bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of Kikuyugrass (Pennisetum clandestinum) Under Clipping. I. Effects of Nitrogen Fertilization, Cutting Interval, and Season on Yields and Forage Characteristics1
Authors: Whitney A. S.
Published: July 2010

Kikuyugrass (Pennisetum clandestinum Hochst. ex Chiov.) is an important pasture forage, soil cover, and weed in many parts of the subtropics. Responses to N have been reported, but the relationships among management, climate, and forage production have not been well defined. We therefore studied the regrowth of kikuyugrass under 3 N levels (22, 56, and 168 kg/ha per year), and 3 cutting intervals (2, 5, and 10 weeks) for 3 years at 2 locations (Kula and Makawao, Maui). The Kula site was at 945‐m elevation on an Eutrandept, and the Makawao site was at 660‐m elevation on a Tropohumult. Average yields ranged from 4.8 to 29.4 metric tons/ha per year at Kula and from 10.2 to 32.5 metric tons/ha per year at Makawao. Average percent N in the forage was little affected by N rate except for an increase at the highest N rate at Makawao.

Cutting at 2‐week intervals reduced yields per unit time to 20 to 50% of the 10‐week yields at Kula and to less than 15% of the 10‐week yields at Makawao. Over a 3‐year period, yields of 5‐week regrowth (per unit time) were 32% of the 10‐week yields at Kula but 65% of 10‐week yields at Makawao. Crude protein levels in the forage under frequent cutting averaged 1.5 to 2.0 times that in 10‐week regrowth. Two‐week regrowth was also higher in acid‐detergent solubles and lower in fiber and cellulose than 10‐week regrowth. Ten‐week regrowth from the high N treatment was higher in fiber and lignin than similar forage from the low or moderate N levels, indicating the need for careful management of N‐fertilized kikuyugrass.

Dry matter yields of 5‐week regrowth fluctuated more with season than 10‐week regrowth yields, ranging from 1.4 to over 100 kg/ha per day. Five‐week regrowth yields were reduced by 11 kg/ha per day for each degree of decrease in average minimum soil temperature below 18 C (r2 = .93). Above 18 C, yields increased about 16 kg/ha per day for each 100 ly/day increase in average solar radiation (r2 = .64). Percent crude protein in the forage was inversely related to air or soil temperature and day length (multiple R2 =.57).

Residual effects of N fertilization were greater on the Tropohumult than on the Eutrandept. After 3 years of clipping, cations were severely depleted from the upper horizons of both soils.
Alkaloids of Reed Canarygrass as Influenced by Nutrient Supply
Authors: Marten G. C. , Simons A. B. , Frelich J. R.
Published: July 2010

Reed canarygrass (Phalaris arundinacea L.) genotypes contain varying amounts of indole alkaloids which are negatively associated with grass palatability to ruminants and which are potentially toxic to animals. Forage researchers need knowledge of the influence of environmental factors such as soil fertility on alkaloid concentration to aid control of these anti‐quality components of reed canarygrass.

We conducted seven experiments to determine whether the alkaloids of reed canarygrass could be modified by inherent soil fertility or by application of nutrient elements to fertile and infertile soils.

Mean alkaloid concentrations in four clones of reed canarygrass were doubled by growing the clones in an infertile peat, compared to a fertile mineral soil. Supplying the deficient nutrients (especially P and K) to an infertile peat significantly reduced alkaloids of grass growing in the soil, provided N levels did not exceed 240 kg/ha.

Ammonium sources of N (NH4Cl and urea) caused greater alkaloid concentrations in reed canarygrass than did a nitrate source (NaNO3), while grass supplied with both sources (NH4NO3) had an intermediate alkaloid concentration.

Relatively low levels of N (as low as 60 kg N/ha) applied to fertile mineral or peat soils caused increased alkaloids in grass clones inherently high in alkaloids. However, over 240 kg N/ha were required to significantly elevate alkaloid concentration in reed canarygrass growing in an infertile peat, and up to 225 kg N/ha in solution culture did not affect alkaloid concentration in a low‐alkaloid clone.

We concluded that N fertilization is likely to increase alkaloid problems of reed canarygrass in situations where alkaloids are already high, but that practical levels of N (up to at least 200 kg/ha) will probably not increase alkaloid concentrations of those strains inherently low in alkaloids. Fertilization of infertile soils with deficient nutrients (other than N) may cause reduction in alkaloid concentration of reed canarygrass, even though P, Mn, or Cu individually did not affect alkaloids.

None of the fertilizer elements changed the type of alkaloids (gramine, DMT, or 5‐MeO‐DMT) of the various clones and seed sources used in the seven experiments, indicating that this variable was genetically controlled.
Light Transmission in Field Communities of Sorghum1
Authors: Clegg Max D. , Biggs William W. , Eastin Jerry D. , Maranville Jerry W. , Sullivan Charles Y.
Published: July 2010

Most plant canopy and solar radiation studies have comprised theoretical considerations, assuming a randomly oriented leaf arrangement. Lacking are field measurements concerning culturally arranged plant canopies in relation to interception of solar radiation. The purpose of this study was to describe the light environment under field conditions below and within grain sorghum (Sorghum bicolor (L.) Moench) canopies.

Visible radiation was measured in sorghum using sensors mounted on a traversing system and having about the same sensitivity to direction and spectrum as does a leaf. As much as 89% more light was transmitted to a sensor when it moved between rows rather than across them. Therefore, measurement across rows is recommended.

