bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Source‐Sink Relationships within Narrow‐Row Cotton Canopies1
Authors: Kerby T. A. , Buxton D. R. , Matsuda K.
Published: July 2010

Cotton (Gossypium hirsutum L.) is an indeterminate crop in which vegetative and reproductive sinks compete for photosynthetic assimilates. The objective of this study was to evaluate the carbon source sink relationship in cotton canopies with differing leaf types grown under narrow‐row culture and to determine if measurement of specific leaf weight (SLW) can be used as a simplified evaluation of photosynthetic rate within cotton canopies. Three near‐isogenic lines of ‘Stoneville 7A’ (normal, okra, and superokra) cotton which differed in blade area/leaf were grown in narrow‐row culture at a plant density of 10 plants m‐2. During the 3rd (29 July) and 5th (13 August) weeks of flowering, whole plants were exposed to 14CO2 and evaluated at three height intervals (0 to 30 cm, 30 to 55 cm, and above 55 cm) for leaf area index (LAI), 14CO2 uptake, and biomass distribution. Okra and superokra leaf types generally had higher 14CO2 uptake within the canopy on a leaf area basis, but lower LAI than normal leaf plants. Uptake of 14CO2 among leaf types on a land area basis was different only on 13 August in the top interval where the ranking was normal > okra > superokra. By 13 August, the top interval accounted for 81, 77, and 69% of the canopy 14Cassimilate production, but contained only 29, 28, and 32% of the fruit dry weight for normal, okra, and superokra leaf plants, respectively. Mutant leaf types had a larger percentage of dry weight as fruit and less as leaves and petioles compared to normal leaf plants. This study suggests that vegetative growth is favored at the expense of reproductive growth due to high LAI at the top of normal leaf canopies when grown in narrow‐row culture. However, the mutant leaf types tend to have less biomass resulting in only equivalent yields to normal leaf plants when grown under full‐season culture. Significant correlation coefficients between C uptake and SLW ranged between 0.72 and 0.89 depending upon time of SLW measurement and sampling date, but were not altered by leaf type. Use of SLW is a simple method for estimating photosynthetic activity of leaves within cotton canopies.
Genotype ✕ Environment Interactions and Stability Analysis for Herbage Yield of Tall Fescue Synthetics1
Authors: Nguyen Hung T. , Sleper D. A. , Hunt K. L.
Published: July 2010

The development of forage grass cultivars which maintain a high level of performance over a wide range of environments is a goal of most breeding programs. Twenty‐five synthetics and two cultivars of tall fescue (Festuca arundinacea Schreb.) were evaluated for 3 years at two locations. Entries differed significantly for reproductive, vegetative, and total herbage dry matter yields. Significant entry ✕ environment (linear) interactions occurred for reproductive and vegetative regrowth, indicating that there were significantly different environmental responses among the 27 entries. Entry mean yields were linearly regressed on the average of all entries La each environment. Regression coefficients of the synthetics ranged from 0.71 to 1.24, 0.76 to 1.17, and 0.84 to 1.15 for reproductive, vegetative, and total herbage dry matter yield, respectively. Linear regression accounted for 95 to 99%, 78 to 99%, and 89 to 99% of the variation in yields of the 27 entnes for reproductive, vegetative, and total herbage dry matter yield, respectively. Mean square deviations from regression were found to be homogeneous, using the Bartlett test, for the three yield measurements. In the regression analysis of variance, the pooled deviations were not significant for all three yield measurements. The mean square deviations, coefficient of determination, and ecovalence stability indexes were highly and significantly correlated. We concluded that the mean herbage yield was a sufficient statistic for the selection of synthetics which have high and stable total yield. The regression coefficient was a useful statistic, in addition to mean herbage yield, if the goal was selection for desirable stable herbage regrowth yield.
Influence of Mechanical Damage and Fungicide Seed Treatments on Germination and Stand with Cottonseed1
Authors: Green Janet A. , Minton Earl B.
Published: July 2010

Mechanical damage to the seed coat of cotton (Gossypium hirsutum L.) seeds may occur during harvesting, ginning, and processing. The extent of damage vanes considerably among seed lots and it is impossible to remove all damaged seed while processing seed for planting. Fungicide‐treated and non‐treated seed with damaged seed coats germinate slower and produce poorer stands than seed with nondamaged seed coats. The percentage germination at standard temperatures in the laboratory and the stands and seedling growth in the greenhouse were inversely related to the extent of damage to the seed coat of acid‐delinted cottonseed. Scratches or cracks in the seed coats that did not expose the embryonic tissues adversely affected germination and stand less than did damage that exposed the embryonic tissues. Coating cottonseed with fungicides improved the performance of all seed classes, but the most improvement was obtained from seed with a damaged seed coat. However, no fungicide treatment completely compensated for the damage to the seed coat.
Resistance to Soybean Rust and Mode of Inheritance1
Authors: Bromfield K. R. , Hartwig E. E.
Published: July 2010

A study was conducted in containment facilities to determine the reaction to Phakopsora pachyrhizi Syd. (soybean rust) isolates from widely separated geographic areas on seven soybean [Glycine max (L.) Merr.] strains rated moderately resistant in field planting in Taiwan. Additional studies were conducted to determine the mode of inheritance of resistance to several rust isolates. Soybean strains PI 230970 and PI 230971 were resistant when inoculated with P. pachyrhizi isolates Australia‐72‐1, India‐73‐1, Philippines‐77‐1, and Taiwan‐72‐1. The other five soybean strains, although rated moderately resistant in field planting in Taiwan, were rated susceptible in these studies. All were rated resistant to an isolate with low virulence from Puerto Rico.

