bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Water Stress on the Diurnal Exchange of Mass and Energy between the Atmosphere and a Soybean Canopy1
Authors: Baldocchi D. D. , Verma S. B. , Rosenberg N. J. , Blad B. L. , Garay A. , Specht J. E. 
Published: July 2010

AbstractA micrometeorological‐physiological study was conducted at Mead, Nebr., during the summer of 1980 to examine the diurnal exchanges of mass and energy of well‐watered and water‐stressed soybean (Glycine max (L.) Merr. cv. Harosoy) canopies and to relate these exchanges to environmental and physiological variables. Data are presented for 2 clear days when the canopy was fully‐developed. Measurements of CO2, latent heat and sensible heat flux were made using the Bowen‐ratio energy balance technique. The soil of the area is a Sharpsburg silty clay loam (a fine, montmorillonitic, mesic Typic Argiudoll). Water stress greatly influenced the partitioning of available energy between latent and sensible heat flux. When the crop was well‐watered, sensible heat (H) was directed toward the crop and caused latent heat exchange (LE) to exceed net radiation (Rn). When the crop was water stressed, only two‐thirds of Rn was consumed as LE; the remainder was converted into sensible heat. Since both Rn and vapor pressure deficit were greater on the day when the crop was water‐stressed, stomatal closure appears to have been the primary cause of the reduction in LE.Carbon dioxide exchange was not sensitive to water stress in the morning but was severely limited by such stress during midday. The midday reduction in CO2 exchange appears to have been caused by a combination of high stomatal resistance limiting CO2 diffusion to the cell chloroplasts and low leaf water potential coupled with high air temperature affecting the enzymatic reactions associated with photosynthesis. Water use efficiency (defined in terms of the CO2‐water flux ratio) was greater when the crop was well‐watered than when it was stressed for water. A combination of water stress, a large vapor pressure deficit, and high air temperature reduced the CO2‐water flux ratio.
Tomato Plant Response to Soil Salinity1
Authors: Papadopoulos I. , Rendig V. V. 
Published: July 2010

AbstractTomato (Lycopersicon esculentum var. VF 145) plants were grown in a greenhouse to determine the effects of salinity on growth and yield. The plants were grown in soil (Typic Xerofluvents, coarse‐loamy, mixed, nonacid, thermic) using regular or four‐compartment containers allowing splitting of the root systems. Nutrient solutions made saline with NaCI and CaCl2 to electrical conductivities (EC) of 1, 2, 3, 4, and 5 dS/m (dS/M = mmho/cm, referenced at 25°C) were applied twice a day in the undivided root systems. In the split‐root series, each of the four compartments was irrigated with solutions of different EC, while the regular containers were irrigated with a nutrient solution satinized to a level equivalent to the mean value of the solutions used for irrigating the four‐compartment units. The nutrient solutions were recycled through the containers, so that responses of plants subjected to increasing salinity up to 35 dS/m could be evaluated. With increasing salinity fruit fresh weights decreased markedly, with lesser decreases in shoot weights in both systems. Plants with their root systems divided and growing in containers with differentially salinized soil were less severely affected. Yield and growth correlated better with the initial electrical conductivity (ECin) of the nutrient solutions applied than with the EC values of the solutions extracted from the soil. Roots were less sensitive to root‐zone salinity than were tops. In the split‐root system, any reduction in the root growth in the compartments with high salinity levels was compensated for by more growth of those portions of the root system in the less saline environment. During the latter part of the growing period, levels of soil solution salinity were generally greater in the soils in which plants were grown in the undivided root systems than in soils in the split‐root systems.
A Method for Inducing Controlled Moisture Stress on Seedlings1
Authors: Sikurajapathy M. , Cappy J. J. , Gross H. D. 
Published: July 2010