Light transmission profiles of sorghum canopies on clear and cloudy days were similar. Differences between transmission values over a diurnal period were less on cloudy than on clear days indicating more uniform light distribution. Visible radiation transmitted through sorghum canopies of .51‐m rows as compared to sorghum canopies of .76‐ and 1.02‐m rows or sorghum canopies of .76‐m rows as compared to sorghum canopies of 1.02‐m rows was less. This would indicate more visible radiation would be available for photosynthesis with narrower row spacings.

Extinction coefficients (K) for canopy layers were calculated and for each layer proceeding downward K decreased. Extinction coefficients of sorghum canopies of different row spacings decreased as row spacing increased. Differences between hourly values of K were less on the cloudy day than on the clear day. For all conditions minimum values of K occurred at solar noon. These results agree with theoretical data.
Effect of Leaf Orientation, Leaf area, and Plant Densities on Corn Production1
Authors: Whigham D. K. , Woolley D. G.
Published: July 2010

The effect of corn (Zea mays L.) leaf orientation on grain yield and production practices has been the subject of conflicting reports over the past few years. Plant population is reported to be the cause of the discrepancies. The objectives of the present study were to determine the effect of plant population and leaf orientation on corn plant efficiencies and their interaction. Two contrasting leaf angles were compared by the use of near‐isogenic versions of the single‐cross hybrid (Hy2 ✕ C103) consisting of the liguleless (lg2) and its normal counterpart. Light penetration, light reflection, total dry matter production, and grain yields were measured to determine the effect of the leaf orientation, leaf area, and plant densities on corn production.

Leaf angles of the two versions differed by 20°. Nine percent more light was intercepted by the horizontally oriented leaf type (HL). Plant populations (from 39,305 to 88,958 plants/ha) had no effect on leaf angle. High populations resulted in mutual shading which reduced the yield per plant. The mean leaf area per leaf of the HL was 17% larger than the vertically oriented leaf type (VL). Plants grown at 69,189 plants/ha had smaller leaves than those at the 49,421 population. Defoliation above the ear removed less leaf area than any of the other treatments and produced the smallest grain yield. All defoliation treatments reduced grain yield. Reflectors did not increase yield. Leaf orientation had little effect on corn production in rows spaced 76 cm apart.
Influence of Altitude on Seed Yield and Other Characters of Soybeans Differing in Maturity in Sikkim (Himalayan Kingdom)1
Authors: Basnet B. , Mader E. L. , Nickell C. D.
Published: July 2010

A need exists for information on effects of altitude on yield and other characteristics of soybeans (Glycine max (L.) Merr.). Accordingly we evaluated the response of several imported varieties and a local variety for 2 years at altitudes of 1,394 and 1,636 m.

Soybean growth and development was retarded at the higher altitude, and plants were shorter, lodged less, and had fewer nodes. Seeds with better quality were produced at the higher altitude. Seed weight varied with years at the two altitudes. Yield of most varieties was lower at the higher altitude. Seed yield differences among varieties were not consistent between years.

The higher altitude prolonged the intervals from planting to first flowering 3 to 13 days, and planting to maturity 2 to 24 days. Dates of first flowering and maturity of groups V through VII soybeans were delayed more than those of earlier maturing groups.
Accumulation and Distribution of Mineral Nutrients, Carbohydrate, and Dry Matter in Soybean Plants as Influenced by Reproductive Sink Size1
Authors: Kollman G. E. , Streeter J. G. , Jeffers D. L. , Curry R. B.
Published: July 2010

The purpose of this experiment was to determine the extent to which the number of pods per node (“sink Size”) controls the accumulation of mineral nutrients, carbohydrate, and total dry matter in soybean plants (Glycine max (L.) Merrill). A quantitative description of the relationship between sink size and nutrient accumulation will help to identify nutrients which might limit yield at higher reproductive loads. Plants were grown in the field and various numbers of pods were removed as they formed to give an average of 0, 0.8, 1.1, 1.9, 2.4, or 2.7 pods per node. Leaf blades, stems plus petioles, pods, and seeds from mature plants were analyzed for N, P, K, Ca, Mg, and carbohydrate concentration. Increasing the sink size resulted in decreases in N and P concentration in leaves, stems, pods, and seeds and in Mg concentration in stems plus petioles. Conversely, K concentration in all plant parts and Ca concentration in leaf blades increased in response to increasing sink size. These increases in K and Ca concentration appeared to be due to a greater decline in the matter content than in K and Ca content as sink size increased, resulting in concentration of K and Ca. As sink size increased from zero to 2.7 pods per node: 1) carbohydrate content of leaf blades decreased 64%; 2) carbohydrate content of stems plus petioles decreased 40%; 3) mineral nutrient content of leaves plus stems decreased as follows, N — 72%, P — 64%, K — 28%, Ca — 18%, and Mg — 55%; and 4) total dry weight of leaves plus stems decreased 37%. When nutrient content of leaves and stems was plotted against sink size the result was a nearly perfect fit to a straight line for all nutrients except potassium. A comparison among nutrients of the slopes of these curves suggested that maximum reduction of N and P content in leaves and stems would occur at sink sizes smaller than required for maximum reduction of other mineral nutrients. Total Mg and Ca accumulated by above‐ground plant parts was not dependent on sink size, whereas total N, P, and K accumulated was strongly dependent on sink size.
Manganese Nutrition of Cotton Under Two Boron Levels. II. Critical Mn Level1
Authors: Ohki K.
Published: July 2010

