bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Leaf Orientation on Leaf Resistance to Water Vapor Diffusion in Soybean (Glycine max L. Merr) Leaves1
Authors: Stevenson K. R. , Shaw R. H.
Published: July 2010

Soybeans (Glycine max L. Merr) were grown in 75‐liter potometers within an area that could be covered by a movable shed during rainfall periods. Leaves on 3 of 10 plants in each potometer were tied upright, while leaves on the other plants were left naturally exposed. Two soil moisture levels were used.

The leaf resistance values for upright leaves were less than those of naturally exposed leaves on 8 of the 9 sunny days and averaged 1.38 sec/cm less. Similarly, leaf temperatures were less for upright leaves. On overcast days, leaf orientation had no effect on leaf resistances or temperatures.

These differences were measured on individual plants and not on whole canopies. The data do suggest, however, that less leaf resistance to water vapor diffusion and lower temperatures of leaves would occur in soybean canopies with upright leaves and that this characteristic could be a worthwhile objective in breeding soybean varieties with tolerance to moisture stress.
Plot Seeding of Light, Chaffy Grass Seed1
Authors: Schmid A. R.
Published: July 2010

Light, chaffy grass seed and seed with appendages were planted successfully with a cone‐type plot seeder when seed was mixed with No. 2 granite grit. Chaffy seed that had been mixed with cleaned granite grit passed through openings and tubes without difficulty.
Water and Air Changes in Grapefruit, Corn, and Cotton Leaves with Maturation1
Authors: Allen William A. , Gausman Harold W. , Richardson Arthur J. , Cardenas Ruben
Published: July 2010

Recent progress in remote sensing of agricultural areas from aircraft and spacecraft has motivated new research in the basic understanding of the interaction of light with plant leaves. Many plant leaves can be simulated by a transparent plate model with rough plane‐parallel surfaces. A plant leaf can be specified in this model by two optical parameters associated with an imaginary index of refraction and two parameters that represent the geometrical configuration of the internal leaf structure. The model leads to determination of water and air in a leaf by non‐destructive procedures. Previous work that reported on maturation of cotton leaves grown hydroponically in a growth chamber has been extended to leaves of potted grapefruit seedlings, field‐grown corn, and field‐grown cotton plants. Significant differences are observed between the measured water in a leaf and the equivalent water thickness (EWT) calculated from spectrophotometric measurements. The EWT is about 15% greater than the thickness of water that can be removed from the leaf by oven drying at 68 C for 72 hours. Measures of the intercellular air spaces in the leaves are in general agreement with previous results except that the corn leaves are not as compact as expected.
Evaluation of Selected Clones of Phalaris arundinacea II. Indole Alkaloid Derivatives1
Authors: Barnes R. F. , Simons A. B. , Marten G. C.
Published: July 2010

Indole alkaloid derivatives have been reported in reed canarygrass (Phalaris arundinacea L.). We measured the contents of three alkaloids in two palatable and two unpalatable clones of reed canarygrass to study the relationship between alkaloids and palatability. The palatability ratings had been previously determined in cafeteria grazing trials with sheep. Chopped frozen forage from four harvests of each clone was available from previous in vivo digestion and intake trials conducted in 1962 and 1963. Samples from the initial growth and first regrowth of 1962 and first and second regrowth of 1963 were analyzed for gramine (3‐dimethylaminomethylindole), 5 methoxy‐N,N‐dimethyltryptamine (5‐MeO‐DMT), and N,N.dimethyltryptamine (DMT). The assay procedure involved ascending paper chromatography followed by elution and spectrophotometry for quantitative estimation of each compound. The palatable clones contained up to 0.1% gramine, but no DMT. Conversely, the unpalatable clones contained up to 0.02% DMT, but no gramine. All clones contained 5‐MeO‐DMT; however, the palatable clones had 0.01% or less, compared to 0.07% in the unpalatable clones. We found the lowest concentrations of total alkaloids in the initial growth forage and the highest concentrations in the first regrowth of 1963.
Nitrogen Release from Sulfur‐Coated Urea, as Affected by Coating Weight, Placement and Temperature1
Authors: Allen S. E. , Hunt C. M. , Terman G. L.
Published: July 2010

Greenhouse and laboratory studies were conducted to measure the factors controlling release of N from sulfurcoated urea (SCU). Results of two greenhouse pot experiments with common bermudagrass (Cynodon dactylon) and a third with uncropped soil in controlled environment regimes showed that the rate of dissolution of SCU increased greatly with higher temperatures of cropping or incubation. Dissolution rates of SCU granules were decreased by heavier coating with S, by inclusion of 0.5% coal tar oil microbicide in the coating, and by surface application, as compared to mixing with the soil. Satisfactorily coated urea (SCU) or split applications of uncoated ammonium nitrate (AN) or urea both resulted in more uniform distribution of forage production and N uptake than did a single application of urea or AN at time of seeding. Greater yields of forage were obtained from single applications of some SCU products than from urea or AN. Apparent volatilization losses of surface‐applied urea were severe, particularly at higher growth or incubation temepratures. Losses of N were reduced, but not entirely eliminated by S‐coating.
Germination of Caryopses of Annual Grasses in Simulated Litter1
Authors: Young James A. , Evans Raymond A. , Kay Burgess L.
Published: July 2010

