bluuebunny/crossref_metadata_2025 huggingface dataset:
A Sunfleck Theory for Plant Canopies II. Penumbra Effect: Intensity Distributions along Sunfleck Segments1
Authors: Miller E. E. , Norman J. M.
Published: July 2010

The finite (1/2°) angular diameter of the sun causes the fuzziness of the shadow cast onto the ground by a leaf edge to increase in proportion to increase in height of the leaf. When a straight‐line sunfleck segment is terminated by a leaf edge that cuts across it at a slant, the apparent width of the penumbral fringe displayed upon the segment is stretched by the slant.

In this paper the intensity distribution along a slanting traverse of a penumbral shadow edge is computed, the statistical distributions of leaf‐edge angles at the ends of segments are analyzed, and these two distributions are combined into a statistically‐averaged intensity distribution along the segment, the distribution being dependent upon the segment length. When this intensity distribution is incorporated into the segment length distribution from the preceding paper of this series, a useful prediction is obtained for the complete distribution of intensity within a plant canopy.
Reflectance and Internal Structure of Leaves from Several Crops During a Growing Season1
Authors: Sinclair T. R. , Hoffer R. M. , Schreiber M. M.
Published: July 2010

The reflectance spectra from 500 to 2600 nm were measured for the leaves of six agronomic crops. Leaf samples were collected at three periods during the growing season; water content was determined and cross sections of the internal leaf structure were observed microscopically. The reflectance spectra of all fresh, green leaves were very similar. However, reflectance at all wavelengths increased as the crop matured and their leaves senesced. Decreased absorption by chlorophyll apparently increased the reflectance of the visible wavelengths (500 to 700 nm). Similarly, water loss accompanying senescence resulted in an increased reflectance in the far infrared wavelengths (1300 to 2600 nm). Changes in the internal structure of leaves caused increases in the near infrared wavelengths (700 to 1300 nm).
Critical Levels of P in Subclover (Trifolium subterraneum L.)1
Authors: Jones M. B. , Ruckman J. E. , Lawler P. W.
Published: July 2010

Phosphorus deficiencies are widespread in California annual grasslands and in other areas of the world where subclover (Trifolium subterraneum L.) is an important legume. Therefore, the effects of clipping frequency and stage of growth on critical levels of P in subclover were studied. Critical P level was defined as percent P in the clover part when lack of P limited clover yields to 95% of those obtained with adequate P.

In pot experiments subclover was grown in P‐deficient soils fertilized with increasing amounts of P until no additional increase in yield was obtained. When leaves were sampled from plants 48 to 151 days of age, the critical level decreased from 0.61 to 0.11% P, but changes after 120 days were not statistically significant.

At day 120, leaves from plants previously defoliated 0, 1, 2, or 3 times had critical values of 0.11, 0.18, 0.23, and 0.28% P, respectively. The last three determinations were for leaves of the same physiological age harvested 13 days after the previous clipping. At 120 days critical P values in stem tissue also increased with increasing frequency of defoliation.
Relationships between Soil Properties, Management Practices, and Corn Yields on South Atlantic Coastal Plain Soils1
Authors: Sopher Charles D. , McCracken Ralph J.
Published: July 2010

Correlations between individual soil properties, management practices, and corn (Zea mays L.) grain yields were observed for 441 corn plots on selected North Carolina Coastal Plain soils. Correlations between different soil properties within soil horizons and correlations between the same properties in adjacent soil horizons show that many of the variables in the crop‐soil ecological system are highly intercorrelated. These intercorrelations limit the usefulness of both simple and multiple regression to characterize cause and effect relationships within the system. However, they can be useful in helping to understand the complex system and to develop soil sampling techniques for future characterizations of the system.

Of the 101 independent variables (23 soil properties on each of 4 horizons plus nine management variables) included, 56 variables were significantly correlated with corn grain yields on the well‐drained (Udultic) soils Upper and Middle Coastal Plains (mainly Hapludults and Paleudults). Sixty‐one variables were significantly correlated with yields on the very poorly drained (Aquultic) soils of the Tidewater region (mainly Umbraquults and Ochraquults). The factors most affecting yields on both soil groups were soil moisture holding capacities, certain combinations of clay and sand, extractable P, percent base saturation and properties which control soil acidity, the amount of charge on the cation exchange complex, plant populations, and planting dates. Because of previous high management levels of the fields sampled, applied nutrients were deemed important but not highly limiting on the two soil groups studied.
Nitrogen Utilization by Rice Using 15N‐Depleted Ammonium Sulfate1
Authors: Patrick W. H. , Delaune R. D. , Peterson F. J.
Published: July 2010

A field experiment utilizing 15N‐depleted ammonium sulfate was carried out to determine the efficiency with which lowland rice utilized fertilizer nitrogen in large (2.1 ✕15.2 m) plots. Relative uptake of labelled and nonlabelled nitrogen was followed throughout the growing season. At the soft dough stage, small (0.84 m2) subplots were cut and the total aboveground uptake of labelled and non‐labelled nitrogen determined. Labelled and non‐labelled nitrogen contents of the harvested grain was determined.

