bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of a New Brachyism in Corn, Zea mays L.1
Authors: Legg J. G. , Fleming A. A.
Published: July 2010

The mode of inheritance for a new brachyism in Zea mays L., which shortens the internodes of the plant only above the top ear, was studied using the partitioning method of analysis. Chi‐square values for the F2 frequency distribution suggest that two major pairs of genes differentiate the parents used. The genes for nonbrachyism showed a partial phenotypic dominance in the F1 of three families. In a fourth family, partial phenotypic dominance for brachyism occurred, but genic dominance was toward the nonbrachytic character.

Estimates of heritability in the narrow sense for families 1 and 4 were 85 while families 2 and 3 had .29 and –.34, respectively. A negative association with an average r value of –.41 occurred between the brachytic trait and plant height, whereas the average positive value between brachyism and stalk diameter was only .18. Ear height and brachyism were correlated significantly in family 1. Ear number per plant and ear weight showed no significant correlation with brachyism at the 40,772 plant population per hectare (16,500 per acre).

These results indicate the possibility of the breeder using this new brachyism to lower plant height without altering ear height and of developing a plant with a new type of canopy for more efficient use of light in high plant populations.
Single Height‐Gene Effects in Doubled Haploid Sorghum bicolor (L.) Moench as Influenced by Stand Density1
Authors: Schertz K. F.
Published: July 2010

The expression of distinctive characteristics of short and tall sorghum (Sorghum bicolor (L.) Moench) was determined in two stand densities. A short doubled‐haploid line, recessive at four major height loci (4‐dwarf), was compared with two tall mutant derivatives, recessive at three loci (3‐dwarf) and dominant at the Dw3 locus. The 3‐dwarf plants exceeded the 4‐dwarf plants in height, internode length, leaf‐blade length, grain yield, and kernel weight. The 4‐dwarfs, however, had longer panicles and peduncles. The denser stand had a depressing effect on panicle length of the 3‐dwarf plants but not on the panicle length of the 4‐dwarf plants. The two tall lines differed in leaf‐blade width and in weight per 1,000 kernels.
Nitrate Reductase Activity in Corn Leaves as Related to Yields of Grain and Grain Protein1
Authors: Deckard E. L. , Lambert R. J. , Hageman R. H.
Published: July 2010

The objective was to determine whether a relationship between nitrate reductase activity (NRA) and grain yields and grain protein could be detected for six corn (Zea mays L.) hybrids grown under field conditions with supplemental N and irrigation. NRA was expressed as seasonal input of reduced N (kg N ha‐1) and as seasonal averages of activity (µmoles N, g fresh wt‐1, hr‐1). The treatment variables were plant density (59,300 and 79,000 plants ha‐1) and tune of application (14 days after tassel initiation, at tassel emergence, and at silking) of nitrate‐N (337 kg N ha‐1).

Each supplemental N treatment, regardless of time of application, significantly increased the percent of grain protein for all genotypes and amount of grain protein ha‐1 for all but one hybrid (No. 3). In contrast, the supplemental N treatments did not cause significant increases in grain yields within a given genotype. There were significant differences in grain yield and grain protein among the genotypes. The treatments increased leaf blade nitrate concentration which resulted in a corresponding increase in NRA. However, each successive N application was less effective in increasing and maintaining leaf nitrate content and enzyme activity. None of the hybrids were able to maintain a high concentration of leaf blade nitrate after silking, even though massive amounts of nitrate were applied to the soil. Compared to all other hybrids, hybrid No. 4 maintained a slightly higher level of nitrate concentration and enzyme activity in the leaves during the post‐anthesis stage.

NRA of the total leaf canopy, expressed as seasonal averages or converted into seasonal input of reduced N, showed a significant positive correlation with grain protein (kg N/ha), grain yield, and total reduced N in the vegetative material (above ground) and grain and stover at maturity. The highest correlations between NRA and yields of grain and grain protein (kg N/ha) were obtained during the stages of ear initiation and development. This suggests that a minimal number (1 to 3) of samplings would be as effective as the laborious full season samplings (12 or more dates) in selecting individual plants or varieties that have a high potential for grain yields or grain protein production.
Protein Distribution in the Oat (Avena sterilis L.) Kernel1
Authors: Youngs Vernon L. , Peterson David M.
Published: July 2010

Kernels of 25 selections of Avena sterilis were dehulled, and the groats were hand‐dissected into the embryonic axis, scutellum, bran, and starchy endosperm. All fractions were weighed, analyzed for protein, and compared with one cultivar of Avena sativa L., Markton. Groat yield and groat size were lower for A. sterilis L. than for Markton. Protein concentration (%) was higher in the A. sterilis selections, but protein content per groat was lower, due to smaller groats. A. sterilis groats were mostly starchy endosperm (58.0%) and bran (39.1%), with scutellum and embryonic‐axis fractions contributing little to the total groat weight. These values were similar to those of Markton. Both bran weight and endosperm weight were positively correlated with groat size, although the proportion of endosperm was higher in larger groats. Protein concentration was lowest in the starchy endosperm. Except for a few selections, protein concentration of all fractions was higher in A. sterilis than in Markton. Selections with high protein showed higher protein concentrations in both the bran and starchy endosperm. As a single fraction, bran contained the greatest amount of the total groat protein in all but three of the selections.
Changes in Efficiencies and Numbers of Chloroplasts Associated with Divergent Selection for Juvenile Productivity in Zea Mays (L.)1
Authors: Hanson W. D.
Published: July 2010

