bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ Nuclear Magnetic Resonance Imaging of Roots: Influence of Soil Type, Ferromagnetic Particle Content, and Soil Water1
Authors: Rogers Hugo H. , Bottomley Paul A. 
Published: July 2010

AbstractThe paucity of root information combined with the difficulty in obtaining it make new approaches imperative. The observation of roots is essential to the understanding of plant growth and productivity. Proton (1H) nuclear magnetic resonance (NMR) imaging offers a noninvasive method for the study of both root morphology and function in situ. Herein, NMR imaging of plant root systems was evaluated for southeastern U.S. agricultural soil series from 30 different sites, and eight common artificial soil substrates, as a function of soil type, ferromagnetic particle content, and soil water, using a 1.5‐tesla medical research NMR imaging system and Vicia faba L. seedlings grown in the soils. Roots of about 1 mm in diameter and 1‐mm‐diam capillaries of water were undetectable by NMR imaging and conventional NMR in soils with ferromagnetic particle contents of greater than about 4% by weight. Below 4%, ferromagnetic particle content did not correlate well with NMR image quality, but the presence or absence of NMR signals from water‐containing capillaries embedded in soil samples in a conventional NMR experiment reliably reflected soil suitability for NMR root imaging. Images of seedlings in four of the artificial soils (perlite, Ottawa sand, peatlite, and peat) and seven of the native soils (Wynnville fine sandy loam, Lucy loamy sand, Dothan sandy loam, Lakeland sand, Kinston loamy sand, Blanton loamy sand, and Eustis fine sandy loam) showed excellent spatial resolution and accurate reproduction of the root systems when they were extricated from the soils. However, the results from three of the artificial soils (perlite, Ottawa sand, and peat) were significantly compromised by background NMR signals that derived from soil water. In the seven native soils, soil water to near saturation was rendered essentially invisible by the NMR imaging sequence employed, thereby demonstrating excellent root‐to‐soil image contrast. Several root pathologies apparent in the images were identified. The results reveal that 1H NMR imaging is a practical tool for the nondestructive, noninvasive investigation of plant root systems in many natural agricultural soils at virtually any stage of a water stress cycle.
Yield Responses of 16 Winter Wheat Cultivars to Row Spacing and Seeding Rate1
Authors: Marshall G. C. , Ohm H. W. 
Published: July 2010

AbstractGrain yields of winter wheat (Triticum aestivum L.) may increase as the spacing between rows is decreased. Results in previous studies have varied with other management variables and environments, however, and only one or a few wheat genotypes were used in any one study. We used a wide genetic base of 16 cultivars to obtain estimates of yield response at two row spacings and two seeding rates to determine if there was a consistent response across cultivars and years. Row spacings of 64 and 192 mm were compared at seeding rates of 377 and 538 kernels m−2. There were large year ✕ row spacing and year ✕ seeding rate interactions. The narrow row spacing treatments averaged 6.8 and 5.3% more grain than the standard spacing in 1983 and 1984, respectively. Cultivar responses to narrow row spacing ranged from 1.1 to 17.4% in 1983, and from −8.0 to 19.7% in 1984. No response to seeding rate was observed in 1983, but the higher seeding rate yielded 7.1% more grain in 1984 when tillering was low. A significant row spacing ✕ seeding rate interaction was detected over both years as 9.1% increase in grain yield was observed with both narrow row spacing and high seeding rate compared to wide row spacing and low seeding rate. We concluded that (i) row spacings narrower than the conventional 192‐mm spacing have the potential to significantly increase grain yields, but the response may vary depending on the cultivar and environmental conditions, and (ii) a combination of increased seeding rate and narrow row spacing is important for increasing grain yield.
Aluminum Effects on Growth, Mineral Uptake, and Efficiency Ratios in Red Clover Cultivars1
Authors: Baligar V. C. , Wright R. J. , Kinraide T. B. , Foy C. D. , Elgin J. H. 
Published: July 2010