The results showed that nitrogen utilization by lowland rice (Oryza saliva L.) was poor, with 17 and 23% recovery of applied nitrogen in the aboveground portion of the crop at the soft dough stage for 56 and 112 kg/ha rates, respectively. Approximately 12% of the applied nitrogen was recovered in the unmilled grain. The fraction of plant nitrogen coming from fertilizer was relatively high (about three‐fourths) early in the season but decreased to as little as one‐fifth as the season progresssed. Yield response, total nitrogen uptake, and uptake of fertilizer nitrogen were higher for the 112 kg/ha rate than for the 56 kg/ha rate. Even though nitrogen utilization was low, fertilizer nitrogen markedly increased the yield of grain.
Late Summer Irrigation and Establishment of Winter Annual Legumes in a Mediterranean‐type Climate1
Authors: Taggard K. L. , Delmas R. E. , Raguse C. A.
Published: July 2010

Winter annual legumes have low fall and early winter forage yields in California's Mediterranean‐type climate. A 2‐year field study was conducted to determine the effects of late summer irrigation on seedling development, forage yield potential, and management problems of subterranean clover (Trifolium subterraneum L.), rose clover (Trifolium hirtum All.), and bur clover (Medicago polymorpha Gaertn). A mixture of three annual grasses, slender wild oats (Avena barbata Pott. ex Link), ‘Blando’ brome (Bromus mollis L.), and annual ryegrass (Lolium multiflorum L.), and a natural stand of indigenous species were included in the study for comparison. By irrigation prior to fall rains, we subjected six successive seedings, 2 weeks apart, to higher temperatures and longer fall‐growth periods than usual.

Rates of morphological development of subclover and rose clover were measured until the seven‐leaf stage. In the 1972‐73 season, rose clover showed the largest differences in growth rates between planting dates. Rose clover from the 23 October planting required 90 more days to reach the seven‐leaf stage than when planted 29 September. Early‐flowering subclover from the 23 October planting grew more rapidly than did mid‐flowering subclover and rose clover. In the 1973‐74 season, late‐flowering sub‐clover had the fastest growth rate following 7 August irrigation; there were no differences between clovers following 20 September irrigation.

Forage yields for August and September plantings were similar but were greater than those from the October planting. Plants irrigated in August were subjected to daylengths which promoted fall flowering. Summer insect problems, primarily with beet armyworm (Spodoptera exigua Hübner), were associated with August plantings. Subterranean clover produced more dry matter and had fewer problems than did the other legumes tested.
Winter‐Annual Cover Crops for No‐Tillage Corn Production1
Authors: Mitchell W. H. , Teel M. R.
Published: July 2010

No‐tillage corn (Zea mays L.) production minimizes soil moisture and wind erosion losses on sandy soils. Use of leguminous cover crops for no‐tillage mulches would provide these benefits while at the same time supplying a source of biological nitrogen to supplement the N produced with fossil fuel energy. Hairy vetch (Vicia villosa Roth.) and crimson clover (Trifolium incarnatum L.) were grown alone and in combination with non‐leguminous species to determine their value as no‐tillage mulches and sources of biological N. Field tests were conducted on Evesboro loamy sand, a mesic coated Typic Quartzipsamments, involving eight cover crops, three levels of N, and two moisture regimes. Nitrogen was applied, just prior to killing the mulch covers with Paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) (0.28 kg a.i./ha) at rates to deliver 0, 56 and 112 kg N/ha. Hairy vetch and crimson clover mixtures produced grain yields comparable to those obtained by the application of 112 kg N/ha. Approximately one‐third of the total N from mulch covers was released to the corn in a single season, with about 90% of this derived from cover crop top growth. Heavy growth of rye mulch covers was associated with irregular and low corn populations. Mulch covers were less reflective than the bare soil surface, resulting in mulch surface temperatures up to 10 C higher than those with unprotected soil surface. Temperatures immediately below the mulch covers were more than 10 C lower than those at the soil surface.
Soybean Water Extraction, Leaf Water Potential, and Evapotranspiration During Drought1
Authors: Reicosky D. C. , Deaton D. E.
Published: July 2010

Soil water is often the most limiting factor in soybean production in the southeastern US. To increase wateruse efficiency in soybean production, it is necessary to characterize the plant's response to the evaporative demand and to soil water stress when the root distribution changes with depth. ‘Davis’ and ‘McNair 800’ soybean cultivars (Glycine max (L.) Merr.) were grown in a field experiment conducted on Norfolk sandy loam (Thermic Typic Paleudults) to evaluate the effect of irrigation on soybean yields and to determine the combined effects of soil matric potential and evaporative demand on evape transpiration (ET) in nonirrigated and irrigated treatments. Water was applied to the irrigated treatment when the matric potential at the 15cm depth was −0.2 bar. Leaf water potential was measured using the pressure chamber technique and ET was measured using a portable chamber during a 34day drought. Only small differences in the midday leaf water potential were found between the two cultivars, whereas ET on the nonirrigated treatments was about two‐thirds of that on the irrigated treatments 25 and 32 days into the drought. Soil matric potential data indicated significant water extraction at the 153‐cm depth in the nonirrigated treatments near the end of the drought. The maximum incanopy air temperature during the drought in the nonirrigated Davis was 6.7 C higher than in the irrigated treatment. Irrigation resulted in a 351‐ and 364‐kg/ha increase in Davis and McNair 800, respectively. Even though the nonirrigated plants exhibited severe wilt symptoms during the drought, the results point out the importance of the root distribution and subsoil water in partially meeting the evaporative demand during drought.
Volunteer Legume Control in Legume Seed Crops with Carbon Bands and Herbicides. II. Red Clover and Alfalfa1
Authors: Rolston M. Philip , Lee W. Orvid , Appleby Arnold P.
Published: July 2010