Reference guideline values relating Mn concentration in plant tissue to growth is necessary for the assessment of the Mn nutritional status in cotton. Many of the presently available critical Mn levels were related to the presence or absence of deficiency symptoms. Refinement appeared necessary particularly in relation to the inter‐action of another nutrient. Therefore, a Mn ✕ B interaction study was conducted in nutrient solution under greenhouse conditions to determine the influence of low and adequate B levels on critical Mn levels of Upland cotton (Gossypium hirsutum L.) with 11 manganese rates from 0 to 4000 μg Mn/1 at two B levels of 35 and 500 μg B/1. The objectives were to determine 1) the most sensitive tissue relating Mn content to growth, 2) the critical Mn level in relation to growth and 3) the interaction of B on the critical Mn levels.

Critical Mn levels of blade 1 through 5 ranged from 10 through 15 ppm Mn on a dry weight basis. Although Mn content in .blade 1 was the most sensitive in relating nutrient content to growth, the recently matured leaf (blade 3) was selected as the most practical tissue on the basis of sampling ease to use for evaluating the Mn status of cotton. The critical Mn level was 10 ppm Mn in blade 3. The critical Mn levels in blades 1 through 4 were independent of the B levels; however, low B increased the critical Mn level in the older blade (Blade 5). The stem and petiole tissue contained a small fraction of the Mn in blade tissue at high Mn levels. This reduced the desirability of selecting any of the vascular tissues for estimating the Mn nutrient status of cotton plants.
Water Uptake by Seeds as Affected by Water Stress, Capillary Conductivity, and Seed‐Soil Water Contact. II. Analysis of Experimental Data1
Authors: Hadas A. , Russo D.
Published: July 2010

Chickpea, pea and vetch seeds were germinated in pure, aerated water and in sand or aggregate fractions of various grain‐size classes. These were either 1) packed in columns at various water contents kept constant by passing water at different rates equaling the conductivity of the least conductive layer in every column or 2) sown in aggregated soil at equilibrium with different matric water potentials. Water uptake rates, seed diameter, and time of germination were determined, and seed‐soil water contact area was calculated. Water uptake data were analyzed to yield an approximation of the seed‐soil water contact impedance by using a simplified model.

The results show that the seed‐soil water contact impedance increased as the wetted seed area and/or soil hydraulic conductivity decreased. The data also show that for optimal seed‐soil water contact in aggregated soils, the mean aggregate size should be one‐fifth to one‐tenth of the seed's diameter. Possible application to field practice, such as seed‐bed preparation, is discussed.
Responses of Grasses and Legumes to Soil pH1
Authors: Palazzo A. J. , Duell R. W.
Published: July 2010

Species adaptation to soil pH has been generalized in the literature. This study was conducted to determine the responses of 19 varieties of grasses and legumes to soil pH ranging from pH 4.2 to 7.6 in field plots of a l~reehold sandy loam. Profiles of soil pH and relationships of pH to availability of nutrient elements, plant weights, and tissue analyses are presented. Different pH levels were developed over a period of 4 years as a result of surface application rates of NH,NO3 and Ca(OH)2= to a split‐split plot, randomized field design. Magnesium was included as a variable and applied to sub‐sub plots at rates of 0 and 44.8 kg of Mg/ha from MgSO4. Aluminum, manganese, iron, and zinc analyses of foliage of three grasses were made along with chemical analyses of the soil. The ph of the soil profile was taken at seven increments to a depth of 150 cm.

Ca(OH)2 applications tended to raise soil pH to depth of 40 cm and NH4,NO3 applications depressed soil pH to a depth of 60 cm. Four fine fescue (Festuca rubra L.) varieties produced their greatest growth in the most acid plots (pH 4.2) studied. Negative linear correlations between plant weights and soil pH were found. Quadratic and curvilinear relationships were found for all other grasses which did best in a pH range from 6.0 to 6.5. The legumes required a higher soil pH for optimum growth than the grasses.

‘Pennlawn’ red fescue (Festuca rubra L.), which did well in plots of the most acid soils, had lower contents of AI in above ground tissue than did ‘Kenblue’ Kentucky bluegrass (Poa pratensis L.) or ‘Manhattan’ perennialryegrass (Lolium perenne L.) which were limited in these soils. Tissue contents of Mn and other elements were neither too high nor too low to limit growth.
Stomatal Guard Cell Integrity and Resistance to Rumen Fluid Digestion1
Authors: Chatterton N. J. , Powell Jerrel B.
Published: July 2010

Scanning‐electron micrographs were made of Dactylis glomerata L. leaf tissue following digestion in rumen fluid to observe differential digestion of various cell types. Fresh leaf blade sections were subjected to the activity of rumen fluid at 39C obtained from a rumen‐fistulated Black Angus steer. Digestion by rumen microorganisms allowed the cuticle to float free as the mesophyll was digested. Close examination revealed that the stomatal guard cells were slow to digest and that they remained attached to the interior surface of the cuticle. The lack of significant microorganismal entrance into fresh leaf tissue, except through cut edges, may be explained by the combined resistance of the cuticle and stomatal guard cells to digestion. We propose that the cellulose of guard cell walls of Dactylis glomerata L. is infused with either a cutin‐like compound or with silica. Possibly a combination of cutin and silica provides guard cells with resistance to digestion by rumen fluid organisms. Additionally, electron micrographs are presented that vividly display the shape and orientation of the guard cells from a new perspective.
Estimation of Leaflet, Trifoliolate, and Total Leaf Areas of Soybeans1
Authors: Wiersma J. V. , Bailey T. B.
Published: July 2010

The importance of rapid, nondestructive, and accurate measurements of leaf area for agronomic and physiological studies is well known. Several mathematical formulas have been derived for estimating leaf areas for numerous crops, but there is little information available for soybeans [Glycine max (L.) Merr.]. The purpose of this study, therefore, was to develop prediction equations for estimating leaflet, trifoliolate, and total leaf areas of soybeans.