AbstractRed clover (Trifolium pratense L.) is an important hay or pasture crop of the humid region of the United States, and its adaptability to acid infertile soils is still unknown. Research was undertaken to evaluate the effects of five levels of Al (0, 25, 50, 75, and 100 µmol L−1) on growth, uptake, and mineral nutrient efficiency ratios (ER) in 23 red clover cultivars. The ER is defined as milligrams of dry shoot weight produced per milligrams of element in the shoot. The initial solution pH of 4.5 changed due to crop growth, and such effects might have altered the concentrations of Al; however, relative comparisons between cultivar responses were possible. The growth of shoots and roots showed significant differences with respect to Al levels, cultivars, and their interactions. At 50 µmol L−1 Al, the average reduction of shoot and root growth was 73 and 57% of control, respectively. Overall shoot nutrient content showed a significant positive correlation with shoot and root dry weight, and inverse relations with treatment Al levels and shoot Al concentrations. The ER assisted in differentiating cultivars into efficient and inefficient utilizers of the absorbed nutrients. With the exception of the ER for Ca, Mg, and Mn, overall inverse relations were observed between Al levels and ER. The cultivars used in this study showed intraspecific genetic diversity in growth and ER values for the essential elements in the presence or absence of Al. ‘Kuhn’ and ‘Prosper I’ are the recommended cultivars for moderately acidic soils.
Soybean Response to Potassium Fertility under Four Tillage Systems
Authors: Vasilas B. L. , Esgar R. W. , Walker W. M. , Beck R. H. , Mainz M. J. 
Published: July 2010

AbstractBecause tillage affects root growth and activity, it affects the ability of plants to utilize soil and fertilizer nutrients. It has not been determined if K fertility recommendations developed for clean tillage systems are appropriate for reduced tillage systems. Therefore, an experiment was conducted on a Muscatine silt loam (fine‐silty, mixed, mesic Typic Haplaquoll) and a Sable silty clay loam (fine‐silty, mixed mesic Aquic Argiudoll) to determine the response of soybean [Glycine max (L.) Merr.] cultivars Williams 82 and Century to three levels of soil K fertility under four tillage systems over 2 yr. The tillage systems were moldboard plow (fall plowed plus spring disk), chisel plow (fall chisel plowed plus spring disk), spring disk, and no‐till. Soil K treatments were 336 kg exchangeable K ha−1, 336 kg exchangeable K ha−1 plus 73 kg banded K ha−1, and 560 kg exchangeable K ha−1. A corn (Zea mays)‐soybean rotation was used. Grain yields were similar for the moldboard plow, chisel plow, and disk systems. Grain yields were consistently lower for the no‐till system. This response was greatest for the cultivar Century in a year when herbicide carryover and Phytophthora (Phytophthora megasperma) damage under no‐till reduced final plant populations by 44% compared to that with the moldboard plow system. Increasing the exchangeable soil K level from 336 to 560 kg ha−1 increased grain yields of Century during a dry growing season. Tillage did not affect the magnitude of response, and banded K had no effect on grain yield. We concluded that the tillage system should not influence K fertility recommendations for soils such as these.
Effects of Inoculation Rate, Rhizobia1 Strain Competition, and Nitrogen Fixation in Chickpea
Authors: Somasegaran Padma , Hoben Heinz J. , Gurgun Velittin 
Published: July 2010

AbstractChickpea (Cicer arietinum L.) is the third most widely cultivated legume in the world, but N‐fixation studies addressing its inoculation response and rhizobial strain competition are limited. We investigated N fixation and competition by three strains of chickpea Rhizobium (TAL numbers 480, 620, and 1148) on ‘Desi’ and ‘Kabuli’ chickpea genotypes grown in vermiculite and two soils (Ultisol and Oxisol) free of chickpea rhizobia. Chickpea grown in vermiculite was inoculated with single and mixed strains. A three‐strain mixture was inoculated at 10, 102, 104, 106, and 108 rhizobia per seed on seeds planted in the two soils. Nodulation and N‐fixing parameters were significantly different for chickpea genotypes and rhizobial strains, with no genotype × strain interaction in the vermiculite experiment. TAL 620 was the most competitive strain in both chickpea genotypes. Maximum N fixation in both genotypes was achieved at 104 and 106 rhizobia per seed in the Ultisol and Oxisol, respectively. Nitrogen fixation by chickpea in response to different inoculation rates was best described by a quadratic model. The three strains of Rhizobium competed differently in the two soils. Competition in the Ultisol was due to significant strain differences and genotype x strain interaction. In the Oxisol, there was no strain competition. Different inoculation rates did not influence strain competition. In general, the Kabuli genotype had a greater N‐fixing potential than the Desi. Maximum N fixation in the two soils was a function of the different inoculation rates for both genotypes. Competition among chickpea rhizobia was influenced by the growth medium, chickpea genotypes, and strain differences but not inoculation rates.
Response of Corn and Tomato Plants to Fluorine Concentration in Solution Culture
Authors: Bar‐Yosef B. , Rosenberg R. 
Published: July 2010

