bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal Internode Development and Sugar Metabolism in Sugarcane
Authors: Lingle Sarah E.
Published: July 2010

The profile of sugar concentration along the stalk of sugarcane (Saccharum sp. hybrids) varies during the growing season and between cultivars. This study was conducted to determine how sucrose accumulation and metabolism in storage tissue changes with development, how sucrose metabolism changes as the growing season advances, and if differences in sugar cleavage could be detected between an early cultivar, CP70‐324, and a late cultivar, TCP81‐3058. Elongating intemodes of both cultivars were tagged at intervals from July to October during 1993 and 1994 in field plots near Mercedes, TX. The tagged intemodes were periodically sampled during their development, and sugars and enzymes of sucrose cleavage, sucrose synthase (SS), acid invertase, and neutral invertase, were assayed. Intemodes which developed later in the growing season were shorter and accumulated less dry weight than those that developed earlier. Total sugar and sucrose concentrations in the late intemodes approached those of early intemodes as they matured. Water content of all intemodes decreased from about 900 to about 720 g kg−1 during development; late intemodes reached this low water content in less heat units than did early intemodes. Activities of SS and both invertases were greatest in the youngest intemodes. SS activity decreased with intemode age to a steady state of 1.5 to 2 (µmol mg−1 protein h−1, while acid invertase activity decreased to about 0.5 to 0.8 (µmol mg−1 protein h−1. Neutral invertase activity was highly variable both among intemodes of the same age and between sampling dates. No significant differences in sugar concentrations or enzyme activities were observed between the cultivars.
Downy Mildew Resistance of the Cucumber Germplasm Collection in North Carolina Field Tests
Authors: Wehner Todd C. , Shetty Nischit V.
Published: July 2010

Downy mildew [Pseudoperonospora cubensis (Berk. & Curt.) Rostov] is an important disease in most cucumber (Cucumis sativus L.) production areas of the world. Resistant cullivars are available, but higher levels of resistance are needed if yield losses are to be avoided. The objective of this experiment was to evaluate all available plant introduction accessions (from the U.S. National Plant Germplasm System), cultivars, and breeding lines (hereafter collectively referred to as cultigens) of cucumber for downy mildew resistance under field conditions in North Carolina. All available cultigens were tested in four blocks (2 yr and two replications) under natural field epidemics of the disease. Mean ratings for downy mildew leaf damage ranged from 1.3 to 9.0 on a 0 to 9 scale. The most resistant nine cultigens originated from the USA, and were primarily adapted cultivars or breeding lines. The most resistant cultigens, for which multiple‐year data were available, were Gy 4, ‘Clinton’, PI 234517, ‘Poinsett 76’, Gy 5, ‘Addis’, M 21, M 27, and ‘Galaxy’. The most susceptible cultigens for which multiple year data were available, were P1288995, P1176952, PI 178886, and P1211985. We classified 17 cultigens as highly resistant (1.3–3.0), 87 as moderately resistant (3.3–5.0), 311 as moderately susceptible (5.3–7.0), and 248 as highly susceptible (7.3–9.0) for the cultigens with multiple‐year data. No plant introduction accessions were found to be more resistant than the most resistant elite cultivars and breeding lines tested.
Genetic Variation for Traits Related to Temperate Adaptation of Rice Cultivars
Authors: Mackill David J. , Lei Xiaomao
Published: July 2010

Rice (Oryza saliva L.) is cultivated in diverse environments including temperate, subtropical, and tropical regions. Temperate rice areas are dominated by the japonica subspecies, while indica cultivars are confined to the tropical or subtropical zones. The present study was conducted to characterize a diverse set of predominately japonica rice cultivars for traits related to adaptation to temperate environments. The 117 cultivars were previously classified into indica and two japonica (temperate and tropical) groups based on RAPD markers. While considerable diversity existed within groups, temperate japonica cultivars had better seedling‐stage cold tolerance (i.e., less chlorosis at 9 and 13°C treatments), higher seedling vigor, shorter growth duration, higher panicle exsertion, and lower threshability (i.e., less shattering or seed shedding) than indica cultivars. Cultivars from the same class were grouped together based on principal components analysis using the above traits, but the distributions were continuous. Tropical japonica cultivars were usually intermediate between temperate japonicas and indicas; however, there was no appreciable difference in seedling cold tolerance between tropical and temperate japonicas. Despite their association with tropical environments, the tropical japonicas possess many of the traits relative to low‐temperature adaptation present in the temperate types.
Soybean Germplasm Resistant to Races 1 and 2 of Heterodera glycines
Authors: Arelli A. P. , Wilcox J. A. , Myers O. , Gibson P. T.
Published: July 2010

