bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods of Measuring Drought Tolerance in Corn1
Authors: Williams T. V. , Snell R. S. , Ellis J. F.
Published: July 2010

Three methods for measuring drought tolerance in corn are presented. They include: exposing corn seedlings to a 52 C temperature for 6 hours followed by recovery counts; germinating corn seed in mannitol solution at 15‐atm osmotic pressure and selecting genotypes showing the highest percent germination; and subjecting corn seedlings to a 14‐day permanent wilting period in a greenhouse followed by wilt ratings. Results were supported by observations from successive field plantings, one subjected to drought and one receiving normal rainfall. Any one method should be useful in screening a large number of corn genotypes for drought tolerance. Field evaluation is recommended to substantiate the data.
Effect of High Plant Density on Silage and Grain Yields of Six Corn Hybrids1
Authors: Rutger J. N. , Crowder L. V.
Published: July 2010

Six hybrids, ranging in maturity from early to late, were evaluated at 2 locations for 3 years in densities of 40, 50, 60, 70, and 80 thousand plants per hectare. The diverse nature of the six hybrids resulted in significant hybrid differences for all traits measured. Hybrids differed in response to density only for grain yield and ears per 100 stalks. The hybrid most responsive to high planting rates had more ears per 100 stalks at high populations than the other hybrids. At high populations, ear height (but not plant height) was increased and stalk diameter decreased. Highest silage yields were obtained from 80,000 plants but were not significantly higher than yields from 70,000 plants per hectare. Highest grain yields were obtained at 70,000 plants per hectare. Ear weight at this population was 127 g. Because greater mechanical harvesting losses tend to occur at higher populations, near‐maximum grain yields probably would be obtained at 60,000 plants per hectare. Significant population ✕ location interactions were observed for both silage and grain yields.
Effects of Freezing and Mechanical Injury on Viability of Sorghum Seed1
Authors: Kantor D. J. , Webster O. J.
Published: July 2010

Our purpose was to determine the effect of freezing temperatures on the viability of sorghum seed at different moisture levels and the damage to seed which may result from threshing.

Viability of sorghum seed with a moisture content of less than 40% was not reduced when the seed was frozen for 12 hours at 1.7 or 0 C (29 or 32 F). The damage to seed with 35% moisture or higher increased with the duration of the freezing period when frozen at 3.3 C (26 F). The results from the two years indicate that the mid‐twenties is a critical temperature for causing injury to seed with an excess of 20% moisture.

Increased cylinder speeds of the thresher not only increased, the percentage of cracked seed, but also reduced the germinability of ‘sound’ seed and increased the percentage of abnormal seedlings. Injury also increased as the moisture content of the seed increased. Abnormal seedlings are probably due to injury to the radicle and plumule in the dormant embryo.
A Bioassay for Alfalfa Saponins Using the Fungus, Trichoderma viride Pers. ex Fr.1
Authors: Zimmer D. E. , Pedersen M. W. , McGuire C. F.
Published: July 2010

Extracted alfalfa saponins and leaf meal extracts from alfalfa influenced the growth rate of some fungi more than others. Of seven fungi whose growth rate was studied on media to which different concentrations of extracted alfalfa saponins or Leeben, a commercial saponin, were added, only Trichoderma viride was fonnd highly sensitive at concentrations below 1 mg of saponin per milliliter of medium.

A correlation coefficient of —0.952** was found between the growth of T. viride on 2% potato‐dextrose‐agar containing leaf meal extracts from 36 F1 and S1 plant families and saponin percentage. This, together with a correlation coefficient of —0.922** between the growth of T. viride on media containing leaf meal extracts from individual alfalfa plants and saponin percentage, suggests the use of T. viride for bioassays for saponins.
Effect of Second‐Brood European Corn Borer Infestation on 45 Single‐Cross Hybrids1
Authors: Scott Gene E. , Guthrie W. D. , Pesho G. R.
Published: July 2010

Plots of corn artificially infested with second‐brood corn borer egg masses were compared with plots treated with an insecticide to prevent infestation. Our studies were conducted to determine if the resistance of inbreds would be expressed in hybrids and if the present level of resistance was sufficient to prevent serious yield losses.

Resistant ✕ resistant crosses were reduced in yield by second‐brood corn borer damage on the average slightly less than 4%, but the susceptible ✕ susceptible crosses were reduced in yield by 12%. Corn borer infestation decreased yield and the moisture content of the grain, but increased stalk lodging and ear droppage. The number of cavities per plant, which we used as a direct measure of resistance, increased with the susceptibility of the inbreds in the single crosses.
Yield Reductions in Reed Canarygrass Caused by Frit Fly Infestation1
Authors: Wolf Dale D.
Published: July 2010

Yields of reed canarygrass were reduced 0.52 metric ton per hectare in second harvest due to frit fly infestation. Plant height and weight of individual tillers were reduced by as much as one‐half by infestation. Insect control resulted in aftermath yield increases of 32% in low nitrogen plots and 17% in high nitrogen plots. Infestation interrupted normal morphological and physiological development. It is proposed that residue left by the feeding larvae may influence forage acceptability of grazing animals.
Thermal Stability of Fraction I Protein from Heat‐Hardened Phaseolus acutifolius Gray, ‘Tepary Buff’1
Authors: Sullivan Charles Y. , Kinbacher E. J.
Published: July 2010