Individual trifoliolate leaves of soybean plants of an F2 population of ‘Centennial’ × PI 230970 were inoculated with rust isolates from three different geographic areas. Plants rated as resistant to one isolate were resistant to all isolates. Similarly, plants rated susceptible to one isolate were susceptible to all isolates. A ratio of 92 resistant to 31 susceptible was obtained. Twenty‐five F2 plants from the cross D75‐10169 × PI 230971 gave 19 resistant and six susceptible plants after inoculation with the Taiwan isolate. The results suggest a single dominant gene for resistance to soybean rust.
Selecting Lines of Vetch that Breed True for Hard Seed1
Authors: Donnelly E. D.
Published: July 2010

Ten advanced‐generation, hard‐seeded vetch lines (Vicia sativa type) from V sativa L. × V. narbonemis f. serratitolia (Jacq.) Hermann were studied to determine whether or not these were breeding true for hard seed (impermeable seedcoat). Eight lines maintained a high level of hard seed over a 3‐year period whether planted from successive generations of hard seed only or from hard and soft seed as produced. Two other lines that received these same treatments produced considerably less hard seed when hard and soft seed was planted each generation than when hard seed only was planted. Data indicated that eight lines apparently were homozygous for the gene or genes conditioning hard seed and that two lines were segregating. The eight lines that apparently breed true for hard seed were composited to form the reseeding vetch cultivar, ‘Vanguard’.
Identification of Alfalfa Plants by Enzyme Electrophoresis1
Authors: Quiros Carlos F.
Published: July 2010

The objective of this study was to apply the technique of starch gel electrophoresis to the identification of alfalfa (Medicago sativa L.) mother plants. These plants, preserved in field nursery plots for breeding and genetic studies, are subject to disease and pests. In many instances heavily diseased or dead plants are replaced by unidentified volunteers, thereby genetically contaminating the plots. Anodal isozyme peroxidases, esterases, and acid phosphatases from leaf tissue were very useful for “fingerprinting” each of the 21 mother plants tested: 18 tetraploids and three hexaploids. Zymograms were consistent for each plant when tested four times in a 3‐month span. The technique consisted of running crude extracts of apical meristems at 300 V for 3 hours on starch gels holding up to 16 different samples. After the run, the gels were sliced horizontally in three or four sections and each of these was assayed for a different enzyme. Starch gel electrophoresis is a simple, inexpensive, and reliable technique for the identification of alfalfa plants.
Sampling Sorghum Plots for Kernel Protein1
Authors: Ross W. M. , Ritter R. , Maranville J. W.
Published: July 2010

When yields of sorghum [Sorghum bicolor (L.) Moench] plots are determined from unthreshed head weights, as is common in large breeding programs, grain quality analyses must be based on head sampling. Protein contents of kernel samples composited from midpanicle branches of five to seven heads per plot were compared with the protein in samples from threshed whole plots in two grain hybrid experiments of 100 and 120 entries each and in one experiment of 20 parental lines to evaluate the accuracy of head sampling.

Protein differences between sampling methods were low (0.5, 0.1. and 0.4%), but statistically significant within the three experiments. Simple correlation coefficients between sampling methods were highly significant (0.65, 0.70, and 0.83) for the three experiments.

The method ✕ entry Interaction was significant for protein only in the first hybrid experiment, probably due to sampling problems arising from selfed heads of certain female parents. In all cases, the entries ✕ methods mean squares were relatively low, which suggested that analyses of five to seven head samples using near‐infrared reflectance would be satisfactory for screening homogeneous lines and hybrids for grain protein.
Effects of Seed Density on Stand, Verticillium Wilt, and Seed and Fiber Characters of Cotton1
Authors: Minton Earl B. , Supak James R.
Published: July 2010

Rapid germination and emergence and vigorous seedling growth enhance the opportunities for profitable production of cotton (Gossypium hirsutum L.). Within seed lot, the heavier, more dense seed are most likely to exhibit these traits. In 1976, acid‐delinted, gravity‐graded seed of ‘Paymaster 909’ and ‘Tamcot SP37’ were separated into four density classes by a liquid separation process. These classes were: D1 = very low density (floaters); D2 = low density; D3 = medium density; and D4 = high density. Seed with cracked coats were included in the D4 class. Commercially gravity‐graded (DG) seed of each cultivar were used as standards. All samples were treated with carboxin‐captafol {(5,6‐dihydro‐2‐methyl‐1, 4‐oxathiin‐ 3‐carboxanilide plus cis‐N‐[(l,l,2,2‐tetrachloroethyl) thio]‐4‐cyclohexene‐l,2‐dicarboximide)} 2‐2 F SP (2 lbs. of each fungicide as aflowable seed protectant) at g/kg of seed. Enough seeds of each class were obtained to conduct tests for 2 years. The Paymaster 909 select seed were representative of the type commonly planted by area farmers. Tamcot SP37 seed were obtained from a planting of registered seed that failed to mature properly and consequently failed to meet germination reqmrements for certification in Texas. Seed index, germination, and stand were highest and the prevalence of Verticillinm wilt (caused by Verticillium dahliae Kleb.) was lowest in plants from D3 seed, but plants from D2 seed performed almost as well. The poorest overall performance was shown by plants from D1 seed, whereas the performance of plants from D4 seed lots equaled or slightly exceeded that of plants from DG seed. The liquid seed‐separation process may enable seed proeessors to isolate seed for significantly improved germination, seedling survival, and lint yield, and reduced prevalence of Verticillium wilt. The liquid separation process may be used in breeding and seed‐increase programs to select high‐quallty planting seed for performance evaluations. The process also may be used to isolate seed of acceptable quality for planting from seed that fail to meet quality standards after commercial gravity grading. Seed index may be used to select density classes for planting seed.
Parent‐Progeny Regression Estimates and Associations of Height Level with Aluminum Toxicity and Grain Yield in Wheat1
Authors: Camargo C. E. O. , Kronstad W. E. , Metzger R. J.
Published: July 2010