Volunteer legumes from seed in the soil may contaminate seed lots of red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.). No herbicides are available to selectively control these volunteers. Experiments were conducted in western Oregon to determine the potential of using activated carbon applied in 25‐mm bands over the seed row during planting to protect the crop from nonselective herbicides applied to control volunteer legumes. Control of volunteer legumes was estimated visually, and white clover stand and seed yields were measured. Greenhouse and field experiments demonstrated that both red clover and alfalfa can be established with carbon bands and diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea]. Tolerance of red clover to diuron varied with the season of establishment; the greatest injury occurred when diuron was applied in the fall to soils that were wet on the surface. Seed yields for red clover established with carbon bands and 0, 2, and 4 kg/ha diuron averaged 566, 560, and 348 kg/ha, respectively, across all treatments. Seed yield for the two legumes established in 30, 50, and 80‐cm row widths were: alfalfa, 264, 354, and 424 kg/ha, respectively; and red clover, 635, 584, and 376, respectively. In the greenhouse, EPTC (S‐ethyl dipropylthiocarbamate) granules at 10 mg/m of row applied as a mixture with the alfalfa seed, controlled perennial ryegrass (Lolium perenne L.) in the carbon band without reducing the number or weight of the alfalfa seedlings. Atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] or diuron at 1 and 3 kg/ha, respectively, controlled 85 to 99% of red clover volunteers.
Cultivar Response of Festuca rubra Seedlings to Aluminum1
Authors: Nittler L. W. , Kenny T. J.
Published: July 2010

Even though several characteristics useful for testing fescue (Chewings fescue Festuca rubra var. commutata Gaud., and red fescue, Festuca rubra L. var rubra) for cultivar purity have been identified, additional methods are needed for distinguishing similar cultivars. The investigation reported here was conducted to determine if cultivar differences not observable on untreated plants would develop in response to a high concentration of aluminum. Seedlings of 20 Chewings fescue and red fescue cultivars were grown in sand nutrient culture with a complete nutrient solution and with continuous light. Twenty‐eight days after seeds were planted a solution of Al2(SO4)3 in water with a concentration of 216 ppm actual Al was applied to the surface of the sand until solution drained from the bottoms of the flats. Thereafter the Al solution was applied 6 days a week and a complete nutrient solution was applied once a week. Plants were evaluated 15 days after the first Al application. Cultivars differed in percentage of plants that developed purplish red leaf blades and also in the percentage of plants that developed necrotic leaf blades. Plants classed as having red leaf blades were 63% and 61% respectively for Kensington and Banner, and, at the other extreme, 16%, 24%, and 24% for ‘Ensylva’, ‘Fortress’ and ‘K4‐21’. Plants classed as having necrotic leaf blades were 57%, 40% and 40% respectively for ‘Ruby’, Ensylva, and Fortress and 0% for ‘Banner’, 1% for ‘Highlight’ and 2% each for ‘Cascade’, ‘Encota’, and ‘Erika’. Cultivar differences were not great enough to place cultivars into discrete categories, but they were great enough to be useful for distinguishing contrasting types.
Root Growth and Morphology, Nutrient Uptake, and Nutrient Status of Soybeans as Affected by Soil K and Bulk Density1
Authors: Hallmark W. B. , Barber S. A.
Published: July 2010

Due in part to the difficulty of isolating roots from soil and measuring them, little research has been conducted on root growth and morphology and its relation to shoot growth, nutrient status of shoots, and net nutrient influx. A soil experiment was conducted to measure the effect of increasing soil K and soil bulk density on the above parameters and their interaction. A 2 × 2 × 3 factorial experiment (soil bulk density × K added × date of harvest) was conducted in a greenhouse using soybeans [Glycine max (L.) Merr.] grown in Raub silt loam soil (Aquic Argiudoll). Increasing soil K increased root and shoot growth but had a variable effect on net nutrient influx and plant nutrient content. Increasing soil bulk density reduced root growth, shoot growth, and nutrient composition of shoots but increased net nutrient influx. The detrimental effect of increasing soil bulk density on shoot growth and nutrient status of soybean plants may have been caused by decreased root growth, coarser roots, and lower root surface area/g shoot. Changes in nutrient influx and root surface area/g shoot in some cases counteracted each other in determining plant nutrient status.
An Analysis of Temporal and Regional Variation in Wheat Yields1
Authors: Feyerherm A. M. , Paulsen G. M.
Published: July 2010

The important meteorological and agronomic factors contributing to variation in grain yields over large areas are generally known, but their relative impact on temporal and regional variation has not been generally quantified. In any given year, one or more factors may be given undue credit for high or low yields. This investigation determined the contribution of certain meteorological and agronomic variables to variation in grain yields of fall and spring‐planted wheat (Triticum aestivum L. and T. durum Desf.) on a large‐area basis.

We previously developed a winter wheat (WW) and a spring wheat (SW) model to predict grain yields over large areas without the benefit of direct measurement of plant characteristics. The derived relations of meteorological events, applied N, and certain soil characters to yield were considered to be universally applicable temporally and globally. In this study, we applied the models to different years (1955 through 1976) and regions in the U.S. Great Plains and Corn Belt.

For WW in semiarid regions of the U.S. Great Plains, soil moisture deficiencies were more important than high temperatures or excessive precipitation as a yield determinant but, for SW, high temperatures were more important than soil moisture‐related variables. During 1955 to 1976 weather conditions for WW yields were poorest during 1956 and best during 1973. Weather conditions for SW yields were poorest during 1961 and best during 1958.

Increases in WW yields between 1955 and 1976 attributed to applied N varied from 1.0 quintals/ha in semiarid zones to 2.9 quintals/ha in the more humid Corn Belt. Increases attributed to higher‐yielding cultivars ranged from 7% in the Southern Plains to 25% in the Corn Belt for WW and from 15% in the western portion to 25% in the eastern portion for SW.