AbstractSelectively permeable sleeves filled with soil were held in tanks containing various polyethylene gylcol (PEG) 10 000 solutions in order to evaluate seedling tolerance to soil moisture stress. The soil columns, made of 7.6 cm diam dialysis tubing (molecular weight (MW) cut off 8000), were fitted to plexiglas bases and placed in tanks containing PEG 10 000 solutions calibrated to provide the desired soil water potentials (−0.01, −0.1, −0.5, and −1.5 MPa). The columns contained 2.5 kg soil. The membrane maintained its integrity over a 30‐day period. Soil water moved in response to gradients created by the osmoticum; the small pore size of the permeable sleeves prohibited the PEG from entering the soil. Water loss measured for soil columns immersed in PEG solution maintaining −0.01 MPa potential revealed no movement in either direction. At −0.5 MPa, water moved gradually out of the soil column. At the lower potentials (−0.01 and −0.1 MPa), rapid movement of water out of the soil occurred within 20 h, leading to a loss of 60% of the water in the columns. Water content at various column depths after 12 and 30 days immersion at the different potentials were very uniform. No detectable amounts of PEG were found in roots, shoots, or leaves of mungbean [Vigna radiata (L.) Wilczek] or rice (Oryza sativa L.). The technique makes possible precise control of water‐stress intensity (water potential), water‐stress duration, and recovery from water stress.
Plant‐Parasitic Nematode Populations in Bermudagrass as Influenced by Cultural Practices1
Authors: White R. H. , Dickens Ray 
Published: July 2010

AbstractPlant parasitic nematodes can be a limiting factor in the production of high quality bermudagrass (Cynodonspp.) putting greens. A 3‐year study was initiated in May 1978 on Dothan sandy loam (fineloamy, siliceous, thermic Plinthic Paleudult) to determine the effects of N sources, core aerification, vertical mowing, and topdressing on plant parasitic nematode populations. Nematode populations were determined in the fall of 1978 and 1980 and in the spring of 1979, 1980, and 1981 by a modified flotation sieving technique. Stubby root (Trichodorusspp.), ring (Criconemoidesspp.), stunt (Tylenchorhynhusspp.), and spiral (Helicotylenchusspp.) were the principal nematodes present. Differences in overall populations of nematodes due to N treatment occurred only in the Spring 1980 sampling. Lower populations occurred where activated sewage sludge was the source of N than where NH4NO3was applied. Topdressing, vertical mowing, or core aerification treatments had no consistent effects on nematode populations. Interactions occurred between bermudagrass cultivars and nematode species. ‘Dothan’ selection supported higher populations of stunt and stubby root nematodes than did ‘Tifdwarf’ or ‘Tifgreen’. In contrast, Tifdwarf and Tifgreen supported more spiral nematodes than Dothan. Tifdwarf suported the greatest overall plant parasitic nematode population.
Sunflower for Strip, Row, and Relay Intercropping1
Authors: Robinson Robert G. 
Published: July 2010

AbstractYield is greater for some intercropping systems than from sole cropping. The culture and morphology of sunflower (Helianthus annuusL.) indicated that it had potential for intercropping. Consequently, sunflower was evaluated as a component of strip, row, and relay intercropping systems that would be practical for mechanized farming. Trials were conducted on Typic Hapludoll soils. Strip intercropping sunflower with corn (Zea maysL.) or soybean [Glycine max(L.) Merr.] compared with sole cropping showed that the percentage gain in sunflower yield was offset by about the same percentage reduction in corn or soybean yield. Increased yields of sunflower and mustard (Brassica hirtaMoench) from intercropping over sole cropping were confined to the border rows of the sunflower strips and the two border rows of the mustard strips. Yields from intercropped sunflower and soybean in alternate rows 38 cm apart were less than from sole cropped soybean, but 450 kg ha−1higher than from sole cropped sunflower. Fieldbean (Phaseolus vulgarisL.) as a row intercrop with sunflower increased in yield as sunflower population decreased, but its highest intercrop yield was 59% that of sole cropped fleldbean. Relay intercropping involved broadcast sowing of winter rye (Secale cerealeL.) in sunflower and fleldbean. Rye stands in sunflower were unsatisfactory, those in fieldbean ranged from poor to satisfactory, and those established alone on prepared seedbeds were excellent. Sunflower is not a promising species for intercropping. Sunflower‐mustard strip intercropping may be useful in honeybee (Apis melliferaL.) management and in reducing harvest losses of mustard.
Introduction and Survival of an Inoculant Strain of Rhizobium japonicumin Soil1
Authors: Dunigan E. P. , Bollich P. K. , Hutchinson R. L. , Hicks P. M. , Zaunbrecher F. C. , Scott S. G. , Mowers R. P. 
Published: July 2010