Selections of maize (Zea mays L.) which differed in vegetative productivity also differed in photosynthetic efficiencies. The nature of the associated response was evaluated. Selections for high productivity had similar chloroplast diameters but larger guard and epidermal cells than selections for low productivity. The high selections had 90% the DNA per cm2 leaf area but 110% the DNA per leaves 4 to 6 of the low selections. They had similar mg chlorophyll per mg DNA, lower net photosynthetic rate per unit area, but higher net photosynthetic rate per mg chlorophyll than the counter low selections. The high heritability (57%) for leaf width was noted. One should be able to modify photosynthetic potential by selecting for leaf width and, thus, for chlorophyll production.
Interaction of Two Basic Color Factor Genes in Alfalfa1
Authors: Bingham E. T.
Published: July 2010

A basic color factor gene C1 in diploid alfalfa (Medicago saliva L.) (S‐2128) was found to be nonallelic with the basic color factor gene C2 in tetraploid alfalfa. The tetraploid recessive c2 was transferred down to diploid level by haploidy, and the diploid recessive c1 was transferred up to the tetraploid via 2n gametes. Both genes produced monohybrid segregation ratios of about 3:1 at the diploid level and tetrasomic ratios of about 35:1 in the tetraploid. The dihybrid F2 segregation of both genes at the diploid level was about 9:7, indicating recessive epistasis. The homozygous recessive condition of either c1 or c2 produces a white flowered, white seeded phenotype. Additional research is needed to determine the independence or linkage of the two genes. The genetic stocks were made available for this and other research.
Hexaploid Cotton: Some Fiber and Spinning Properties1
Authors: Muramoto H.
Published: July 2010

Fibers from a strain of hexaploid cotton derived from an interspecific cross of Gossypium hirsutum L. × G. sturtianum Willis were evaluated. Due to the short fiber length and other characteristics of the hexaploid, 16 tex yarns were the finest spinnable at the laboratory. The overall spinning performance of the hexaploid was poor. The only acceptable traits, to date, seem to be fiber and yarn tenacity.
Trypsin Inhibitor in Corn (Zea mays L.) as Influenced by Genotype and Moisture Stress1
Authors: Halim A. H. , Wassom C. E. , Mitchell H. L.
Published: July 2010

This study was undertaken to evaluate the distribution of trypsin inhibitor in kernels of genetically different strains of corn (Zea mays L.) and to determine the levels of the inhibitor in kernels as affected by water stress conditions. Crude extracts of endosperms and embryos (including scutellum) were separately analyzed for trypsin inhibitor activities.

Corn kernels contained more trypsin inhibitor in endosperms than embryos. The endosperm inhibitor level varied widely from line to line. Endosperms containing the opaque‐2 gene exhibited much higher concentrations of trypsin inhibitor than normal corn, but the reverse was the case for endosperms containing the floury‐2 gene.

Trypsin inhibitor activities varied within strains when plants were subjected to differential water stress at different growth stages. Generally, there was less inhibitor in endosperms of all lines when irrigation was discontinued at pollination time, but when irrigation was discontinued about 21 days before pollination some genotypes had increased inhibitor activities. However, the increase was not significantly different from that under highest water conditions for most varieties. Trypsin inhibitor in embryos seemed to be influenced little by water stress.

The amounts and pattern of trypsin inhibitor activities of corn strains suggest that both genotype and environmental stress influenced formation of inhibitors, particularly in the endosperms.
Electrophoretic Analysis of SBTI‐A2 in the USDA Soybean Germplasm Collection1
Authors: Hymowitz T.
Published: July 2010

Soybean [Glycine max (L.) Merrill] seeds from 1,595 plant introductions were analyzed for the presence or absence of electrophoretic forms of SBTI‐A2. Seed of all accessions tested had SBTI‐A2. The frequency of Rf 0.79 and Rf 0.75 electrophoretic bands in the population was 0.79 and 0.21, respectively. An electrophoretic variant was located in seed protein of two plant introductions at Rf 0.83. The frequency of Rf 0.75 among soybean introductions from northeast China, south and central China,Indonesia, Japan, and Korea was .09, .08, .03, .37, and .30, respectively.
Photoperiodic Responses of Peanuts1
Authors: Wynne J. C. , Emery D. A. , Downs R. J.
Published: July 2010

In an initial experiment the response to photoperiod of six lines representing the two subspecies of Arachis hypogaea L. was measured under two long‐day and two short‐day photoperiodic treatments in the North Carolina State Unit of the Southeastern Environment Laboratories. All treatments were at constant day/night temperatures of 30/26 C for 64 days.

Vegetative growth of the plants was reduced by shortday treatments. However, plants grown under short days produced more fruit than plants subjected to long‐day treatments.

A second experiment tested the interactions of photoperiod with temperature and their effects on reproductive and vegetative characters of peanuts. Three lines of A. hypogaea were exposed to long and short days at 30/26, 26/22, and 22/18 C.

Plants grown under short days were smaller in size but produced more fruit than plants grown under long days. The greater fruit production of plants grown under short days was not caused by differences in flowering intensity, but by factors that occurred after flowering.
Distribution and Utilization of 14C‐labelled Assimilates in Soybeans1
Authors: Hume D. J. , Criswell J. G.
Published: July 2010

Individual soybean [Glycine max (L.) Merr.] plants grown in the field during 2 years were allowed to assimilate 14CO2 either during vegetative growth, at first flowering, at early pod development, or during rapid seed development. Some of the labeled plants were harvested immediately after labelling, and others after 1 week, at incipient leaf drop, or at maturity. Radioactivity was measured in the component parts of each labelled plant.