AbstractTo understand and control the delicate balance between beneficial and detrimental contents of F in plants, the functional relationships between F concentration in ambient solutions and F uptake rate by plants must be known. The objectives of the present work were: (i) to study the effect of F solution concentration (CF) on F content in plants and on the rate of dry matter production and root elongation in young corn (Zea mays L.) and tomato (Lycopersicon esculentum L.) plants, and (ii) to define fluxes of F uptake versus CF in the two crops. The growth rate (GR) of corn and tomato plants decreased significantly as CF increased from 0.26 to 0.53 and from 0.05 to 0.26 mmol/L, respectively. The root elongation rate (RER) of corn 2 to 7 d old was maximum at CF = 0.26 mmol/L, and decreased when CF was raised to 2.63 mmol F/L. Tomato RER decreased when CF was increased from 0 to 0.53 mmol/L, and was unaffected when CF was raised further to 2.63 mmol/L. The threshold F shoot content at which the GR started to decline was about 12 mg F/kg in both crops. At any CF, F content in the roots exceeded that in the shoots by a factor that varied between 1.2 and 10. The maximal F content in shoots and roots of corn and tomato plants was 54 and 680, and 126 and 1310 mg F/kg, respectively, obtained at a CF of 2.63 mmol/L. The CF had no effect on N, P, and K contents in tomato, but had a suppressive effect on K content in the shoots of corn plants. At a CF between 0.05 and about 3 mmol F/L in the solution, the rate of F uptake per unit root weight (FF) increased exponentially with CF in both test crops, indicating a diffusive F permeation into the roots. At a CF of about 3 mmol F/L, FF of tomato was nearly twice that of corn.
Prediction of Alfalfa Herbage Mass Using Sward Height, Ground Cover, and Disk Technique
Authors: Griggs T. C. , Stringer W. C. 
Published: July 2010

AbstractRapid, nondestructive methods of estimating herbage mass (HM) are vital to experiments involving frequent collection of data, especially where physical sampling may alter growth. Herbage mass estimation techniques are based on double‐sampling, in which clipped HM and corresponding nondestructive sward measurements are used in regression analysis to obtain prediction equations. Our objective was to evaluate the precision and accuracy of sward height (SH), ground cover (GC), and disk height (DH) as predictors of HM in alfalfa (Medicago sativa L.) at weekly intervals after cutting. Sward height was measured with a sliding crossbar on an upright meter stick. Ground cover was estimated using a 0.18‐ by 0.22‐m grid subdivided into 20 cells. Disk height was measured with 0.96‐ and 1.76‐kg, 0.2‐m2 aluminum disks, allowed to settle on the sward canopy. All nondestructive measures were accompanied by clipping ofthe areas measured. Clipped HM ranged from 12 to 794 g m−2. Herbage mass prediction equations were developed following stepwise regression of sample HM on SH, DH, GC, days of growth, and derived variables. The most precise HM prediction models were based on SH and DH, accounting for 79 to 94% of variation in HM of calibration samples. Applying prediction equations to a validation data set generated predicted HM values. Sward height and DH models accounted for 59 to 86%, and 80 to 97%, respectively, of the variation in HM of validation samples. Herbage mass of validation samples was predicted with lower standard errors of validation by DH models (19.5–35.9 g m−2) than by SH models (60.8–65.6 g m−2) on the same stands in the same year. The disk technique provides a rapid, accurate means of nondestructively monitoring growth in alfalfa plots.
Kernel Weight Increase in Response to Decreased Kernel Number in Sorghum
Authors: Kiniry J. R. 
Published: July 2010