Yields of WW over the 22‐year period averaged 9.8 quintals/ha higher in the Corn Belt than in the Southern Plains. That difference was attributed to more favorable weather, heavier applications of N, higher‐yielding cultivars, and better soils in the Corn Belt. The difference would have been larger were it not for irrigation in the Southern Plains. Higher yields in the eastern SW region were attributed to more favorable weather, better soils, and higher‐yielding cultivars.
Germination of Great Basin Wildrye Seeds Collected from Native Stands1
Authors: Young James A. , Evans Raymond A.
Published: July 2010

Great Basin wildrye (Elymus cinereus Scribn. & Merr.) is a valuable forage species adapted to saline/alkaline and upland soils on western North American rangelands. Currently, selections are being evaluated for release as cultivators. Germination under high osmotic stress is an important factor in these evaluations. We collected seeds from widely differing habitats and germinated them under osmotic potentials varying from 0 to −16 bars. Osmotic potentials were reduced either with polyethylene glycol (PEG) or NaCl. Under reduced osmotic potentials, germination was strongly negatively correlated with the electrical conductivity (EC) and sodium‐absorption ratios (SAR) of the surface soils where the seeds had been produced. Seedling emergence and growth in a saline/alkaline soil (aquic Durorthidic Torrorthent) were better with seeds produced from plants growing on nonalkaline upland soils than from those growing on saline/alkaline soils. There was no marked correlation between germination with no osmotic stress, seed weight, or percent fill and the characteristics of the soil where the seeds had been produced. It would seem that plants of Great Basin wildrye adapted for growth on saline/alkaline soils produce seeds ill adapted for germination in this environment. Conversely, seeds produced from plants growing under nonalkaline conditions are more adapted to germinate in saline/alkaline soils.
Anthracnose Development on Annual Bluegrass in Response to Nitrogen Carriers and Fungicide Application1
Authors: Danneberger T. K. , Vargas J. M. , Rieke P. E. , Street J. R.
Published: July 2010

Anthracnose caused by Colletotrichum graminicola (Ces.) Wils., is a serious disease of annual bluegrass (Poa annua L.) turf. In the northern and pacific‐northwestern United States, annual bluegrass is the predominant golf course turfgrass and in some instances the main turfgrass species of home lawns. In turf, cultural practices are effective ways of controlling many turfgrass diseases. However, no reports are available on cultural practices that may reduce or control anthracnose development on annual bluegrass. The purpose of this study was to look at one cultural practice, N fertilization, along with fungicide treatments for controlling anthracnose. A field study was initiated in November of 1979. Three N carriers (isobutylidene diurea, sulfur‐coated urea, and urea), applied at two rates (1.46 kg N/are/year and 2.92 kg N/are/year) and two timings spring (April initiation) and summer (June initiation), with or without fungicide treatments were evaluated for anthracnose control. Triademefon [1‐(4‐Chlorophenoxy)‐3,3‐dimethyl‐1‐(1H‐1,2,4‐triazol‐1‐yl)‐2‐butanone] fungicide treatments provided the most effective management of anthracnose. Fungicide treated plots averaged 1.9 and 1.7% infected area for 1980 and 1981 whereas non‐fungicide treated plots were 29.6 and 30.6% infected, respectively. Type of N carrier, whether isobutylidene diurea (IBDU), sulfur‐coated urea (SCU) or urea, had no effect on anthracnose development. Moderate N levels (1.46 kg/are/year) were associated with less disease incidence than the higher level of N (2.92 kg/are/year). Nitrogen applications during the months of June, July, August, September, and November resulted in less disease than N applied in April, May, June, August, and September. Growth chamber inoculation studies showed the number of acervuli formed decreased with increasing N at 22 C. At 32 C, the number of acervuli decreased with increasing N to 0.90 kg/ are but increased at the 1.80 kg/are N rate. In conclusion, N fertilization program of applying moderate levels of N (1.46 kg/are/year) with applications beginning in June followed with applications in July, August, September, and November at 0.24, 0.24, 0.24, 0.24, and 0.48 kg N/are, respectively, resulted in less anthracnose damage than the higher level of N (2.92 kg/are/year) or the alternate application schedule (April, May, June, August, September). If the N program was combined with fungicide applications, anthracnose was effectively controlled.
Relative Grazing Preference of Panicum Germplasm from Three Taxa
Authors: Burns J. C. , Timothy D. H. , Mochrie R. D. , Fisher D. S.
Published: July 2010

