn contents; at an equivalent Zn addition, tissue values at pH 6.5 were approximately one‐third as great as at pH 5.5. Differential absorption and translocation of Zn was shown by the cultivars; at both pH levels, Hudson Manchu absorbed more Zn but translocated less than the other cultivars.

Generally, leaf yield reductions of 20% corresponded to leaf Zn contents greater than 620 ppm at both pH levels; however Hudson Manchu had only 370 ppm Zn in its leaves at 20% yield reduction at pH 6.5. Cultivar differences in both soil and leaf Zn contents at a 20% reduction for leaf dry weight illustrate the inherent weakness of foliar analysis as a monitoring tool for available metals at toxic levels.

Root Mn was increased linearly by soil Zn additions at both pH levels, while leaf Mn increases were curvilinear at pH 5.5 and linear at pH 6.5. Leaf Mn concentrations at both pH levels reached reported toxic levels (> 500 ppm) illustrating the complex nature of Zn phytotoxicity. DTPA‐extractable Mn was unaffected by soil Zn additions at both pH levels.

Foliar (combined trifoliolate leaves) Fe, at pH 5.5 and 6.5, and P at pH 6.5, decreased with increasing soil Zn, but did not approach reported deficiency levels. Similar amounts of Fe and P were found in Zn‐tolerant and Znsensitive cultivars.

These results illustrate the complex nature of Zn phytotoxicity and the importance of cultivar selection for cropping soils amended with metal‐containing wastes.