AbstractProcesses involved in the increase of individual kernel weight (KWT) in sorghum [Sorghum bicolor (L.) Moench] in response to reduced kernel number per panicle (KNO) have not been investigated. A better understanding of these would aid modelers in predicting grain yield, and crop physiologists in understanding yield component compensation. This study examined whether rate of kernel filling, effective filling period (EFP), or both were responsible for the increase in KWT. A widely used single‐seeded hybrid, ‘ATx399 × RTx430’, and an expermental twin‐seeded hybrid, ‘ATx623 × 77CS256TS’, were grown on a Houston black clay (fine, montmorillonitic, thermic Udic Pellustert) at Temple, TX, in 1985 and 1986. Seventy‐nine percent shading during the 16 d prior to 50% anthesis caused KNO to be reduced by 72%. Kernels from the apical, middle, and basal portions of the panicles were sequentially harvested to determine the rate of filling and the EFP. Kernel weight of these shaded plants was 31% greater than for the control. Effective filling period for shaded plants was not increased significantly compared to the control. Rate of filling was, therefore, the primary means by which the increased KWT was attained. Neither the number of endosperm cells per kernel 10 to 16 d post‐anthesis nor the number of starch granules per kernel 14 to 16 d post‐anthesis were increased significantly by shading. Number of starch granules was three times greater at maturity than at 14 to 16 d post‐anthesis, and was significantly greater for the shaded treatment. While final kernel volume was greater for the shaded plants, a volume limitation did not appear to be the cause for the difference in dry weights. Kernel dry weight was already different between treatments by the time maximum volume was achieved. Further investigation is needed to determine the reasons for the increase in both rate of filling and KWT in response to decreased KNO.
Seasonal and Soil Fertility Effects on the Response of Waterlogged Cotton to Foliar‐Applied Nitrogen Fertilizer
Authors: Hodgson A. S. , MacLeod D. A. 
Published: July 2010

AbstractThe majority of irrigated cotton (Gossypium hirsutum L.) soils in Australia are poorly drained, and the short‐term waterlogging associated with extended furrow irrigation reduces cotton yield, partly by reducing the uptake of N. Foliar application of N before irrigation can overcome a transient shortage, but yield responses have been variable. Seasonal and soil N fertility effects on the response of waterlogged cotton to foliar‐applied N fertilizer were studied over three seasons at Narrabri, N.S.W., Australia. A cracking grey clay soil (Typic Pellustert) was waterlogged by furrow irrigations lasting 4 to 32 h. Climatic and soil fertilizer conditions included a cool, moist season with optimal soil fertilizer N; a hot, arid season with high soil fertilizer N; and a hot, arid season with a wide range of soil fertilizer N. Foliar N was applied at 0, 5, 10, and 20 kg ha−1 in the first season, 0, 15, 30, and 60 kg ha−1 in the second season, and 0, 60, 120, and 180 kg ha−1 in the third season. Increased waterlogging reduced N uptake and lint yield. Nevertheless, there was no response to foliar N in the cool, moist season because factors other than N limited growth and yield whether or not N was supplied to the foliage. Lack of response to foliar N in the hot, arid season with high soil N fertility was attributed to high uptake of N (163 kg N ha−1) by untreated shoots, which compensated for reduced uptake by the roots during waterlogging. A three‐factor interaction in the third season confirmed that more cotton yield was recovered by applying foliar N under more severe waterlogging when soil N levels were not high. At N rates of 120 and 180 kg ha−1, shoots recovered more soil‐applied N than foliar‐applied N. Recoveries were similar at 60 kg N ha−1. The results confirmed that foliar N can ameliorate the effects of waterlogging in cotton, defined some of the conditions under which responses to foliar N occur, and explained some of the variability in response to foliar N found under commercial conditions.
Calibrated Heat Pulse Method for Determining Water Uptake in Cotton
Authors: Cohen Y. , Fuchs M. , Falkenflug V. , Moreshet S. 
Published: July 2010