A technique was developed for germinating grass caryopses in simulated litter, without the base of the caryopses in contact with a liquid moisture‐supplying substrate. Litter germination of five annual species of bromegrass and medusahead differed markedly in response to temperature from 10 to 25 C, compared to germination of the same species in petri dishes. The species also differed in their rates of root elongation and root persistence under repeated drying cycles at incubation temperatures from 10 to 25 C. The differences in litter germination among the annual grasses investigated may be the basis for dominance of one species over another under specific temperature regimes.
Response of Plant Water Potential to the Irrigated Environment of Southern Idaho1
Authors: Cary J. W. , Wright J. L.
Published: July 2010

Laboratory studies have shown that plant water potential affects a number of key processes involved in growth, but there has been almost no information on what levels of water potential occur under irrigated conditions in the field. Before assessing the practical implication of laboratory results on soil and crop management, this type of information must be available. Consequently, plant water potential in irrigated crops of Zea mays, Triticum aestivum, Hordeum vulgaris, Phaseolus vulgaris, Pisum sativum, Solanum tuberosum, Beta vulgaris, and Medicago sativa, L. was measured throughout the growing season in southern Idaho. Soil moisture conditions and potential evapotranspiration were monitored. Daily changes in plant water potential varied from less than 5 bars to more than 20 bars, while random sampling of supposedly homogeneous sets of plants showed an average variation of about 2 bars. Changes due to differences in soil moisture were also detected, even though the soil moisture potential was kept high enough for near‐optimum crop production. Though the crops differed widely in their response to changes in environment, the plant water potential was strongly affected by microclimatic conditions. Day‐to‐day changes in plant water potential generally correlated more closely with changes in potential evapotranspiration than with changes in soil moisture content. Many of the daily changes observed in the plants remain unexplained, however. In general, the average water potential levels of all the field‐grown plants were lower than levels reported from growth chamber studies. Potentials seldom rose above —8 bars and were never observed above —5 bars.
Reliability of Salinity Sensors for the Management of Soil Salinity1
Authors: Oster J. D. , Willardson L. S.
Published: July 2010

Laboratory‐constructed and commercial salinity sensors were evaluated for stability of calibration and accuracy of measurement of soil salinity. Of the commercial sensors 85% were stable and performed satisfactorily for at least 1.5 years with an estimated accuracy of ± 0.6 mmho cm‐1. Laboratory‐constructed sensors were accurate to ± 1 mmho cm‐1. Commercial sensors were used to monitor soil salinity in a field in the Imperial Valley, demonstrating their value for salinity control. The salinity data revealed differences in water infiltration caused by surface topography and by the disturbance of soil during the installation of the sensor.
Iron and Zinc Response of Chlorotic Rice Grown on Calcareous Soils1
Authors: Westfall D. G. , Anderson W. B. , Hodges R.J.
Published: July 2010

Iron and Zn source and rate experiments were carried out in the field on soils where rice (Oryza sativa L.) grain yields had been reduced drastically in previous years by seedling chlorosis.

Soils where seedling chlorosis occurred were higher in pH, HCO3 and Ca content and lower in Fe and Zn than adjacent soils where normal growth occurred. Iron sulfate, alone or in combination with ZnSO4, was the most effective in correcting seedling chlorosis. A maximum yield increase of over 2,100 kg/ha was obtained with the application of 100 kg/ha of Fe (from Fe2(SO4)3). Organic sources of Fe and Zn were less effective in correcting needling chlorosis and producing yield increases.
Potassium Effects on Regrowth of Alfalfa (Medicago sativa L.)1
Authors: Kimbrough E. L. , Blaser R. E. , Wolf D. D.
Published: July 2010

Field experiments were conducted to investigate the relationship of K in alfalfa (Medicago sativa L.) plant tissues on dry‐matter yields and other growth characteristics at different stages of maturity.

Yield increases were highly correlated with increases in percent K in alfalfa leaves or herbage (leaves and stems). The correlations of percent K in tissue with the dry‐matter yields were highest when sampling in a bud stage of growth, and declined with advancing maturities with later samplings. Sampling for K at the time of harvesting underestimated the percent K needed for high yields; herbage that had accumulated for 18 days (bud stage) averaged 143% more in K than at 39 days (full bloom).

The percent K in leaves and herbage was augmented by K fertilization, but the herbage was higher than leaves in K. The percent K in herbage declined sharply with advancing maturity; this did not occur for leaf tissue.

Yields and LAI's increased faster with liberal than with low K. The faster regrowth rates with high as compared with low K may make it possible to shorten cutting intervals, and make an additional cutting during the season. During advanced maturities after 32 days of growth, the LAI's generally stabilized or declined because of leaf losses.

Factors that influence the percent K in tissue should be considered when associating K composition with yields of alfalfa.
Relations Between Fe in Irrigation Water and Leaf Quality of Cigar Wrapper Tobacco1
Authors: Rhoads F. M.
Published: July 2010

Damage, appearing to result from irrigation water, reduced the value of cigar wrapper tobacco (Nicotiana tabacum L.) from about $4.00 per pound to 0.25 in 1969. Dark leaf tips and dark spots over the entire leaf rendered damaged leaves unfit for wrapper use. Leaf analysis indicated that Fe and Mn were associated with the dark coloration.