AbstractA 7‐year experiment was begun in 1976 to determine if a nonindigenous inoculant strain of Rhizobium japonicumcould be introduced into, and survive in a soil in Louisiana. The soil was an Olivier silt loam (fine‐silty, mixed, thermic Aquic Fragiudalf) located at Baton Rouge. Inoculation rates were 104or 108R. japonicumstrain 110 cells cm−1of row. The inoculum was applied directly into the furrow as a liquid suspension. The same plots were inoculated for 3 consecutive years. In 1978, a third treatment, 108rhizobia cm−1of row was used as the inoculant and 250 kg NH4NO3‐N ha−1was applied in five equal split applications. None of the plots were inoculated after 1978. ‘Lee’ cultivar was planted in the first 3 years while ‘Dare’, ‘Lee’, ‘Bragg’, and ‘Coker 338’ cultivars were planted in each plot from 1979 through 1982. The cultivars represented Maturity Groups V through VIII. Recovery of the inoculant rhizobia from the soybean (Glycine maxL. Merr.) nodules was quite low during the first 4 years. General recoveries were within the range of 0 to 17% as reported by other researchers for 1 year studies. In 1980 and thereafter, recovery of the inoculant rhizobia increased considerably. Average recoveries over all rates of inoculation ranged from 29 to 33% in 1980 and were up to 54% by 1982. Individual treatment values were as high as 60% from the 108R. japonicumcm−1of row plots in 1982. Results of this study were interpreted to indicate that 3 years of massive soil inoculation with a nonindigenous strain of R. japonicumallowed the permanent establishment of this strain into the soil. Once established, this strain became competitive with the native rhizobia in the soil, and each year formed a higher percentage of the nodules on the soybean roots.
Restricted Rooting Decreases Tillering and Growth of Winter Wheat1
Authors: Peterson Curt M. , Klepper Betty , Pumphrey F. V. , Rickman Ron W. 
Published: July 2010

AbstractWinter wheat [Trificum aestivum(L.) em Thell. cv. Stephens] seedling growth and development were observed for plants grown in a greenhouse in 1.65 × 10 ‒4m3or 3.40 × 10 ‒3m3of potting soil to determine the effect of restricted root development on plant growth with adequate water and minerals supplied. Plants grown in a smaller volume of soil were significantly reduced in size as measured by number of leaves and culms/plant, main stem height, and final dry weight/plant. These results suggest that confining roots to a small volume of rooting medium will in itself limit coordination of plant growth in an otherwise suitable environment.
Methods of Placement for Increasing the Efficiency of N Fertilizers Applied in the Fall1
Authors: Malhi S. S. , Nyborg M. 
Published: July 2010

AbstractIn portions of the Prairie Provinces of Canada, fall‐applied fertilizer N is often less effective in increasing yields of cereal crops than fertilizer N applied in the spring. Field experiments were conducted in northern and central Alberta on Udic Boroll, Boralfic Boroll, and Boralf soils to find if there was a consistent increase in yield and N uptake of barley (Hordeum vulgare L.) when fall‐applied urea was placed in bands and in nests as compared to the conventional mixing into the soil. There were 14 field experiments with the fallapplications during 3 years, and 13 of the experiments were cropped. The crop was spring‐sown barley. Fall‐applied urea gave higher grain yield, recovery of N in grain and recovery of N in grain + straw when placed in 46 cm spaced bands, and more so in nests, than when urea was incorporated into soil in the conventional manner. Nests were obtained by placing the N fertilizer at a point in each area of 46 ✕ 46 cm and at a depth of approximately 5 cm. The average increases in grain yield from urea incorporated in the fall, from urea banded in the fall, from nest placement of urea applied in the fall, and from urea incorporated in the spring at seeding time were 810, 1220, 1530, and 1680 kg ha−1, respectively. In the same order, the recoveries of fertilizer N in grain plus straw were 26, 40, 53, and 61% although values were similar for banding and nest placement in 5 of the 13 experiments. Nitrification of fall‐applied N was slowed with banding and especially with nests, as compared to incorporation. With less nitrification, there was less over‐winter loss of fall‐applied N, apparently through reducing denitrification. As with urea, fall‐applied aqua NH3 placed in nests produced greater grain yield, N uptake by grain and N uptake by the whole plant as compared to aqua NH3 injected in bands. There were six other cropped experiments where there was only spring application of nesting, banding, and mixing. With spring application, nest placement of urea was inferior to banding or mixing of urea, unless the spacing of nests was reduced from 46 ✕ 46 cm to 23 ✕ 23 cm or the application of nests was made 2 weeks before sowing with subsequent cultivation. Nest placement is an alternative to chemical inhibitors of nitrification with fall‐applied N fertilizers.
Dinitrogen Fixation in Alfalfa‐Orchardgrass Pastures1
Authors: West C. P. , Wedin W. F 
Published: July 2010

