bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed Weight Influence on Seedling Hydrocyanic Acid Potential in Sorghum
Authors: Lamb J. F. S. , Haskins F. A. , Gorz H. J. , Vogel K. P.
Published: July 2010

Grain sorghum [Sorghum bicolor (L.) Moench) typically produces larger seeds than sudangrass [S. bicolor, formerly S. sudanense (Piper) Stapf]; and grain sorghum seedlings are higher in hydrocyanic acid potential (HCN‐p) than sudangrass seedlings. Previous studies have shown a seed‐parent effect on seed weight and HCN‐p in reciprocal F1 hybrids of sorghum ✕ sudangrass. This study was conducted to determine whether the seed‐parent effect on HCN‐p could be attributed primarily to the difference in seed size between reciprocal sorghum ✕ sudangrass hybrids. Large and small seeds of low‐HCN‐p sudangrass, high‐HCN‐p sorghum, and their reciprocal hybrids, were visually selected, individually weighed, and planted in growth chambers. Height, fresh weight, and HCN‐p of the resulting 7‐d‐old shoots were measured. On average, the selected large seeds weighed ≈1.6 times as much as the small seeds. Shoots from the large seeds were ≈1.2 times as tall and 1.4 times as heavy as those from small seeds, and they contained ≈1.3 times as much HCN per shoot as did shoots from small seeds. However, the HCN‐p (mg kg−1 fresh wt.) of the shoots from large seeds was only slightly greater than that of shoots from small seeds (709 and 701 for first leaves of shoots, and 278 and 267 for shoot remainders from large and small seeds, respectively). Shoots from 5‐d‐old light‐grown and etiolated seedlings also failed to show appreciable differences in HCNp due to seed size. It was concluded that the seed‐parent effect on shoot HCN‐p in crosses of sorghum and sudangrass was not caused primarily by the seed‐parent effect on seed weight.
Physiological Basis for Inhibition of Maize Seed Germination by Flooding
Authors: Martin B. A. , Cerwick S. F. , Reding L. D.
Published: July 2010

Field emergence of maize (Zea mays L.) can be severely reduced by flooding shortly after planting. This study was conducted to characterize the response of several maize inbreds to soaking injury and to examine the importance of ethanol and acetaldehyde accomulation as determinants of tlooding tolerance. Seeds of four maize inbreds (Z38, B49, G49, and GS0) were soaked from 0 to 7 d 27 °C. Subsequent germination of Z38 and IM9 was relatively unaffected by this treatment, while germination of G49 and GS0 was reduced to <10%. Soak temperature affected germination, with minimal inhibition at 15 to 20 °C and maximal effects at 0.1 and 40 °C. All inbreds excreted ethanol and acetaldehyde during soaking, but amounts excreted were not significantly correlated with subsequent germination. Purging the soak water with air or N2 gas during soaking resulted in subsequent improvements in germination. Soak‐induced inhibition of germination was partially reversed by venting the seed after soaking but prior to planting. Venting was accomplished with flowing air, N2 gas, or a vacemn treatment. Treatment with ≈0.15 MPa (1.5 atm) of total pressure resulted in no improvement in germination after soaking. These data are consistent with the concept that soak‐induced inhibition of germination results from accumulation of volatile metabolite(s) other than ethanol or acetaldehyde.
Modeling Light and Temperature Effects on Leaf Emergence in Wheat and Barley
Authors: Volk Tyler , Bugbee Bruce
Published: July 2010

Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by >70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than ± 5% for wheat and less than ± 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar.
Developmental Regulation and Organ‐Specific Expression of Soybean Alcohol Dehydrogenase
Authors: Newman Kurt D. , VanToai Tara T.
Published: July 2010

The Adh1 gene coding for alcohol dehydrogenase (ADH) enzyme is one of the most widely studied genes in plants. Some controversy exists, however, concerning the induction of ADH activity in soybean [Glycine max (L.) Merr.] by flooding stress. Thistudy showed that the induction of ADH in 5‐ to 21‐d‐old soybean seedlings by flooding was organ‐specific and changed with seedling age. A single ADH isozyme was resolved by native polyacrylamide gel electro‐phoresis of protein extracts from control and flooded soybean leaves, hypocotyls, and roots. The cotyledons of unstressed soybean contained three ADH isozymes: two were distinct, one was faintly visible. Following plant submersion, all three isozymes in the cotyledons increased in activity. RNA blot hybridization revealed the accumulation of Adh‐specific transcripts in flooded soybean cotyledons and roots. A two‐gene model for soybean ADH is proposed, where one gene is expressed in roots, hypocotyls, leave, and cotyledons, while the other gene is expressed only in cotyledons.
Cytological Analysis of Macro‐ and Microsporogenesis of a Diploid Alfalfa Clone Producing Male and Female 2n Gametes
Authors: Tavoletti S. , Mariani A. , Veronesi F.
Published: July 2010