Heterodera glycines Ichinohe is a serious pest of soybean [Glycine max (L.) Merr.] in the USA. Several Races of H. glycines occur in the soybean growing areas. Soybean accessions with resistance to Races 3, 5, and 14 have been identified. Data on reaction of these accessions for Races 1 and 2 are not available. Our objective was to bioassay these accessions for resistance to H. glycines Races 1 and 2. Eighty‐six accessions, host differentials, and susceptible control were bioassayed during 1995 to 1996 for each of the two Races in thermoregulated water baths in the greenhouse. The results indicated that 52 accessions had resistance to H. glycines Race 1, and 24 accessions had resistance to Race 2, respectively. Soybean PIs 89772, 90763, 404166, 404198A, 437654, 437690, 438489B, 567491A, and 567516C were either resistant or moderately resistant to both Races. These are potential resistance sources to H. glycines Races 1, and 2 for developing resistant soybean cultivars. These PI lines are being fingerprinted by means of molecular markers to identify the unique lines to allow broadening the diversity of resistance gene utilization.
A Small Scale Method for the Production of Soymilk and Silken Tofu
Authors: Evans D. E. , Tsukamoto C. , Nielsen N. C.
Published: July 2010

Interest in traditional Asian foods such as tofu and soymilk has developed in the USA during the past few years. Lacking, however, is a small scale, rapid test that will permit plant breeders and food technologists to evaluate the potential of various soybean [(Glycine max L.(Merr)] cultivars and breeding lines to produce these foods. A procedure is described in which 80 g of ground soybean is used to make silken tofu. Glucono‐δ‐1actone serves as the coagulant in the procedure. The method results in tofu whose characteristics are reproducible among different preparations, and whose quality compares favorably with imported Japanese silken tofu that is available commercially in the USA. To evaluate the method, soymilk and tofu were made from 182 experimental, public, and private soybean cultivars grown in Indiana in 1990. Differences were observed among cultivars for soymilk yield, tofu whiteness, and texture (tofu fracturability and hardness). Significant correlations were found between soybean protein content, soymilk protein content, and tofu fracturability. The same correlations have previously been established in the literature based on comparisons of material made by traditional large scale manufacturing methods. A correlation between soymilk solids content and fracturability was also observed when the ratio of water used to process the ground soybean was varied. The small scale method will be useful to evaluate soybean lines from breeding programs.
Variation in the Pattern of Nitrogen Accumulation and Distribution in Soybean
Authors: Pazdernik D. L. , Graham P. H. , Orf J. H.
Published: July 2010

The contribution of early nodulation and dinitrogen (N2) fixation to overall soybean [Glycine max (L.) Merr.] plant performance the cooler northern states of the U.S. Midwest needs further investigation. In a previous growth chamber study, we identified traits associated with improved early nodulation and N2 fixation in this crop. This study examined the nodulation, N accumulation, and N distribution patterns for the same 19 soybean lines in the field, and relates field performance to previous growth chamber results. The study was conducted in 1992, 1993, and 1994 at Becker, MN, in a soil with 7 to 15 kg NO−3 ha−1. The following data was recorded: nodule fresh weight (NFW), plant dry weight (PDW), and total N accumulation (TNA) at 20 to 60 d after planting (DAP), PDW and TNA at the R3 and R6 growth stages, and grain and seed protein yield at maturity. Differences in NFW, PDW, and TNA were found at most sampling dates, and were indicative of significant genetic differences in N2‐fixing ability. Lines also differed in partitioning of N, with the cultivar Lambert distributing 88% of total N accumulated to reproductive tissue at the R6 growth stage, compared with only 31% for PI 437966. Two canonical variables, one created by analyzing together the NFW data collected at 20, 40, and 60 DAP in the field, the other derived from NFW, PDW, and nodule soluble protein data obtained in the previous growth chamber study each correlated with the seed protein yield of field‐grown plants. This suggests that the measurement of early nodulation and N2 fixation in either the growth chamber or field can serve as an indicator on which to base selection for enhanced N2 fixation.
Temperature Effects Prior to Double Ridge on Apex Development and Phyllochron in Spring Barley
Authors: Frank A. B. , Bauer A.
Published: July 2010

Number of spikelets is a major component of grain yield in spring barley (Hordeum vulgare L.). Since air temperature strongly affects spike components in spring seeded cereals, the large variations in daily temperature or delays in planting dates, common to spring barley growing areas in the Northern Great Plains, make it important to understand temperature effects on spike and whole plant development for managemenat nd modeling purposes. The objectives of this study were to determine effects of changing temperature regimes on the phyllochron, apex development, and spike components in spring barley. ‘Bowman’ (two‐rowed) and ‘Azure’ (six‐rowed) were grown in controlled environment chambers and at constant temperatures of 18 and 26°C and at either 18 or 26°C for 4, 8, and 12 d after emergence and then transferred to the other temperature. Phyllochron was greater for control plants at 26 than at 18&C and for plants first grown at 18 then at 26&C compared with those grown at 26 then at 18&C. Apex double ridge stage occurred between 8 and 12 d after seedling emergence. Temperature following apex double ridge stage had a greater affect on duration of spikelet formation stage than temperatures prior to double ridge. Spikelets, kernels, and heads per plant were generally fewer for plants first grown at 18 then at 26°C compared with plants first grown at 26°C then at 18°C. These data suggest that temperature during the critical spikelet development phase had the greatest effect on spike components. Spike development coincided more with plant Haun than accumulated growing degree‐days (GDD), whereas the phyllochron responded oppositely. Thus, knowing when the apex forms spikelets is necessary for interpretation of plant responses, making management decisions, and model development.
Vernalization Requirements among Selected Genotypes of Annual Bluegrass (Poa annua L.)
Authors: Johnson Paul G. , White Donald B.
Published: July 2010