Statistical analyses of soybean leaf areas were divided into three levels: leaflet, trifoliolate, and total leaf area. At each level, we compared the predictive abilities of three regression equations, each involving a different independent variable. On the basis of these results, we chose one independent variable at each level for subsequent regression analyses of various hypotheses. Prediction equations derived from independent variables involving measurements of length and width were superior at each level to those involving measurements of only length or width. Our data indicate, however, that considerable savings of time, with little loss of predictive ability, could be possible by measuring only length or width in each instance.

With the use of independent variables involving measurements of length and width, regression analyses were performed to assess the effects of cultivars at each level and also the effects of leaflet orientation on the trifoliolate and the trifoliolate position on the plant at their respective levels. In general, these analyses indicated that a single regression equation could be used at each level. Leaflet, trifoliolate, and total leaf areas of the 12 cultivars we studied could be estimated by the following equations, respectively: A = 0.624 + 0.723LW (R2 = 0.985); A = 0.411 + 2.008LW (terminal leaflet) (R2 = 0.983); A = 6.532 + 2.045 (∑L1W1 terminal leaflets) (R2 = 0.965).
Evaluation of Kentucky Bluegrass and Red Fescue Cultivars for Sod Production1
Authors: Hurley R. H. , Skogley C. R.
Published: July 2010

Until recently, much of the commercial sod produced in the Northeast has been ‘Merion’ Kentucky bluegrass (Poa pratensis L.) Many turf authorities now feel that blends of improved Kentucky bluegrass and red fescue (Festuca rubra L.) cultivars should be used to broaden the genetic base of the mixture. This type of mixture would be adaptable to a wider range of environmental conditions.

‘Merion’, ‘Baron’, ‘Fylking’, and ‘Pennstar’ Kentucky bluegrasses and ‘Jamestown’, ‘Highlight’ (Festuca rubra var. commutata Gaud.) and ‘Pennlawn’ red fescues were studied singly and in mixtures for commercial sod production. Cultivar compatibility in mixtures were evaluated by turf quality ratings and tiller counts, rate of establishment, durability as measured by tensile strength of harvested sod, and rate of sod knitting after transplant.

All cultivars and mixtures provided acceptable visual turf quality with Baron, Pennstar, and Baron‐Pennstar, Merion‐Baron mixtures providing the highest turf quality ratings.

Tensile strength was not altered by use of improved Kentucky bluegrass cultivars alone or in mixtures. Red fescue significantly reduced sod strength when included in mixtures with Kentucky bluegrass. This reduction did not affect handling of the harvested sod when up to 67% red fescue by weight was included in the seed mixture.

Jamestown and Highlight red fescue produced significantly more tillers than Pennlawn, and those cultivars were better able to compete with Merion Kentucky bluegrass.
Influence of Aluminum Ions on Developmental Morphology of Sugarbeet Roots1
Authors: Keser M. , Neubauer Benedict F. , Hutchinson F. E.
Published: July 2010

High concentrations of aluminum in low pH soils are toxic to sugarbeet (Beta vulgaris L.). In a test to determine the effect of increased concentrations on seedling development, 4, 8, and 12 ppm Al nutrient culture caused significant reduction of root and hypocotyl growth. The primary root curved and the root cap broke away. Lateral roots emerged as small outgrowths on the primary root axis and developed abnormally. Anatomical examination of primary and lateral roots revealed extraneous material in the apical meristem, root cap, and cortical region. Apical regions of the primary and lateral roots did not exhibit their typical organization and cells divided in an irregular pattern. Aluminum can be an important factor in the suppression of sugarbeet growth in acid soils.
Turfgrass Wear Tolerance Mechanisms: III. Physiological, Morphological, and Anatomical Characteristics Associated with Turfgrass Wear Tolerance1
Authors: Shearman R. C. , Beard J. B.
Published: July 2010

This investigation was conducted to assess the relationship of various turfgrass physiological, morphological, and anatomical characteristics to wear tolerance. No data of this nature is available in turfgrass literature. Species differences were noted for verdure, shoot density, leaf width, load bearing capacity, leaf tensile strength, percent moisture, and percent relative turgidity. However, no significant correlations were found between species wear tolerance and the afore mentioned characteristics. Analysis of the combined relationship of these factors to wear tolerance indicated that only leaf tensile strength and leaf width contributed significantly to the variation in turfgrass wear tolerance among seven turfgrass species.