Heat hardened ‘Tepary Buff’ bean plants were shown to have significantly greater heat tolerance than unhardened plants using a modified electrical conductivity 1nethod for assessing the heat injury. The objectives of the investigation were to determine whether heat hardening increases the thermal stability of a major leaf protein, and whether protein disulfide bonds contribute to the thermal stability. Fraction I protein was isolated from the plants by fractional ammonium sulfate precipitation and filtration through Sephadex. The thermal stability of the isolated protein was tested by changes in ultraviolet light absorption and scattering as the protein denatured at elevated temperatures. Fraction I extracted from heat hardened plants was found to be more heat stable than that from unhardened plants. Blocking the sulfhydryl groups with para‐chloromercuribenzoate did not change the relatively greater thermal stability of protein from the hardened plants, whereas cleavage of disulfide bonds with mercaptoethanol and sodium sulfite decreased the stability of protein from the hardened plants and caused them to respond to increased temperatures much the same as protein from the unhardened plants. Disulfide bonds were measured quantitatively, after the sulfhydryl groups were blocked at the time of homogenizing the leaves, by the method of argentometric amperometric titration after reduction with mercaptoethanol or sodium sulfi(e. There was no significant difference found between the number of disulfide bonds in the hardened and unhardened plants. It is suggested that there may be a disulfide interchange during hardening which results in a repositioning of the disulfide bonds in such a way as to increase the thermal stability of the fraction I protein.
Effects of a Gene for Cotyledon Color in Lima Beans, Phaseolus lunatus L.1
Authors: Tucker C. L. , Sanchez R. L. , Harding James
Published: July 2010

Isogenic lines for GG and gg of three commercial lima bean varieties were compared for seed yield and emergence in five environments. Significant differences for yield were found for environments, genotypes, and genotype ✕ environment interaction. However, the G/g locus did not affect yield in the three genetic backgrounds. Significant differences were also found for all emergence comparisons. There was an interaction between genetic background and the G/g locus and this interaction interacted with the environments. The substitution of gg for GG had an effect on emergence in two of the three varieties but had no effect in the third. Two hypotheses were presented which could explain this locus by genetic background interaction.
A New Technique for Culturing and Measuring Barley Seedlings
Authors: Myhill R. R. , Konzak C. F.
Published: July 2010

A highly efficient space and labor saving technique for culturing barley seedlings is described. The seeds are planted at the top edge of 2″ x 3″ blotter “sandwiches”. The bottom ends of the “sandwiches” are wedged in slots in polyethylene racks sitting in trays of water. The trays are placed in a small plastic growth chamber for uniform seedling growth. The seedling length is measured on a board covered with metric system graph paper. This technique has been successfully used for determining growth of seedlings from mutagen‐treated barley seeds.
Use of Control Plots in Yield Trials1
Authors: Baker R. J. , McKenzie R. I. H.
Published: July 2010

Theoretical considerations based on Smith's coefficient of soil heterogeneity suggest that the use of systematically arranged control plots as fertility indexes in yield trials is of questionable value. Data from a 2‐year study in Avena sativa L. support this conclusion. It is shown that analyses of covariance will avoid the possibility of overadjustment of yields in relation to a fertility index.
Cytogenetics of Crested Wheatgrass Triploids1
Authors: Dewey Douglas R. , Pendse P. C.
Published: July 2010

Meiosis and fertility were studied in triploids derived from diploid Agropyron cristatum, 2n=14; tetraploid A. desertorum, 2n=28; and A. cristatum ✕ A. desertorum crosses. Chromosome associations in autotriploid A. cristatum averaged 4.39 I. 4.51 II, and 2.53 III in 278 meta phase‐I cells. Trivalent associations were less common in autotriploid A. cristatum than in other known Gramineae autotriploids. Triploid A. desertorum averaged 3.88 I, 4.20 II, and 2.91 III in 116 cells at metaphase I. The A. desertorum genomes appeared to be essentially homologous except for a possible inverted segment in one chromosome and cryptic structural differences. The A. cristatum ✕ A. desertorum triploid averaged 2.43 I, 3.50 II, 3.10 III, 0.53 IV, and 0.03 V in 70 metaphase‐I cells. The A. cristatum and A. desertorum genomes apparently differ from one another by several structural chromosome rearrangements including interchanges and inversions.

Diploid A. cristatum, triploid A. cristatum, tetraploid A. desertorum, triploid A. desertorum, and A. cristatum ✕ A. desertorum triploids were represented by genome formulas of CC, CCC, C1C1C1C1, C1C1C1 and C1C1C1, respectively. Although A. desertorum is an apparent autotetraploid, it appears doubtful that it originated directly from the only known form of diploid A. cristatum.