AbstractInformation on amounts and proportions of alfalfa N derived from symbiotic N2 fixation is needed to more effectively exploit this source of N in alfalfa‐orchardgrass (Medicago sativa L.‐Dactylis glomerata L.) pastures. Our objectives were to describe the seasonal trends in N2 fixation and to assess the relationships among alfalfa dry matter (DM) yield, percentage alfalfa in the mixture, and N2 fixation. The trial was carried out in south‐central Iowa in 1979 and 1980 on Aquic Argiudoll and Typic Argiaquoll soils, 2 to 13% slope. A 15N‐dilution technique was used to estimate the percentage of alfalfa N derived from N2 fixation during individual harvest intervals. The percentage of alfalfa N derived from N2 fixation varied slightly among harvest dates and averaged 91%. As percentage alfalfa in the mixture and alfalfa DM yield increased, the percentage of alfalfa N derived from fixation tended to decrease. The amount of N2 fixed was highly positively correlated with percentage alfalfa and alfalfa DM yield in both years. The total annual amount of N2 fixed averaged 70 kg ha−1 with a range across microplots of 15 to 130 kg ha−1. In conclusion, alfalfa DM yield was the major determinant of the amount of N2 fixed. The coefficient 0.90 can be used under these conditions to estimate the proportion of harvestable alfalfa N derived from N2 fixation when growing with orchardgrass. The low variability associated with measurements of percentage of alfalfa N derived from fixation illustrated the usefulness of the 15N‐isotope dilution method in this study.
The Fate of Diazinon Applied to Thatched Turf1
Authors: Branham B. E. , Wehner D. J. 
Published: July 2010

AbstractDiazinon [0,0‐diethyl‐0‐(2‐isopropyl‐6‐methyl‐4‐primidinyl) phosphorothioate] is widely used to control turfgrass insect pests. Poor control of soil‐inhabiting insects has been found where diazinon has been applied to thatched turfgrass stands. The purpose of this study was to evaluate the environmental fate of diazinon applied to turfgrass stands. A microecosystem was used to follow the fate of radiolabeled diazinon surface applied to Kentucky bluegrass (Poa pratensis L.) turfs, with or without a thatch layer, growing on Flanigan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) irrigated daily or every 4 days. Loss of diazinon by volatilization, leaching, and degradation accompanied by release of 14CO2 or incorporation of label into soil compounds was measured. The most degradation of parent compound occurred on turf containing a thatch layer irrigated daily where only 7% of the applied diazinon remained after 3 weeks. Between 32 and 47% of the parent compound remained in either turf with thatch irrigated every 4 days or turfs without thatch. The majority of the diazinon (96%) remained in the top 10 mm of the turf profile regardless of whether this was thatch or soil. In the presence of thatch, there was an accelerated rate of diazinon degradation as measured by release of 14CO2 from the two position on the pyrmidine ring. Increasing irrigation frequency on the thatched turf did not cause an increase in leaching but did increase diazinon breakdown. The results of the study suggest that where thatch is present, reduced control of insects is due both to a failure of the insecticide to move through the thatch and an increased rate of degradation.
Leaf Area Index and Evapotranspiration of Taro1
Authors: Shih S. F. , Snyder G. H. 
Published: July 2010