A study was made in 1970 to determine the effect of Fe in irrigation water on quality of cured wrapper tobacco leaves and to find a potential source of Fe contamination of irrigation ponds. Two forms of Fe were added to irrigation water applied to field plots, and Fe content of leaves, leaf quality, and leaf tensile strength were used to evaluate the effects. Soil and organic material were collected from a shallow area of a “problem” pond, after it had been drained, for use in laboratory studies.

Damaged tobacco, similar to that observed in commercial fields, was produced in field plots in 1970 when Fe was added to the irrigation water. Laboratory incubation studies showed that pond sediments were a potential source of Fe buildup in irrigation water. Leaf strength decreased with increasing content of Fe in the tissue. A visible coating was produced on green leaves in the greenhouse when 5 and 10 ppm Fe in water were sprayed on the plants.
Stabilization of Newly Formed Soil Aggregates1
Authors: Arya L. M. , Blake G. R.
Published: July 2010

The stabilization of newly formed soil aggregates was observed. Stabilization was postulated from previous research to be time dependent. Three kinds of newly formed aggregates were collected, aged at constant water content, and tested for changes in relative stability in water at frequent intervals after formation.

Stability of 3‐ to 5‐mm diameter aggregates collected immediately after plow‐shearing on four soil types increased with time after plowing when water content was held constant. The rate of increase was high during initial aging times and decreased as aging progressed. Increases of about 0.17 for sandy soils and about 0.24 for finer‐textured soils were observed in 72 hours of aging. For all soils, stability increase after about 10 to 12 hours was small.

Earthworm casts were simulated by extruding kneaded, moist soil through a sieve with 2‐mm round holes. Extrusions aged at four water contents showed considerable increases in relative stability in the 24‐hour period following formation. Stabilities determined shortly after extrusion varied with water content of the extrusions. The largest change in stability was from 0.68 to 0.98 at a water content of 0.36 g/g.

Aggregates were also prepared by placing water drops on dry soil powder and collecting the individual coalesced portions. These aggregates were aged at two water contents. Initially, stabilities were near 0 but attained values ranging from 0.14 to 0.31 in about 120 hours. Stability differences due to water content were inconclusive.

These facts raise important questions regarding timing of tillage operations following plowing. Soils in humid climates with a tendency to weakly developed aggregates may have better tilth if further tillage is delayed a few hours. The data suggest that an intense rain soon after plowing will puddle the soil to a greater extent than if it is delayed a few hours.
Calcium‐stimulated 32P Accumulation by Corn Roots1
Authors: Miller Raymond J. , Peverly John H. , Koeppe D. E.
Published: July 2010

The polyvalent cation‐stimulated uptake of phosphate (P) by plant roots has been acknowledged for some time. However, the mechanism of this stimulation and the site of activity have been poorly defined. Most evidence indicates that mitochondria are involved with ion uptake, thus suggesting the possibility that the polyvalent cation stimulation of P uptake by plant roots might be associated with mitochondria. This paper correlates the P accumulation (32P) by isolated corn (Zea mays L.) shoot mitochondria and intact corn roots in the presence of various known inhibitors of electron transport or phosphorylation. In both intact roots and isolated mitochondria, Ca+2 treatment stimulated the uptake of P when compared to either Mg+2 treatment or control treatment. But a ratio of 4 mM Ca:l mM Mg produced optimal stimulation of P uptake when compared to other ratios of these cations. Oligomycin, azide, and 2,4‐dinitrophenol reduced the uptake of P by whole roots, but only 2,4‐dinitrophenol abolished the Ca+2 preferential stimulation of P uptake. These results are compared to similar studies with isolated mitochondria and suggest that the accumulation of P by intact corn roots is at least partially controlled by mitochondria and that the Ca+2 stimulation of P uptake by roots may be explained in terms of mitochondrial reactions.
Diurnal Variation in Nitrogenous Constituents of Alfalfa (Medicago sativa L.)1
Authors: Youngberg H. W. , Holt D. A. , Lechtenberg V. L.
Published: July 2010

Alfalfa (Medicago sativa L.) was sampled eight times daily for 3 days during a third growth period in order to detect diurnal changes in concentrations of various classes of nitrogenous constituents. The implications of these changes with regard to N metabolism were considered.

Total N was determined by predigesting forage samples with salicylic‐sulfuric acid and assaying with the Nessler reagent. Total water‐soluble N was determined by performing the same procedure on aqueous extracts of the tissue. Nitrate N was assayed by the phenol‐disulfonic acid procedure. Ninhydrin was used to determine amino N. Potassium concentration in an acid digest of tissue was measured spectrophotometrically. Analyses were performed on leaflets and on stems and petioles.

The percentages of total N, water‐soluble N, amino N, and K in alfalfa leaves and stems were highest between 3 and 6 AM and declined through the light period during 3 days of frequent sampling in the field. Nitrate N in alfalfa stems followed a similar trend, but there was no diurnal change in nitrate concentration in leaves.