Concerns regarding possible associations between plant height and A1 tolerance in wheat (Triticum aestivum L. em Thell) led to this investigation. Standard height, low grain yield potential, A1 tolerant cultivars ‘BH 1146’ and ‘Atlas 66’ and semidwarf, high grain yield potential, A1 sensitive cultivars ‘Tordo’ and ‘Siete Cerros’ were crossed in a diallel fashion. Parents, F1's, F2's and reciprocal backcrosses were tested for their seedling reaction to 6 ppm of A1. Plant height and grain yield were determined for the same populations at maturity.

Parent‐progeny regression estimates for A1 tolerance and plant height were high (b = 0.903) but intermediate (b = 0.507) for grain yield. Genotypic, phenotypic and environmental correlations, between A1 tolerance with plant height and grain yield, respectively, were not significant. Grain yield and plant height correlations ranged from 0.274 to 0.813 and were significant (P = 0.01).

Results suggest it would be possible to select plant types which combine A1 tolerance and semidwarf height levels; however, large F2 populations will be required. Tordo appears to be the most promising dwarfing source for the development of semidwarf cultivars adapted to soils with high A1, but poor seed quality could be a limiting factor using this source of germplasm.
Maintenance of Parental Lines for Hybrid Red Clover1
Authors: Taylor N. L. , Anderson M. K.
Published: July 2010

Seed maintenance of parental lines of red clover (Trifolium pratense L.) was examined in an I1 sib, population derived from a single clone to determine amounts of selfing and sibbing. Seeds per head produced by pseudoself‐compatibility (PSC) on uniformly heterozygous S‐allele clones under cage varied from 0 to 8.8. Twelve cages with paired leafmarked (LL or Ll) and non‐leafmarked (ll) clones produced progenies which, as shown by leafmarking, resulted more from selfing than sibbing. Cages with a high percentage of selfing produced fewer seeds than those with a high percentage of sibbing. Amount of PSC in field cages was comparable to that produced on excised stems at 40 C in the laboratory, indicating that the growing of red clover in warmer climates for PSC seed production may not be necessary. The prevalence of selfing rather than sibbing may result in high inbreeding depression manifested by loss of vigor and PSC. However, the possibility remains that selfs can be eliminated by selection and the line propagated by the remaining sibs. Further investigation of seed maintenance schemes seems justified.
Influence of Triticum timopheevii Cytoplasm on Pollen Production and Dispersal in Common Wheat1
Authors: Johnson Jerry W. , Patterson F. L.
Published: July 2010

Breeders of hybrid hexaploid wheat (Triticum aestivum L. aestivum group) are developing R‐lines (pollinators) with cytoplasm and male‐fertility restorer genes derived from Triticum timopheevii (Zhuk.) Zhuk. var. timopheevii. It is important to determine if such R‐lines have reduced pollen production and dispersal compared to their respective B‐lines.

The soft wheat cultivar ‘Monon’ was compared to three recovered backcross Monon‐type R‐lines with both cytoplasm and nuclear male‐fertility restorer factors derived from T. timopheevii. Pollen production and dispersal were measured by pollen collection in automatic spore traps, percent anther extrusion, and percent seed set on A‐lines.

In spore trap comparisons A‐line 68846L2 dispersed significantly fewer total pollen grains than Monon, 1559 vs. 1975. The patterns of daily dispersal over the 7‐day period were generally similar for the R‐line and Monon although a significant day × pollinator interaction occurred.

The three R‐lines were equal to Monon in anther extrusion with an average of 92% of the anthers extruded. The R‐lines and Monon were equally effective as pollinators in effecting seed set on three A‐lines (mean=60%). The small reduction in pollen dispersal of R‐lines was not great enough to reduce the effectiveness of the R‐lines as pollinators when compared to Monon at the 60% level of seed set for A‐lines in these experiments.
Effect of Alfalfa Ploidy on Nitrogen Fixation1
Authors: Leps Walter T. , Brill Winston J. , Bingham E. T.
Published: July 2010

Genetically similar families of alfalfa (Medicago sativa L.) at diploid (2×), tetraploid (4×), and octaploid (8×) ploidy levels were assayed for acetylene‐reduction activity to determine the effect of ploidy on N2 fixation by nodulated plants. Tetraploids had higher rates of acetylene reduction than diploids during the first 10 days of growth. After that time, both tetraploid and diploid plants reduced acetylene at the same rate. The higher acetylenereduction activity found during the first 10 days may reflect the ability of the tetraploids to fix more N2 than the diploids early in growth and may explain why tetraploids had higher N contents than the diploids when the plants obtained their N from N2 fixation. Increasing the ploidy of alfalfa plants from tetraploid to octaploid did not result in increased acetylene‐reduction activities or N content.
Effect of Temperature on the Heading Date of Wheat Cultivars under a Lengthening Photoperiod1
Authors: Pirasteh B. , Welsh J. R.
Published: July 2010