Sclerenchyma tissue and lignified cell comparisons were made between Kentucky 31 tall fescue (Festuca arundinacea Schreb.) and rough bluegrass (Poa trivialis L.). Results were presented as percent of the total cross‐sectional area of leaf blades and stems. Sclerenchyma tissues of Kentucky 31 composed 18.6% of leaves and 23.4% of stems, while the contents of rough bluegrass were 8.9 and 10.3%, respectively. The percent lignified cells of Kentucky 31 tall fescue and rough bluegrass were 49.8 and 21.4%, respectively, based on total leaf cross‐sectional area. The percent Sclerenchyma fibers and lignified cells were closely associated with the wear tolerance observed for the two species.
Performance of Three Warm‐season Perennial Grasses and a Native Range Mixture as Influenced by N and P Fertilization1
Authors: Taliaferro C. M. , Horn F. P. , Tucker B. B. , Totusek R. , Morrison R. D.
Published: July 2010

Several perennial, warm‐season grass species are being used to revegetate depleted rangeland in parts of the southern Great Plains, particularly Oklahoma and Texas. This experiment was conducted to provide comparative data on the yield and quality of forage of three introduced grasses and a native range grass mixture as influenced by nitrogen and phosphorus fertilization.

‘Midland’ bermudagrass [Cynodon dactylon (L.) Pers.], ‘Morpa’ weeping lovegrass [Eragrostis curvula (Schrad.) Nees], ‘Plains’ bluestem [Bothriochloa ischaemum (L.) Keng var. ischaemum] and an existing native range grass mixture consisting largely of Bouteloua and Andropogon sp., with some Panicum and Sorghastrum sp., were evaluated for dry matter (DM) yield for 3 years and crude protein (CP) and in vitro dry matter digestibility (IVDMD) for 2 years under four levels of N and two of P. Levels of N were 0, 67, 135, and 269 kg/ha applied annually in split applications. Levels of P were 0 and 90 kg/ha; the 90 kg level applied annually in a single March application.

All grasses and the range mixture responded to increasing N levels with increased DM yield and CP percentage. The three introduced grasses also responded to increasing N levels with increased IVDMD, but the native range mixture did not. The three introduced grasses and the native range mixture responded in yield to application of 90 kg/ha of P. Yield response to P was significant and increased in response with increasing amounts of N. This response was greatest at the 135 and 269 kg/ha N levels. The addition of P had no discernible effect on the IVDMD of the introduced grasses or native range mixture but decreased their CP percentage. Significant interactions included grass (G) × N, G × P, G × year, and N × P. Morpa weeping lovegrass and Plains bluestem were more productive than Midland bermudagrass, particularly in the absence of and at the 67 kg/ha N level. At the higher N levels, Midland bermudagrass was most responsive to P. The native range mixture was least responsive to N and P fertilization and its DM yield was significantly less than that of the other three grasses.
Yield, Regrowth, and Persistence of Sainfoin under Fertilization1
Authors: Meyer D. W.
Published: July 2010

Sainfoin (Onobrychis viciaefolia Scop.) forage yields frequently are inferior to alfalfa (Medicago sativa L.) where seasonal rainfall is adequate due to sainfoin's poor regrowth and plant vigor. Inoculated sainfoin plants typically show nitrogen deficiency symptoms at Fargo, N. Dak.; therefore, N, P, and K were applied broadcast on a 3‐year‐old, inoculated ‘Eski’ stand attempting to reduce deficiency symptoms, stimulate substantial regrowth, and thereby yield.

N increased sainfoin's weed‐free forage yield during the third and fourth harvest years for each increment applied up to 448 kg/ha. Plants vigor and regrowth, as indicated by aftermath harvest, was enhanced by N fertilization. Stand persistence was poor for all treatments except 448 kg N/ha. Sainfoin forage yields do not compare favorably with the third and fourth harvest year productivity of unfertilized, inoculated alfalfa even when fertilized with 448 kg N/ha. Phosphorus and K treatments, alone or in combinations with N, had little detectable influence on yield, recovery, or stand persistence.
Effect of Liming a Highly Al‐saturated Soil on the Top and Root Growth and Soybean Nodulation1
Authors: Sartain J. B. , Kamprath E. J.
Published: July 2010

Relatively little information is available on the effects of liming on roots as compared with tops. To study the effect of various Al saturations on the growth of tops, roots, nodules, and nutrient accumulation of soybeans (Glycine max L.), several rates of lime were added to an acid soil in a greenhouse experiment. Dry weight of tops increased as the Al saturation was decreased by liming. Total dry weight and length of roots were unaffected by the soil treatments. Primary root weight was increased by liming. Root morphology, however, changed in that the lateral root weight decreased and the length per gram fresh weight of lateral root increased with decreasing Al saturation. Liming promoted the formation of a larger number of small diameter lateral roots. Nodulation, best expressed by nodule number, increased with liming and was highly correlated with the Ca content of the primary root.

Top dry weight was significantly correlated with the K concentration of the tops, Ca and Al concentration of the nodules, Mg concentration of the root mass, and the Zn concentration of the primary root. Total uptake/cm of root and equivalent elemental ratios were not as highly correlated with growth as concentration. Nodule number was significantly correlated with the total Ca and P content of the primary root, total P and Mg content of nodules, and the Ca/Al ratio of the nodule.
Soil Water Extraction by Alfalfa1
Authors: Brun L. J. , Worcester B. K.
Published: July 2010

Saline seeps have developed because of the accumulation of water beyond the rooting zone of annual crops. The purpose of this experiment was to show the potential of alfalfa (Medicago sativa L.) to extract soil water under a variety of textural and salinity conditions. Soils examined belong to suborders Ustoll and Boroll.