Nitrogen compounds are diluted during each light period by the considerable amount of nonstructural carbohydrate synthesized. This probably accounts for the observed decline in percentage of nitrogenous constituents.
Effect of Trampling by Cattle on Bluegrass Yield and Soil Compaction of a Meadowville Loam1
Authors: Bryant H. T. , Blaser R. E. , Peterson J. R.
Published: July 2010

The objective of this research was to evaluate both the tolerance of a Meadowville loam soil (Typic Hapludult; fine‐loamy, mixed mesic) and bluegrass (Poa pratensis L.) grown in this soil to three levels of trampling by cattle. The protective effect of 2.5 cm, 7.6 cm, and 20.3 cm of bluegrass at tune of trampling, as measured by the resistance of the soil to penetration, was studied. The trampling pressures, repeated four times during the year, were 0, 60, and 120 trips/cow. The pressure, kg/cm2, required for the point of the penetrometer to penetrate the soil was significantly different among trampling pressures for 1, 3, and 4 trampling dates. As trampling intensity increased, maximum resistance to the penetrometer was encountered closer to the soil surface. The height of forage at trampling had no significant affect on either the force required to penetrate the soil or depth of soil at which maximum resistance to penetration was encountered.

Yields of herbage from plots clipped from 20.3 cm to 7.6 cm prior to trampling and after trampling to 2.5 cm were compared with yields from plots clipped prior to and after trampling from 20.3 cm to 2.5 cm, respectively. Yields from plots clipped at 2.5 cm prior to trampling compared to plots not clipped prior to trampling were slightly lower. Increasing trampling pressure had a significantly adverse affect on forage yield for tramplings in June and September.
Establishment, Hay Yield, and Persistence of Two Sainfoin Growth Types Seeded Alone and With Low‐Growing Grasses and Legumes1
Authors: Cooper Clee S.
Published: July 2010

‘Eski’ sainfoin (Onobrychis viciaefolia Scop.), a “one‐cut” cultivar, and ‘Remont’ sainfoin, a rapid regrowth “two‐cut” cultivar, were evaluated for hay production in pure stands and in mixtures with low‐growing grasses and legumes on irrigated land over a 4‐year period. Measurements were made of seedling establishment, yield, and persistence. Yields of Remont were slightly greater than those of Eski for the 4‐year period. The difference in yield was primarily due to greater seeding year yields of Remont. Within a given year, Eski yielded more at the first harvest and less at the second harvest than Remont. Yields of both cultivars decreased in the fourth year due to a partial loss of stand.

Sainfoin mixtures containing either birdsfoot trefoil (Lotus corniculatus L.) or black medic (Medicago lupulina L.) were most productive and those containing Ladino or common white clover (Trifolium repens L.) least productive. The latter species were more competitive with sainfoin, particularly Eski, because of rapid regrowth following clipping.

Pure stands of both sainfoins were heavily invaded by dandelion (Taraxacum officinale Weber) in 1971, and mixtures of sainfoin with either birdsfoot trefoil, black medic, or common white clover were invaded to a lesser degree. Sainfoin cultivars grown with Ladino clover, Kentucky bluegrass (Poa pratensis L.) or red fescue (Festuca rubra L.) were not invaded by dandelion. The relative merits of the two sainfoin types are discussed.
Wheat Response to Short‐term Heat Stress and to Soil Oxygen Stress at Three Stages of Growth1
Authors: Sojka Robert E. , Joseph H. A. , Stolzy L. H.
Published: July 2010

Wheat (Triticum aestivum L.) was grown under controlled environmental conditions for 47 days in two experiments to examine responses to low aeration beginning at various stages of growth, and to determine whether an interaction between temperature and soil aeration status is measurable in wheat. In both experiments oxygen was eliminated from the soil beginning at three different times in the growth cycle. In the second experiment the wheat was subjected to 36 hours of heat stress (42 C) on the 23rd day of growth.

There was a trend toward greater water use with low soil aeration. The root:shoot ratio was significantly decreased by poor aeration in the experiment without heat treatment; all three low‐aeration treatments exhibit essentially the same root:shoot ratio despite different treatment starting times, which indicates that the duration of the low oxygen treatment necessary to alter the root:shoot ratio is relatively short. Interaction of low aeration and heat stress sharply reduces root weight and increases water use per dry weight plant tissue produced, with the effect generally more dramatic with low aeration for longer periods of time. After only a brief period of treatment all characteristics measured, except root:shoot ratio, were significantly affected by heat stress. The effects are partially interpreted in terms of increased respiration rate, leading to degradation of cytoplasm as a result of induced oxygen scarcity.
Effect of Inoculum Size on Nodulation of Glycine max (L.) Merril, Variety Ford1
Authors: Weaver R. W. , Frederick L. R.
Published: July 2010

A criterion for determining adequacy of inoculation of Glycine max by Rhizobium japonicum is needed for testing of commercial inoculants and for determining adequacy of nodulation. This study was undertaken to determine the inoculum level needed for maximum nitrogen fixation of Glycine max and to find a qualitative nodulation pattern that would be useful in recognizing good nodulation. To accomplish this end, soybeans were inoculated and grown in pots containing sand or soil in the greenhouse. Inoculation levels up to 2.4 ✕ 105 and 1.4 ✕ 107 Rhizobium japonicum cells per seed were used for soil‐ and sand‐grown plants respectively. Taproot nodulation was still increasing at the highest inoculum level in soil and sand, but lateral root nodulation had leveled off. Maximum total nitrogen fixed in plant tops was achieved at inoculation levels of 2 ✕ 103 and 1 ✕ 105 cells per seed for soil‐ and sand‐grown plants, respectively. At these inoculation levels at least four taproot nodules were formed. Results suggest that taproot nodulation of soybeans is a qualitative characteristic that may be useful in determining the adequacy of nodulation and may indicate abundance of rhizobia for a soybean variety.
Growth Analysis of Two Sainfoin (Onobrychis viciaefolia Scop.) Growth Types1
Authors: Cooper C. S.
Published: July 2010