Plant parts that were growing actively at the time of labelling accumulated more 14C than those parts that were not growing actively. When the plants were growing vegetatively, most of the 14C was incorporated into structural leaf and stem tissue. As labelling tunes became later during ontogeny, stems contained decreasing amounts of 14C, and more 14C accumulated in seeds by maturity. After rapid seed development began, roots and nodules accumulated little 14C.

If plants were labelled before vegetative growth was completed, 30 to 40% of the 14C present immediately after labelling was recovered in plants grown to maturity. Plants labelled during rapid seed development retained 65% of the original 14C at maturity. Calculated losses of 14C due to respiration averaged 20%. Most of the 14C lost by maturity was in abscised tissue.

The proportions of 14C assimilated at the four stages of development and recovered in seeds at maturity were quite similar to comparable proportions of assimilated 14C recovered in the seeds of maize (Zea mays L.) grown nearby,
Effects of Genetic Background on Monogenic Resistance to Helminthosporium turcicum in Maize (Zea mays L.)1
Authors: Calub A. G. , Dunn G. M. , Routley D. G.
Published: July 2010

A “drop‐diffusion” technique was used to determine the effects of genetic background upon the production of phytoalexin or other inhibitory substances in corn (Zea mays L.) with monogenic resistance (Ht/Ht) to Helminthosporium turcicum Pass. Seedling leaves were inoculated with drops of an aqueous suspension of spores of H. turcicum in a humid chamber at 21C, 100% RH, and a light intensity of 3230 lux for up to 6 days. Drops of the suspension were then withdrawn from the leaf surfaces 1 to 6 days after inoculation and centrifuged. The supernatant or diffusate, then free of spores and germ tubes, was mixed with a drop of fresh spore suspension. Diffusates that inhibited spore germination or delayed the growth of the germ tube was assumed to contain phytoalexin or other inhibitory substance. Five standard susceptible inbred lines (ht/ht), their nearly isogenic resistant counterparts (Ht/Ht), and the five F1 hybrids (Ht/ht) of paired isogenic lines were bioassayed.

The incorporation of the Ht gene into any of the five inbred lines significantly increased the amount of inhibitory substances. Homozygous resistant inbred lines (Ht/Ht) produced significantly more phytoalexin or other inhibitory substances than the heterozygotes (Ht/ht) which in turn produced significantly more inhibition than susceptible inbred lines (ht/ht). The genetic background affected the amount and to a certain extent the time of production of inhibitory compounds. Bioassay tests and percent leaf infection following standard inoculation were not significantly correlated.
Effect of Temperature on Pollen‐Tube Growth in Trifolium repense after Cross‐ and Self‐Pollinations1
Authors: Chen Chi‐Chang , Gibson Pryce B.
Published: July 2010

The effect of temperature on pollen‐tube growth in a self‐incompatible clone of white clover (Trifolium repens L.) was studied under controlled environment‐chamber conditions of 15, 25, and 35 C. After cross‐pollinations, the overall growth rate increased with each increase in temperature, but the effect on early stages of growth was more prominent. After self‐pollinations, the incompatible pollen tubes temporarily made steady growth comparable to the growth of the compatible pollen tubes, and then their growth was arrested. At 15 C, the arrest occurred in the upper and middle parts of the style; no pollen tubes penetrated into the ovary. At 25 C, the arrest occurred in the lower part of the style and the upper part of the ovary; no pollen tubes entered the ovule. At 35 C, cessation of tube growth was less common, and a large proportion of the ovules were fertilized. These observations indicate that at low and intermediate temperatures, self‐incompatibility in T. repens is caused by abnormal growth of the pollen tubes. High temperature enhances pollen‐tube growth and thus tends to break down or circumvent the incompatibility mechanism.
Photosynthesis, Diffusion Resistance and Relative Plant Water Content of Cotton as Influenced by Induced Water Stress1
Authors: Harris Donald G.
Published: July 2010

Frequent and simultaneous measurements of photosynthesis, transpiration, and relative plant water content were made on large cotton (Gossypium hirsutum L. ‘Empire’) plants. Measurements were made after adding polyethylene glycol to the nutrient solution to induce plant water stress. Reducing the solution water potential by 0.5, 1.0, and 2.0 bars had no observable effect upon the plant. The 4.0‐bar treatment reduced photosynthesis, transpiration, and relative plant water content of a 97‐ day‐old plant. The effect of the 4.0‐bar treatment diminished as plant maturity increased and no residual effect of the treatment was detected after 48 hours of recovery in a standard nutrient solution.
Simulation Model to Predict Germination and Emergence of Corn (Zea mays L.) in an Environment of Changing Temperature1
Authors: Blacklow W. M.
Published: July 2010