An experiment was conducted to evaluate the effect of temperature on the number of days to heading of five vernalized winter and five spring commonly grown wheat (Triticum aestivum, L. em Thell.) cultivars under an increasing daylength. Controlled environment chambers were set at 15.5 C (day) and 7.2 C (night), and 21.0 C (day) and 12.7 C (night). Temperatures, cultivars, and the temperature × cultivar interaction were all highly significant tor both days and degree‐hours to heading. Winter and spring cultivars had approximately the same range in values. All cultivars headed more rapidly at the higher temperatures. Within each growth habit, the cultivars maintained the same approximate ranking at both temperatures, but varied in their interaction with temperature. More degree‐hours were used by all cultivars at the warmer temperature indicating that only part of the increased temperature was translated into accelerated heading. Each cultivar has a specific set of phenological control mechanisms which can affect the interaction with environment in final yield expession.
Influence of Seed Maturation on Germinability in Soybean1
Authors: Obendorf R. L. , Ashworth E. N. , Rytko G. T.
Published: July 2010

Few studies have related seed formation to germinability in soybean [Glycine max (L.) Merrill]. Our objectives were to evaluate seed growth, seed maturation, and germination capacity of ‘Chippewa 64’ soybean seeds and isolated axes in greenhouse and field environments. Flowers were tagged on the main stem, and pods were harvested at 4‐day intervals between 22 and 58 days after flowering (DAF). Seeds and embryonic axes were removed, weighed, and rapidly desiccated. Germination and axis growth were determined upon rehydration. Mean growth rates were 7.8 and 4.9 mg seed−1 day−1 in greenhouse and field‐grown seeds, respectively. Mature seed weights were 200 and 160 mg seed−1 for greenhouse and field‐grown seeds, respectively, and percent moisture at maximum seed dry weight was 59 and 61% at 50 DAF. Air‐dried immature seeds had increasing capacity for germination between 34 and 46 DAF (73 and 140 mg seed−1 dry weight). Embryonic axes reached maximum dry weight 4 days before maximum dry weight of seeds. Upon rehydration germination of air‐dried seeds and isolated axes was similar. Immature seeds and isolated axes harvested before one‐half maximum seed weight did not germinate after desiccation. When seeds reached 140 mg dry weight seed−1, whole seeds and isolated axes had developed the capacity to withstand desiccation and had a high percentage germination upon rehydration. We conclude: 1) the capacity for germination of soybean is developed before the seed reaches maximum seed weight, and 2) seed maturation is not a major factor altering the sensitivity of isolated axes to hydrational stress.
Epistasis in Some Crosses of I1 Red Clover Clones1
Authors: Cornelius P. L. , Taylor N. L.
Published: July 2010

Epistasls was examined in red clover (Triticum pratense L.) by the method of Kearsey and Jinks. Six I1 clones from a red clover introduction bulk were crossed with three testers, viz., I1 fines 684 and 713, and their F1 Epistasis was tested by the comparison of crosses to the I1 testers vs. crosses to the F1 tester. Significant epistasis (p ≤ 0.05) was indicated for survival on one of four dates after transplanting seedlings to a field near Lexington, Ky. No epistasis was indicated for vigor scores. Significant dominance variance was indicated for survival on three dates, and for vigor on one date. The data in general suggested that epistasis was not the major contrlbutor to heterosis in red clover single crosses.
Effects of Infection by Phytophthora megasperma var. sojae on the Water Relations of Soybean
Authors: Kittle D. R. , Gray L. E.
Published: July 2010

Soybeans infected by Phytophthora megasperma var. sojae had reduced transpiration rates, lower leaf water potentials, smaller leaves, and higher leaf temperatures than noninfected ones. Flow rates of water through infected soybean roots were one‐tenth those through healthy roots. Recovery from water stress by infected plants was slower than that observed among healthy plants. A 20‐fold greater whole root resistance to water flow was observed in excised roots of infected plants compared to controls. The influence of infection on root resistance greatly exceeded the influence of infection on the size of root systems.
Aneuploids in Safflower1
Authors: Estilai A. , Knowles P. F.
Published: July 2010

Triploids found in populations of autotetraploids of cultivated safflower (Carthamus tinctorius L.) were assumed to be products of outcrosses to diploid plants during the previous generation. The progenies of open‐pollinated triplolds had 2n=24, 25, 26, 46, 47, and 48 chromosomes. The plant with 25 chromosomes was a primary trisomic whose PMCs showed 12 bivalents plus one univalent or 11 bivalents plus one trivalent at metaphase I. The plant with 26 chromosomes was considered to be a double trisomic of a 2n + 1 + 1 type which showed chromosome associations of 12II + 2I, llII + lIII + lI, and 10II+ 2III. The expected frequencies of one trivalent in the 2n + 1 plant and two trivalents in the 2n + 1 + 1 plant were compared with their respective observed values.
Relationship Between Harvest Indices and other Plant Characteristics in Soybean1
Authors: Schapaugh W. T. , Wilcox J. R.
Published: July 2010

Indeterminate, semideterminate, and determinate soybean [Glycine max (L.) Merr.] strains in maturity groups I, II, III, and IV were grown to examine relationships among actual harvest index (seed yleld/above‐ground bicmass), apparent harvest index (seed yield/above‐ground mature plant weight), seed yield, plant height, maturity, and other plant characteristics.