Adaptation of sainfoin (Onobrychis viciaefolia Scop.) to dryland may be related to differences in growth habit that permit the most efficient use of available moisture and incident radiation during the active growing season. This study was conducted to quantitatively analyze growth of ‘Remont,’ a “two‐cut” type cultivar, and ‘Eski,’ a “onecut” type cultivar, in relation to adaptation to dryland or to areas with limited irrigation water. Growth was studied during three periods in the spring of 1971. Yields of Remont were significantly higher than those of Eski when sampled on May 12, but because of a greater relative growth rate (RGR, g/g/wk), Eski surpassed Remont in yield when sampled on June 21. The greater RGR of Eski was associated with a significantly greater leaf area ratio (LAR, dm2/g). The LAR of both species decreased with advancing maturity as a result of increasing stemleaf ratio. Net assimilation rate (g/dm2/wk) of these two cultivars was not significantly different. Crop growth rate (CGR, g/m2/da) increased as the season advanced and appeared to be greatest for Eski. Both species produced the majority of their leaves early with maximum leaf area index occurring on or before June 8. Specific leaf weight (cm3/g) of cultivars was similar at the first three sampling dates, but was significantly greater for Remont at the last sampling date. The data indicate that a late‐maturing “one‐cut” type sainfoin would most efficiently utilize soil moisture and incident radiation in areas where soil moisture is limiting after July 1.
Effect of Soil Temperature on Rhizobium japonicum Serogroup Distribution in Soybean Nodules1
Authors: Weber D. F. , Miller V. L.
Published: July 2010

Studies were conducted to determine if temperature, as suggested in a previous study, influenced the distribution of serogroups in nodules of soybeans grown in these same soils. The soybean variety ‘Lee’ was grown at constant soil temperatures of 10, 20 and 30 C and 15, 20, 25 and 30 C, respectively, in two greenhouse experiments. Codorus silt loam containing an established population of Rhizobium japonicum was taken from sites of a previous date of planting study and incubated for one week at the desired temperature before uninoculated seed was planted.

Plant growth characteristics, nodulation and distribution of R. japonicum serogroups in the nodules were recorded. Plant development and nodulation generally were favored by increasing temperatures with 30 C the most favorable temperature for all characteristics except nodule size.

Serological distribution of R. japonicum in the nodules was influenced by soil temperature. Serogroups which were infrequently recovered at the lower temperatures became dominant at 30 C whereas serogroups forming the majority of nodules at 10 or 15 C formed fewer nodules at 30 C. Leaf chlorosis which is induced by R. japonicum serogroup 94 was evident only at 30 C where its incidence in the nodules was highest.
Herbicidal Effects on the Nodulation of Glycine Max (L.) Merrill1
Authors: Dunigan Edward P. , Frey J. Patrick , Allen L. D. , McMahon Aithel
Published: July 2010

Nodulation of legumes is one of the processes in the soil that is liable to be adversely affected by the application of herbicides. This investigation was conducted in a greenhouse and in the field to determine what effects selected pre‐ and post‐emergence herbicides had on total number, dry weight, fresh volume, and Fe content of nodules formed on soybeans [Glycine max (L.) Merrill]. Five soils were employed in greenhouse experiments. Several rates of seven herbicides were surface‐applied to the air‐dried, soils in pots at planting and each pot was watered immediately. After 5 to 7 weeks of growth the roots were carefully isolated from the soil, the nodules were removed, and the total number and dry weight of the nodules were determined. Analyses of the results indicated that different rates of several of the herbicides had detrimental effects on the nodulation process in four of the five soils used. Dry weight was more readily affected than was total number of nodules. With three of the soils, analyses were made to determine the effects of the herbicides on tap‐root and lateral‐root nodulation. Adverse effects were found at both sites with the greater sensitivity being noted on the tap‐root nodules. Field studies were conducted for 3 years on an Olivier silt loam soil using both pre‐ and post‐emergence herbicides. Plants were excavated from the soil after 8 to 12 weeks of growth and the nodules were removed from the roots. Analyses of the data obtained from determining both the dry weight and the Fe content of the nodules did not reveal any detrimental effects from any of the herbicides used.
Effect of Hormone‐Directed Presoaking on Emergence and Growth of Osmotically Stressed Wheat (Triticum aestivum L.) Seeds
Authors: Darra B. L. , Seth S. P. , Singh Harvinder , Mendiratta R. S.
Published: July 2010

The water potential gradient between a planted seed and the surrounding soil largely controls water absorption by the seed. Salinity of soil water affects this balance, which in turn lowers germination and seedling growth. Overcoming the inhibition of water intake by presoaking and the use of auxins and gibberellins has been shown to be advantageous for certain crops,but studies with wheat are limited. This approach constitutes the objectives of this investigation.