Core samples were taken in alfalfa fields and fields under crop‐fallow management to evaluate their present water content, 15 atm. percentage, texture, and salinity level.

Significant extraction of soil water occurs to depths of 3 to 4 m. Alfalfa extracted soil water held at a tension greater than 15 atm. in both saline and non‐saline segments of the soil profile. A minimum soil moisture level was reached at the 1.22 to 2.44 m depth in alfalfa fields maintained 5 years.

Alfalfa is an invaluable crop for reducing soil wetness to alleviate the saline‐seep problems of western North Dakota and eastern Montana.
Effects of Organic Preservatives on the Quality of Aerobically Stored High Moisture Baled Hay1
Authors: Sheaffer C. C. , Clark N. A.
Published: July 2010

Aerobic storage of hay at high moisture levels results in losses of forage quality due to microbial growth. Yet, the determination of safe forage moisture levels in the field is difficult, and farmers also must often store hay at above optimum moisture levels in order to avoid losses due to inclement weather. Two experiments were conducted in which propionic acid and ammonium isobutyrate were manually applied to high moisture alfalfa‐timothy (Medicago sativa L. ‐ Phleum pratense L.) hay in order to evaluate their effectiveness in preventing mold growth. Rates of preservative application for hay baled at 31% moisture content were: O, 1.00, 1.50, 1.75, and 2.00% by weight; for hay baled at 40% moisture content, rates were: O, 2.00, 3.00, 4.00, and 5.00%. Temperatures were monitored and in vitro digestibility (IVDMD), acid detergent fiber (ADF), and acid detergent insoluble N (ADIN) were determined.

There were no significant differences in the preserving effects of the two compounds; however, there were significant differences in rates necessary to preserve the hay at a given moisture level. Hay baled at a moisture content of 31% and treated with preservatives at rates of 1.50 to 2.00% had significantly lower storage temperatures and significantly higher IVDMD than untreated hay and hay sprayed at the 1.00% rate. Rates of application of 3.00 to 5.00% were effective in significantly reducing storage temperatures and maintaining forage quality of hay baled at 40% moisture.

Propionic acid and ammonium isobutyrate can effectively preserve high moisture aerobically stored hay. Rates of application must be based on the moisture content of the hay at the time of baling.
Ultraviolet Radiation Reflectance, Transmittance, and Absorptance by Plant Leaf Epidermises1
Authors: Gausman H. W. , Rodriguez R. R. , Escobar D. E.
Published: July 2010

Partial destruction of ozone in the earth's upper atmosphere (stratosphere) will increase levels of ultraviolet (UV) radiation that reach the earth's surface; consequently, plants could be exposed to harmful amounts of UV‐B radiation (280 to 320 nm). The objective of our research was to characterize the reflectance, transmittance, and absorptance of UV‐B radiation by leaf epidermises. Accordingly, measurements were made spectrophotometrically over the 260 to 360‐nm wavelength, to encompass the UV‐B waveband, on epidermises of different thicknesses from six plant genera: Century plant (Agave americana L.), onion bulb (Allium cepa L.), peperomia (Peperomia obtusifolia A. Dietr.), yucca (Yucca treculeana Carr.), kalanchoe (Kalanchoe laciniata DC.), and pricklypear (Opuntia lindheimeri Engelm.).

Thick epidermises of pricklypear, peperomia, century plant, and yucca reflected and transmitted less and absorbed more UV radiation over the 260 to 360‐nm waveband than thinner epidermises of onion and kalanchoe. Absorptance of the critical UV‐B radiation ranged from 91 to 96% for the thick epidermises and from O to 66% for the thinner epidermises.

It is concluded that leaves of plants with thick epidermises would have less internal damage to inner tissues of their mesophylls by UV‐B radiation than leaves with thinner epidermises; however, UV‐B radiation may damage the epidermis itself.
Yield Response to Soil Warming: Vegetable Crops1
Authors: Rykbost K. A. , Boersma L. , Mack H. J. , Schmisseur W. E.
Published: July 2010

Waste heat appears in the form of warm condenser cooling water from power generating plants. It has been proposed to use this water with temperatures ranging from 25 to 40 C for warming soils by pumping it through buried pipes. Experiments were conducted to determine the effect of warming soils in this manner on the growth rates and yields of several crops. The proposed system was simulated with electrical heating cables buried 92 cm deep at a spacing of 183 cm. Heat source temperatures ranged from 35 to 38 C during the growing period. Heating increased the average temperature of the soil layer from O to 100 cm deep by about 10 C. The average temperature increase of the O to 10 cm depth soil layer was μ 3 C. The crops tested were bush beans (Phaseolus vulgaris), lima beans (Phaseolus lunatus), tomatoes (Lycopersicmi esculentum), broccoli (Brassica oleracea), peppers (Capsicum annuum), and strawberries (Fragaria virginiana).