Gametes with the somatic chromosome number (2n gametes) are important in germplasm transfer and in the evolution of polyploidy. In this work a stain‐clearing methodology was applied to the cytological study of both macrosporogenesis and microsporogenesis in the diploid (2n = 2x = 16) clone H33 of alfalfa (Medicago sativa L.), which produces both male and female 2n gametes. Normal diploid and tetraploid plants were analyzed as controls. The analysis of macrosporogenesis indicated that done H33 produced ≈19% 2n macrospores of the second division restitution (SDR) type as a consequence of the absence of cytokinesis in the chalazal dyad. The analysis of microsporogenesis showed clone H33 produced a high frequency of dyads with two 2n microspores. About 64% of these dyads were of the first division restitution (FDR) type, as a consequence of parallel or nearly parallel spindles at metaphase II; the other dyads originated by abnormal cytokinesis at the end of meiosis and therefore they could be either FDR or SDR type. Abnormal cytokinesis was also responsible for the production of dyads with one n and one 3n microspore; moreover some rare 4n microspores originated by the total lack of cytokinesis. Clearing methodology proved very effective in alfalfa for the study of both macro‐ and microsporogenesis. It can therefore be efficiently used for the analysis of meiotic mutants that produce male and/or female 2n gametes at high frequency.
Duplications Complicate Genetic Mapping of Rf4, a Restorer Gene for cms‐C Cytoplasmic Male Sterility in Corn
Authors: Sisco Paul H.
Published: July 2010

Previous studies of the genetics of fertility restoration for C‐type cytoplasmic male sterility (cms‐C) in corn (Zea mays L.) have produced conflicting results. The objective of this study was to localize the restorer gene(s) for cms‐C using restriction fragment length polymorphism (RFLP) analysis. Rf4, a single dominant restorer gene for cms‐C found in inbred A619, was localized to Chromosome 8, ≈2 centimorgans from an RFLP marker locus, NPI114A. The presence in corn of extensive nucleotide duplication complicated the analysis. Because the region of Chromosome 8 near Rf4 is duplicated on Chromosome 3, an additional restorer gene for cms‐C may eventually be found on Chromosome 3.
White Clover Yield and Persistence As Influenced by Cypermethrin, Benomyl, and Root‐Knot Nematode
Authors: Pederson G. A. , Windham G. L. , Ellsbury M. M. , McLaughlin M. R. , Pratt R. G. , Brink G. E.
Published: July 2010

White clover (Trifolium repens L.) stands commonly decline within 2 to 3 yr after establishment, due to insects, fungi, nematodes, viruses, and other factors. This study determined the effect of application of insecticide and fungicide, and infestation of southern root‐knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood, alone and in all combinations, on white clover persistence, yield, and crude protein (CP) concentration. The insecticide was cypermethrin [(±)‐α‐cyano‐3‐phenoxy benzyl (±)‐cis,trans‐ 3‐(2,2‐ dichlorovinyl)‐2,2‐dimethylcyclopropanecarboxylate] and the fungicide was benomyl [methyl l‐(butylcarbamoyl)‐2‐benzimidazole‐carbamate]. ‘Regal’ white clover was grown on a Marietta fine sandy loam (fine‐loamy, siliceous, thermic Fluvaquentic Eutrochrept) for 3 yr after establishment in 1986. No effects of the treatments on yield, stand, or CP were observed in 1987. In 1988 and 1989, yields were 52 to 85% greater in cypermethrin‐treated plots, 12% greater (1988 only) in benomyl‐treated plots, and 6 to 17% lower in M. incognita‐infested plots compared with untreated plots. The number of stolons per meter was 27 to 39% greater in cypermethrin‐treated plots, 20% greater (1988 only) in benomyl‐treated plots, and 12 to 20% lower in M. incognita‐infested plots, compared with untreated plots. All treatments had little effect on CP concentration. Fewer Sitona hispidulus Fab‐larvae were found in the cypermethrin‐treated than untreated plots in 1989. White clover decline in the field was not due to any synergistic interactions between the factors evaluated in this study. When stresses such as insect, fungi, nematode, or virus are present and limit white clover growth, selection for resistance to these stresses should contribute to improved stand longevity and production of white clover.
Apparatus for Automatic Measurement of Kernel Weight, Length, and Thickness
Authors: Paige D. , Geng S. , Jongkaewwattana S.
Published: July 2010

Many plant research projects require the acquisition of kernel weight and size data. The lack of automated devices and software systems to measure individual kernel weight, length, width, and thickness restricts the number of samples that can be studied in a project, and compromises the quality of research. In this paper, we present a design approach and a prototype of an apparatus which can separate each kernel from a bulk sample, present it to an image analysis system, weigh it with a custom‐designed mechanism, log the acquired data, and return the kernel to a collection vessel, all automatically. Results of testing three grain types of rice (Oryza sativa L.) showed that the computer image data have a high degree of accuracy and precision. With suitable hardware modification for size differences and improved image processing software to eliminate kernel orientation requirements, there should be no impediment to developing a similar apparatus to measure other kernel types.
Variation in Seed Size Uniformity among Peanut Genotypes
Authors: Knauft D. W. , Gorbet D. W. , Martin F. G.
Published: July 2010

Peanut (Arachis hypogaea L.) seed size is an important characteristic that determines both quality and value of a cultivar. The 100‐seed weight may differ among genotypes from <30 g to > 150 g. Size also varies within a genotype, and cultivars with more uniform seed size are desired for improved processing efficiency and marketing of peanut products. This study was conducted to obtain information about differences in seed size uniformity among peanut genotypes. Thirteen peanut genotypes were grown at Gainesville and Marianna, FL from 1987 to 1989 in a four replicate, randomized complete‐block experiment. Seed size variation was determined at harvest maturity by weighing the seeds that were separated by a series of screens conforming to official grade standards. Analysis of variance was used to examine differences in standard deviations of seed size. One genotype, F1037, had the most uniform seed size at both locations and in all years of the experiment. F1011 was similar in variability to F1037 in each year of the study at Gainsville but was more variable at Marianna. Conversely, UF86107 had more variation in seed size at Gainesville than F1037 but was similar to F1037 at Marianna. Genotypes with larger seed had more variation in seed size, although differences in uniformity existed for lines with similar sizes. Because some genotypes were less variable than the standard cultivar Florunner, development of cultivars with more uniform seed size should be possible.
Development of Cyst Nematode‐Resistant Soybean Population S89‐3151
Authors: Anand S. C. , Myers G. O.
Published: July 2010