Switchgrass (Panicum virgatum L.) has shown potential in the humid United States for being a valuable livestock feed. Its contribution would be enhanced, however, by improved quality and palatability. The objective of this study was to determine if relative preference differences existed within germplasm of the Panicum taxa. Twenty‐four accessions representing three Panicum taxa [Panicum amarum Elliot var. amarum, P. amarum var. amarulum (Hitch. and Chase) P.G. Palmer, and P. virgatum L.] were selected from a collection of 92 naturally occurring accessions based on desirable morphological and quality traits. These accessions represented grazing (G), hay (H), and intermediate (I) morphological types. The eight accessions selected to represent each type varied considerably in morphology. The G and I types evaluated in one experiment and the H types in a second, were established in four replicates on a Cecil clay loam (clayey, kaolinitic, thermic Typic Hapludult) soil. Relative preference scores (1 = least preferred and 10 = most preferred) achieved by defoliation with yearling steers (>BOS taurus) showed a consistent preference difference among accessions within types. The strongest differential in palatability was noted within the G types. Entry #16, the most preferred with a mean rating of 8.1, scored 7 to 10 for 45 out of 48 defoliation opportunities. Entry #13, the least preferred with a mean rating of 3.4, scored 1 to 3 for 31 out of 48 opportunities. Preference was not taxon related. Animal defoliation scores (preference) were not highly correlated (r < 0.60) with in vitro dry matter disappearance, considered the best laboratory index of quality, nor with fiber fraction concentrations or agronomic measurements (canopy height and percent stand). Those entries identified with highest preference in each of the G, I, and H types offer potentially valuable germplasm sources for incorporating desirable traits into switchgrass cultivars. The presence of relatively unpalatable naturally occurring germplasm in the Panicum taxa cautions against indiscriminate use of wild types for agronomic improvement of present cultivars.
Genotypic Sensitivity to Drought and Yield Potential of Peanut
Authors: Rao R. C. Nageswara , Williams J. H. , Singh Murari
Published: July 2010

It is important to understand genotype ✕ drought pattern (timing, duration) interactions in peanut (Arachis hypogaea L.) to develop managerial and breeding strategies for improving and stabilizing yields in drought‐prone areas or in environments with limited water resources. This study investigated genotypic sensitivity to various patterns of drought (yield decrease per unit of water deficit) and its relationship with yield potential (yield under nonstressed conditions) in a range of peanut genotypes grown on a medium deep Alfisol at ICRISAT center, Patancheru, A.P. India. In the first experiment, 22 peanut genotypes of similar maturity were evaluted in 12 drought patterns. Single and multiple periods of water deficits were created during various crop growth phases. In the second and third experiments, 60 and 64 genotypes were subjected to droughts during pod set and seed filling stages, respectively. When water deficit occurred during seed filling phase, genotypic yield potential accounted for approximately 90% of the variation in pod yield sensitivity to water deficits. It is unlikely, therefore, that breeders will be able to combine high yield potential with low sensitivity to drought spanning the seed‐filling phase, therefore other improvement strategies are necessary. Pod yield potential accounted for less of the variation in drought sensitivity (15 to 64%) in early and midseason droughts. For these circumstances it may be possible to identify genotypes with both high yield potential and relatively low drought sensitivity.
Design and Evaluation of a Neutron Access Tube Extractor
Authors: Weaver Barry A. , Morgan Jack A. , Whitt Douglas E.
Published: July 2010

The labor and material costs associated with extracting neutron access tubes used for neutron probe soil water determinations can be substantial. Present commercially available access tube extractors are clumsy to use, and can ruin tubes that are being extracted from high clay content soils. To remedy these problems, a new access tube extractor was designed. The extractor slips over the tube to be removed and is secured in place by a threaded collar that provides the initial pressure to hold it in place until the extraction force is applied. As the extractor pulls on the access tube during removal, conically‐tapered jaws exert additional clamping pressure on the tube in greater proportion than the pulling force required to remove the tube. The device easily extracts access tubes against a resistance of up to 13.7 kN (3086 lb.) with no damage to the tubes. Either a mechanical jack or a hydraulic lift on a tractor may be used to extract access tubes.
Foliar Feeding of Cotton: Evaluating Potassium Sources, Potassium Solution Buffering, and Boron
Authors: Howard Donald D. , Gwathmey C. Owen , Sams Carl E.
Published: July 2010

Foliar applications of K may be used to supplement soil applications to maximize yields of cotton (Gossypium hirsutum L.). Response to foliar K applications may be improved by choice of K source, buffering the spray solution, or applying K with B. Research was conducted on a Collins silt loam (coarse‐silty, mixed, acid, thermic Aquic Udifluvents) and on a Memphis silt loam (fine‐silty, mixed, active, thermic Typic Hapludalfs) to evaluate KNO3, K2SO4 K2S2O3, and KCl as K sources. A second study evaluated foliar KNO3 and K2SO4 solutions applied unbuffered and buffered to pH 6 and 4 on cotton K nutrition and yield. Foliar K in both studies was applied at 4.1 kg K ha−1 per application. A third study evaluated combinations of soil‐applied and foliar‐applied B and K. Foliar treatments were applied in 93.5 L ha−1 water at early flower or 2 wk after and repeated on a 9‐ to 14‐d interval between the four applications. Yields from the four K sources averaged 10% higher than the untreated check and yields with KNO3 were 4% higher than the other K sources. Buffering two K source solutions to pH 4 resulted in 10% higher yields than the check or unbuffered K solutions. Adding a surfactant (ethoxylated alkyl aryl phosphate esters) to KNO3 resulted in 5% higher yields then the check. Compared with untreated check yields, soil‐applied B at 0.56 kg B ha−1 increased yields by 6%, four foliar applications of 0.11 kg B ha−1 increased yields by 8%, and four foliar applications of 0.11 kg B plus 4.1 kg K ha−1 increased yields by 13%. Foliar K solution buffering and/or the inclusion of foliar B are relatively inexpensive ways of improving yield response. Based on yield increases in this study, these treatments should return 8 to 10 times the product costs.
‘Georgia‐5’ Tall Fescue Establishment Responses to Amendment of Louisiana Coastal Plain Soils
Authors: Pitman W. D.
Published: July 2010