Although A. cristatum and A. desertorum differ in ploidy level and morphology, they contain the same basic genome and do not appear to be distinctly different species. It is suggested that A. desertorum and all other crested wheatgrass be designated as subspecies and varieties of A. cristatum. Grass breeders are advised to consider all crested wheatgrasses, regardless of ploidy level, as a single breeding population.
Internal Breakdown and Persistence of Red Clover1
Authors: Cressman R. M.
Published: July 2010

Field and greenhouse experiments have implicated internal breakdown (IB), a necrosis of the pith of the crown, as a major factor limiting the persistence of red clover. Less persistence in early‐flowering types appears to be related to reduced capacity of the plants to survive the effects of IB. Survival of plants with IB appears to be a function of the extent to which an adventitious root system develops. Various treatments failed to affect the incidence of IB. No pathogen was consistently isolated from early stages of IB. Histological studies also failed to reveal any pathogen. A histological description, including the occurence of nuclear anomalies, is presented.
Development of Maize Hybrids through Selection among Full‐Sib Families1
Authors: Lonnquist J. H. , Williams N. E.
Published: July 2010

A total of 102 full‐sib families (cryptic double crosses) were made up between two maize populations which had undergone several cycles of recurrent selection for general combining ability. The families exhibited an average heterosis of 31% and averaged 6% higher yields than three elite double‐cross hybrid checks with which they were compared over a 2‐year period. The prolific parent plants used in making the full‐sib families were self‐pollinated at the time crosses were made. A second round of full‐sib families using the F2 progenies from parents of selected crosses gave evidence of further yield improvement. The procedure can be used to develop sister‐line or modified hybrids with relative ease.
Effects of Different Gene‐Cytoplasm Systems on Quantitative Characters in Reciprocal F2 Crosses of Maize (Zea mays L.)1
Authors: Crane Paul L. , Nyquist W. E.
Published: July 2010

The inbred WF9 genotype was incorporated into 41 diverse cytoplasms by backcrossing 4 times. Cytoplasmic donor lines were thus formed with largely WF9 genotype in cytoplasms of diverse origins. Seventeen of 60 reciprocal plant‐to‐plant F1 crosses between donor lines and 2 inbred testers gave significantly different yields in 1962. Subsequent experiments utilized reciprocal F2 pairs to eliminate maternal seed effects. Six of 16 reciprocal F2 pairs gave significant differences in yield in one experiment. In a more extensive study with 11 cytoplasmic donor lines plus the original WF9 crossed with 4 tester inbreds, the F2 pairs were tested 2 years at 2 locations. Fed reciprocal differences and interactions with reciprocals were significant for yield of grain, percent moisture at harvest or lodged plants at harvest. Only 2 of 48 differences between reciprocal crosses were significant for yield. However, 2 of the 4 overall mean reciprocal differences for testers were significant, and in these cases exotic cytoplasms were superior.

Cytoplasmic and genotype ✕ cytoplasmic interaction effects on the three characters as measured in reciprocal F2 hybrids were of low magnitude and probably interacted with years and locations. The results give little encouragement to the breeder to select cytoplasms with superior performance over years for even a limited region.
Breeding Alfalfa for Resistance to the Stem Nematode, Ditylenchus dipsaci1
Authors: Sherwood R. T. , Dudley J. W. , Busbice T. H. , Hanson C. H.
Published: July 2010

An experimental synthetic, combining agronomic characteristics of Flemish alfalfa with stem nematode resistance equivalent to that found in ‘Lahontan’, was developed largely by backcrossing. Selections were made in a naturally infested field. Certain selected plants were further evaluated by inoculating their S1 progeny under controlled conditions in a laboratory.

A second resistant synthetic was developed by recurrent selection in the susceptible variety ‘Cherokee’. Laboratory tests of seedling reaction were the basis for all selections; in each of two successive cycles, mass selection was followed by S1 progeny testing of selected plants.

The procedure followed in developing resistance in the second synthetic appeared to be more efficient than the one used in the first. Results from laboratory tests agreed well with those from field tests, but laboratory evaluation was found to be more reliable and economical for determining resistance.
Response of Soybeans to Tiba (2,3,5‐Triiodobenzoic Acid)and High Fertility Levels
Authors: Hicks D. R. , Pendleton J. W. , Scott W. O.
Published: July 2010

Glycine max (L.) Merr., ‘Wayne’, was used to study the effects of the antiauxin TIBA (2,3,5‐triiodobenzoic acid) at high levels of fertility in field trials at Urbana, Illinois.

The following responses were observed for TIBA treated plants. Leaf area was reduced 20%. Plant height was decreased 33% due to shorter internode lengths. The nitrogen content of leaves and protein content of the seed were decreased; the oil content was unaffected. Pod set increased while the number of seeds per pod decreased. The number of seeds per plant increased, but reduction in seed size caused the total seed yield to remain approximately the same. Standability was improved by TIBA.

Large broadcast applications of fertilizers on this highly productive Corn Belt soil did not increase soybean yields.

There was also no interaction found for fertility and TIBA.
Inheritance of Quality and Quantity of Seed‐Oil in Safflower (Carthamus tinctorius L.)1
Authors: Yermanos D. M. , Hemstreet S. , Garber M. J.
Published: July 2010

A safflower introduction from India and the variety ‘N‐10’ were crossed reciprocally to produce F1, F2, F3 and backcrossed generations. The same 2 lines were grafted reciprocally. Seed samples from these materials were analyzed for oil content and composition. Seed‐oil of N‐10 has high iodine value while that of the other line has low iodine value.

It was found that the iodine value of safflower oil: (a) is determined by the genotype of the seed and not by that of the sporophyte on which the seed develops; (b) is not influenced by maternal effects; (c) is controlled by a single locus with one recessive allele producing low iodine value and the other, partially dominant, producing high iodine value; and (d) has a very high heritability.