Highly significant correlations between the actual and apparent harvest index means indicated that the apparent harvest index adequately reflected the actual harvest index of a genotype. Therefore, measurement of the apparent harvest index should permit a valid comparison of the relative efficiency of a set of genotypes.

The actual and apparent harvest indices were inversely correlated with biological yield (above‐ground biomass), vegetative yield (above‐ground non‐grain biomass), the components of vegetative yield (straw weight and leaf weight), maturity, and plant height. The latter six characteristics were positively correlated. Harvest index and seed yield were not consistently related from one season to the next. No relationship was detected between the growth habit and the harvest index of a genotype.

Correlations between the 1975 and 1976 means revealed that the relative performance of the entries based on harvest index means was less erratic than the relative performance based on seed yield.
Combining Ability for Agronomic and Fiber Properties in Cotton Stocks Resistant to Pink Bollworm1
Authors: Wilson F. D. , George B. W.
Published: July 2010

Twelve agronomic and fiber properties were studied in six cotton parents (Gossypium hirsutum L.) and their hybrid and reciprocal combinations in 1977 and 1978 in insecticide‐free environments at Tempe Ariz. Two parents, ‘Deltapine 61’ (DPL‐61) and ‘Stoneville 256’ (St 256), are commercial cultivars and the other four are race and breeding stocks selected for resistance to pink bollworm (PBW), Pectinophora gossypiella (Saunders), in earlier tests. One race stock, Texas 167 (T‐167), was similar in all 12 characters with at least one cultivar.

Significant general combining ability (GCA) estimates for most characters suggested that transferring resistance to PBW from T‐167 to a cultivar should pose no formidable breeding problems. Significant specific combining ability (SCA) estimates were few and probably of little consequence except perhaps for lint yield in DPL‐61 ✕ T‐167 in 1977.

A resistant Upland breeding stock, AET‐5, did not perform as well in relation to the cultivars as T‐167 in 1977 when seed damage from PBW was low, but performed better in 1978, when damage was much higher. Results of the diallel analysis suggest that AET‐5 will be more difficult to handle than T‐167 as a breeding stock. Apparently, the mechanisms of resistance in T‐167 and AET‐5 are different. It may be possible to extract a segregate from T‐167 ✕ AET‐5 hybrids with enhanced resistance, but probably not with agronomic and fiber properties equal to those of the cultivars. The best use for such segregates would be as sources of PBW resistance to be incorporated into superior germplasm. The other two race stocks, T‐31 and T‐55, were inferior to the cultivars as well as to T‐167 and AET‐5 for most characters.
Breeding Methodology in Wheat. I. Determination of Characters Measured on F2 Spaced Plants for Yield Selection in Spring Wheat1
Authors: McVetty P. B. E. , Evans L. E.
Published: July 2010

Three crosses of spring wheat (Triticum aestivum L.) involving the cultivar ‘Glenlea’ as a common female parent were used to evaluate the use of physiological and/or morphological parameters alone or in combination on F2 plants as selection criteria to identify high‐yielding F4 bulks. The F2 generation was grown as spaced plants in the field under two types of environmental regimes: (1) a regime and (2) a normal regime. Stress‐free plants were given regular irrigation, optimum fertilization and complete weed control to minimize stress while the normal‐regime plants were given no special treatment. Two hundred plants of each cross were measured for physiological, morphological, yield‐component, and phenological traits. A random sample of 50 seeds from each of these plants was used to generate F4 bulks. For each cross, groups of 45 F4 bulks derived from stress‐free F2's and 75 F4 bulks derived from normal F2's were tested for yield in the F4 in a six‐replicate, partially balanced lattice design.

The results indicated that single F2 parameters which described source capacity, sink capacity or plant morphology all identified high‐yield potential in the F2; however, at 15% selection intensity only 17 out of 53 high‐yielding F4 bulks were retained. A multiple regression analysis was found to be better than a single parameter approach, retaining nearly half (24 out of 53) of the high‐yielding lines. A combined‐cross analysis indicated that yield, productivity, kernel number, peduncle length, and productivity per tiller were all significantly correlated with F4 bulk yields. A multiple regression analysis of the combined crosses indicated that productivity and peduncle length were the only significant common parameters.
Aflatoxin Concentration in Corn as Influenced by Kernel Development Stage and Postinoculation Temperature in Controlled Environments1
Authors: Thompson D. L. , Lillehoj E. B. , Leonard K. J. , Kwolek W. F. , Zuber M. S.
Published: July 2010

Developing kernels of two cultivars of corn (Zea mays L.), ‘Gaspe Flint’ (Gaspe) and ‘W103 ✕ Gaspe,’ were inoculated with Aspergillus flavus Link ex Fr. at three kernel‐development stages (early‐dough, medium‐dough, and late hard‐dough) and grown in four post inoculation temperature regimes of 9.5, 12.5, 14.5, and 17.5 C thermal units/day (mean daily temperature minus 10 C) in controlled environments. Kernels were assayed for aflatoxin B1 after plants were grown for about 365 cumulative thermal units after inoculation. The highest toxin levels (48,641 and 31,046 ppb for Gaspe and W103 ✕ Gaspe, respectively) were observed hi kernels inoculated at the latest kernel‐development stage (late hard‐dough) and grown at the highest postinoculation temperature regime (17.5 C thermal units/day, i.e., day/night temperatures and times of 30/26 C and 9/15 hours, respectively). Toxin levels were low hi kernels inoculated at earlier development stages and grown at lower temperatures. Longer postinoculation growth at lower temperatures did not raise aflatoxin concentrations to levels observed with shorter postinoculation growth at higher temperatures.
Stability of Hybrids Produced from Selected and Unselected Lines of Maize1
Authors: e Gama Elto E. G. , Hallauer A. R.
Published: July 2010