A simulation model was developed based on a system that included the processes of imbibition and elongation of the corn (Zea mays L.) radicle and shoot and the events of germination and emergence. The response of the processes to temperature were described in previous papers. Germination was predicted at a critical level of rehydration of the seed. Subsequent to germination, the radicle and shoot were elongated until the shoot emerged from the soil. The objective of the model was to give a continuous record of the change in state of the system until emergence occurred. The system was updated each hour by simulation based on a knowledge of soil temperature. The model gave good predictions under fluctuating temperatures in controlled environments and in the field. The verified model supported the hypotheses that the germinating seed and its elongating axes respond to prevailing temperatures with no adaptation to preceding conditions, and that the system responds within minutes to changes in temperature. The model was not developed to predict responses to temperature stress (<1OC or >32C) or to temperature if other soil factors were limiting.
Locating Genes for Maize Dwarf Mosaic Resistance by Means of Chromosomal Translocations in Corn (Zea mays L.)1
Authors: Findley W. R. , Dollinger E. J. , Louie Raymond , Knoke J. K.
Published: July 2010

Chromosomal translocations were used to locate genes for resistance to the maize dwarf mosaic virus disease (MDM) in corn (Zea mays L.) inbreds Oh07 and Mo22. The translocations were converted to inbred M14 background, which is susceptible to MDM. Each chromosome arm of the resistant inbreds was tested at least once during 1968 or 1969, under conditions of natural infection near Portsmouth, Ohio. The data indicated that genes for resistance common in Oh07 and Mo22 were located in both arms of chromosome 6; the long arms of chromosomes 1 and 2; possibly the long arm of chromosome 10; and the short arms of chromosomes 3, 7, 8, and 10. A gene(s) for resistance was associated with the long arm of chromosome 7 in Mo22 but not in Oh07. Major genes for resistance in Oh07 were associated with both arms of chromosome 6 and the short arm of chromosome 8. Other associations of importance were with the long arm of chromosome 1 and the short arms of chromosomes 3 and 10. In Mo22 there is some evidence for a major gene in the short arm of chromosome 10. It is suggested that different genetic systems control resistance to the various virus strains comprising the MDM complex, but the systems probably have some genes in common.
Cultivar‐Environment Interaction Study of Alfalfa Yields in Oklahoma1
Authors: Taliaferro C. M. , Denman C. E. , Morrison R. D. , Holbert D.
Published: July 2010

Forage yield data from 14 alfalfa (Medicago sativa L.) cultivars harvested for 3 years (1966 through 1968) at each of 5 Oklahoma locations were used to study CE (cultivar × environment) interactions. Mean squares, estimated variance components, and regression analyses statistics were used to draw conclusions.

Statistically nonsignificant mean squares and small variance components for the first order CL (cultivar × location) and CY (cultivar × year) interaction components suggested minimal effects of locations and years per se on relative yields of alfalfa cultivars. The second order CLY (cultivar × location × year) interaction effect was of large magnitude and highly significant, indicating that CE interactions in alfalfa yields were attributable to factors other than years and locations. These results emphasized the necessity for multiple environment testing but gave little information which would elucidate how these tests should be distributed over years and locations. Cultivar regression coefficients, though in most cases not statistically different from unity, suggested some possible differential cultivar reaction to varying environments. Cultivars with regression coefficients above one had either a better than average response to high yield environments or a smaller than average response to low yield environments. Mean square deviations from regression (s2d) revealed specific instances of yield instability which presumably resulted from CE interaction.

Due to the perennial nature of alfalfa and the need to evaluate stand persistence in new lines, it would seem most feasible to extend tests over years using a minimum of test locations. Locations, however, should probably be divided to include both high‐ and low‐yielding sites. In Oklahoma, alfalfa strains and cultivars can very likely be adequately evaluated for forage yield ability by testing for 3 years (4 years including the year of seeding) at three to four selected locations.
Floral Induction and Development in Festuca rubra L. — Differential Clonal Response to Environmental Conditions1
Authors: Murray J. J. , Wilton A. C. , Powell J. B.
Published: July 2010

Development of suitable procedures for production of inflorescence and subsequent seed production of red fescue, Festuca rubra L., under controlled conditions would facilitate earlier completion of breeding procedures and genetic tests. Two studies were conducted in 1970–71.

The first study was to determine the date of floral induction. Propagules from 15 clones were removed from the field every 14 days beginning October 28, 1970 through January 14, 1971, and grown under cool temperature and long photoperiods for 24 days to initiate floral primordia. They were then grown under warm temperature and long photoperiods for the production of inflorescence. Variation among clones in the required length of exposure to the field environment for floral induction was 30 days. By January 1 virtually all plants were induced. Days to heading decreased and number of panicles increased with increasing exposure to the field environment.

The second study was to determine the controlled temperature and photoperiod favorable for floral development after induction in the field. Twenty‐four clones brought from the field on January 24 were placed under cool temperature and either normal daylight or continuous light for 28 days. They were then grown under controlled temperature and photoperiod regimes. Heading was earlier, number of panicles increased 17%, and number of seeds increased 45%, where the initial treatment was normal daylight. Number of panicles and seeds was greatest where the final treatment was normal daylight supplemented with 1 hour of light at midnight and 21 to 24 C. Biotypes within this species differed in their environmental requirements for floral production. By manipulating environmental conditions, we produced sufficient seed of good quality for experimental use during winter months in the greenhouse.
Liquid Water Content of Cell Walls in Frozen Tissues Evaluated by Electrophoresis of Indicators1
Authors: Olien C. R. , Chao Su‐En
Published: July 2010

The content of liquid water at equilibrium with ice in a frozen cellulose model was evaluated by electrophoretic mobility of indicators, and a method of translating relative moisture data of the type previously obtained from plant tissues to absolute values is presented. Absolute water distribution data are required for coordination with calorimetric data, so that stress energies can be calculated and plant systems capable of modifying stress can be identified.
Cytology of Backcross Offspring Derived from a Maize‐Tripsacum Hybrid1
Authors: Engle L. M. , de Wet J. M. J. , Harlan J. R.
Published: July 2010