A soybean [Glycine max (L.) Merr.] population (S89‐3151) has been developed by intermating nine different soybean plant introductions (PIs) using genetic male sterility. The PI lines carried resistance to two or more races of soybean cyst nematode (Heterodera glycines Ichinohe). Soybean population S89‐3151 is available for distribution for research and developmental purposes.
Tolerance to Phytophthora Rot in Soybean: II. Evaluation of Three Tolerance Screening Methods
Authors: McBlain B. A. , Zimmerly M. M. , Schmitthenner A. F.
Published: July 2010

Five screening methods for tolerance to Phytophthora megasperma f. sp. g1ycinea (Drechs.) T. Kuan & D.C. Erwin (Pmg) in soybean [Glycine max (L.) Merr.] have been published. This study compares three of these methods. The 45 soybean strains used were reported susceptible to Race 4 of Pmg. Field tests were grown in 1985 and 1986 near Vickery, OH, on Fulton silty‐clay (fine, illitic, mesic Aeric Ochraqualt) known to be infested with Race 4 and other races of Pmg. Inoculum‐layer and slant‐board tests were conducted in a greenhouse and growth chamber, respectively, in 1986 and 1987. Height and maturity data were obtained from replicated yield tests with low Pmg pressure. The inoculum‐layer test gives tolerant lines high scores, whereas the slant board and field tests give low values to tolerant lines. The inoculum‐layer and slant board data correlated well (r = ‐0.77, P < 0.01) but neither correlated as well with the field data (r = ‐0.41, P < 0.05; and r = 0.49, P < 0.01, respectively). Field tolerance scores were correlated with maturity (r 0.46, P < 0.01); however, the field scores of the 15 latest maturing strains were not correlated with maturity and correlated well with the inoculum‐layer and slant board scores (r = ‐0.74, P < 0.01; and r = 0.76, P < 0.01, respectively). Apparently, field scores must be taken prior to onset of pod yellowing (R7). Both laboratory methods are suitable substitutes for the field test, but they evaluate seedling tolerance only. The inoculum‐layer method is easier, less expensive, and allows both root rot ratings and tolerance scores based on shoot growth.
Field Resistance to Russian Wheat Aphid in Barley: II. Yield Assessment
Authors: Calhoun D. S. , Burnett P. A. , Robinson J. , Vivar H. E. , Gilchrist L.
Published: July 2010

Host‐plant resistance could reduce yield losses due to feeding of Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), on barley (Hordeum vulgare L.). Most RWA screening procedures rely on differential expression of foliar RWA feeding symptoms identify resistant genotypes. This study was conducted to determine if field expression of foliar symptoms in barley is a good indicator of yield reduction due to RWA feeding damage. Spring barley genotypes representing a range in foliar symptom expression were evaluated in the field in infested and uninfested hill‐plots in summer 1989( 14 genotypes) and winter 1990 (19 genotypes). Plants were scored for foliar symptoms on a 1 to 6 scale (1 = no symptoms). Grain yield (GY), spike number (SN), 100‐kernel weight (KW), and yield (SY, 1990 only) were measured. Reduction in GY among genotypes due to RWA feeding ranged from −10 to 48%i n 1989 and from −17 to 59% in 1990, and was highly correlated (r = 0.71, df = 31, P < 0.01) with foliar symptom scores. Reduction in SN ranged from −3 to 42% in 1989 and from −14 to 39% in 1990, and was also highly correlated (r = 0.77, df = 31, P < 0.01)) with foliar symptom scores. Kernel weight was unaffected by RWiAn festation. Reduction in SY ranged from −16 to 43% and was correlated (r = 0.65, df 17, P < 0.01) with foliar symptom scores. Visual rating based on foliar RWA feeding symptoms in artificially infested hill‐plots in the field was an effective method to identify genotypes that show minimal yield reduction under RWA infestation.
Phenotypic Diversity and Associations of Some Potentially Drought‐responsive Characters in Durum Wheat
Authors: Yang R.‐C. , Jana S. , Clarke J. M.
Published: July 2010

Genetic improvement of crop plants for drought resistance is hindered by lack of information on variability and associations of drought‐response characters in breeding materials. We evaluated 3430 accessions in a world collection of durum wheat (Triticum turgidum L. var. durum) for 19 characters under severe moisture‐limiting field conditions at Swift Current, SK, Canada in 1984. Phenotypic diversity (H) and multicharacter associations were investigated in germplasm from nine durum wheat growing regions. The Middle East was one of the regions with a high level of diversity (H = 1.132). The rate of excised‐leaf water loss (RWL) was used as a possible indicator of drought resistance. Glaucousness, plant height, chlorotic leaf spots, days to flowering, and days to maturity were significantly associated with RWL in six to seven regions. The discrete multivariate log‐linear analysis involving these six characters revealed the first order (two‐character) and some second‐order (three‐character) associations. These five characters were chosen along with RWL as drought‐response characters that may be useful for establishing selection criteria for drought resistance. These results have important implications for developing durum wheat ideo‐types for high and stable production in drought‐prone environments.
Genotype and Environment Effects on Oat Beta‐Glucan Concentration
Authors: Peterson D. M.
Published: July 2010