Poa annua L. is a common turfgrass species in golf turf. The species is usually considered to be annual because of characteristics including continuous flowering throughout a growing season. In reality, the species exhibits a wide diversity of flowering habits from continual to seasonal, or only in spring. In efforts to study the flowering physiology of the species and to improve hybridization work, we initiated experiments to determine environmental conditions for floral induction in one P. annua var. annua and four P. annua var. reptans genotypes. Growth chamber and greenhouse environments were used to test (i) the minimum length of time needed for vernalization, (ii) the effective temperature for vernalization, and (iii) whether juvenility exists with regard to vernalization. Poa annua var. reptans genotypes were vernalized after 10 to 12 wk at 4 and 8C, but not at 12C. Poa annua var. annua did not respond to vernalization treatments, Poa annua var. reptans also exhibited variation in juvenile period ranging from 25 d to greater than 35 d after germination. Incomplete vernalization resulted in inflorescence development, but flowers were deformed. Vernalization requirements differed between var. annua and var. reptans genotypes, as well as among var. reptans. This information can be used to improve P. annua breeding, as well as to investigate the diversity within this species.
Near Infrared Reflectance Spectroscopy for Analysis of Turf Soil Profiles
Authors: Couillard A. , Turgeon A. J. , Shenk J. S. , Westerhaus M. O.
Published: July 2010

The evaluation of soil profiles is important in turf management. To characterize soil physical and chemical properties, samples can be sent to a laboratory for analysis. This process is time consuming and expensive, however. The use of near infrared reflectance spectroscopy to predict soil physical and chemical properties was investigated using turf soil profiles and compared with standard laboratory techniques. Turf soil profiles from Michigan State University (East Lansing) were scanned undisturbed and dried‐ground with an NIRSystems 6500 monochromator (NIRSystems, Silver Springs, MD) by analyzing four depths each 1.25 cm thick. The reflectance measurements of monochromatic light were made from 400 to 2500 nm at 2‐nm intervals. Computer‐selected samples were analyzed in the laboratory for water content, organic matter, sand, silt, clay, and some chemical properties. The explained variance ranged from 0.16 for total N to 0.93 for sand. The organic matter, sand, silt, clay, P, Mg, and total N predictions were more accurate for the undisturbed samples than for the dried‐ground samples. Expanding the Michigan State University database with turf soil profiles from Pennsylvania resulted in lower accuracies but broadened the application range of the calibration. More research is needed to improve the prediction accuracy of expanded databases before near infrared reflectance spectroscopy can be used to determine soil properties from golf greens or fairways of different locations.
Two Microsatellite Markers That Flank the Major Soybean Cyst Nematode Resistance Locus
Authors: Mudge J. , Cregan P. B. , Kenworthy J. P. , Kenworthy W. J. , Orf J. H. , Young N. D.
Published: July 2010

The use of resistant cultivars is the most effective method for controlling soybean cyst nematode (Heterodera glycines Ichinoe; SCN) on soybean [Glycine max (L.) Merrill]. However, resistance to SCN is oligogenic, making inheritance patterns complex and breeding difficult. One major partial‐resistance locus for SCN resistance is located on molecular linkage group (MLG) ‘G’. This locus'controls more than 50% of variation associated with response to SCN and resistant alleles are present in many important sources of SCN resistance, including PI 209332, PI 88788, P1 90763, PI 437654, and ‘Peking’. Restriction fragment length polymorphisms (RFLPs) linked the major SCN resistance alleles on MLG G have proven effective in tracking the alleles and predicting SCN response. These RFLPs are much more efficient in terms of time and labor than greenhouse assays for SCN. Nevertheless, more efficient DNA markers are needed to screen the many lines required for marker‐assisted selection. Polymerase chain reaction‐based markers, such as microsateilites (simple sequence repeats), have been sought because they are faster, less expensive, more polymorphic, and require less labor than RFLPs. In this study, we report two microsatellites, BARC‐Satt038 and BARCSatt130, that flank the major SCN resistance locus on MLG G. These microsatellites efficiently identify the chromosome fragment carrying the resistance allele and are also good predictors of SCN phenotype response.
Genetic Variation within Switchgrass Populations for Acid Soil Tolerance
Authors: Hopkins Andrew A. , Taliaferro Charles M.
Published: July 2010