The oil content of the seed is controlled by several genes without any apparent dominance gene action. Significant positive correlations were found: between (a) iodine value and palmitic, stearic and linoleic acid; and (b) between oil content and palmitic acid, linoleic acid, and iodine value. Significant negative correlations were found between oleic acid and palmitic acid, linoleic acid, iodine value and oil content.

Oil composition was not affected by maternal effects, flower color, spinines
Performance of Inbred Lines in Hybrid Combination During the Transfer of a Single Gene (ae) Locus in Maize (Zea mays L.)1
Authors: Duclos Z. M. , Patterson F. L. , Kramer H. H.
Published: July 2010

The effects of the gene ae and possible linked factors were studied with regard to yield during the transfer of ae to the four inbreds of the double cross hybrid U.S. 13. The effects of the gene and its linkage block in the inbreds were studied in backcross test during three generations of backcrossing and selfing. The effects of the gene and its linkage block in hybrids were studied in single cross tests following various generations of back crossing to the four inbreds.

Expected lengths of linkage block segments around the ae locus held heterozygous for the different generations were calculated. From these the percent heterozygosity was calculated for ae and normal phenotypes. Observed and expected yields were compared with the t‐test. The expected yield was calculated by equating the difference between the mean of the inbreds and the single cross to 100% heterozygosity. Expected yield was based on percent hetorozygosity.

The ae gene and not genes linked with it appeared to have a strong adverse effect on yield. Evidence from ae kernels and normal kernels from the same ear indicated that the effect of gene ae was on kernel size, supporting existing evidence that ae blocks the formation of branch chain polysaccharides without a corresponding increase in straight chain polysaccharides.
Effect of Temperature, Light, and Nitrogen on Growth and Metabolism of ‘Cohansey’ Bentgrass (Agrotis palustris Huds.)1
Authors: Schmidt R. E. , Blaser R. E.
Published: July 2010

Bentgrass growth, carbohydrate reserves, and NP were influenced by temperatures. Evidently, after carbohydrates were utilized to a certain degree at high temperatures, growth was reduced below the yield of bentgrass grown at lower temperatures. Carbohydrate reserves apparently reflect the energy balance between photosynthesis and respiration and growth. This was verified by stimulated top growth but decreased carbohydrates when bentgrass was grown under warm days and cool nights.

Although bentgrass fertilized liberally with N had high photosynthetic rates, much of the stored energy was reduced and root development was less than with low N. Shade caused a reduction in photosynthesis which decreased the carbohydrate content and growth.

Data suggest that seasonal temperature must be considered in timing N fertilization for best bentgrass development.
Response of Seedling of Festura rubra Varieties to Environmental Conditions1
Authors: Nittler L. W. , Kenny T. J.
Published: July 2010

Seedlings of red rescue (Festuca rubm L.) varieties and of Chewings rescue (Festuca rubra vat. commutata Gaud.) were grown under controlled conditions in growth chambers. Seedlings differed in growth habit, color of lower leaf sheaths, and green weight. A high correlation was found between decumbent growth habit and green color of lower leaf sheaths. Daily cold periods induced up to 50% of common plants to become decumbent in growth habit. Decumbent plants did not occur if they were grown with continuous warm temperatures. All varieties and seed samples tested with daily cold periods produced mixtures of plants decumbent, intermediate, and upright in growth habit. However, seed samples differed in percentages of these types. Varietal differences were not great enough for precise varietal purity determinations, but some samples of comomn seed could be distinguished from seed of improved varieties.
Crown Rust Resistance of the Oat Strain P. I. 1745441
Authors: Simons M. D.
Published: July 2010

The oat strain P.L 174544 (Arena sativa L.) has adult plant but not seedling resistance to race groups 202 and 264, and some races of group 290 of crown rust (Puccinia coronata Cda. var. avenae Fraser and Led.). Its resistance was conditioned by a single major gene, but minor genc effects were also important under some conditions. The resistance of P.I. 174544 was nonallelic to that of certain other well‐known sources of field resistance. Pure lines derived from crossing P.I. 174544 with the susceptible ‘Clinton’ were obtained that had the full resistance of P.I. 174544, as measured in terms of effect of crown rust on yield, seed weight and seed density.
Pollen Dispersal and Cross‐Pollination of Soft Red Winter Wheat (Triticum aestivum L.)1
Authors: Bitzer Morris J. , Patterson Fred L.
Published: July 2010

Hand emasculated wheat spikes left exposed to wind borne pollen and vaseline‐coated slides were used to measure pollen dispersal and seed set on several females under conditions of high and limited pollen loads. Seed set was directly related to wind‐borne pollen load. Some females were quite superior in the ability to set seed from wind‐borne pollen. About 4 or 5 days of good pollen load were required for maximum seed set. Timing of the female exactly with pollinator generally gave the maximum seed set.
Monosomic Analysis of Fertility‐Restoration in Common Wheat (Triticum aestivum L.)1
Authors: Robertson L. D. , Curtis B. C.
Published: July 2010

Monosomic analysis of the restoration genes in Triticum timopheevi Χ Marquis3, a hexaploid fertility‐restorer with T. timopheevi cytoplasm known to possess two major dominant genes Rf1Rf1Rf2Rf2, revealed that chromosome 1A carries one of the major genes. Inconclusive data prevented identification of the other chromosome carrying a major gene. Chromosome 3A was not studied.