The effects of presoaking wheat seeds in 10, 20, 50, and 100 ppm each of GA, IBA, IAA, and NAA at O, 3, 6, and 9 atm osmotic pressure on seedling development were observed. Auxins had little influence on emergence at 0 atm but promoted emergence at 3, 6, and 9 atm. Three‐indole acetic acid (IAA) and α — naphthalene acetic acid (NAA) at 50 ppm produced maximum shoot length, whereas gibberellic acid (GA) and three‐indole‐butyric acid (IBA) gave better results at 100 ppm. Increased concentrations of GA and NAA significantly reduced primary root length, whereas IAA increased root length. All hormones increased proliferation of lateral roots, but auxins produced more lateral roots at all salinity levels. Root/shoot ratio was decreased by NAA and GA. Water absorption was increased by all treatments. IAA and NAA at 50 ppm gave the better results. The data support the hypothesis that the beneficial effects of hormones may be the result of increased water absorption, which improves plant growth even under high salt concentrations in the growth medium.
Nitrogen and Boron Effects on Protein and Oil of Corn Grain
Authors: Jellum M. D. , Boswell F. C. , Young C. T.
Published: July 2010

This study was conducted to determine the effect of nitrogen and boron on protein and oil percentages and fatty acid composition of corn (Zea mays L.) grain. In one study, two rates (90 and 180 kg/ha) of nitrogen, two periods (December and preplant), with and without a nitrification inhibitor were applied to corn on a Norfolk loamy sand soil in the Coastal Plain region of Georgia. In a second study, three rates (0.28, 0.56, and 1.12 kg/ha) of boron were applied to the same soil as for study one. Check plots with no treatment were included in each experiment. Grain samples from each plot were analyzed for protein and oil percent by standard A.O.A.C. methods and the fatty acid composition of oil was determined by gas‐liquid chromatography. Protein percent increased with increasing rates of N without any effects from time of application or of the nitrification inhibitor. Nitrogen had no effect on oil percent or oil composition. Boron fertilization had no effect on any of the chemical characters measured in this study.
Water Loss from an Irrigated Sorghum Field: I. Water Flux within and below the Root Zone1
Authors: Stone L. R. , Horton M. L. , Olson T. C.
Published: July 2010

Knowledge of actual water movement within field soil profiles under cropped conditions is important in aiding our understanding of water supply to plants and movement of water soluble fertilizers and pesticides. This work was done to evaluate water movement within and below the root zone of a sorghum (Sorghum bicolor (L.) Moench) crop during a 31‐day field study following water application. Hydraulic potential data from tensiometers placed at eight depths in the soil profile were used to determine the hydraulic gradients. Soil water flux in various depth layers was calculated using the hydraulic potential gradients and the determined hydraulic conductivity vs soil water content relationships. Upward water movement commenced in the 15 to 30 cm layer 3 days foflowing water application and 130 to 150 cm layer after 19 days. The upward water flux into the root zone reached a maximum of approximately 0.2 cm/day near the end of the study period. During the 31‐day study period, 6.0 cm of water were lost from the 150 cm soil profile by flux below the root zone. This illustrates the importance of considering water loss due to flux below the root zone in crop situations.
Drought‐Affected Mitochondrial Processes as Related to Tissue and Whole Plant Responses1
Authors: Koeppe D. E. , Miller Raymond J. , Bell David T.
Published: July 2010

The purpose of this study was to correlate the respiratory rates of whole seedlings, excised shoots, and isolated mitochondria of Zea mays L. (Wf9 ✕ M14) water stressed to various degrees. Drought stress was imposed by two different methods and monitored with a Peltier psychrometer. Respiration was determined in whole plants with an infrared gas analyzer and in excised shoots and mitochrondrial suspensions with an oxygen electrode. Substrate oxidation rates by mitochondria isolated from water‐stressed tissue decreased with increased stress. Similar decreased respiration rates were observed with excised shoots and whole seedlings when stressed on paper toweling. When the seedlings were stressed with carbowax 6000 in vermiculite, the respiration of excised shoots increased to a potential of about —16 bars and then decreased as stress was increased. The water content of these seedlings also appeared to increase and then decrease in a manner analogous to respiration. When water stress was alleviated by rewatering, the seedling water potentials soon returned to prestress levels in all but severely stressed samples. Respiration rates of excised shoots and mitochondrial suspensions and mitochondrial swelling‐contraction responses recovered more slowly. The results showed that in vitro mitochondrial processes were altered by water stress and that these alterations persist even when the mitochondria were isolated from the growing tissue. These results suggest that the decrease in the rate of whole plant respiration with increased stress may be due to membrane alterations that effect the ability of mitochondria to oxidize substrate.
Time Constants for Thermal Equilibration of Leaf, Canopy, and Soil Surfaces with Change in Insolation1
Authors: Wiegand C. L. , Swanson W. A.
Published: July 2010

Experiments were conducted to determine the time constant for thermal equilibration of a cotton (Gossypium hirsutum L.) plant leaf, the plant canopy, and a soil surface with a change in incident solar radiation (insolation). The time course of surface temperatures sensed by portable radiation thermometers during periods of full sun and artificial shading were the data obtained. The plant leaf and the canopy equilibrated in 40 seconds to 1 minute, but the soil required more than 10 minutes. These results have important implications in interpreting airborne thermal scanner data obtained under partly cloudy sky conditions.
Protein Content of Winter Wheat in Relation to Rate and Time of Nitrogen Fertilizer Application1
Authors: Hunter Albert S. , Stanford George
Published: July 2010

The effects of N fertilization in the northeastern states on percent protein in soft winter wheat (Triticum aestivum L.) need to be evaluated in relation to time and rate of application and variety as a basis for developing practices that achieve the desired range in wheat protein.