Interpopulation and intrapopulation single‐cross hybrids of maize (Zea mays L.) produced from selected and unselected lines were compared [or grain yield productivity and stability. Selected lines were chosen from paired plant interpopulation crosses tested from S0 ✕ S0 through S4 ✕ S4 generations, whereas unselected lines were derived by single‐seed descent from the S0 plants. Our objective was to compare relative stability of grain yield among hybrids produced from selected and unselected lines. Mean grain yield and stability analysis of variance, which included linear regression coefficient (bl) and deviations from the regression (sd2), were used to determine relative stability of the single‐cross hybrids. Simple correlation coefficients among mean grain yield, bl, and sd2 also were determined.

Hybrids of selected lines produced significantly greater grain yield than did hybrids of unselected lines. Significant hybrid‐environment interactions were detected for both groups of hybrids, and both groups had similar contributions to total hybrid‐environment variances. Hybrids of selected and unselected lines had significantly different regression coefficients, as indicated by the hybrid‐environment (linear) mean squares. Both groups hybrids had similar number of stable hybrids when both stability parameters (bl and sd2) were considered. Simple correlations between mean yield and bl and mean yield and sd2 for both groups of hybrids were highly significant (P ⩽ 0.01), but they were not great enough to have predictive value. It seems selection of hybrids for mean yield across environments should be emphasized first, and then the relative stability of the elite hybrids over environments should be determined.
Induced Mutants in ‘Floratam’ St. Augustinegrass1
Authors: Powell J. B. , Toler R. W.
Published: July 2010

The breeding improvement of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Ktze.] is slowed by poor seed set, weak seedlings, and triploidy. New methods are sought to improve disease resistance and winterhardiness for cultivation of this warm‐season grass at the northern limits of the warm‐season growing areas of the United States. Mutation induction with gamma ray treatments of vegetatively propagated parental material offers a possibility of improvement. Stolons of ‘Floratam’ St. Augustinegrass were irradiated with various dosages of 4.5–7.0 Krads. Emerging single‐plant propagules were separated from the parental vegetative bud material. Propagules set into the field were evaluated for mutation induction. The 14 mutants ranged from dwarfs to very fine leaf types. Color changes were also noted in the mutants. Genes already present in ‘Floratam’ for resistance to the St. Augustine Decline Strain of Panicum Mosaic Virus were not modified in the mutants. Developing improved cultivate with mutation breeding procedures could be a major step forward in breeding this species.
Inheritance of a Variegated Testa Color in Peanuts1
Authors: Branch W. D. , Hammons Ray O.
Published: July 2010

Testa color in peanuts, Arachis hypogaea L., has a subjective value for market quality, and an understanding of testa color inheritance is prerequisite to breeding cultivars acceptable for marketing. The genetic relationship between two solid testa colors (pink and red) and their interaction with variegated (red/white) testa were investigated with progenies from intrasubspecific crosses involving nine parents. The variegation gene, V, was expressed as incompletely dominant to solid color and a 1:2:1 ratio was obtained from red ✕ red/white crosses. The pink ✕ red testa crosses gave the 1:2:1 ratio for the R2 locus, In crosses of peanuts with pink ✕ red/white testa, the F2 segregation fit the 1:2:1:2:4:2:1:2:1 phenotypic, also genotypic, ratio — the distribution expected from two independent loci with incomplete dominance for each gene pair. The nine genotypes were: R2R2vv, R2R2Vv, R2R2VV, R2r2vv, R2r2Vv, R2r2VV, r2r2vv, r2r2Vv, r2r2VV. Linkage was not detected between any of the testa colors investigated.
Seedling Age and Cold Treatment Effects on Induction of Panicle Production in Reed Canarygrass1
Authors: Heichel G. H. , Hovin A. W. , Henjum K. I.
Published: July 2010

The objective of this investigation was to determine plant age and environmental factors influencing panicle emergence and production in reed canarygrass (Phalarls arundinacea L.). Seedlings of ‘Rise’ and ‘Vantage’ grown in the glasshouse at 27/19 C (day/night, warm) temperatures and a 16‐hour photoperiod for seven periods ranging from 1 to 13 weeks of growth after emergence, were exposed to cold treatments at 6 ± 1 C in a growth chamber for an 8‐ or 16‐hour photoperiod. About 75% of 4‐week or older seedlings were vernalized effectively with 12 to 15 weeks of cold treatment, and flowered 3 weeks after being returned to warm, 16‐hour days. Twenty‐two percent of the seedlings that received cold treatment starting 3 weeks after emergence produced panicles, but 1‐ and 2‐week‐old seedlings did not. Four‐week old seed. lings required at least 9 weeks of cold treatment before some panicles were produced. Panicle production per plant after 12 weeks of cold treatment was greater for 13‐ than for 4‐week‐old seedlings.