Chromosomes 1B, 2A, 3D, 6A, and 6B of ‘Chinese Spring’ appear to carry modifier genes which prevent normal expression of restoration when absent, even though Rf1 and Rf2 genes are present.
Effects of Sodium 2,3‐dichloroisobutyrate Sprays on Anther Development and Microsporogenesis of Fenu‐greek (Trigonella foenum‐graecum L.)1
Authors: Kaul C. L. , Singh S. P.
Published: July 2010

Comparative cytological and histological studies were made of anthers from untreated and sodium 2,3‐dichloroisobutyrate treated plants of fenu‐greek (Trigonella foenum‐graecum L.). Early stages of anther development, meiosis, and microspore formation was similar in both cases. Microspores in untreated plants continued to enlarge and formed mature pollen grains, whereas micro spores from treated plants degenerated. The degeneration of microspores was believed to result from the combined effect of competition from persistent tapetal cells and mechanical pressure exerted by hypertrophied tapetal cells.
Heterosis and Combining Ability in Intraspecific and Interspecific Crosses of Cotton1
Authors: Marani A.
Published: July 2010

Trials were conducted in 1961 and 1962 on seven and eight varieties, respectively, of G. hirsutum L. and G. barbadense L. and all possible reciprocal crosses between them. The average magnitude of heterosis for lint yield was 24.5% and 21.6% in the intraspecific crosses of G. Oirsutum L. and G. barbadense L., respectively, and 72.8% in the interspecific crosses. Heterosis for lint yield was associated in all cases with heterosis for yield of seedcottou and in many cases also for the number of bolls per m2. Heterosis for boll‐weight was found only in G. hirsutum L. intraspecific crosses where it was associated with heterosis for seed‐index, lint‐index, and number of seeds per boll. The interspecific crosses had a low lintpercent because heterosis for seed‐index was much more pronounced than heterosis for lint‐index in these crosses.

Effects of general combining ability in the interspecific crosses, which were more pronounced than effects of specific combining ability, corresponded to the performance of the parental varieties themselves. If heterosis in interspecific crosses is to be used to breed F1 hybrids, the selection of parental varieties should be made on the basis of their own performance for those traits that have shown consistent and significant effects of general combining ability.
Use of Self‐Incompatibility to Produce Commercial Seed‐Propagated F1 Bermudagrass Hybrids1
Authors: Burton Glenn W. , Hart Richard H.
Published: July 2010

Many clones of bermudagrass exhibit a high degree of self‐incompatibility. Most of these appear to be crosscompatible. Six superior clones set an average of six times more seed when mutually pollinated with the other five clones than when selfed. Four of the 15 diallel (mutual pollination) crosses involving these six clones tested in plots established from seed yielded as much (or more) forage as the best vegetatively propagated clone in the test. One clone, unrelated to the others, gave high‐yielding hybrids and high general combining ability effects when crossed with the other five dories. Commercial F1 hybrid seed could be produced by harvesting all seed from a field vegetatively planted to alternate rows of two such clones. These clones may not yield enough seed, however, to make hybrid bermudagrass seed production competitive with alternate land uses in Arizona.
Natural Selection of Ball Clover Ecotypes in Reseeding Pastures1
Authors: Hoveland C. S. , Johnson W. C.
Published: July 2010

Local ecotypes of ball clover developed in fields reseeding for 5 to 9 years. Ecotypes originating in southern Alabama made more rapid autumn growth, considerably more winter forage, and bloomed slightly earlier than those from further north in the State.
Boll Retention in Relation to Leaf and Boll Development in Cotton (Gossypium hirsutum L.)1
Authors: Johnson R. E. , Addicott F. T.
Published: July 2010

The effect of leaf area and gibberellic acid (GA) boll retention was studied on cotton plants growing in nutrient culture. Leaf area was reduced to approximately half the control by two methods of leaf clipping, and two concentrations of GA were applied to all flowers.

In control plants, the ratio of leaves to retained bolls was initially high. It declined to approximately three at midseason, and thereafter remained constant to the end of the fruiting period. After adjustments for differences in leaf size, ratios for partially defoliated plants were similar to those of the control. Percent boll retention paralleled leaf‐boll ratios.

Seed cotton yield and percent retention were significantly reduced in the partially defoliated treatments; however, no differences were found when seed cotton yield was expressed as a function of maximumle af area developed. There were no differences between the GA treatments and control for any of the characters measured. That retention was not increased by treating all the flowers contrasts with results obtained when only a few flowers or young bolls were treated.

The number of seeds per retained boll for all treatments was low initially, increasing to a maximum at the time of greatest shedding. This may indicate that a high seed complement is required for a boll to be retained when competition for assimilate occurs.