Fall and spring applications of different N rates to ‘Blueboy’ and ‘Redcoat’ varieties of soft winter wheat were compared at five locations on limestone‐derived Pennsylvania soils. Average protein contents were increased from 10.9!)% with no N applied to 14.3% with N fertilizer. The optimum rate of N for maximum grain yield often resulted in higher protein content than is considered desirable in grain used for pastry making. Under comparable conditions, the average protein contents of Redcoat and Blueboy wheats, respectively, were 13.3 and 11.8%. Spring application consistently gave higher protein contents than fall application, although the average difference was small (0.6%).

Yields of protein were higher for Blueboy than for Redcoat, despite higher percent protein in the latter, because grain yields of Blueboy were substantially greater than yields of Redcoat. The importance of soil N as a source of N in these experiments was illustrated by the significant correlation that existed between relative N mineralization rates of soils from zero‐N plots and corresponding protein yields.
Effect of Temperature and Plant Water Stress on Photosynthesis, Diffusion Resistance, and Leaf Water Potential in Spring Wheat1
Authors: Frank A. B. , Power J. F. , Willis W. O.
Published: July 2010

Plants growing under field conditions are usually subjected to varying degrees of water stress, but the effect of temperature on the development of plant water stress and subsequent recovery is not well‐known. Therefore, a study was conducted in growth chambers to determine the combined effects of temperature and soil water supply on the development of plant water stress and subsequent recovery in spring wheat (Triticum aestivum L. ‘Waldron’). Measurements were made of leaf water potential, photosynthesis, and stomatal diffusion resistance on the fifth leaf at tillering and the flag leaf at heading, flowering, and grain‐filling growth stages for plants grown at 10, 18, and 27C. Stomatal closure of stressed plants was affected by both leaf position and age. Closure occurred at −13, −13, and −15 bars leaf water potential at tillering and at −18, −17, and −26 bars at heading for 10, 18, and 27C, respectively. As the flag leaf matured, stomata closed at progressively lower leaf water potential. In nonstressed check plants, temperature greatly influenced leaf water potentials. At heading, plants at 10C had a significantly lower leaf water potential than plants at 18 and 27C, probably resulting from chill‐induced water stress caused by increased internal resistance to water movement in the plant. At 18C, leaf water potential at tillering and at heading recovered to prestress levels 6 hours after stress ceased, but not until after 48 hours at the grain‐filling stage. Stomatal diffusion resistance recovered to prestress levels within 2 hours, except at grain‐filling, when recovery was incomplete after 48 hours. Recovery of photosynthesis was related to recovery of stomatal diffusion resistance at tillering and heading, except that photosynthesis never fully recovered to prestress levels, and photosynthesis of plants stressed at grainfilling showed no sign of recovery due to stress‐induced senescence.
Determination of Wheat Growth‐Environment Relationships1
Authors: Haun J. R.
Published: July 2010

Wheat (Triticum aestivum L. em. Thell.) growth data were obtained from field plantings in North Dakota by observing morphological development at intervals of 1 to several days. The system of observation was based on rate of production of leaves and other plant parts. The emergence of each leaf or other unit was subdivided into appropriate decimal divisions. The rate of development was determined by subtraction of the previous day's observation from the current observation of morphological development.

Environmental data collected in the vicinity of the plants included solar radiation, maximum and minimum air temperature, maximum and minimum soil temperature, rainfall, soil moisture, and evaporation. The status of soil moisture was also estimated by the Thornthwaite‐Mather method. In subsequent statistical analyses, environmental data were evaluated with respect to their current effects as well as to the delayed or lagged effects for each of the 4 days prior to growth observations. These variables were used in their original form and also transformed into the square, cube, and selected cross products of important variables to account for curvilinear effects and interactions of various environmental factors. Daily growth rate was used as the dependent variable; age, cumulative development, and environmental data, with appropriate lags and transformations, were used as independent variables. Multiple regression analyses were conducted to determine the overall relationship of the various environmental factors to growth rate. A prediction equation was obtained.

The objective of this research was to determine whether data from daily visual quantification of wheat development could be related to variations in the major environmental variables. Daily growth rates for 1966, predicted by the equation obtained from analysis of 1967 data, were in close agreement with observed growth rates. Due to the complex interrrlationships of environmental factors, the 13 independent variables of this equation are not necessarily an exclusive or unique expression of the environment. However, tests of significance and tests of the prediction equation on unrelated data indicated that quantitative morphological observations may provide a potent dependent variable for relating plant growth to environmental factors.
Response of Nodulating and Nonnodulating Soybeans to a Species of Endogone Mycorrhiza1
Authors: Schenck N. C. , Hinson K.
Published: July 2010