Hybrids combining 10 Zea (Zm) and 36 Tripsacum (Tr) chromosomes are produced when diploid Zea mays L. (2n = 20) is crossed with tetraploid Tripsacum dactyloides (L.) L. (2n = 72). In these hybrids the 36 Tr chromosomes pair, while the 10 Zm chromosomes remain as univalents and are usually eliminated during meiosis. Backcrossing with maize frequently reconstitutes the 2n = 46 hybrid. After four generations of backcrossing, the frequency of multivalents increased while the frequency of univalents decreased in 2n = 46 individuals, suggesting that segmental chromosome exchanges between genomes of Zea and Tripsacum had taken place. In the third and fourth backcross generations, individuals with 36 Tr + 6, 10, 12, 14, 16, 18, or 20 Zm chromosomes were obtained. Chromosome pairing in these individuals suggests that an extensive amount of gene transfer is feasible from Tripsacum into maize.
Storage of Sugarbeet Roots in Controlled Atmospheres to Conserve Sucrose1
Authors: Wyse R. E.
Published: July 2010

Storage of sugarbeet (Beta vulgaris L.) root in controlled atmospheres showed no consistent effect of oxygen and carbon dioxide on raffinose, reducing sugar, or amino acid content in the varieties studied. Controlled atmosphere (CA) storage reduced the tendency of one variety to accumulate reducing sugars, but showed no consistent improvement in the other varieties tested

Carbon dioxide concentrations up to 10% had no beneficial effect on sucrose conservation or impurity accumulation. Although decreasing the oxygen content to 3 to 5% significantly reduced storage losses of sucrose in these experiments, large‐scale studies will be required to determine if CA storage has any practical advantage over low‐temperature storage in air.
Characterization of Chloroplast and Nuclear DNAs of Zea mays L.1
Authors: Shah D. M. , Levings C. S.
Published: July 2010

Highly purified chloroplasts and nuclei were isolated from two hybrids of maize (Zea mays L.), ‘McNair X210N’ containing normal and ‘X210 cms T’ containing Texas‐type male‐sterile cytoplasm. Chloroplast and nuclear deoxyribonucleic acids were obtained from their respective organelles and purified by CsCl density gradient centrifugation. These DNAs were compared with respect to thermal denaturation temperature (Tm), buoyant density (ρ) and the guanine‐plus‐cytosine content (molar % GC).

Nuclear DNA (nDNA) had a mean buoyant density in CsCl of 1.7019 g/cm3 and a Tm of 86.9 C. Mean molar GC was calculated to be 43.3%. In contrast, Chloroplast DNA (cDNA) had a lower buoyant density in CsCl (1.6998 g/cm3) and a lower Tm (85.9 C). Mean molar GC was determined to be 39.5%. Thus, cDNA was distinguishable from nDNA by its lower buoyant density, lower Tm, lower GC content, and the absence of 5‐methylcytosine, which was present in significant amounts (6.9%) in nDNA. GC content, Tm, and buoyant density values of cDNAs did not differ between normal and Texas cytoplasms, and therefore, cannot account for their cytoplasmic differences.
Light‐Induced Leaflet Orientation in Phaseolus vulgaris L.1
Authors: Wien H. C. , Wallace D. H.
Published: July 2010

The effect of light on change of leaflet angle of attached and detached leaves of four cultivars of dry beans (Phaseolus vulgaris L.) was measured. Light receptor and response site were both found to be the pulvinule at the base of each leaflet. All three pulvinules of the trifoliolate leaf responded. Light impinging on the top of pulvinules of all varieties caused them to bend upward, i.e. toward the light. This rotated attached leaflets upward, orienting them more parallel to the overhead source‐direction of the light. Light from the side also caused the pulvinules of all four varieties to bend toward the light. However, the more prominent response to light impinging upon the side of pulvinules was a twisting of the pulvinule which, with reference to the light source, rotated the far side of the leaflet upward and the near side downward. This positioned the leaflets more perpendicular to the horizontal source‐direction of the light. Thus, light from the side caused the leaflets to orient themselves so that they would intercept more light energy, whereas light from above oriented them so that they would intercept less. The four varieties differed in amount and type of leaf orientation under a given light intensity. For one variety only, in addition to causing the pulvinule to bend toward the light, light impinging upon the top of the pulvinule also caused it to twist. With this variety, both responses oriented leaflets more parallel to the overhead source‐direction of the light, with the result that the leaflets would intercept less light energy.

It is hypothesized that leaf characters maximizing both pulvinule exposure to light and the leaf‐orientation response would maximize light penetration into the leaf canopy and lead to higher photosynthetic rates, especially at close spacings with high leaf area index.
Modification of Saponin Characteristics of Alfalfa by Selection1
Authors: Pedersen M. W. , Berrang Bertold , Wall M. E. , Davis K. H.
Published: July 2010

Recurrent phenotypic selection for low‐ and high‐saponin concentration in alfalfa (Medicago sativa L.) was practiced in each of six alfalfa varieties for up to five generations. In the last cycle of selection the low series did not differ significantly from one variety to another, and the saponin index averaged 0.34%. In the last cycle of the high series the saponin index averaged 3.14% and ranged from 1.12% for ‘Lahontan’ to 4.72% for ‘Uinta.‘ The saponin concentrations of leaves and stems were correlated (P < 0.01). Concentrations of saponin in first and second crops were also correlated (P < 0.01). There was a low correlation between saponinconcentration index and leaf percentage (P < 0.05). With the exception of high‐saponin Uinta, selection for saponin‐concentration did not significantly change the leaf percentage from that of the original variety. Changes in leaf percentage accounted for only a small part of the change in saponin concentrations. Yield and protein concentration were not affected by low‐ or high‐saponin selection.