Release of ‘Georgia‐5’ tall fescue (Festuca arundinacea Schreb.) expanded the range of this species into the Coastal Plain of the southeastern USA. Initial plantings indicated that responses to lime and P may be greater on infertile, acid Coastal Plain soils than reported within the primary area of adaptation. Three field experiments and a greenhouse experiment were conducted on Louisiana Coastal Plain soils. In the field, all combinations of 50 kg P ha−1, 90 kg K ha−1, and 4.0 Mg lime ha−1 were applied. In one experiment, all treatments which included P increased establishment‐year forage yield, with an increase from 310 kg ha−1 for the control to 1500 kg ha−1 with P alone. Plant responses to lime were obtained at this site in the second year. In the other experiments, drought apparently precluded responses at one site, while plant stands improved with lime at the other site. Linear plant responses to P up to 80 kg ha−1 (soil P of 142 mg kg−1) and a quadratic response to lime were obtained in the greenhouse. These results illustrate variation in responses to be expected with fertility, rainfall, and other growing conditions, but still indicate the importance of P and lime to Georgia‐5 tall fescue seedlings on acid, infertile Coastal Plain soils. Responses in stand establishment are suggested to soil levels of P and Ca or pH beyond those typically recommended for other regions.
Identification of Super Cup Mutant in Cotton, Gossypium hirsulum L.1
Authors: Kohel R. J.
Published: July 2010

An aberrant plant with an extreme cup leaf expression was found in a population of true breeding cup leaf plant~;. The mutant was called super cup. Cytological analysis revealed that the super cup mutant was a trisomic plant. A crossing program with known translocations identified the replicated chromosome as chromosome 4 of the A genome. Genetic tests determined that the cup leaf locus is independent of the replicated chromosome; and the super cup phenotype is due to an interaction of the cup leaf locus with the replicated chromosome.
Interspecific Hybridization in the Genus Phaseolus1
Authors: Al‐Yasiri Salih Aziz , Coyne D. P.
Published: July 2010

Seven species of Phaseolus, namely P. Calcaratus, P. mungo, P. angularis, P. lunatus, P. acutifolius, and P. vulgaris, were interpolinated in all possible combinations. On the basis of pod development, three types of compatibility are suggested: Compatible crosses that yield mature hybrid seeds; partially compatible crosses where the pods collapse in the early stages of development: incompatible crosses that fail to develop pods. A compatible cross was P. vulgaris ✕ P. coccineus. Partially compatible crosses were: P. vulgaris ✕ P. acutifolius, P. acutifolius ✕ P. coccineus, P. coccineus ✕ P. acutifolius, P. vulgaris ✕ P. mungo, P. mungo ✕ P. calcaratus, P. vulgaris ✕ P. lunatus, P. angularis ✕ P. acutifolius, P. angularis ✕ P. vulgaris, P. mungo ✕ P. vulgaris, P. angularis ✕ P. calcaratus, P. vulgaris ✕ P. calcaratus, and P. angularis ✕ P. mungo. The remaining combinations of species crosses were incompatible.
Effects of Self‐Compatibility on Chance Crossing in Medicago sativa L.1
Authors: Gartner Alvaro , Davis Ralph L.
Published: July 2010

Nineteen M. sativa clones were evaluated for percent pod set, seeds/pod, seeds/100 flowers tripped and ovules/‐ovary. Pod set was significantly correlated with seeds/pod (r = +0.96). Ovules/ovary was not significantly correlated with either seeds/pod or pod set.

Eight of the 19 clones ranging in pod set from 6.9 to 91.2% averaged over 2 self‐pollinations were selected to study the effects of self‐incompatibility on chance crossing without emasculation. These 8 clones were used as females and hand crossed with and without emasculation to 2 different yellow‐flowered clones as males. When the emasculated progenies were compared to the unemasculated progenies, only 1 of the 16 comparisons was significantly different with either the "t" test or X2 of the frequency distribution.

The data suggested no relationship between percent self compatibility and selfing when hand crosses were made without emasculation.
Chromosomal Location of Genes for Flour Quality in the Wheat Variety ‘Cheyenne’ Using Substitution Lines1
Authors: Morris Rosalind , Schmidt J. W. , Mattern P. J. , Johnson V. A.
Published: July 2010

The individual chromosome substitution method was used to determine the chromosomes responsible for the long mixing time and satisfactory baking properties of the hard red winter wheat variety, ‘Cheyenne’. The 21 Cheyenne substitution lines were developed in the variety ‘Chinese Spring’ by crosses between Chinese Spring monosomic stocks and Cheyenne disomic plants, followed by a series of backcrosses of monosomic progeny to Chinese Spring monotelocentric or monoisochromosome stocks. Disomic lines were obtained by self‐pollinating monosomics from a backcross, and selecting disomics in the progeny for seed increase. Mixing curves and baking tests were made for the parental varieties and for the 21 lines, of which 17 had four backcrosses to Chinese Spring, the rest, none to two backcrosses. The tests indicated that Cheyenne chromosomes 4B, 7B, and 5D contributed genes for the strong dough mixing characteristics. Important contributions to loaf volume, crust appearance, and grain and texture characteristics were made by chromosomes 1B, 4B, 7B, and possibly 1A, with lesser effects from 4D, 5D, and 7D.
Activity of Chloroplasts Isolated from Maize Inbreds and Their F1 Hybrids1
Authors: Miflin B. J. , Hageman R. H.
Published: July 2010

An investigation into the genetic basis of possible differences in the activity of isloated chloroplasts was conducted with 5 maize inbreds (WF9, R151, R177, R181, and Oh43) and 7 hybrids (WF9 ✕ Oh43, WF9 ✕ Rl51, WF9 ✕ R181, R151 ✕ R177 and reciprocals of the last 3). The ability of the chloroplasts of the various inbreds and hybrids to carry out the Hill, cyclic and noncyclic photophosphorylation recations was demonstrated. These reactions were found to vary in the same manner from genotype to genotype; thus one reaction could serve as an indicator for all three. After establishment of this relationship, the cyclic photophosphorylation reaction was used as the criterion for chloroplast activity.