The results are interpreted as supporting the view that boll retention depends on the presence of a sufficient number of developing seeds to mobilize the assimilates required for contiuued growth, and upon the availability of assimilates as governed by the vegetative‐reproductive status of the plant.
A Laboratory Technique to Evaluate Boll Weevil Oviposition Preference Among Cotton Lines1
Authors: Buford William T. , Jenkins Johnie N. , Maxwell Fowden G.
Published: July 2010

A technique was developed to evaluate a large number of cotton lines in a minimum of time as oviposition sites for the boll weevil. Mississippi field weevils and the A & M laboratory strain were tested for a comparison of their response to various cotton lines. We concluded that: (1) Evaluating cotton lines with the laboratory strain of weevile would closely approximate the cotton varietal differences evident in evaluating with field weevils; (2) Boll weevil oviposition was an insect biological response which could be modified by the host plant genotype; and (3) ‘Triple Halhnark Sea Island,’ ‘Seaberry Sea Island,’ their F1 hybrid, ‘Brown Egyptian’, and Seaberry Sea Island ✕ Brown Egyptian were less preferred for oviposition by the boll weevil than ‘Deltapine Smooth Leaf.’
Spread of an Undesirable Gene in Populations of Phaseolus lunatus L.1
Authors: Tucker C. L. , Prout Timothy , Harding James
Published: July 2010

An experimentally purified population of Phaseolus lunatus L. ‘Concentrated Fordhook’ was used to estimate the recurrent mutation rate of the recessive allele w to the dominant allele W. No mutations were found in the sample of 387,684 gametes tested and the maximum possible mutation rate was estimated to be 1.5 × 10−5. The frequency of the dominant allele was estimated in a commercial (unpurified) population and found to be 3.1 × 10−3. A mathematical analysis indicated that this maximum recurrent mutation rate could not account for the spread of the undesirable W allele in commercial populations of Concentrated Fordhook. A minimum selective advantage of 11% for the WW genotype was proposed and the disparity between this estimate and the previously reported estimate of a 40 per cent disadvantage was discussed.
Helminthosporium setariae on Pearl Millet, Pennisetum typhoides, as Affected by Age of Host and Host Differences1
Authors: Wells Homer D. , Burton Glenn W.
Published: July 2010

A late‐maturing synthetic (Late Synthetic), the three cultivars, Common, ‘Starr,’ and ‘Gahi 1,’ the four inbred lines which serve as parents in the production of Gahi 1 seed (Tift 13, Tift 18, Tift 23, and Tift 26), and the six diallel crosses from these four inbreds of pearl millet, Pennisetum typhoides, were inoculated at weekly intervals (1 to 13 weeks of age) with a mycelial‐conidial blend of three isolates of Helminthosporium setariae. The average disease reactions were most severe when plants were inoculated at 1 week of age and reactions were progressively less severe each week until about the 6th or 7th week, when reactions began to increase in severity. However, Late Synthetic, Gahi 1, and two of the diallel crosses tended to remain resistant after the 6th week. There were significant differences in average disease reactions of the pearl millet entries. Late Synthetic was the most resistant. Gahi 1 and four of the six diallel crosses were more resistant than the four parent inbreds.
Heterosis and Combining Ability in Barley1
Authors: Upadhyaya B. R. , Rasmusson D. C.
Published: July 2010

Eight parental varieties of barley and the 28 possible F1 and F1 populations were evaluated in spaced plantings in two environments. The traits studied were yield, kernel weight, kernels per head, heads per plant, and height.

The average heterosis values of F1's based on midparent means for yield, kernel weight, kernels per head, heads per plant, and height were 21.5, 5.9, 7.1, 7.6, and 3.2%, respectively. When the F1's were compared to the high parent, the average heterosis for yield was 9.1%. The average inbreeding depression for yield in the F2 generation was 26.1%

General and specific combining ability variances were obtained from the F1 data, using Griffing's experimental method 4, model II. A substantial amount of additive and nonadditive genetic variance for yield was indicated. Most of the genetic variance for kernel weight, heads per plant, kernels per head, and height was additive.

The yield of the best hybrid exceeded the highest yielding parental varieties, Liberty and Traill, by 22 and 38%, respectively. A hybrid advantage of this degree combined with evidence of considerable nonadditive genetic variance for yield indicates the desirability of additional research on hybrid barley. The results reported indicated that performance per se can be used as a basis for initial screening in evaluating potential parental varieties for use in a hybrid breeding program.
Development of High‐Amylose Corn (Zea mays L.) by the Backcross Method1
Authors: Helm J. L. , Fergason V. L. , Zuber M. S.
Published: July 2010

Alternate backcrossing and selling has been employed to convert 5 corn belt inbreds to high‐amylose inbreds, with selection in each generation for maximum amylose content. Genetically, the ultimate amylose content is determined by the ae gene in combination with a modifier complex. After three generations of backcrossing, all possible single crosses were made among the inbred lines from each backcross generation and among the recurrent parents. These single crosses were grown under three environments to determine the rate of convergence to the recurrent parent. Significant deviations from expected indicated that selection for maximum amylose content slowed the theoretical rate of convergence to the recurrent parent for such traits as whole kernel oil and protein content, test weight, shelling percentage, ear height, and grain yield. During successive generations of backcrossing the amylose level was maintained, indicating that selection for modifier genes was effective. Selection for positive modifiers in each backcross generation may have carried along linked genes, inhibiting the convergence to the recurrent parent for some traits. These results indicate that when sdection pressure is applied for maximum amylose content, more than the expected number of backcrosses will be necessary to convert corn belt inbreds to equally desirable high‐amylose inbreds.
Cold Resistance in Wild Oats1
Authors: Suneson C. A. , Marshall H. G.
Published: July 2010

Wild oats, Avena fatua L., with selection‐site implications for cold hardiness were screened for winter growth habit, BYDV reaction and maturity. Nine decumbent lines had good cold resistance in freezing tests, and may possess diverse genes needed to develop winter oat varieties with improved winter hardiness.
Internode Length in Height Mutants of the Sorghum Variety Wheatland1
Authors: Brooks James S.
Published: July 2010

Four lines were established in the sorghum variety ‘Wheatland,’ each homozygous for a separate mutation from dw2 to Dw3. A replicated planting of these mutants and three normal Wheatland plants was made to study the effect of the Bw3 allele on the length of the various internodes among otherwise isogenic lines.