Our purpose was to determine the effect of an Endogone endomycorrhizal fungus on nodulating and nonnodulating isolines of ‘Hardee’ soybeans (Glycine max (L.) Merr.) growing in methyl bromide‐fumigated soil in the field. Inoculation with Endogone significantly increased seed yield and other traits of the nodulating but not the nonnodulating isoline. Indirect evidence suggested Endogone did not significantly increase nitrogen absorption of the nonnodulating isoline.
Influence of Soil Water Status and Meteorological Conditions on Evaporation from a Corn Canopy1
Authors: Ritchie J. T.
Published: July 2010

In predicting evaporation rates for field crops, it is important to consider the influence of soil water status on the actual evaporation rate relative to the potential rate. This study was conducted to determine actual evaporation rates of corn (Zea mays L.) as influenced by soil water status and potential evaporation rate. Actual evaporation rates were measured during the 1972 growing season with a weighing lysimeter. Evaporation rates were found to be practically independent of the soil water status for all existing conditions of potential evaporation. During the season more than 20 cm of soil water was removed from the 120‐cm deep profile.

Leaf diffusion resistance and leaf water potential measurements indicated that at least 80% of the extractable soil water was freely available to plant roots. These findings differ from those of Denmead and Shaw (Agron J. 54:385–390, 1962) who found that evaporation reduction in container grown corn plants started when about 20% of the extractable water was removed from the soil for potential evaporation rates above 6 mm/day. The difference between the results from the experiment reported by Denmead and Shaw and this experiment point out that serious errors are possible when using their results for predicting evaporation from corn plants growing under field conditions.
Influence of Potassium Nutrition on Net CO2 Uptake and Growth in Maize (Zea mays L.)1
Authors: Estes G. O. , Koch D. W. , Bruetsch T. F.
Published: July 2010

A heavy dependence on K fertilization in the northeastern U. S. coupled with the luxury accumulation of this element in plants suggest a need for further research. The objective of this greenhouse experiment was to relate CO2 uptake, determined by a radioactive carbon method, and yield of maize (Zea mays L., var. Wisconsin 335A') with K concentration and content of tissue. Plants were grown at substrate levels of K from O to 9 mM/liter of K in hydroponic culture.

A significant correlation existed between both concentration and content of K and dry weight of plants. There was a curvilinear relationship between both leaf (youngest fully expanded) and plant K percentage and net CO2 uptake. Leaf content of K between 0.75 and 1.0% was considered critical (42‐day‐old maize) because CO2 fixation was seriously reduced at lower concentrations. There was a close agreement between CO2 assimilation and dry weight over the range in substrate K concentrations, .50 to 9.0 mM/liter. An increase in dry weight at the K level of 0.25 mM/liter was not accompanied by an increase in CO2 fixation. Uptake of CO2 increased nearly 60% between K concentrations of 0.25 and 0.50 mM/liter but at a much slower rate between 0.50 and 9.0 mM/liter.
Relationship of Sericea Lespedeza Leaf and Stem Tannin to Forage Quality1
Authors: Donnelly E. D. , Anthony W. B.
Published: July 2010

The leaves of sericea lespedeza (Lespedeza cuneata [Dumont] G. Don) have been found to contain more tannin than stems. Tannin has been found to reduce digestible dry matter (DDM) of sericea and digestibility of crude protein. An experiment was conducted to study quality of high and low‐tannin sericea leaves and stems separately. Low‐tannin sericea leaves averaged 20 percentage points higher in DDM than high‐tannin leaves, and 19 percentage points higher than low‐tannin stems as indicated by the in vivo nylon bag method. The DDM of low‐tannin stems was as high as that of high‐tannin leaves. High‐tannin leaves averaged only slightly higher in DDM than stems of high‐tannin plants. Tannin in both leaves and stems of the high and low‐tannin groups was negatively associated with crude protein. Data indicate that lowering the tannin content of sericea by breeding increases both the percentage and digestibility of crude protein. Much improvement in sericea forage quality can be made by breeding for low‐tannin and high leaf percentage.
Model of Light Penetration into a Wide‐Row Crop1
Authors: Allen L. H.
Published: July 2010

This model predicts direct‐beam radiation penetration into wide‐row crops. The crop is modeled as “hedgerows” with an open middle between the rows. Leaf area density is given height and cross‐row functional distributions, but is considered uniform along the length of the row. Input parameters which can be varied are: time of day, time of year, latitude, longitude, atmospheric trans‐missivity, slope of the soil surface, row direction, row spacing, crop height, width of the hedge‐row, leaf area density distribution functions, and mean leaf angle. The model can predict the average direct‐beam penetration to any depth as a function of distance from the row, and the average penetration for the whole hedge‐row system. Light penetration was predicted for E‐W, N‐S, NE‐SW, and NW‐SE row orientations for August 17, 1967, using row geometry of E‐W wide‐row grain sorghum (Sorghum bicolor L. Moench) grown at Akron, Colorado. Low predictions of light interception in the morning and afternoon by E‐W rows resulted in the lowest predictions of daily total intercepted light. Under the input conditions, the model predicted 37, 44, 42, and 42% daily interception for E‐W, N‐S, NE‐SW, and NW‐SE row orientations, respectively. The NE‐SW row orientation may be best since the model predicted that the most light would be absorbed at 1000 hours, when moisture stress would be low, and the least at 1400 hours, when moisture stress would be high.