Tolerance to acid soil would be a desirable trait for switchgrass (Panicum virgatum L.) cultivars that are to be grown across the southern Great Plains. The objeclives of this research were to estimate genetic variation for, and examine the level of, acid soil tolerance at the seedling stage within two switchgrass populations. Seedlings of ‘Kanlow’ and ‘Blackwell’ were grown during 1993 and 1994 in acid soils (pH 3.9–5.0) in the greenhouse and harvesled 7 to 8 wk after planting. Seedlings were allowed to regrow and planted in polycross field isolation where half‐sib seed was produced. Progeny families were grown during 1995 and 1996 in acid soils (pH 4.4–5.1) in the greenhouse, and seedling shoot weight data collected 7 to 8 wk after planting. Heritability (h2) for weight of seedlings grown in acid soil was estimated by parent‐progeny regression. Growth ofhalf‐sib families in a limed and non‐limed acid soil was also examined. Estimates of h2 were low or non‐significant, ranging from 0.18 ± 0.08 to 0.06 ± 0.02 for Kanlow and 0.06 ± 0.02 for Blackwell. The low h2 estimates, coupled with a lack of significant variation for seedling shoot weight among families grown in acid soil, indicate little or no genetic variation for acid soil tolerance among seedlings of Blackwell or Kanlow. Seedling weight of half‐sib families grown in a soil limed to near‐neutral pH was not significantly different from seedling weight of the identical families grown in an acidic soil. Thus, at the seedling stage Kanlow and Blackweil switchgrass appear to have substantial tolerance to acid soil.
Inheritance of Cadmium Concentration in Five Durum Wheat Crosses
Authors: Clarke J. M. , Leisle D. , Kopytko G. L.
Published: July 2010

High cadmium concentration in cereal grains has been cited as a human health concern. Several reports showed that grain cadmium concentration was higher in durum (Triticinn turgidum L. var. durum) than in common wheat (T. aestivum L.). The objective of this research was to determine the inheritance of observed differences in grain cadmium concentration of durum wheat. This information could be used to facilitate breeding of cultivars with low grain cadmium concentration. Grain cadmium concentration was determined in the F2 and in F2:3 families of one cross and in F2:3 and F3:4 families of two crosses. Grain and leaf cadmium concentration was measured in random F8:9 and F8:10 families of three crosses. All trials were conducted in the field on Aridic Haploborall, Vertic Cryoborall, or Gleyed Black soils. Grain cadmium concentration was largely controlled by a single gene, with low cadmium dominant. Leaf cadmium concentration was highly correlated with grain cadmium concentration (r = 0.87–0.89, P < 0.01). Therefore, leaf cadmium concentration can predict the plant phenotype, which would be useful in backcrossing the low cadmium trait into high cadmium cultivars. Heritability in standard units, estimated by F2:3 progeny regression on F2 parent or F2:4 progeny regression on F2:3 parent, ranged from 0.84 ± 0.06 to 0.88 ± 0.08, indicating that breeding of low grain cadmium cultivars is feasible. Heritability estimated from variance components (years, locations, replications, and genotypes) was 0.78, with 90% confidence limits of 0.88 and 0.67. The simple inheritance and high heritability of grain cadmium concentration will facilitate the breeding of low cadmium concentration durum cultivars.
Identification of Marker Loci for Seed Dormancy in Rice (Oryza sativa L.)
Authors: Wan J. , Nakazaki T. , Kawaura K. , Ikehashi H.
Published: July 2010

In rice breeding, genes for seed dormancy as well as the markers for each of them are required for incorporation of an adequate seed dormancy into japonica cultivars. To screen genetic loci for seed dormancy in rice (Oryza sativa L.), two kinds of populations were tested: (i) an F2 population of a hybrid Milyang 23 / Todorokiwase, and (ii) F1 populations from a three‐way cross, in which an indica donor of strong dormancy, IR 36, was crossed with non‐dormant japonica cultivars, Nekken 2 and Miyukimochi, in the form of IR 36 / Nekken 2 // Miyukimochi. The seeds produced on the F2 plants from the single cross and those on F1 plants from the three‐way cross were tested at three times: immediately after maturation, after 60 d storage at 4°C, and after breaking dormancy (7 d at 50°C). Of 24 marker loci assayed, at least four loci linked to seed dormancy were detected. The strong seed dormancy of Milyang 23 was linked with three isozyme genes: Pgi‐11 on chromosome 3, Amp‐32 on chromosome 6, and Est‐92 on chromosome 7, while the strong seed dormancy of IR 36 was linked with C+ (apiculus color) on chromosome 6, Est‐92 on Chromosome 7, and Acp‐21 on chromosome 12. The high level of seed dormancy in indicas was found to be due to a cumulative effect of several loci. Differential responses of such loci to a dormancy‐breaking treatment were detected. An allele from IR 36 at a locus on chromosome 6 seemed to be responsible for strong seed dormancy after maturation and to be easily broken during storage. This allele may be incorporated into japonica rices by means of marker C for apiculus color.
Association of Fiber Quality Parameters and Within‐Boll Yield Components in Upland Cotton
Authors: Smith C. Wayne , Coyle Gwen G.
Published: July 2010