Internodes one and five were most effected and internode three least effected by the Dw3 allele.
Inheritance of Soybean Seed Quality I. Heritability of Laboratory Germination and Field Emergence1
Authors: Green D. E. , Pinnell E. L.
Published: July 2010

Individual plants of parental, F1 and F2 populations, and F3 progenies of soybeans were evaluated for seed quality as measured by seedling emergence percentage in the field and by six determinations made in a standard laboratory test. The laboratory determinations were percent normal seedlings plus hard seed, normal seedlings at 5 days, total normal seedlings, abnormal seedlings, decayed or dead seed, and hard seed. Five parental populations consisted of two commercial varieties, Chippewa and Harosoy 63, and three Japanese strains, Wasedaizu No. 1 (PI261469), Matsuura (PI200499), and Kimusume (PI229336). Six F1 and six segregating (F2 and F3) populations were produced from crosses of each Japanese strain as female parent with each of the commercial varieties.

Estimates of broad sense heritability for the field emergence and laboratory germination characters were generally low positive or negative values because of high environmental variances in parents and F1's. Narrow sense heritabilities ranged from 3 to 29% for field emergence, from 2 to 60% for the three determinations of normal seedlings in laboratory germination tests, and from 31 to 71% for hard seed. Fa population means for the seed quality characters were usually equal to or higher than the mid‐parent values. In each cross 10 to 20% of the F3 families exceeded the high parent for field emergence. Thus, improvement in this character from selection would seem easy, in spite of the low calculated heritabilities, if selection pressure is applied on F3 to Fn families rather than on single plants and if some replication is used in producing family seed for testing.

Percentages of normal seedlings plus hard seed, normal seedlings at 5 days, and total normal seedlings were about equally well correlated with percentages of normal seedlings in field emergence tests. Abnormal seedling and hard seed percentage in laboratory tests were not as closely associated with field emergence.
Inheritance of Soybean Seed Quality II. Heritability of Visual Ratings of Soybean Seed Quality1
Authors: Green D. E. , Pinnell E. L.
Published: July 2010

Seed from the parental, F1, and segregating (F2 and F3) soybean populations were evaluated for quality by visual ratings for wrinkled seedcoats, shriveled cotyledons, green cotyledon color, an arithmetic average of the three previous ratings, and an overall visual rating. These ratings were on a 1 to 5 scale, with 5 being the most extreme expression of the character.

The variance among single plants in the commercial varieties for the visual ratings was generally high in relation to the variance in the Japanese strains and in the F1 populations. However, the variance in the F2 populations was generally large in comparison to the arithmetic mean of the variances within the respective parental and F1 populations resulting in broad sense heritability estimates ranging from 41 to 63% for wrinkled seedcoats, 14 to 57% for shriveled cotyledons, 52 to 82% for green cotyledons, 41 to 71% for the average visual rating, and 22 to 64% for the overall visual rating. Narrow sense heritability estimates for the visual ratings ranged from 6 to 30% for wrinkled seedcoats, 10 to 38% for shriveled cotyledons, O to 29% for green cotyledons, 1 to 28% for the average visual rating, and 7 to 28% for the overall visual rating.

Low visual ratings for wrinkled seedcoats, shriveled cotyledons, green cotyledons, low average visual ratings, and low overall visual ratings were generally associated with high percentages of normal seedlings in field emergence tests. This was especially true in the F3 and ‘Chippewa’ parental populations in which more variation existed in each of the characters being tested.

The average visual rating was somewhat more consistent in predicting relative field emergence than any of the ratings of separate seed characters. However, the overall visual rating appeared to be about equal in this respect. Considering both precision of measurement and time utilization, an overall visual rating followed by field emergence testing may be the most efficient means of evaluating segregating populations of soybeans for seed quality.
Combining Ability Studies in Birdsfoot Trefoil1
Authors: Miller John D.
Published: July 2010

Diallel progenies of four clones were grown for 3 years. The mean squares for general combining ability (g.c.a.) were significant for flowering date and forage yield. The mean squares for specific combining ability (s.c.a.) were significant for flowering date, vigor score, disease score, and forage yield. Mean squares for crosses, g.c.a., and s.c,a. were not significant for survaval or growth type. The interrelationship of several variables were investigated by means of correlation and multiple regression. Significant correlation (P = 0.001) existed for yield with vigor, disease score, and flowering date. Disease score and survival were also highly correlated. No correlation was found for growth type with yield or flowering date. Multiple regression showed that most of the variation in yield was related to vigor rather than to other characters.
Forage Density Gauging with Sr90 for Estimating Green Forage Yield in situ1
Authors: Barta A. L. , Teare I. D.
Published: July 2010

An accurate and reliable technique for estimating green forage yield in situ has been developed which utilizes beta particle attenuation by plant material.