Oat (Avena sativa L.) and oat bran have beneficial effects as human food and animal feed, including the lowering of serum low density‐lipoprotein (LDL) cholesterol, a risk factor for cardiovascular (LDL) cholesterol, a risk factor for cardiovascular disease. This effect has been attributed to the high concentration of (1→3)(1→4)‐β‐D‐glucan in oat. To efficiently breed oat cultivars higher in this beneficial constituent, the influence of genotype and environment must first be determined. Twelve cultivars were grown in nine different locations in randomized complete blocks to measure the leval and variation in β‐glucan concentration. Samples were dehulled, ground, and the β‐glucan concentration measured by a flow‐injection analysis system. Significant differences were found for the main effects of genotype and location and their interaction. The variance ratio for the interaction was much smaller than those for the main effects and, except for one location, the rank order of the cultivars was generally with 100‐groat weight. It was concluded that selection for high β‐glucan in a simple environment should be representative of relative performance in other environments.
Meiotic Stability of 56‐Chromosome Tall Fescue Hybrid Derivatives
Authors: Eizenga G. C. , Burrus P. B. , Pedersen J. F. , Cornelius P. L.
Published: July 2010

Tall fescue, Festuca arundinacea Schreb., has been hybridized with annual ryegrass, Lolium multiflorum Lam., and/or giant fescue, F. gigantea (L.) Vill., in order to incorporate the genes for higher digestibility, and improve the nutritive value of tall fescue. The objective of this study was to determine meiotic stability of the KY‐ 2N56 tall fescue germplasm at the octoploid level. The germplasm was selected from hybrid derivatives of annual ryegrass ✕ tall fescue and tall fescue ✕ giant fescue over two generations of restricted recurrent selection for 56‐chromosome, fertile phenotypes. Meiotic configurations, micronuclei per dyad, micronuclei per quartet, stainable pollen, and seed yield were determined for the 8 parent, 7 firstgeneration, and 35 second‐generation plants used in the development of the KY‐2N56 germplasm. Univalents significantly increased and chain quadrivalents significantly decreased over generations. Chain quadrivalents differed among generations of certain parental families. The other meiotic configurations, micronuclei per dyad, micronuclei per quartet and stainable pollen did not differ. Seed yield (g panicle−1) showed significant linear and nonlinear effects of generations, and significant interactions for generations ✕ parental families. No significant correlations were found between seed yield and the other variables examined which suggested that seed set was more strongly influenced by other factors, most likely environmental. The KY‐2N56 germplasm appeared meiotically stable although the frequency of univalents and multivalents was low.
Saturated Rates of Photosysnthesis in Water‐Stressed Leaves of Common Bean and Tepary Bean
Authors: Castonguay Y. , Markhart A. H.
Published: July 2010

The tepary bean, Phaseolus acutifolius A. Gray var. latifolius G. Freeman, is adapted to arid conditions and is a potential source of genes to improve the drought tolerance of common bean, P. vuigaris (L.). The mechanisms of drought tolerance in P. acutifolius are still unclear. Light and CO2 saturated rates of photosynthetic O2 evolution (Pn) measured in a Hansatech leaf‐disk chamber and roomtemperature chlorophyll fluorescence transients at 740 nm were used to assess the mesophyll tolerance to dehydration. Detached P. acntifolius leaves maintained higher relative water contents (RWC) and water potentials that those of P. vulgaris. Rapidly dehydrated leaves from both species showed identical responses of their saturated rates of photosynthesis to RWC changes. Mesophyll photosynthetic capacity was very toleranto dehydration even at water deficits known to cause severe reduction of CO2 assimilation. Similar results were obtained with samples taken from plants acclimated to water‐deficit stress. Apparent quantum yield of photosynthetic O2 evolution and variable fluorescence suggest that the slow Pn decline with dehydration was not related to an inhibition of photosynthetic electron transport. These results indicate that genotypic variability in drought tolerance between P. vulgaris and P. acutifolius is not related to differences in mesophyll tolerance to dehydration. P. acutifolius adaptation to an arid environment relies more on dehydration postponement than on tolerance.
Physiological Maturity and Vigor in Production of ‘Florida Staysweet’ Shrunken‐2 Sweet Corn Seed
Authors: Wilson Dale O. , Trawatha Susan E.
Published: July 2010

Shrunken‐2 (sh‐2) sweet corn (Zea mays L.) exhibits relatively poor germination and seedling vigor. Early harvest is sometimes advocated for avoidance of seedborne fungi. Our objectives included studying the effect of maturity on seed vigor, defining physiological maturity, and optimizing vigor testing. Six crops of ‘Florida Stay sweet’ seed were produced in 1987 and 1988 and harvested 22 to 90 days after silking (DAS). Maximum kernel dry weight was obtained 43 to 47 DAS except for very late (mid‐June) plantings, which required 48 and 66 DAS. Decline in kernel moisture content was linear. Unreated seed, harvested 72 to 75 DAS from mid‐April plantings. produced an 80% stand in the field the following year. Harvest at maximum dry weight (43 to 47 DAS) produced final stands of 20% of lower. Delaying planting of the seed crop until mid‐May resulted in a decrease of maximum attainable field emergence to 50% in 1987 but not in 1988. Delaying planting until mid‐June lowered maximum attained field emergence to 30% in 1987 and 40% in 1988. laboratory germination test maxima preceded field emergence maxima by 12 to 26 d. Black layer formation preceded low vigor resulting from immaturity. The soil cold test, accelarated aging, and mean leachate conductance (ASA 610) were more highly correlated wiht final stand (median r = 0.87, 0.85, and ‐0.88, respectively) than was rolled‐towel germination (median r = 0.71). In conclusion, early harvest (45 to 60 DAS) resulted in seed with high germination and low vigor. Leaving the crop in the field as long as 80 to 90 DAS resulted in consistent production of relatively high vigor seed, as long as the crop was not planted very late (mid‐June).
Genetic Analyses of Male Fertility Restoration in Wheat: IV. Fertile Line without Major Rf Genes
Authors: Maan S. S.
Published: July 2010