Lint yield and fiber quality in upland cotton, Gossypium hirsutum L., are interrelated through a series of individual components such as fiber length and the number of fibers produced on each seed. Numerous studies have reported the relationships among various components of yield and yield per unit land area, but none have reported on the relationships among the most basic within‐boll yield components and fiber quality parameters. The objectives of this study were (i) to determine the association of fiber quality parameters with basic within‐boll yield components for six diverse cotton genotypes and (ii) to determine if repulsion phase linkage explained the high negative correlations reported among fiber quality parameters and lint yield. The second objective was investigated by comparing the associations of fiber length, strength, and micronaire with within‐boll yield components among selected F1 populations developed by mating parents with similar direction of general combining ability (GCA) for fiber quality and within‐boll lint yield components with selected F1 populations derived by mating parents with dissimilar direction of GCA. Parents and F1s were grown at College Station, TX, in 1989 and 1992. Fiber quality parameters were determined by high volume instrumentation. Within‐boll lint yield components were determined by direct measurement or through calculations. Fiber strength and length were negatively associated with the most basic within‐boll lint yield components. Repulsion phase linkage appears to play a role in the negative association of fiber quality and within‐boll lint yield but pleiotropic effects could not be ruled out.
QTL Mapping in Tropical Maize: II. Comparison of Genomic Regions for Resistance to Diatraea spp.
Authors: Bohn M. , Khairallah M. M. , Jiang C. , González‐de‐León D. , Hoisington D. A. , Utz H. F. , Deutsch J. A. , Jewell D. C. , Mihm J. A. , Melchinger A. E.
Published: July 2010

Southwestern corn borer (SWCB), Diatraea grandiosella (Dyar), and the sugar cane borer (SCB), Diatraea saccharalis (Fabricius), are serious insect pests in maize (Zea mays L.) production areas of Central America and the southern USA. We mapped and characterized quantitative trait loci (QTL) affecting resistance to the leaf feeding generation of SWCB(1 SWCB), compared these QTL with those for resistance to the leaf feeding generation of SCB (1SCB) identified in the same mapping population, and assessed the consistency of QTL for 1SWCB across two populations. One hundred seventy‐one F2 genotypes from cross CML131 (susceptible) × CML67 (resistant) and 100 RFLP marker loci were used for the QTL analyses. 1SWCB and 1SCB resistance were assessed in F2:3 lines by leaf damage ratings (LDR) after artificial infestation in field experiments with two replications at one subtropical environment in 2 yr. The method of composite interval mapping (CIM) was used for QTL detection. Estimates of genotypic (σ2g) and genotype × year interaction variance (σ2g) were highly significant for 1SWCB LDR and 1SCB LDR. Phenotypic and genotypic correlations between both traits were 0.62 and 1.02, respectively. for 1SWCB LDR, six QTL were detected explaining 53.3% of σ̂2g, with two QTL displaying significant QTL × year interactions. Ten QTL were detected for 1SCB LDR, accounting for 98.2% of σ̂2g. The QTL showed predominantly additive or partially dominant gene action. Seven out of 10 QTL were pleiotropic to both Diatraea spp. Three genomic regions, on Chromosomes 5 and 9, were consistent with a second mapping population derived from cross Ki3 (susceptible) × CML139 (resistant), for which seven QTL for 1SWCB LDR were found. Marker‐assisted ‘gene stacking’ is recommended for transferring pleiotropic QTL into susceptible germplasm and for pyramiding QTL from different sources of insect resistance.
Stem‐Tip Inoculation of Alfalfa with Sclerotinia trifoliorum: I. Development of Necrosis on Resistant and Susceptible Selections
Authors: Halimi E. S. , Rowe D. E.
Published: July 2010