Evidently a shift occurred towards an increase of saponins that contain carboxylic acid‐type aglycones in the high‐saponin selection and towards saponins that do not contain carboxylic acid‐type aglycones in the low‐saponin selections. This conclusion was supported by 1) chromatographic separations, 2) bioassays of butanol extracts, and 3) bioassays with water extracts with added cholesterol. Apparently more toxic fractions of saponins were increased by selection for high saponin and decreased by selection for low saponin.
Genome Relations Between Tetraploid Paspalum dilatatum and Four Diploid Paspalum Species1
Authors: Burson Byron L. , Lee Heng‐shiung , Bennett Hugh W.
Published: July 2010

Reciprocal hybridizations were made between yellow‐anthered dallisgrass, Paspalum dilatatum Poir (2n=4X=40), and four diploid species (2n=2X=20), P. intermedium Munro. ex Morong, P. jurgensii Hackel, P. notatum Flugge, and P. vaginatum Swartz. Percent cross‐ability ranged from 0 to 10.5. Generally a greater number of hybrids were produced with yellow‐anthered dallisgrass as the female parent. All hybrids were 2n=3X=30. The mean meiotic pairing relationships were: 10.14 I and 9.93 II for 63 yellow‐anthered P. dilatatum ✕ P. intermedium hybrids; 10.27 I and 9.86 II for one reciprocal hybrid; and 10.30 I and 9.85 II for 20 yellow‐anthered P. dilatatum ✕ P. jurgensii hybrids; and 10.38 I and 9.81 II for three reciprocal hybrids. Mean pairing relationships were: 27.96 I and 1.02 II for 28 yellow‐anthered P. dilatatum ✕ P. notatum hybrids; 28.56 I and 0.72 II for five reciprocal hybrids; and 28.07 I and 0.96 II for 38 yellow‐anthered P. dilatatum ✕ P. vaginatum hybrids. All hybrids were completely sterile. The P. intermedium and P. jurgensii genomes are homologous to those of yellow‐anthered P. dilatatum. These two diploid species are possible progenitors of yellow‐anthered P. dilatatum. Lack of chromosome pairing in the hybrids with P. notatum and P. vaginatum indicates they are not closely related to yellow‐anthered P. dilatatum.
Effects of Temperature and Method of Pollination on the Frequency of Aborted Seed in Alfalfa1
Authors: Dane Fenny , Melton Bill
Published: July 2010

Effects of temperature and method of pollination on the frequency of normal and aborted seeds were determined for five selected alfalfa clones, Medicago sativa L. Numbers of normal seeds were greatest at 21 to 27 C and lowest at 32 C. Aborted seeds were more frequent at 32 C.

Self‐pollination resulted in lower numbers of normal and aborted seeds than crossing; however, the ratio of normal to aborted seeds was the same under self‐or cross‐pollination.

Abortion of “mature” seeds appeared to be independent of factors conditioning embryo abortion in the early stages of seed development.
Adventitious Bud Development of Soybean Hypocotyl Sections in Culture1
Authors: Kimball S. L. , Bingham E. T.
Published: July 2010

Tissue culture methods were used to study the capacity of soybean (Glycine max (L.) Merrill) to differentiate adventitious buds. Hypocotyl sections from the cultivar ‘Dunn’ were placed on various media for preliminary observations, and ‘Corsoy’ was tested later to determine if ‘Dunn’ responses were variety‐specific. Those sections placed on media containing 0.5 to 2.0 mg/liter 2,4‐dichlorophenoxyacetic acid (2,4‐D) or 2.0 mg/liter 2‐naphthylacetic acid (NAA), and 0.5 or 2.0 mg/liter kinetin, produced callus tissue with or without roots. Sections placed on media containing 0.1 to 2.0 mg/liter indole‐3‐acetic acid (IAA) and either 15% (v/v) coconut milk (CM) or 0.5 or 2.0 mg/liter kinetin formed little or no callus, but instead enlarged slightly and produced roots (35 to 90% of sections) or shoots (1 to 8% of sections), depending on the particular treatment. Roots usually formed on sections that previously had differentiated shoots, but shoots seldom formed on sections that already had roots. Soybean hypocotyl sections, when cultured under the appropriate conditions, formed adventitious buds.
Sterile Culture of Immature Maize Seeds and Embryos1
Authors: Mock J. J. , Dahmen W. J.
Published: July 2010

We cultured immature maize (Zea mays L.) seeds and excised embryos (sampled at 5‐day intervals from 5 through 30 days after pollination) on solid‐agar nutrient medium containing 2% sucrose. Immature, intact seeds germinated poorly under our sterile culture conditions. Embryos germinated within seeds, but were incapable of emerging from the seed coat (even at 30 days postpollination). Excised embryos 15 days old and older germinated and developed normally.
Symbiotic Nitrogen Fixation in Soybeans. II. Interrelationship Between Carbon and Nitrogen Assimilation1
Authors: Lawn R. J. , Fischer K. S. , Brun William A.
Published: July 2010

Reciprocal intervarietal grafts were made in all root: shoot combinations using seedlings of eight soybean (Glycine max (L.) Merr.) genotypes, grown in sandfilled pots in the greenhouse. After grafting, the plants were inoculated with Rhizobium japonicum (USDA strain #138) and watered with a low‐nitrogen nutrient solution. Two replicate plants of each root:shoot combination were sampled at each of four times, 28, 38, 50, and 58 days after grafting, for photosynthetic rate of leaves; leaf area, shoot and root dry weight; and number, fresh weight, and acetylene reduction activity of nodules.