Substitution of the common wheat (Triticum aestivum L.) nucleus into T. timopheevii Zhuk. cytoplasm results in cytoplasmic male‐sterility. Two partially dominant Rf1 and Rf4 genes on chromosomes 1A and 6B, respectively, restore fertility. But lines with individual RflRfl or Rf4Rf4 genes are known to have unidentified recessive gene(s) that complement fertility restoration. In this study, expression of recessive genes was examined in the absence of major Rf genes. The procedure involved crossing male‐sterile ‘Chris’ monosomic 1A (cms‐Chris mono‐1A) to a RflRfl rf4rf4 line, backcrossing cytologically identified F1 mono‐lA to euploid Chris (rf1rf1 rf4rf4), selfing fertile backcross F1 mono‐lA, and selecting fertile disomics in the selfed progeny. Thus, Rf1 was replaced by rf1 of Chris. Similarly, rf4 replaced Rf4 in monosomics of a second cross: cms‐Chris mono‐6B/rf1rf1 Rf4Rf4 line, F1 mono‐6B//Chris. In the latter backcross progeny, monosomics were male steriles, but some mono‐lA were fertile in the former backcross progeny. In their selfed progeny fertile disomics were selected. Thus, a true‐breeding fertile line with T. timopheevii cytoplasm, but without the major Rf genes was obtained.
Selection for Early Heading and Correlated Response in Maturity of Soft Red Winter Wheat
Authors: May L. , Van Sanford D. A.
Published: July 2010

Heading date in wheat (Triticum aestivum L. emend. Thell.) is an easily identifiable trait, and previous research has shown it can be modified. However, several studies have shown that heading date is not always highly correlated with harvest maturity. This study was conducted to gain a more thorough understanding of the relationships between heading date and traits related to maturity such as kernel growth rate (KGR), effective filling period (EFP), and time physiological maturity. We evaluated direct and correlated response to two cycles of phenotypic recurrent selection for early heading date in two wheat populations in 1989. Direct response to selection for early heading date was −5 and −10 d, respectively, in the two populations, In Population 1, correlated response to selection was not significant. We observed a significant reduction in mean KGR from 2.56 to 2.13 mg kernel−1 d−1 from the C0 to the C2 in Population 2, with no significant change in mean EFP. Heritability estimates ranged from 0.10 for yield in population 1 to 0.81 (P<0.01) for heading date in Population 2. Mean estimated date of physiological maturity (EPM) was significantly reduced in both populations after two selection cycles. Early EPM of the C2 apparently reflected an early heading date and not a reduced grain filling period. However, the earliest heading entries were not always the first to reach EPM. Thus we suggest a maturity rating based on EPM in later generations to ensure continued selection pressure for early physiological maturity.
Genetic Relationship between Fiber and Sugarcane Yield Components
Authors: Gravois K. A. , Milligan S. B.
Published: July 2010

Sugarcane (Saccharum spp.) fiber, the dry, water‐insoluble component of the stalk, is an important quality component because of its inverse relationship to juice extraction and milling efficiency. Sugarcane cultivars in temperate regions are enhanced with S. spontaneum L. germplasm to provide increased vigor and cold tolerance. Unfortunately, S. spontaneum L. clones typically have low recoverable sucrose and high fiber content. Our objective was to estimate genetic and genotype × environment (G × E) interaction variances for sugarcane fiber content, not previously reported for a temperate sugarcane population. Twenty‐two clones from the first replicated testing stage of the Louisiana Sugarcane Variety Development Program (LSVDP) were studied in a first and second ratoon crop at three locations. Genotype × crop (G × C), genotype × location (G × L), and genotype × crop × location (G × C × L) variances were much smaller than genetic and error variances. Heritability of fiber on a single‐plot basis was 0.71 and 0.91 when heritability was based on three locations, two replicates, and one crop. From path analysis, the direct effect of fiber content on recoverable sucrose was −0.203, indicating a weak inverse relationship between these two traits. Fiber content was significantly correlated with stalk diameter, rg = −0.585, indicating that indirect selection for larger stalk diameter should decrease fiber content. Direct selection for optimum fiber content by evaluating clones in a single crop and/or location would be effective. Evaluation at different locations and during different crops, however, would offset the relatively large error variance, thereby increasing the statistical power to determine differences among clones for fiber.
Vernalization of Embryogenic Callus from Immature Embryos of Winter Wheat
Authors: Whelan Ernest D. P. , Schaalje G. B.
Published: July 2010