A stem‐tip inoculation procedure has been successfully used in divergent selection for resistance to Sclerotinia trifoliorum (Eriks) on alfalfa (Medicago sativa L.). One unreported observation made in early studies was that lesion development was not continuous for some alfalfa plants over the 14‐d incubation. A more in‐depth study of disease development was needed to quantify the variability, and the stem‐tip inoculation procedure was modified for this purpose. Inoculated stems were placed in plastic sleeves and marks were made daily on the plastic to show the development of necrosis over time. Eight plants previously selected for their higher levels of resistance and eight plants selected for minimal resistance (susceptibility) developed necrosis after 14 d in the plastic sleeves, which was similar to that measured in earlier studies. The length of the lesion on susceptible plants was described by a linear equation with 0.9 to 1.3 cm of necrosis d−1. Six of the resistant plants stopped the lengthening of the necrotic stem lesion about 8 d after inoculation while two of the resistant selections continued linear development at rates much less than that measured on the susceptible selections. When the necrotic region stopped developing, a dark border usually developed between the green and necrotic tissues which was not seen when disease continued to develop. Statistical analysis suggested disease resistance might be effected by either of two qualitatively different systems.
Agronomic Effects from Chromosome Translocations 7DL.7Ag and 1BL.1RS in Spring Wheat
Authors: Singh R. P. , Huerta‐Espino J. , Rajaram S. , Crossa J.
Published: July 2010

In hexaploid wheat (Triticum aestivum L.) disease resistance genes transferred from alien sources are often associated with undesirable traits. Replicated trials using near‐isogenic lines of spring wheat ‘Seri 82’ were conducted for 2 yr under non‐moisture stress and simulated moisture stress conditions to determine the effects of the 7DL.7Ag and 1BL.1RS translocations [from Agropyron elongatum (Host) Beauv. and Secale cereale L., respectively] on grain yield and related traits. Mean grain yield of the 1B lines was significantly higher (3.2%) than that of the 1BL.1RS translocation lines in non‐moisture stress trials, but not significantly higher in the moisture stress trials. The mean grain yields of the five highest yielding reconstituted Seri 82 genotypes (1BL.1RS) were significantly lower than that of the genotypes without the 1BL.1RS translocation in non‐moisture stress (3.2%) and moisture stress (5.2%) conditions. Incorporation of the 7DL.7Ag translocation caused a significant increase (9%) in biomass at harvest in non‐moisture stress trials. The mean grain yields of the five highest yielding 7DL.7Ag lines were significantly higher (8.2%) than the reconstituted Seri 82 genotypes in non‐moisture stress conditions and more than 16% lower under moisture stress. Lower grain yields of the 7DL.7Ag lines under moisture stress could be due to their excessive pre‐heading biomass production. Several yield‐related traits of the near‐isogenic genotypes varied significantly. Presence of each translocation caused lateness and, when present together, the 1BL.1RS and 7DL.7Ag translocations delayed heading and maturity by 7 and 5 d, respectively. The genetic background of the recipient wheat can affect the utility of a translocation.
Determination of Minimum Number of Growing Seasons for Assessment of Disease Resistance Stability in Rice
Authors: Guimarães E. P. , Amézquita M. C. , Lema G. , Correa‐Victoria F.
Published: July 2010

The literature reports that evaluations over a number of growing seasons are required to identify stable disease resistance in rice (Oryza sativa L.). CIAT's Rice Breeding Program alms to develop lines with stable resistance; therefore, the knowledge of how long a germplasm should be assessed before being used in crosses is important. For this research, 69 commercial cultivars grown in Latin America and the Caribbean were evaluated during 11 growing seasons in a ‘hot spot’ site for the four most important diseases of rice: leaf and panicle blast (caused by Pyricularia grisea Sacc.), leaf scald [caused by Microdochium oryzae (Hashioka & Yokogi) Samuels & I.C. Hallett syn. Gerlachla oryzae (Hashioka & Yokogi) W. Gams syn. Rhynchosporium oryzae (Hashioka & Yokogi)], and grain discoloration (caused by species of Sarodadium, Bipolaris, Alternaria, Gerlachia, Fusarium, Phoma, Curvularia, Trichoconiella, and Pseudomonas). Cultivar mean disease severity (M), its response to increase in disease pressure (b), and the standard deviations from the regression (Sb) were calculated. Eleven evaluation seasons were considered as the most reliable period, in which an ideal set of 13 cultivars was identified based on their disease resistance stability (M, b, and Sb values). To identify the minimum number of seasons required to assess stability of resistance, simulations were made with these 13 cultivars and the 11 seasons and the coincidence in selection and the number of misclassified entries were calculated. The M and b correlation values and the number of misclassified entries suggested that seven consecutive growing seasons (two per 12‐mo. period) are necessary to identify germplasm with stable reaction to leaf and panicle blast, leaf scald, and grain discoloration.
Evaluating Wheat Cultivars for Waterlogging Tolerance
Authors: Musgrave M. E. , Ding N.
Published: July 2010