This technique involves the attenuation of beta particles from a strontium‐90 source by the vegetative mass of a forage stand. By measuring the intensity of the transmitted beta beam through different forage stands, a yield calibration curve was made which relates green forage yield to counts per minute. It was also found that the slope of the yield calibration curve was independent of the three crops tested as well as moisture content, thereby allowing a single yield calibration curve to be used for all forages.

A field instrument was constructed to measure the practical value of density gauging to estimate green forage yield.

Regression analysis of the experimental field data showed that this method accounted for 86% of the variation in yield and affirmed its usefulness in pasture research.
Photorespiration and Glycolate Metabolism in Tobacco Leaves1
Authors: Moss Dale N.
Published: July 2010

The stimulating effect of light on the evolution of CO2 from tobacco leaves into CO2‐free air was suppressed by inhibition of glycolate oxidase with α‐hydroxy‐2‐pyridinemethanesulfonic acid. The inhibitor strongly inhibited photosynthesis at both 25 and 35 C. The CO2 compensation concentration increased indefinitely for leaves treated with inhibitor. Glycolate accumulation in leaves treated with inhibitor was strongly dependent on inhibitor concentration and light intensity and was linear with time up to one hour. Temperature for growth or during the experiments had little effect on accumulation.

The possible internal CO2 from the oxidation of glycolate calculated on the basis of glycolate accumulation under optimal conditions indicates that photorespiration from glycolate as a substrate may be at least 2‐fold dark respiration. Although the possible rate of respiration from glycolate metabolism was large, it was not sufficient to account for the differences in photosynthesis between maize and tobacco on the assumption that this difference was due to internal recycling of CO2 in tobacco.
Cumulative Gene Effects and the Nature of Heterosis in Maize Crosses Involving Genetically Diverse Races1
Authors: Castro M. G. , Gardner C. O. , Lonnquist J. H.
Published: July 2010

Five open‐pollinated varieties each representative of a different racial group and 35 other populations developed from them (the five varieties selfed, 10 F1 crosses, and the random mated and selfed progenies of the F1 crosses), were grown in three environments in Mexico. Data were taken on grain yield, days to flower, plant height and number of ears per 10 plants. The phenotypic means of the 40 populations for each trait were analysed separately by analysis of variance technique, and the variance among populations was subdivided according to the model and analysis I outlined by Gardner and Eberhart (1966).

In the case of yield, the greatest contributing factor to genetic variation was intravariety dominance effects (52.4% of the total). Additive gene effects contributed most to variation among means in days to flower (87.9%), plant height (79.3%) and ear number (60.9%). Average heterosis in the crosses explained 5.1% of the total variation in yield means whereas varietal and specific heterosis effects accounted for only a minor portion of the variation and were nonsignificant statistically. In the other traits, “the variation accounted for by heterosis effects was, in all cases, nonsignificant.

Estimates of the gene effects were used to compute predicted means of the entries in the experiment, the advanced generations of crosses of three and four races and more precise estimates of heterosis. The highest yielding predicted crosses in advanced generations are suggested as basic genetic material to be used in a mass selection program prior to initiating any breeding procedure involving inbreeding.

The data obtained are considered to fit the genetic model used. No evidence was found to indicate that epistasis contributes to heterosis in the traits studied even though genetically diverse varieties of maize were crossed. The possible presence of undetectable types of epistasis and the stability of the estimated gene effects in different environments are discussed.
Inheritance of Anther Size and Spikelet Characteristics: Their Interrelationship in Crossing Cultivars, ‘Bronco,’ Avena, sativa L. and A. sterilis L. Ssp. Macrocarpa (Moench.) Briq
Authors: Kim Heung Bae , Atkins I. M. , Pawlisch P. E.
Published: July 2010

Inheritance of anther length and width in a cross of ‘Bronco’ X ‘Macrocarpa’ oats gave dihybrid ratios with incomplete dominance. Inheritance of lemma length, lemma and basal pubescence, basal and floret separation, and awn development were each monofactorial but with considerable apparent environmental influences. Large anthers were rather closely associated with heavy awns and other Avena sterilis characters of Macrocarpa, but linkage tests showed that it is possible to recombine larger anthers with spikelet characters similar to the Bronco parent.
Heterosis and F2 Performance in Intraspecific Crosses Among Varieties of Gossypium hirsutum L. and of G. barbadense L.1
Authors: Marani A.
Published: July 2010

Three trials, conducted in 1964 and 1965 in Israel, included a set of four varieties of G. hirsutum L. and their intraspecific crosses in all combinations in the F1 and F2 generations, and a similar set of four G. barbadense L. varieties and their F1 and F2 intraspecific crosses. Heterosis for lint yield was 15 to 24% and 21 to 28% in G. hirsutum L. and G. barbadense L. intraspecific F1 crosses, respectively. This was always associated with heterosis for yield of seed‐cotton and for the number of bolls produced. Heterosis for boll‐weight was found in G. hirsutum L., but was not always shown by G. barbadense L. Heterosis for boll number was associated with a higher percentage of boll retention in G. hirsutum L. and with more flower production in G. barbadense L.

F2 deviations from the average of mid‐parent and F1 performances were relatively small for lint yield, indicating that although some epistatic effects may be operative for this trait, additive and dominance genetic effects are more important. In G. hirsutum L. significant F2 deviations were found for lint‐index and lint‐percent, and in some cases also for seed‐index. In G. barbadense L. a significant F2 deviation was found only for flower number in one experiment.