Winter wheat (Triticum aestivum L.), or somaclones obtained from tissue culture require vernalization to induce flowering. The objective of this study was to compare the vernalization requirements of planted seeds of ‘Norstar’ winter wheat with those of embryogenic callus obtained from immature Norstar embryos. Seeds required 8 wk at 6 °C (12‐h photoperiod) for vernalization, after which heading occurred ≈42 d later when grown at 20 °C with an 18‐h photoperiod. Vernalization of embryogenic callus required 8 to 12 wk at 6 °C. Plantlets obtained from embryogenic callus flowered 8 to 9 wk after transplanting to soil, without further vernalization. These procedures eliminate the need for low‐temperature growth cabinets with supplementary lighting, thus reducing the cost of producing large numbers of regenerants.
Hybrid Performance among Maize Populations Selected for Resistance to Insects
Authors: Widstrom N. W. , Bondari K. , McMillian W. W.
Published: July 2010

Improvement of resistance to insects while maintaining other desirable agronomic traits in maize (Zea mays L.) populations has been an elusive goal for breeders. This study was conducted to evaluate crosses among II insect‐resistant breeding populations to identify paired populations for selection or extraction of inbreds. A complete diallel was evaluated for lodging, plant height, ear height, yield, ear damage by insects, and maturity in a complete‐block experiment with five replicates at two locations. Locations were combined because errors were homogeneous and the crosses × locations interaction was nonsignificant. General combining ability (GCA) effects were significant (P ≤ 0.01) for all traits, specific combining ability (SCA) effects were significant (P ≤ 0.01) for all traits except yield and maturity, reciprocal effects were significant (P ≤ 0.01) for all traits except yield, and maternal effects were significant (P ≤ 0.05) for all traits except yield and damage by insects. Hybrid checks were earlier, Shorter, higher yielding, and less prone to lodging but also less resistant to insects than were population crosses. Paired crosses resistant to corn earworm (Helicoverpa zea Boddie) and maize weevil (Sitophilus zeamais Motschulsky) that performed well for other traits are available fdr selection and inbred extraction. Paired crosses with resistance to fall armyworm (Spodoptera frugiperda J.E. Smith) were not identified. The information on GCA, SCA, reciprocal, and maternal effects will assist in identifying critical population crosses.
Intermating Schemes Used to Synthesize a Population Are Equal in Genetic Consequences
Authors: Fatmi A. , Wagner D. B. , Pfeiffer T. W.
Published: July 2010

Several crossing arrangements can be used to synthesize base populations for recurrent selection. This study compared four Intel‐mating methods (chain cross, convergent cross, diallel cross following pair crossing, and pair crosses following a diallel) with regard to the maintenance of alleles, the amount of recombination, and the genetic variability available in each population. Base populations were produced by interacting 10 soybean [Glycine max (L.) Merr.] isolines that differ in alleles at 12 loci. A 12‐gene additive trait was simulated by designating a favorable allele at each locus, following the fate of these favorable alleles during intermating, and summing the number of favorable alleles present at all loci to obtain genotypic scores. No alleles were lost during the population synthesis. All allele frequencies in all populations fell within the confidence intervals of the expected values associated with genetic drift. No significant differences were found among populations for genetic variability or recombination. This study indicates that the intermating method can be chosen on the basis of resources required for its implementation. The chain cross or pair crosses followed by a diallel were most appropriate in our case.
Carbon Isotope Discrimination: Relationship to Yield, Gas Exchange, and Water‐Use Efficiency in Field‐Grown Crested Wheatgrass
Authors: Read John J. , Johnson Douglas A. , Asay Kay H. , Tieszen Larry L.
Published: July 2010

In previous greenhouse experiments, stable C isotope discrimination (Δ) was negatively associated with water‐use efficiency (WUE) in crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes]. We conducted two field experiments to evaluate associations among Δ, leaf WUE, and shoot WUE (dry weight change/plant transpiration) in clones of crested wheatgrass selected on the basis of low, medium, or high Δ. The first experiment involved leaves of five clones from each Δ class, with WUEi and Δ determined at two field sites. Mean Δ values are always less for low‐Δ than high‐Δ clones, but did not differ significantly between medium‐Δ and high‐Δ clones. Negative correlations were obtained between Δ and WUEi at both the rainfed (r = −0.77**, df = 13, p < 0.01) and irrigated (r = −0.87**, df = 13) sites; however, WUEi of low‐Δ clones exceeded that of high‐Δ clones only under rainfed conditions. The second experiment compared the performance of three low‐Δ and three high‐Δ clones under well‐watered and draughted conditions. Plants were grown in pots imbedded in soil. Soil water content in the pots was maintained at either 0.16 or 0.06 kg H2O kg−1 soil. Within each water level, values for Δ and leaf intercellular CO2 concentration (ci) were less for low‐Δ than high‐Δ clones and were negatively associated with both WUEi and WUEs. Even though shoot dry weight and Δ decreased with drought, the two traits were not correlated for either well‐watered or droughted clones. Across water levels, Δ was negatively correlated with WUEi (r = −0.93**, df = 10) and with WUEs (r = −0.98**, df = 10). Results show Δ in field‐grown crested wheatgrass was consistent across sites and was consistently related to ci, WUEi, and WUEs.
Storage and Remobilization of Water‐Soluble Carbohydrates in Stems of Spring Wheat
Authors: Davidson D. J. , Chevalier P. M.
Published: July 2010