Significant shoot genotype, sampling date, and shoot genotype ✕ sampling date effects occurred for all traits measured. Root genotype effects, independent of the shoot genotype, occurred for all root traits measured, except nodule fresh weight. No overall root effects occurred for any of the shoot traits. Shoot genotype effects were small at the first two sample dates relative to root genotype effects, but were large at the last two sampling dates due to differences in stage of physiological development. Shoot genotype effects on total nodule activity (TNA) per plant were strongly and positively associated with shoot effects on nodule fresh weight, but showed no association with shoot effects on specific nodule activity (SNA). Shoot genotype effects on nodule fresh weight per plant were, in turn, strongly and positively associated with shoot effects on photosynthesis per plant and shoot dry weight. Root genotype effects on TNA per plant were due to inherent differences in SNA.
Seed Dormancy Characteristics of Sideoats Gramagrass, Bouteloua curtipendula (Michx.) Torr.1
Authors: Major Roger L. , Wright L. Neal
Published: July 2010

Seed sources of sideoats gramagrass [Bouteloua curtipendula (Michx.) Torr.] were accumulated from central and western United States, Mexico, and Argentina to evaluate duration and pattern of seed dormancy and to locate and identify dormancy conditioning factors of intact seed units (spikes of multiple spikelets). Dormant and nondormant seed sources were chosen for detailed investigations. Effects of time, removal of floral parts (glumes, lemmas, paleas, and awns), soil, leaching treatments, enriched oxygen atmosphere on germination, and potential inhibitors of seed units on germination of seed were studied. Postharvest dormancy was present in seed units of all sources, but disappeared after 4 to 6 months of dry storage after harvest. Postharvest dormancy was conditioned by nature of the caryopses. Long‐term dormancy persisted in seed units for 5 years in dormant sources without viability change. Long‐term dormancy was broken when floral parts were removed from caryopses. Placing seed units in soil, in enriched oxygen atmosphere, and in sodium hypochlorite was effective in breaking dormancy. The mechanism of longterm dormancy of sideoats gramagrass seed units involved interactions among the following factors: light weight of caryopses, impermeable floral parts of caryopses, and presence of coumarin‐like inhibitory compounds. Association of dormancy with establishment under stress environments of grasslands is to be determined. Results of this investigation offer approaches to select and characterize germplasm with dormancy qualities that may be favorable to establishment.
Predictions of GCA Model Estimates of Total Leaf Area and Leaf Area Distribution from Leaf Area of Parental Inbreds1
Authors: Johnson G. R.
Published: July 2010

The relationships of GCA (general combining ability) for total leaf area per plant and leaf area at leaf positions somewhat distal to the ear leaf to parental total leaf area per plant and leaf area at individual leaf positions were investigated by means of multiple regression procedures applied to data obtained from 10 homozygous inbred lines of corn (Zea mays L.) and the diallel set of crosses among them. In the multiple regression analyses, GCA model estimates of leaf area at leaf positions —4 and 6 (the fourth leaf position below and sixth leaf position above the ear, respectively) and total leaf area were used as dependent variables, while midparent values of leaf area at individual leaf positions and total leaf area were used as independent variables. The regression equations were then appraised for their ability to predict F1 leaf area, based on a GCA effects model, from midparent leaf area values.

The results indicated: 1) GCA model estimates of total leaf area could readily have been predicted from midparent total leaf area; 2) GCA model estimates of leaf area at leaf position 6 could have been predicted by a linear function of midparent observations of total leaf area, leaf area at the upper leaf positions, and leaf area at leaf positions near the ear; and 3) GCA model estimates of leaf area at position —4 could have been predicted by a linear function of midparent values including leaf area at and below the ear leaf. However, since GCA model estimates of leaf area at leaf position —4 were poorly and mostly negatively correlated with parental leaf area, prediction of F1 leaf area at the lower leaf positions might generally be tenuous.
Seasonal Variation in Photosynthesis, Respiration, and Growth Components of Nondormant Alfalfa (Medicago sativa L.)1
Authors: Delaney R. H. , Dobrenz A. K. , Poole H. T.
Published: July 2010

Alfalfa (Medicago sativa L.) plants were grown under field conditions to determine causes of yield fluctuation throughout the growing season. Photosynthesis, dark respiration, forage yield, specific leaf weight (SLW), leaf size, leaf:stem ratio, and leaf area index (LAI) were measured for six harvests.

High atmospheric temperatures during periods of reduced forage yield resulted in a maximum decrease of 38% in apparent photosynthesis and a 19% decrease in dark respiration. This reduction in photosynthesis may contribute to the “summer slump” in yield of alfalfa grown in warm climates. Specific leaf weight decreased with increased temperatures and followed a similar seasonal pattern under two plant densities.