The yield increases, expressed as percentages of yields obtained on unheated plots, ranged from 19% for bush beans to about 100% for broccoli. The greatest advantage gained from soil warming occurred early in the growing season. The advantages decreased as the season progressed. The plants continued to grow fastest on heated plots throughout the growing periods however. Soil warming sustained growth rates of bush beans in the early fall when plants on unheated plots were slowed in growth. A wide variation in yield responses occurred between different years for the same crop and between different crops during the same year. The highest yield increases occurred during years when the yields on unheated plots were lowest. Correlations between yield increases and yields from unheated plots were highly significant.
Moisture Absorption, Mold Growth, and Decomposition of Rice Straw at Different Relative Humidities1
Authors: Sain Pritam , Broadbent F. E.
Published: July 2010

Moisture and humidity relationships of rice straw are important in relation to the extent of decomposition that may occur during the winter season. Ground rice straw was exposed to constant relative humidities to measure moisture absorption, decomposition, and mold growth. Moisture absorption by rice straw was very rapid during the first few hours and approached equilibrium within 1 to 4 days depending upon the relative humidity. Moisture content at equilibrium at a given relative humidity was always greater at 8 than at 25 C. The relation between moisture absorption and relative humidity above 70% followed a parabolic function of the form M = a + bR + cR2 where M = % moisture, R = relative humidity, and a, b and c are constants. The rate and extent of straw decomposition were found to increase and the lag period of decrease with increasing relative humidity and temperature. The transition between slow and active decomposition of rice straw was at about 90% relative humidity. The threshold moisture content of rice straw for mold growth, defined as the highest moisture content at which it takes infinite time for the initiation of fungal growth, was found to be 7.5%.
Nutrient Uptake by Russet Burbank Potatoes as Influenced By Fertilization1
Authors: Jackson T. L. , Carter G. E.
Published: July 2010

Zinc and Mn deficiencies have been observed frequently in potatoes grown on eastern Oregon soils developed under arid conditions. The study was designed to evaluate effects of band and broadcast applications of ammonium sulfate (AS) and monocalcium phosphate (MCP) on yield and uptake of P, Zn, and Mn by Russet Burbank potatoes (Solanum tuberosum L.) grown on calcareous mineral soil deficient in N, P, Zn, and Mn.

Potatoes were grown under field conditions, harvested and evaluated. Fertilizer treatments were broadcast before planting and rototilled or banded at planting. Petiole samples to identify nutrient concentrations were taken when tubers were 2 cm in diam. Whole plants were harvested 3 weeks later to measure nutrient uptake.

Petiole concentrations and plant uptake of both Zn and Mn were greater when AS was banded than when broadcast, with or without band applications of Zn and Mn.

Highest P concentrations were found on check plots or when P alone was applied. Treatments producing increased Zn concentrations in plants were associated with reduced P concentrations. Banded AS with or without Zn and Mn produced the largest yield increase but resulted in reduced P uptake. Increased P uptake occurred only after Zn and Mn deficiencies were corrected. Moderate increases in uptake of Zn and Mn resulted from banding of MCP, Zn, and Mn.
Nitrogen Uptake Characteristics of Corn Roots at Low N Concentration as Influenced by Plant Age1
Authors: Edwards J. H. , Barber S. A.
Published: July 2010

Information is needed on the relation between concentration of N in solution, CN, and the rate of N uptake by corn (Zea mays L.) roots in order to evaluate the soil and crop parameters affecting N fertilizer efficiency. Data on net N influx, In, vs. CN were obtained for N levels below 150 μM on corn plants of seven ages ranging from 15 to 58 days (2 weeks after tasseling). In was determined by measuring rate of N depletion from the solution in which corn plants grew. Both NH+4 and NO‐3 forms of N were used. The experiments were conducted in the growth chamber and greenhouse.

Maximum influx, In‐max, occurred above 21 μM N concentration. Values of In‐max, varied with plant age and were greatest with 18 to 24‐day‐old plants and decreased exponentially to 58‐day‐old plants. In ceased when the averaged CN value decreased to 4 μM. This minimum N concentration varied little with plant age. Since the range of CN values where In varied was only 4 to 21 μM, the time period when CN is within this range for corn growing in the field is probably short so In will usually be at either In‐max or 0.
Response of Cotton to Row Patterns and Plant Populations1
Authors: Baker Shelby H.
Published: July 2010

Theoretically, cotton planted in narrow rows at high plant populations has a potential of reducing production cost by promoting earlier maturity. The cost of controlling insects, weeds, and harvest due to a once‐over harvest would all be reduced.

Studies were conducted to determine how a cultivar developed for conventional production methods would respond to a narrow row system. Coker 310 was planted in conventional 91.4 cm rows at a population of 107,489 plants/ha, in four 40.6 cm rows on a 182.9 cm bed and in twin 25.4 cm rows on a 91.4 cm bed at populations of 214,977; 286,636; and 358,295 plants/ha for 3 years.

There were no differences in yield, earliness, lint percent, fiber length or strength between narrow row and the conventional check. The conventional check produced larger bolls, fewer blooms, a lower potential yield and set a higher percent of early blooms.

Narrow rows gave no differences in total yield, earliness, lint percent, fiber length, or strength resulting from row patterns or plant populations. The highest plant population gave more blooms in twin 25.4 cm rows, but not in 40.6 cm rows. Potential yield was not influenced by population within row patterns, but there was a row pattern response at the same plant population.

Boll size tended to be inversely related to plant population. The highest plant population in the 40.6 cm rows produced a finer fiber than other treatments.