Of the inbreds tested, chloroplasts isolated from R151 had the highest, and those from WF9, the lowest activity. In most instances the chloroplasts from the F1 hybrids had activities intermediate between those of their respective inbred parents. No case of heterosis with respect to activity was observed, although one F1 cross (R151 ✕ R177) was significantly lower in activity than the mean of its parental inbreds. There were no significant differences between the reciprocal crosses.
Localization of Anthocyanins by Peeling the Investments of the Barley Caryopsis1
Authors: Mullick D. B. , Brink V. C.
Published: July 2010

Three tissue layers may be peeled manually and successively from the caryopsis of barley at the dough stage, and at the flinty stage if first soaked in water at near freezing for 4 days. Correspondence of the peelable tissues to those named by histologists several decades ago were determined by sectioning with a cryostat. The technique has made possible a definitive chemical study of the anthocyanins and anthocyanogens of barley and precise grain color classifications of lines and varieties.
Morphology, Cytology, and Fertility of Diploid and Colchicine‐Induced Tetraploid Crested Wheatgrass1
Authors: Tai William , Dewey Douglas R.
Published: July 2010

Treatment of diploid ‘Fairway’ crested wheatgrass, Agropyron cristatum (L.) Gaertn., 2n=14, seeds with colchicine solutions ranging from 0.1 to 0.8% for 12 to 96 hours produced 14 tetraploids. Colchicine solutions of 0.1 to 0.4% applied for 12 to 48 hours appear to be suitable for inducing polyploidy in crested wheatgrass. The induced tetraploids were taller and had fewer but coarser stems than their diploid prototypes. Spike characteristics of the diploids and the tetraploids did not differ significantly. Tetraploid pollen was larger than diploid pollen. Mean chromosome associations of 0.11 I, 7.73 II, 0.06 III, and 3.06 IV where observed in 628 cells at diakinesis and metaphase I. The most common association was 8 II and 3 IV. Irregularities such as laggards, bridges, and unequal chromosome disjunctions occurred in approximately 40% of the anaphase‐I and ‐II cells; however, the induced tetraploids averaged 85.3% stainable pollen. Open‐fertility of the diploids exceeded that of the induced tetraploids, but their mean self‐fertilities did not differ significantly. Induced and natural tetraploids hybridized with relative ease. Many of the hybrids were agronomically desirable and may prove useful in a crested wheatgrass breeding program.
Interaction of Pathogenicity Genes in Puccinia graminis f. sp. tritici and Reaction Genes in Triticum aestivum ssp. vulgare ‘Marquis’ and ‘Reliance’1
Authors: Williams N. D. , Gough F. J. , Rondon M. R.
Published: July 2010

We determined pathogenicity of the parental, F1 and 103 F2 cultures from a cross between cultures 111‐55A (race 111) and 36‐55A (race 36) of Puccinia graminis f. sp. tritici on wheat varieties Reliance, Marquis, and Little Club, and lines homozygous for single genes for resistance derived from Little Club ✕ Reliance and Little Club ✕ Marquis. All cultures were highly virulent on Little Club. Parental cultures 111‐55A and 36‐55A were avirulent and virulent, respectively, on Reliance, Marquis, and the monogenic lines. Pathogenicity on Reliance was conditioned by three gene pairs and on Marquis by two. Pathogenicity was monogenically inherited on three lines, each homozygous for a different gene for resistance derived from Reliance, and on two lines, each homozygous for a different gene for resistance derived from Marquis. A third line, homozygous for a single gene for resistance derived from Marquis, was resistant to culture 111‐SS2 used to select the line, but susceptible to cultures 111‐55A, 36‐55A, and the f1 and F2 from 111‐55A ✕ 36‐55A. The results indicated a 1 to 1 relation between pathogenicity genes in the parasite and reaction genes in the host. Phenotypes resulting from highly specific gene‐for‐gene interactions were sometimes modified slightly by other pathogenicity genes in the parasite and/or reaction genes in the host.
Selection Value of Phenotypic Attributes in Soybeans1
Authors: Caldwell B. E. , Weber C. R. , Byth D. E.
Published: July 2010

The average selection index was used to evaluate the contribution of various phenotypic attributes in selection gain for yield, protein, and oil — individually, and in various combinations.

Selection gain for yield was maximum hen all attributes were used and selection was for yield alone. Deleting any attribute other than yield did not affect selection gain.

Maximum gain for protein and oil (pounds per acre) was obtained from the indices constructed to advance yield; yield and protein; yield and oil; and yield, protein, and oil. Maximum change in percent protein and percent oil was obtained by selecting for these attributes individually, but the total production of oil and protein expressed as pounds per acre was decreased.
Thrips Injury to Upland Cotton (Gossypium hirsutum L.) Varieties1
Authors: Hawkins B. S. , Peacock H. A. , Steele T. E.
Published: July 2010

The purpose of this study was to obtain thrips injury data on Upland cotton varieties currently planted in the Southeast and to associate the effects of the injury with yield. Yield and thrips injury data were obtained on 16 varieties at Experiment, Georgia, in 1960, and thrips injury data on 12 varieties at Jackson, Georgia, in 1961. In 1960, a highly significant (P=.01) negative correlation (0.52) between yield and injury‐index was obtained. The linear regression showed a decrease of 392 pounds seed cotton per acre for each unit increase in thrips injury‐index. A highly significant correlation (0.73) between the 1960 and 1961 thrips injury‐index data was obtained.