Waterlogging is a serious environmental stress on winter wheat (Triticum aestivum L.) grown in the Gulf Coast region. We hypothesized that waterlogging tolerance differs in currently available lines and cultivars and that suitability of physiological parameters to distinguish yield responses could be evaluated. Three types of studies were conducted: a 2‐yr greenhouse study of eight cultivars, a 4‐yr irrigated field study of 20 cultivars and breeding lines, and a 3‐yr field study of six cultivars under rain‐excluding shelters which allowed comparison of performance under waterlogged and well‐drained conditions. In the rainshelter study, waterlogging caused a 45% decrease in grain weight, resulting from a 45% decrease in number of kernels and a 5% decrease in kernel weight. Cultivars differed for grain yield under waterlogged conditions in the field (P = 0.1), and Coker 9877 and line LA 862A16‐3‐3‐X yielded 32 and 33% above the mean, respectively. Greenhouse measures of photosynthesis under waterlogging were weakly predictive of yield (r2 = 0.61) and correlated to measures under well‐drained conditions (r2 = 0.87). Yield was well correlated with biomass (r2 = 0.84) and root mineral content (Fe + Mn + P) (r2 = 0.94). Waterlogged yields × cultivar did not correlate with yield under well‐drained conditions (r2 = 0.14) and the same differential response to waterlogging was shown for biomass and root mineral content. The negative correlation between root mineral content and yield was attributed to processes involved in the formation of a mineral plaque on the surface of the wheat roots. This emphasizes the need to explore differences in root function when selecting wheat lines for enhanced waterlogging tolerance.
Ethephon Induced Changes in Vegetative Growth of ‘Tifton 85’ Bermudagrass
Authors: Shatters Robert G. , Wheeler Richard , West S. H.
Published: July 2010

The establishment rate of warm‐season turf and forage grasses propagated by sprigs or cuttings is of economic importance by determining not only how quickly an area may be utilized but also by influencing the extent of weed invasion. We monitored ‘Tifton 85’ bermudagrass [Cynodon dactylon (L.) Pers.] vegetative growth response to the application of ethephon (2‐chloroethylphosphonic acid), an ethylene‐producing compound, and how this treatment affected subsequent vegetative establishment. Responses of established Tifton 85 plants to ethephon treatment when compared with untreated plants included a 22% reduction in plant height, node swelling, bud swelling at the crown, terminal leaf necrosis, chlorotic striping of young developing leaves, and a 118% and 101% increase in leaf/stem fresh and dry weight ratios, respectively. Swelling of ethephon‐induced buds appeared to be due to a transient arrest in sprouting. Swelled buds finally sprouted 9 d following ethephon treatment. In glasshouse experiments, vegetative cuttings taken from ethephon treated plants produced 112% more roots under a range of water stress conditions 8 d after cutting removal, and produced 10‐fold higher number of tillers at 6 d after planting in soil than untreated cuttings. Tiller production in the soil establishment study was not statistically different between ethephon treated and untreated plants after 21 d. These glasshouse results indicated that it may be feasible to develop ethephon treatments that improve establishment rate and subsequent stand quality of Tifton 85 bermudagrass in field/commercial applications.
Evaluation of Discriminant Analysis in Identification of Low‐ and High‐Water Use Kentucky Bluegrass Cultivars
Authors: Ebdon J. S. , Petrovic A. M. , Schwager S. J.
Published: July 2010

Identification of water conserving Kentucky bluegrass (Poa pratensis L., KBG) is an important objective in turfgrass breeding programs. Warm‐season turfgrass selections with low evapotranspiration (ET) rates have been successfully identified by components of canopy resistance to ET and leaf area. The objective of this study was to determine the effectiveness of discriminant analysis in distinguishing water conserving KBG on the basis of canopy resistance and leaf area from a population of 61 KBG cultivars. By means of cluster analysis, the 61 KBG cultivars were categorized as either low‐ or high‐water use cases based on ET rate evaluated in the growth chamber at three VPD environments (1.263,1.664, and 2.261 kPa). Fourteen morphological and growth characteristics were assessed in the greenhouse with unmowed, spaced plants and mowed turfgrass (20‐cm‐diam. lysimeters). Based on single plant morphology, five‐ and seven‐variable discriminant functions were identified that correctly classified cases into their actual water use groups with an estimated 70.5% actual error rate from cross‐validation with the leave‐one‐out method (LOER). Compared with single plant morphology, turfgrass morphology was more efficient in requiring fewer predictors (hence fewer measurements) to perform classification. Based on turfgrass morphology, two and three‐variable functions were identified that correctly classified an estimated 75.4% of the cases into their true water use groups. A 75.4% correct classification was the best achieved and was as good as that obtained with all 14 original variables in the analysis simultaneously. Leaf angle, a component of canopy resistance, was the most important discriminator of water use group, predicting actual group membership in 72.1% of the cases. Correct classification was improved only slightly over leaf angle alone by incorporating a single leaf area component such as leaf width or leaf extension rate. These results show that discriminant analysis may be an efficient and useful tool for predicting the water use patterns of new cultivars on the basis of a few plant measurements that are routinely assessed by breeders.
A Plant DNA Isolation Protocol Suitable for Polymerase Chain Reaction Based Marker‐Assisted Breeding
Authors: Lange D. A. , Peñuela S. , Denny R. L. , Mudge J. , Concibido V. C. , Orf J. H. , Young N. D.
Published: July 2010