This study indicates the potential of high population — narrow row planting is lost mainly through excessive shedding of young bolls during the first 3 weeks of blooming.
Water Vapor Sorption by the Walls and Sensors of Stomatal Diffusion Porometers1
Authors: Gandar P. W. , Tanner C. B.
Published: July 2010

The operation of stomatal diffusion porometers is affected by sorption of water vapor by the humidity sensor and the walls of the porometer. The objective of this study was to assess the amount of water vapor sorbed by Dunmore lithium chloride humidity sensors and by materials commonly used in porometer construction. Measurements of water sorption by stainless steel, acrylic plastic, wax‐coated acrylic, and humidity sensors were made at different relative humidities (RH) in the range of 22 to 28% RH and temperatures of 20, 25, and 30 C, by measuring the vapor mass balance at different RH. Stainless steel absorbed 0.5 ± 0.25 μg cm−2 of water vapor at 22 to 28% RH and temperatures from 20 to 30 C. Water vapor diffused into acrylic (D ≈ 2.5 × 10−9 cm2sec−1) so the sorption was not constant. Coating acrylic with wax significantly reduced water sorption; at 25 C the sorption of waxed acrylic was in the range 0.9 to 1.2 μg cm−2. The sorption by the humidity sensors varied with RH, temperature, sensor age, and prior treatment. At 25 C and 26% RH the sorption of the external sensor surface was about 40 μg cm−2. Materials with low sorptivities, such as stainless steel or waxed surfaces, should be used in the construction of diffusion porometers. Procedures which minimize variability in sorption, such as storage at RH near the operating range of the sensor, should be followed when porometers are used.
Effect of Fertilizer‐N and Herbicides on the Growth and N Content of Sunflower1
Authors: Sameni A. M. , Maftoun M. , Hojjati S. M. , Sheibany B.
Published: July 2010

Little is known about herbicide‐N fertilizer combinations with respect to the growth and mineral composition of sunflower (Helianthus annuus L.). The present study was undertaken to evaluate the effect of prometryn (2,4‐bis(isopropylamino)‐6‐(methylthio)‐s‐triazine), terbutryn (2‐(tert‐butylamino)‐4‐(ethylamino)‐6‐(methylthio)‐striazine), trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine), and N level on the growth and N uptake by this crop. Sunflower was grown in greenhouse for 60 days in soil to which was added various levels of N and herbicides. Dry matter yields, N concentration and N uptake were determined. Low N levels significantly increased stem diameter and chlorophyll content of leaves as compared to the no N level. Nitrogen application above 25 ppm did not increase stem diameter. All N‐treated plants produced more dry matter and contained significantly higher N than untreated seedlings. Prometryntreated seedlings developed chlorotic symptoms, causing plant death. Nitrogen uptake increased with 1 ppm terbutryn, but 2 ppm terbutryn increased N concentration and uptake but decreased plant height, stem diameter, chlorophyll content, and total plant weight of sunflower. The tendency for terbutryn to increase N concentration was more pronounced when sunflower was under N stress. Trifluralin did not significantly increase top dry weight or N uptake, nor did it interact with N treatments.
Infinite Reflectance of Dead Compared with Live Vegetation1
Authors: Gausman H. W. , Rodriguez R. R. , Richardson A. J.
Published: July 2010

The objective was to compare the infinite reflectance (R∞) of dead and live corn (Zea mays L.) leaves over the 0.5‐ to 2.5‐μm waveband to find a means of distinguishing live from dead vegetation for remote sensing purposes; previous studies have been concerned only with R∞ of live leaves. In this study, for both dead and live leaves, reflectance measurements were made on a single leaf seciton and for sections stacked two, three, four, five, six, seven, and eight at a time over a spectrophotometer's port. Live leaf R∞ was essentially attained by stacking two leaves for the 0.5‐ to 0.75μm waveband (chlorophyll absorption region), eight leaves for the 0.75‐ to 1.35‐μm waveband (near‐infrared region), and three leaves for the 1.35‐ to 2.5‐μm waveband (water absorption region). Dead leaf R∞ was reached over the entire 0.5‐ to 2.5‐μm waveband by stacking only two or three leaves. Thus aircraft and spacecraft reflectance measuring techniques probably cannot distinguish density differences of dead vegetation but they should distinguish density differences of live vegetation. Near‐infrared reflectance differences between dead and live vegetation also should be detectable with satellite multispectral scanner data.
Water Transport in Wheat Plants in the Field1
Authors: Denmead O. T. , Millar B. D.
Published: July 2010

Most previous studies of water transport in crops have been based on simplified models of plant anatomy and canopy transpiration. Usually changes in the water potential of a particular leaf have been related to the water loss from the whole canopy. We present a more detailed analysis of plant water transport which accounts for the spatial distribution of water flows and transpiration losses throughout the canopy, and use it to estimate flow resistances in different segments of the pathway.

Micrometeorological measurements of the flux densities of water vapor in the canopy were used to infer water fluxes through roots, stem sections, leaves, and ears of wheat plants (Triticum aestivum L. ‘Heron’) in the field. Simultaneous measurements of soil‐ and leaf‐water potentials permitted calculation of flow resistances in roots, stems, and leaves.

There were no significant differences in resistances between an irrigated and a dryland crop, although the patterns of stem flow differed markedly. The resistance of the root system of an individual tiller was (1.00 ± 0.37) × 10' bar sec cm‐3 and the resistance/unit length of stems and leaves was (1.59 ± 0.19) × 103 bar sec cm‐4. These large plant resistances may often be as important in determining leaf water potentials as the transmission resistance of the soil. The study shows clearly how the water loss from one part of the canopy influences the development of water potentials in other parts and points up the difficulties of simplified transport models.