Percentage of plants with emerged panicles and panicle production were greater with the 8‐ than with the 16‐ hour photoperiod during cold treatment. When 60% of the herbage was ronoved immediately before onset of the cold treatments, percentage of plants with panicles, duration of panicle emergence, and panicles produced per plant were reduced as compared to those left uncut. Eighty.eight percent of the panicles produced in Vantage arose from tillers that emerged from the soil during cold treatment. The 12‐week cold treatment in a controlled environment was also effective in causing panicle formation on 22 diverse reed canarygrass clones. The procedure will enable plant breeders to reduce intergeneration time and to make crosses in reed canarygrass within 5 months after seeding or vegetative propagation of parent material.
An Association between Resistance to Bacterial Wilt and Nitrogen Fixation in Alfalfa1
Authors: Viands D. R. , Barnes D. K. , Frosheiser F. I.
Published: July 2010

Bacterial wilt (BW), a major disease of alfalfa (Medicago saliva L.), is caused by the bacterium Corynebacterium insidiosum (McCull.) H. L. Jens. Symbiotic nitrogen (N) fixation of alfalfa involves the bacterium Rhizobium meliloti Dang. The objective of this research was to determine if factors conditioning resistance to BW were associated with plant characteristics related to N2‐fixation in alfalfa. In one study, alfalfa gene pools segregating for different types of resistances to BW were grown in nil‐nitrate greenhouse sandbenches. Each plant was evaluated for acetylene reduction rate, top dry weight, nodule mass score, nodule number score, fibrous root score, and secondary root score. The same plants were then inoculated with C. insidiosum and later evaluated for resistance to BW. In two other studies, breeding lines that had been selected in the greenhouse for acetylene reduction rate, top dry weight, nodule mass, and fibrous root mass were evaluated in the field for resistance to BW.

Correlation coefficients between resistance to BW and acetylene reduction rate and between BW and nodule mass were low but significant in one gene pool where resistance to BW was conditioned by an additive gene system. In the second gene pool where a dominant gene conditioned resistance to BW, there was no apparent association between BW resistance and N2‐fixation. In the field studies, lines selected for high levels of N2‐fixation‐associated characteristics, especially nodule mass and top weight, were generally more susceptible to BW than lines selected for low levels of N2‐fixation. Selection for high levels of N2‐fixation did not affect either fall dormancy response, resistance to Phytophthora root rot caused by Phytophthora megasperma Drechs., or resistance to Fusarium wilt caused Fusarium oxysporum Schlecht. f. sp. medicaginis (Weimer) Synd. & Hans. Breeding for high levels of N2‐fixation could increase susceptibility to BW unless plant breeders monitor resistance or utilize the dominant gene (BW1) source of resistance.
Sugarbeet Fruit Germination and Emergence under Moisture and Temperature Stress1
Authors: Akeson W. R. , Henson M. A. , Freytag A. H. , Westfall D. G.
Published: July 2010

Poor fruit germination and emergence of sugarbeet (Beta vulgaris L.) due to moisture and temperature stress can limit satisfactory stand establishment. Our objective was to evaluate laboratory procedures which measure germination and emergence potential under moisture and temperature stress and to use these tests for development of fruit treatments for improving field emergence under stress conditions.

Germination tests were conducted on blotter paper using polyethylene glycol 600 osmotic solutions to induce moisture stress. Emergence through a 2.5 cm layer of greenhouse soil mix (Ascalon sandy loam and peat, 1:1 V/V) was used to evaluate the effect of fruit treatments on emergence under moisture and temperature stress. The soil mix, initially at —1/3 bar matric potential, dried to —10 to —5 bar matric potential during the course of the test. Emergence through a 3.3 can layer of packed silica sand (3.5% water — wt/wt) was used to evaluate treatments under temperature, moisture and impedance stress tests conducted at 9, 15, or 26 C. Field trials were used to confirm results of laboratory tests.

Germination of sugarbeet fruit decreased with increas. ing osmotically simulated moisture stress from 0 to —7 bar water potential after which no germination occurred. Increasing the moisture stress from 0 to —4 bar potential decreased the rate of germination, but not the final germination percent, while both rate and final germination percent decreased sharply as moisture stress went from —4 to —8 bars. Removal of the pericarp decreased the water requirement for germination at a given rate by 2 bars, indicating that the pericarp is a major factor limiting germination and emergence under moisture and temperature stress.

Treatment of the fruit with 1.0 N HCI for 2 hours significantly improved germination and emergence under moisture and temperature stress conditions in laboratory and field trials. Excessive acid treatment damaged the true seed. The acid treatment did not improve the emergence where impedance was the major stress or in the absence of moisture and temperature stress. Temperature affects not only the rate and extent of germination, but also the moisture requirement. The sugarbeet fruit germination at —5 bar matric potential and 26 C was equal to that at —1 bar and 9 C.