AbstractStandard pan evaporation has been used to estimate evapotranspiration under flooded conditions, but it is difficult to determine crop coefficients, which vary with growth stage and leaf area index. Taro [Colocasia esculanta(L.) Schott], a wetland plant, was used to study the relationships among standard pan evaporation, evapotranspiration, and leaf area index. Lysimeter investigations were conducted for 2 yr (1981–1982) on flooded Pahokee muck (Lithic Medisaprists). Total evapotranspiration was about 1200 mm and ranged from 1.5 to 7.2 mm day−1, with an average of 4 mm day−1. The evapotranspiration/standard pan evaporation ratio was inversely related to leaf area index, whereas in nonflooded crops it is directly related
A Comparative Study of Root Distribution and Water Extraction Efficiency by Wheat Grown Under High‐ and Low‐Frequency Irrigation1
Authors: Proffitt A. P. B. , Berliner P. R. , Oosterhuis D. M. 
Published: July 2010

AbstractA number of field experiments have separately evaluated plant responses to water stress, root distribution and soil water extraction patterns, consumptive water use, grain yield, and water use efficiency (WUE); few studies have investigated water movement through the soil‐plant‐atmosphere continuum as a whole. A field study was therefore conducted on spring wheat (Triticum aestivumL. cv. SST33), sown on a Rhodic Paleustalf soil in the Republic of South Africa, to relate the response of the plant and its root system to different water application frequencies. Special emphasis was on a soil dryingout period. Treatments consisted of high‐ and low‐frequency irrigation, with one treatment from each being maintained as a wellwatered control (HFc, and LFc, respectively), and one treatment from each being subjected to a period of water stress after anthesis (HFsand LFsrespectively). Soil water content, root length and distribution, and leaf water potential (ΨL) were monitored before and after irrigations and during the soil drying‐out period. Plants in the HFsand LFstreatments developed shallower rooting systems than plants in both the LFcand LFstreatments. Soil water extraction patterns were correlated to rooting distributions. Deeper roots became increasingly efficient at extracting water as the soil became progressively drier from the surface downwards, but the total water uptake was insufficient to enable the plants to transpire at their potential rate. The departure of the evapotranspiration/potential evapotranspiration (ET/PET) ratio from its well‐wateredvalue occurred at 14% (HFs) and 17% (LFs) depletions from field capacity, and this, coupled with the concomitant decrease in ΨL, suggests that plants can maintain a constant ET/PET ratio only when water is freely available in the upper soil layers. Frequent light applications of water resulted in reduced fluctuations in ΨLthus, higher yields and an improved WUE were obtained.
Growth Analysis of Soybean Isolines Differing in Pubescence Density1
Authors: Clawson K. L. , Specht J. E. , Blad B. L. 
Published: July 2010

AbstractGenetic variation in soybean plant morphology is of interest beause of its possible utility in developing cultivars adapted to unique environments. Growth analysis techniques were used to quantify and compare soybean [Glycine max(L.) Merr.] growth in genotypes differing in pubescence density. The experiment was conducted in 1980 and 1981 at Mead, NE on a Typic Argiudoll soil. Data from frequent samplings of phytomass dry weight (W), leaflet dry weight (LW), leaf area (A) and number of leaflets (N) were collected during two crop seasons from near‐isogenic lines of dense and normal pubescent types of ‘Clark’ and ‘Harosoy’ cultivars. Statistical curve‐fitting tests identified the most plausible mathematical models for describing the change of these four variables over time. Ten growth analysis parameters based on these four model equations were then computed and included crop growth rate (CGR), net assimilation rate (NAR), leaf area ratio (LAR), relative growth rate (RGR), leaf weight ratio (LWR), specific leaf area (SLA), relative leaf growth rate (RLGR), relative leaf area expansion rate (RLAER), leaf area partitioning factor (LAPF), and area per leaflet (APL). Dense pubescence affected the growth parameters differently in the two cultivars. There was no difference in any parameter between dense and normal pubescence lines in Clark. The W, LW, A, N, and CGR were, however, affected by pubescence density in Harosoy. The CGR was about 20% greater at maximum growth in the dense Harosoy isoline. The NAR was unaffected, however, indicating that the higher photosynthetic rate in the Harosoy dense pubescent isoline was due to an increase in leaf area and not an increase in photosynthetic efficiency. The fact that the gene giving rise to dense pubescence had differential effects on growth in the two cultivars suggests that the genetic background into which the gene is introduced influences the effect of the gene on growth.