The order of rank of thrips resistance for varieties tested was ‘Empire,’ ‘DeKalb 108,’ ‘Dixie King,’ ‘Rex,’ ‘Auburn 56,’ ‘Plains,’ ‘Stoneville 7,’ ‘Coker 100A,’ and ‘Deltapine 15.’

Empire and varieties having Empire in their genetic background exhibited more resistance to thrips injury than did other varieties.

The value of Empire genes in a cotton breeding program for thrips resistance is pointed out.
Growth of Clover Leaves — Developmental Morphology and Parameters at Ten Stages1
Authors: Carlson G. E.
Published: July 2010

Ten discrete morphologic stages and several growth parameters were described for ladino clover leaves, Trifolium repens L. These developmental stages were used to measure day‐to‐day growth in response to environment or management. More important, they provide a precise morphologic description of plant development at the time physiologic treatments were imposed.
A Mutable Gene System in Phaseolus vulgaris L.1
Authors: Coyne Dermot P.
Published: July 2010

Variegated plants were observed in the F2 progeny of the Phaseolus vulgaris crosses ‘Yellow Eye PI 209086’ ✕ ‘G.N. Nebraska #1’ and ‘Dark Red Kidney’ ✕ G.N. Nebraska #1. In some environments a phenotypic ratio of 63 normal : 1 variegated plant was observed in the F2, while a 15:1 ratio was found in other enviromnents. The data suggest that the somatic instability which produced the variegated character was due to the action of two genes, one being unstable in the presence of a mutator gene. The third gene apparently had a threshold effect and was only expressed under some conditions. The environment‐sensitive gene was designated as “var,” the mutator gene as “mu,” and the unstable gene as “us.” Each of the parents lacked the mutator‐unstable gene complex for the development of the character. No variegated plants were found in the F2 of Dark Red Kidney ✕ PI 209806, which indicated that each of these parents possessed either the unstable gene or the mutator gene, but not both. Proposed crosses are discussed by which it is planned to distinguish whether G.N. Nebraska #1 carries the unstable gene or the mutator gene.
Pea Responses to MCPB Applications At Different Growth Stages1
Authors: Vostral Henry J. , Buchholtz Kenneth P.
Published: July 2010

‘Alaska’ and ‘New Line Early Perfection’ pea (Pisum sativum L.) varieties responded similarly to 1 pound per acre of 4‐(2‐methyl‐4‐chlorophenoxy) butyric acid (MCPB) at comparable growth stages. Low yields of shelled peas were correlated with reduced numbers of pods formed on the lower bloom nodes. Shelled‐pea yields of both varieties were not reduced by treatments lnade at least three nodes before initial bloom. MCPB applications during a period commencing two nodes prior to initial bloom and continuing up to pod swelling, reduced shelled‐pea yields. Yield reductions were associated with high tenderometer readings, reduced pod numbers, and reduced pea seed numbers per plant.
Inheritance of Resistance to Bacterial Blight (Pseudomonas glycinea Coerper) in Soybeans ( Glycine max L. )1
Authors: Mukherjee Debabrata , Lambert J. W. , Cooper R. L. , Kennedy B. W.
Published: July 2010

Parents and F3 families of seven soybean crosses were studied for reaction to the bacterial blight organism, Pseudomonas glycinea Coerper. Six of the crosses were tested in both the field and the greenhouse to a single colony isolate of the organism obtained at St. Paul, Minnesota, and four were tested under similar conditions to an isolate from Morris, Minnesota.

The two isolates gave distinctly different reactions on the populations studied, indicating the presence of pathogenic races. Also, varietal reactions varied somewhat with the environments used in testing.

Resistance to the St. Paul isolate, designated race 1, was attributed to a single dominant gene, possessed by the varieties ‘Norchief,’ ‘Harosoy,’ and P.I. 132,207. The proposed symbol for this gene is Rpg1. The inheritance of resistance to the Morris isolate, race 2, appeared to involve more than one gene. Delineation of detail, however, must await further study.
Respiration of Leaves in Light and Darkness1
Authors: Moss Dale N.
Published: July 2010

Leaves of six species were placed in a plexiglass chamber. CO2‐free air was admitted to the chamber and the CO2 concentration in the egress air determined in both light and darkness.

The rate of CO2 evolution from the leaves of five species decreased when they were first lighted, passed through a minimum (“dip”), then increased to a higher rate than the original dark rate (“illumination plateau”). Upon darkening, the rate of CO2 evolution rapidly increased to a rate higher than the illumination plateau (“dark surge”), then gradually decayed to the original steady state dark respiration rate. Thus, light enhances a reaction which leads to additional CO2 evolution above normal dark respiration for many species when the CO2 concentration in the atmosphere is low.

Maize did not have this light‐stimulated CO2 evolution.
Comparison of the Chromosome Substitution and Monosomic Methods for Wheat Quality Studies1
Authors: Schmidt J. W. , Morris Rosalind , Johnson V. A. , Mattern P. J.
Published: July 2010

With the individual chromosome substitution method, three chromosomes of the winter wheat variety Cheyenne were identified as contributing factors to dough‐mixing properties. The monosomic method with the same variety failed to identify these. It was concluded that in multigenic inheritance chromosome substitution is much superior to the monosomic method.