Grain yield of wheat (Triticum aestivum L.) depends, in part, on carbohydrate reserves available in the stem. This study was conducted to determine the effects of water deficit during the post‐jointing period on quantitative changes in water soluble carbohydrates (WSC; including simple sugars, starch, and fructans) in the stems of spring wheat. Cultivars Edwall and Waverly were planted in 1983 and 1984 at Spillman Agronomy Farm near Pullman, WA, at rates of 84 and 168 kg ha−1 in rows 30 and 15 cm apart, respectively, in both irrigated and nonirrigated treatments. Beginning at jointing, plants were harvested weekly. Stem material was dried, milled, digested with amyloglucosidase, and analyzed for WSC by iodometric titration. Results were similar for both varieties and both years. Anthesis and peak stem carbohydrate concentration occurred 4 to 7 d earlier in nonirrigated than irrigated plants; and physiological maturity of the grain occurred 6 to 14 days earlier. The concentration of WSC in stems increased to between 250 and 380 mg g−1 dry wt. at ≈10 to 14 d after anthesis and then declined to less than 50 mg g−1 dry wt. by physiological maturity of the grain. From the time of peak WSC content until physiological maturity in 1984, 859 to 1235 mg WSC were lost from the stems of irrigated plants but only 619 to 662 mg WSC were lost from stems of nonirrigated plants. The data indicate that stems are an important temporary storage site for reserve carbohydrates in both irrigated and nonirrigated plants.8
Natural Occurrence and Salient Characters of Nonnodulating Chickpea Plants
Authors: Rupela O. P.
Published: July 2010

Nonnodulating (Nod−1) lines are a valuable reference for assessing the amount of biologically fixed N2 in a legume. Chance observation of a Nod~ plant in chickpea (Cicer arietinum L.) accession ICC 435 encouraged us to study the frequency of natural occurrence of this trait. Six hundred forty to 36260 plants of each of 11 chickpea accessions, field‐grown under conditions favoring good nodulation, were uprooted for nodulation observations at 22 and 112 days after sowing (DAS). Plants identified as Nod‐ at 22 DAS were potted to produce seeds and those at 112 DAS had physiologically mature seeds. Progenies of apparent Nod‐ plants were inoculated with chickpea Rhizobium strain 1C 59 and grown in pots for 28 d for confirmation. The frequency of Nod‐ plants in four accessions (ICC 435, −4918, −5003 and −4993) ranged from 120 to 490 per million. One Nod‐ plant from each of the four accessions was used for reconfirmation studies in the postrainy season 1987‐1988 and for agronomic evaluation in subsequent studies under field conditions. The Nod‐ selections were indistinguishable from their respective parent accessions for plant growth except for nodulation, and most yielded similarly to their Nod* accessions when supplied with 50 to 100 kg N ha−1. On a low‐N field without fertilizer N, the Nod− plants were light green, grew poorly, had a short internodal distance with small leaves and leaflets, and had reddish‐brown pigment on margins of leaflets, rachis, and sometimes branches.
Biomass Partitioning and Root‐Knot Nematode Development in Tomato Plants under End‐of‐Day Red or Far‐Red Light
Authors: Fortnum B. A. , Kasperbauer M. J.
Published: July 2010

The ratio of far‐red to red light received by a growing plant alters the photoequilibrium of the phytochrome system and regulates partitioning of photosynthate among stems, leaves, and roots. This study was conducted in a controlled environment to determine whether red or far‐red light received by tomato (Lycopersicon esculentum Mill. cv. Rutgers) shoots can affect activity of root‐knot nematode, Meloidogyne incognita (Kofoid and White). Nematode‐inoculated and noninoculated plants received 5 min of red (a low far‐red to red ratio) or 5 min of far‐red (a high ratio) light at the end of the daily 12‐h photosynthetic period for 32 d consecutively, after which plant parameters and nematode presence were measured. The red or far‐red light treatments altered plant growth patterns and the reproduction of M. incognita. Plants that received the far‐red light treatment were taller, heavier, and had a greater leaf area than red light‐treated plants. Also, the far‐red light‐treated plants were lighter green in color, developed longer internodes, had greater leaf mass and a higher shoot/root biomass ratio than plants treated with red light. Meloidogyne incognita‐inoculated plants that received the far‐red light had fewer eggs and fewer egg masses than plants that received red light. Crop production procedures such as use of plant residues, colored mulches, and other practices that affect the ratio of far‐red relative to red light in growing plant canopies might influence nematode parasitism of tomato.
Alfalfa Seed Water Management: I. Crop Reproductive Development and Seed Yield
Authors: Steiner J. J. , Hutmacher R. B. , Gamble S. D. , Ayars J. E. , Vail S. S.
Published: July 2010

Alfalfa (Medicago sativa L.) seed production differs from hay production and requires detailed research to determine appropriate water management strategies. Effects of surface‐applied irrigation amount, frequency, and prereproductive soil water content on reproductive development, seed yield, and harvest index were studied for 3 yr in the field. In 1987, 1988, and 1989, six supplemental irrigation treatments representing combinations of two irrigation frequencies (daily and after 75 mm of accumulated evapotranspiration [ETc]) and three rates of water replacement (40, 70, and 100% ETc) were used. These six treatments received 200 mm of water prior to foliage clipback in April. In 1988 and 1989, an additional 100 mm of water was applied prior to clipback to an additional three treatments that were irrigated after 75 mm of ETc and that had water replaced at either 40, 70, or 100% ETc. Seed yield response to amount of applied water differed between the establishment and two subsequent production years. for plants receiving 200 mm of water prior to clipback, increasing amounts of applied water decreased seed yield in the establishment year, but optimized yield at 70% ETc in the two subsequent years of production. Frequency of water replacement generally did not affect seed yield when 200 mm of water were applied to the soil prior to clipback. Replacement amount did not affect seed yield when 300 mm of water was applied prior to clipback. Increasing water replacement amounts increased number of floral buds plus racemes but decreased seed pod number through the growing season. Total season‐end aboveground phytomass was a positive function of water application amount and was not affected by frequency of application or amount of water applied prior to clipback. Water management can affect alfalfa seed crop response and yield.
Inheritance of Resistance in Rice to Races IB‐49 and IC‐17 of Pyricularia Grisea Rice Blast
Authors: Moldenhauer Karen A. K. , Bastawisi A. O. , Lee F. N.
Published: July 2010