AbstractThe heat pulse method for measuring sap flow in cotton (Gossypium hirsutum L. cv. SJ‐2) stems was developed and tested to provide a means for investigating transpiration of single plants under field conditions without disturbing the environment. The temperature difference between two radially inserted thermocouples, one 9 mm above and the other 4 mm below a heater piercing the stem, was measured every 0.3 s following emission of a heat pulse. These dimensions are a compromise solution between ideal configuration, ease of probe construction, and resolution of the signal detector. Two data were recorded: the time elapsed from pulse emission to the first re‐occurrence of the initial temperature difference, and the time at which the temperature difference was maximum. At low and moderate convective sap velocities in the stem (0‐0.17 mm s−1), the first datum can be measured with precision to accurately estimate sap velocity. At velocities higher than 0.22 mm s−1 the initial differential temperature change is too small and evolves too rapidly to detect when temperature returns to its initial value, but the temperature wave has a well defined maximum that is related to sap velocity. For convective velocities between 0.17 and 0.22 mm s−1, both data can be used. Calibration against transpiration measurements in potted cotton plants, grown outdoors, showed that the apparent effective conducting stem area is 0.71 of the total cross‐section. This fraction was found to remain constant over the entire range of stem diameters reached by cotton grown as an annual crop. The transpiration rate of a cotton plant is determined by multiplying the effective conducting area by the sap velocity. The study shows how the heat pulse quantifies water uptake of cotton and can be carried out in field conditions.
Late Fall Fertilization of Kentucky Bluegrass
Authors: Wehner D. J. , Haley J. E. , Martin D. L. 
Published: July 2010

AbstractMany turfgrass managers apply a portion of the total yearly N to cool‐season turfgrasses in the late fall (November). The purpose of this field study was to compare fertilization programs with and without N applications in November using both slow‐release and soluble N sources. Turfs of two different cultivars of Kentucky bluegrass (Poa pratensis L. cv. Baron and cv. Newport) growing on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) received 10 fertilization programs utilizing urea, isobutylidene diurea (IBDU), or sulfur‐coated urea (SCU). Urea was applied four times per year with either a spring application or a late‐fall application combined with applications in early June, mid‐July, and early September (171–196 kg N ha−1 yr−1). For IBDU and SCU, application dates and N rates (kg ha−1) consisted of June 98 + September 98, June 98 + November 98, and June 49 + September 49 + November 74. The turfs were rated for color for 3 yr, and clipping weights were determined weekly for the final 2 yr of the study. Results were generally similar for both cultivars, except fewer significant differences in spring color ratings were found on Newport. An application of urea in November, without a subsequent spring fertilization, resulted in higher turf color ratings in the early spring but lower turf color ratings in May and June, compared to turf receiving a spring fertilization. Results indicate that a late‐fall application of urea may not eliminate the need for spring fertilization but may allow a reduction in the amount of N applied in spring. Turfs fertilized with SCU in November received higher color ratings in the spring than did turf fertilized with SCU in September. With IBDU, the June + September program resulted in the highest number of ratings with acceptable turf color. November IBDU applications did not result in higher color ratings in the spring and resulted in inefficient use of the N applied.
Response of Alfalfa Grown on Acid Soil to Different Chemical Amendments
Authors: Rechcigl J. E. , Edmisten K. L. , Wolf D. D. , Reneau R. B. 
Published: July 2010

AbstractSoil acidity is a major cause of reduced yields of alfalfa (Medicago sativa L.) in the southeastern United States. The purpose of this study was to determine if alfalfa could be grown successfully on acid soils if sufficient Ca, N, Mo, and surface lime were provided. ‘Arc’ alfalfa was planted in March 1985 in a split‐plot design on an Aquic Fragiudult soil. Treatments included surface and incorporated dolomitic lime at either 6.5 or 13.0 Mg ha−1, gypsum at 13.0 Mg ha−1. In addition, each plot was split, with half of the plot receiving 224 kg N ha−1 and half receiving no N. Compared to the control, surface application of lime increased yields of alfalfa in both 1985 and 1986. Yields increased in response to addition of either N or Mo, indicating the importance of Mo in establishing the alfalfa nodule system for N assimilation. Soil pH averaged 4.8 and 6.7, and exchangeable AI averaged 2 and 21 mg kg−1 in the surface 5 cm of the limed and unlimed plots, respectively. The results of this study indicate that surface lime application is adequate for alfalfa establishment and production on acid soils, and that reduced N fixation appears to be a major limiting factor to growth of alfalfa on acid soils.