Leaf area index continued to decrease throughout the season in a pattern similar to forage yield. The data suggest that the decline in leaf area index was not a result of a decrease in leaflet size.
Inheritance and Combining Ability for Oil Content in Oats (Avena sativa L.)1
Authors: Brown C. M. , Aryeetey Andrew N. , Dubey S. N.
Published: July 2010

Analyses of F1 and F2 populations from crosses involving eight oat (Avena sativa L.) parents differing widely in oil content revealed that oil content was highly heritable, with broad‐sense heritability values usually above 70%. A combining‐ability analysis showed that a large part of the phenotypic variation was associated with general combining ability, although significant specific combining ability occurred in several crosses. Differences between F1 hybrids and between F2 populations from reciprocal crosses were nonsignificant, indicating the absence of cytoplasmic control. Polygenic control was evident since the F2 distributions were approximately normal. Mean oil contents of seed from F1 and F2 populations were usually near midparental values. Our results suggest that considerable genetic gain would be expected from phenotypic selection for oil content in oat seeds.
Morphological and Cytological Characteristics of Five Additional Trisomics of Sorghum bicolor (L.) Moench1
Authors: Schertz K. F.
Published: July 2010

This paper describes the second 5 of the 10 primary trisomics of Sorghum bicolor (L.) Moench for which chromosome identities were previously reported. They consist of the light‐green (H), sparse‐branch (B), spear (J), asymmetric (F), and compact (C) trisomics. Gene‐linkage studies should be expedited by these descriptions and by the mutual chromosome identities in the sets of trisomic and translocation stocks.
Maleic Hydrazide Residue from Air‐cured Burley Tobacco1
Authors: Davis D. L. , Atkinson W. O. , Smiley J.
Published: July 2010

The residue of maleic hydrazide, a systemic sucker control agent, was quantified on air‐cured hurley tobacco (Nicotiana tabacum L.) that had been subjected to different application rates, harvest dates, and combination treatments with a fatty alcohol sucker control agent. Residue levels were decreased by allowing longer periods of time between application and harvest, lower application rates, and the use of single rather than split applications. Residue levels were higher from the upper portions of the plant and from laminae compared to midvein tissue. Levels ranged from 21.0 to 152.3 µg/g dry weight. Chemical treatment of burley tobacco with sucker retardants significantly increased yields over the nontreated hand‐suckered plots especially at late harvest dates.
Relationship between Fiber‐Length Increase and Seed‐Volume Increase in Cotton (Gossypium hirsutum L.)1
Authors: Stewart James McD. , Kerr Thomas
Published: July 2010

Three cultivars of Gossypium hirsutum L. were chosen for wide differences in fiber length and seed volume: ‘Stoneville 213,’ ‘Paymaster 54B,’ and ‘Acala 1517‐D.’ Increases in fiber length and seed volume were measured from boll ages of 8 to 17 days. During this period the relationship of fiber length to seed volume in each cultivar fit the model L = βVα with R2 = 0.99, where L = fiber length, V = seed volume, and α and β are the growth parameters. The α value in each was near 0.5, indicating tbat seed volume was increasing as the square of fiber length. This relationship suggests that biological partitioning of available resources within the cotton plant controls some agronomically important parameters.
Interveinal Distance for Carbohydrate Transport in Leaves of C3 and C4 Grasses1
Authors: Crookston R. Kent , Moss Dale N.
Published: July 2010

Among common crop and range Gramineae, we found that species with the C4 pathway for photosynthesis had fewer cells between leaf vascular bundles than did C3 species. We extracted chlorophyll from leaf segments of 10 Ca and 10 C4 species, cleared the segments in 10% aqueous NaOH, counted the number of mesophyll cells between vascular bundle sheaths, and measured the distance (center to center) between the vascular bundles. The C3 species had 9 to 15 mesophyll cells between vascular bundle sheaths, while the C4 species had only 2. The vascular bundles were 0.18 to 0.36 mm (average 0.27) apart in C3 species, but only 0.08 to 0.15 mm (average 0.11) apart in C3 species. The closeness of all leaf cells to vascular tissue in C4 species suggests efficiency for transporting the products of photosynthesis and may be an important factor in their greater capacity to fix CO2.
Stem Anatomy of Turfgrass1
Authors: Stiff M. L. , Powell J. B.
Published: July 2010

Stem anatomy of 20 cultivars or selections of turfgrass genera Cynodon. Zoysia, Agrostis, Poa, Stenotaphrum, Festuca, and Digitaria was compared. Studies were undertaken to discover possible relationships between stem anatomy and induction of vegetative mutations, selection of wear‐resistant turf, potential thatch problems, and identification of cultivars and hybrids. A definite separation into cortex and pith regions by a band of fibers, the fiberond, was found in transverse sections of the mature internode. Three types of stems were distinguished: 1) single ring—a single ring of major vascular bundles was embedded in the fiberond (bluegrass, bentgrass, fescue); 2) multiple rings—A ring of minor bundles was in the periphery of the fiberond, a ring of major bundles was embedded in or connected to the fiberond, a third ring of major bundles was deeper in the pith (bermudagrass, pangolagrass, Japanese lawngrass); 3) complex rings—minor bundles lie in the cortex, major bundles are embedded in the fiberond and disposed throughout the pith (St. Augustinegrass). Two types of nodes were observed, simple and compound. The compound node differed from the simple by the presence of three, occasionally two or four, leaves and two lateral buds (bermudagrass, St. Augustine, Japanese lawngrass). Degree of selerification of fiberond, cuticle, subepidermal layers, and bundle sheaths may be related to thatch accumulation.