Rice blast [Pyricularia grisea (Cooke) Sacc.] is an internationally devastating rice (Oryza sativa L.) disease. This study was conducted to determine the inheritance of rice blast resistance to the blast fungus races IB‐49 and IC‐17. Nine parents were crossed in all possible combinations. Parents, F1, F2, and selected F2‐derived lines in the F3 were tested for their reactions to blast fungus races IB‐49 and IC‐17 separately in the greenhouse during 1986 and 1987. The parents ‘Starbonnet’, ‘Newbonnet’, and ‘M‐201’ were susceptible to both races; ‘Raminad Strain 3’, ‘Pi No. 4’, and ‘Katy’ were resistant to both races; ‘Mars’ and ‘Zenith’ were susceptible to race IB‐49 and resistant to race IC‐17; and ‘NP 125’ was susceptible to race IC‐17 and resistant to race IB‐49. Inheritance of resistance to race IC‐17 was dominant and monogenic in crosses involving resistant parents. Inheritance to race IB‐49 was dominant and monogenic in crosses with the parents Raminad Strain 3, Pi No. 4, and Katy, but was controlled by two dominant complementary genes in crosses involving NP 125. Allelic relationships among the resistant parents indicate that one locus controlled the resistance to race IB‐49 and three loci controlled the resistance to race IC‐17. Resistance to both races was conferred by one gene or group of tightly linked genes in Katy. Diverse sources of resistance are necessary to avoid genetic vulnerability. Resistance to race IC‐17 and IB‐49 is simply inherited and should be relatively easy to incorporate into rice cultivars.
Pubescence Density Effects on Soybean Seed Yield and Other Agronomic Traits
Authors: Zhang Jianhua , Specht James E. , Graef George L. , Johnson Blaine E.
Published: July 2010

An increase in pubescence density can amplify leaf surface reflectivity. Greater leaf reflectivity can reduce transpiration, because it lessens the solar radiation load on the sunlit canopy surface, and can also enhance photosynthesis if more radiation is reflected to the shaded leaves in the lower part of the canopy. Both effects, which improve water.use efficiency, were previously documented when dense (Pd1Pd1) and normal (pd1pd1) pubescence soybean [Glycine max (L.) Merr.] genotypes were tested as near‐isogenic lines in two specific genetic backgrounds. However, the agronomic value of the Pd1 gene must be verified in a much wider array of genetic material before soybean breeders would consider using the gene in a cultivar development program. Accordingly, four dense and four normal genotypes were randomly extracted as F3‐derived F5 lines from each of 20 populations that had been created by mating 10 female pd1pld parents with two male Pd1Pd1 parents. The 80 dense and 80 normal lines were evaluated in a 1988 to 1989 performance trial. On average, lines with dense pubescence had greater yield (53 kg ha−l), maturity (1 d), plant height (4 cm), lodging (0.26 units), and 100‐seed weight (0.7 g), and seed quality (0.06 units). An interaction of pubescence density × test year was evident for yield (dense significantly better in 1988; no better in 1989). The interaction of pubescence density with female parent was significant only for maturity, height, and 100‐seed weight, but the same interaction with male parent was not significant for any trait. Seed yields were somewhat larger for lines with a gray (tt), as opposed to tawny (TT), pubescence color. As a result, dense‐gray lines were higher yielding than dense‐tawny and normal‐gray lines, which in turn were higher yielding than normal‐tawny lines. Selection of the dense‐gray types in breeding populations segregating for pubescence density and color may be of some merit in terms of soybean yield improvement.
Nitrogen Metabolism of Normal and High‐Seed‐Protein Soybean
Authors: Leffel R. C. , Cregan P. B. , Bolgiano A. P. , Thibeau D. J.
Published: July 2010

Nitrogen metabolism differences, including N2 fixation, between high‐and normal‐seed‐protein soybean [Glycine max (L.) Merr.] lines of equivalent plant maturity and seed yielding ability have not been determined in field tests. A replicated field experiment was conducted in 1985 and 1986 to determine such differences on a Mattapex silt loam (fine, silty, mixed, mesic Aqualfic Hapludult) with low soil N. The study used the nodulating‐nonnodulating N difference method to estimate N2 fixation of two soybean lines with contrasting seed protein levels. Eight sequential harvests were conducted from R5 (beginning seed) to combine harvest for the dry weights and N contents of vegetative and reproductive portions of the plants. There was no significant difference between the 2‐yr mean seed yields of the high‐ and normal‐protein lines, but the high‐protein line was 2 d later in maturity. The high‐protein line accumulated more N, fixed more N2, and remobilized more N to the seed than did the normal‐protein line (231 vs. 194, 114 vs. 77, and 87 vs. 76 kg ha−1, respectively). The greater N accumulation by the high‐protein line resulted from N2 fixation being sustained until the late R6 (full seed) stage. Nodule occupancy by strains of Bradyrhizobium japonicum was similar for the high‐ and normal‐seed‐protein lines. Thus, the ability to sustain N2 fixation until later stages of reproduction is a host plant attribute that may contribute to the greater N metabolism of a high‐seed‐protein soybean.