The germination of untreated fruits of eight cultivars ranged from 26 to 72% at —1 bar matric potential and 9 C, and from 6 to 20% at —5 bar and 9 C. Acid treatment improved germination of all cultivars, but low germinating cultivars were improved the most.
Hybrid Vigor in Forage Yields of Crosses between Pearl Millet Inbreds and their Mutants1
Authors: Burton G. W. , Hanna W. W. , Powell J. B.
Published: July 2010

The object of this research was to ascertain if forage yields of F1 hybrids between pearl millet inbreds and their simply inherited mutants will exhibit hybrid vigor. F1 hybrids between normal parents and 102 induced recessive mutants in pearl millet [Pennisetum americanum (L.) Leeke] inbreds ‘Tift 13’ (T13), ‘Tift 18’ (T18), ‘Tift 23’ (T23), and ‘Tift 239’ (T239) and two dominant mutants transferred with four backcrosses to T13, T18, and T23 were compared with their normal parents in precise forage yield trials on a Fuquay loamy sand for 1 to 5 years to detect evidence of hybrid vigor. Three recessive mutants, T13 orange node, T18 early, and T23 stubby head, in F1 hybrids were compared with their normal parents for 5, 5 and 2 years, respectively. They increased forage yields over those of their parents 34.2, 38.2, and 21.7%, respectively. In similar F1 hybrid tests, a dominant sunred mutant significantly reduced forage yield in T23 for 4 years and a dominant purple mutant increased forage yield in T13: and reduced it in T23 for 5 years. Ninety‐nine other iinduced recessive mutants evaluated in similar tests for 1 to 4 years failed to increase forage yields over those of their normal parent. Thirty‐nine of these in Fx hybrids reduced forage yields in 1‐year trials and 25 reduced yields in 2‐year trials. Simply inherited mutants capable o:E giving heterotic forage yields in pearl millet can occur at low frequency but intermating unrelated inbreds is a more efficient method of producing high yielding hybrids.
Variation and Associations of Kernel Growth Characteristics in Maize Populations1
Authors: Poneleit C. G. , Egli D. B. , Cornelius P. L. , Reicosky D. A.
Published: July 2010

The effective filling period (EFP) of maize (Zea mays L.) has been shown to be positively associated with yield and may be useful as a selection criterion for improved yield potential. The objectives of this study were to examine the range, distribution, and associations of EFP, kernel size, and keimel growth rate in unselected, genetically variable maize populations. About 40 individual plants within each of 10 synthetic or composite populations were examined in Experiment 1. In Experiment 2, 20 S1 lines from 5 of the 10 populations were evaluated in two replications of a randomized complete block design. Significant variations for the kernel characteristics were observed among the populations as well as among genotypes (plants or S1 progeny rows) within the populations. The amount of variation appeared large enough so that selection for improved population yield potential would not be restricted by limited initial genetic variation and that certain extreme valiants might be useful as donors of the desirable long grain filling period.

Significant phenotypic correlations were observed for maturity with the kernel characteristics in some but not all of the populations. Genetic correlations generally were of the same sign but larger than the phenotypic correlations. The correlation analyses suggested that physiological functions controlling the kernel growth characteristics could be separated from functions controlling maturity but that genetic linkages might be present in some germplasnis.
A Rapid for Estimating Durum Wheat Gluten Quality1
Authors: Quick J. S. , Donnelly B. J.
Published: July 2010

Firmness of cooked pasta and tolerance to overcooking are important quality characteristics of products made from durum wheat (Triticum turgidum L.) semolina. Stronger gluten has been shown to be associated with greater cooked pasta firmness and overcooklng tolerance.

Our objective teas to evaluate a new bread quality test for predicting gluten strength among durum wheat breeding lines. A wholemeal, sodium dodecyl sulfate (SDS)/ lactic acid solution ‐ sedimentation test requiring 6 g of wheat was compared to the micromixogram test requiring 20 g.

Correlations between sediment volumes and mixogram scores were highly significant, and the coefficients of determination (r2) indicated that about 65% of the variation in micromixogram score was attributed to its association with sediment volume. Selection for strong gluten on the basis of sediment volume was 84% as successful as selection on the basis of micromixogram score. One person can, with adequate simple equipment, mill and evaluate at least 120 samples/day. We conclude that the SDS‐sedimentation test is a major advance in screening for gluten strength differences among small samples of durum wheat.
Rapid Test for Kunitz Trypsin Inhibitor Activity in Soybean Seeds1
Authors: Hildebrand D. F. , Hymowitz T.
Published: July 2010

A rapid test for the detection of the Kunitz trypsin inhibitor (SBTI‐A2) in soybean [Glycine max (L.) Merrill] seeds is described which expedites the previous electrophoretic technique. Digestion of Azocoll particles by trypsin in the reaction mix causes the visible release of a red dye by seed extracts of genotypes which lack SBTI‐A2 (ti ti). Seed extracts of genotypes with normal SBTI‐A2 activity (Tia_, Tib_, Tic_) inhibit the tryptic release of the red dye, thus the solution remains clear.
Proline Accumulation by Water and Nitrogen Stressed Cotton1
Authors: Elmore C. D. , McMichael B. L.
Published: July 2010

Germinating and developing cotton (Gossypium hirsutum L.) seedlings were examined for proline accumulation under severe water stress and N deficiency to examine the relationship of N to proline accumulation. Seeds of ‘Coker 201’ were dark‐germinated for 3 days with one‐half desiccated during the last 12 hours. In another experiment, plants were light grown under well watered conditions with or without nutrient solution containing NO3‐N. On the 12th day they were subjected to severe water stress. Dry weight, free amino acids, and plant water potentials were determined after stress developed. Three‐day desiccated cotyledons accumulated 28% more proline than the unstressed controls. Axes of these stressed seedlings, however, did not accumulate free proline. The older water stressed cotyledons and leaves accumulated free proline, but only when the seedlings had an exogenous source of N. Thus under severe N deficiency, proline accumulation ability is imparied in cotton leaf tissue. Free histidine, on the other hand, accumulated in N deficient leaves, but not cotyledons. The results indicate that proline accumulation by water stressed tissue is related to the N status of the tissue as well.