An important, but often limiting step in marker‐assisted breeding is the efficient isolation of plant DNA for polymerase chain reaction (PCR) amplification. While there are many protocols for plant DNA isolation, they tend to be time consuming or difficult to use on many samples simultaneously. We have optimized an alternative approach to plant DNA isolation that immobilizes DNA on a solid matrix, followed by processing in a 96‐well microtiter plate. A single person can isolate DNA and initiate PCR‐based analyses for 96 individuals in one day. The DNA samples are suitable for several PCR‐based procedures, including random amplified polymorphic DNA (RAPD), microsatellite (simple sequence repeats), and amplified fragment length polymorphism (AFLP) analyses. Because the DNA is immobilized on a solid matrix and processed in 96‐well plates, this protocol could be modified for robotic manipulation.
Chromosomal Location of Genes for Resistance to Karnal Bunt in Wheat
Authors: Nelson J. C. , Autrique J. E. , Fuentes‐Dávila G. , Sorrells M. E.
Published: July 2010

Karnal bunt (Tilletia indica Mitra) infestation of wheat (Triticum aestivum L.) kernels reduces grain quality. Deployment of genetic resistance would be preferable to chemical applications for control of the disease. Inoculation studies were carried out in a wheat mapping population with the aim of locating genes for resistance. Recombinant inbred (RI) lines from a cross between a resistant synthetic wheat (Triticum turgidum ‘Altar 84’ × T. tauschii) and the susceptible common wheat cultivar ‘Opata 85’ were inoculated with Karnal bunt sporidial suspension and evaluated for symptom development in the field for three seasons and in the greenhouse. Based on restriction fragment length polymorphism (RFLP) analyses, regions on chromosome arms 3BS and SAL carrying marker alleles from the Altar durum parent were consistently associated with reduced kernel disease. Main marker effects accounted for up to 32% of disease variation in the field but only 15% in the greenhouse, where the level of disease was higher, suggesting an environmental component of resistance. The tagging of these Karnal bunt partial‐resistance genes in tetraploid and hexaploid backgrounds may facilitate the accumulation of resistance via marker‐assisted transfer to susceptible durum and common wheat cultivars. This practice should reduce laborious disease screening requirements.
Predicting Progeny Variance from Parental Divergence in Hard Red Spring Wheat
Authors: Burkhamer Rebecca L. , Lanning Susan P. , Martens Roy J. , Martin John M. , Talbert Luther E.
Published: July 2010

Selection of parents is an important first step in any breeding program. The ability to assess accurately genetic differences between parents and subsequently to predict progeny performance would enhance the efficiency of breeding programs. This study examined the association between genetic similarity (GS) based on coefficient of parentage (COP) and molecular marker data for 10 hard red spring wheats (Triticum aestivum L.). In addition, we assessed the value of parental diversity based on COP, and molecular marker data, and combinations of them, to predict progeny genetic variance for 12 crosses of hard red spring wheat. Coefficient of parentage was computed for all pair‐wise combinations of the 10 parents. Parents were assayed with 205 sequence‐tagged sites (STS) polymerase chain reaction (PCR) primer sets and 14 arbitrarily chosen selective amplified fragment length polymorphism (AFLP) primer combinations. Fifty random progeny lines from each of 12 crosses among the 10 parents were grown in three field environments. Genetic variance estimates were obtained for nine traits, and an overall variance was obtained as the sum of single trait variance components from standardized data. Genetic similarities estimated from COP, STS‐PCR primer sets, and AFLP primer combinations were interrelated. Genetic distance computed from COP, STS‐PCR primer sets, AFLP primer combinations, or combinations of them was not a strong predictor of progeny genetic variance or number of transgressive segregates for single traits. However, significant correlations were obtained between COP and STS‐PCR‐based genetic distance and overall variance.
Genetic Relationships of Soybean Mutants for Different Linolenic Acid Contents
Authors: Rahman Shaikh M. , Kinoshita Takehito , Anai Toyoaki , Arima Susumu , Takagi Yutaka
Published: July 2010

The normal content (80–90 g kg−1) of linolenic acid in soybean [Glycine max (L.) Merr.] oil adversely affects oil flavor and stability. A new mutant (M‐24) with lower linolenic acid content (62 g kg−1) was developed by x‐ray irradiation. Our objective was to determine the inheritance of linolenic acid content in M‐24 and to determine the genetic relationships of this trait with the fan and fanx loci known to control linolenica acid in M‐5 and KL‐8 mutant, respectively. Reciprocal crosses were made between each mutant and ‘Bay’, and among the three mutants No maternal or cytoplasmic effects were observed in any of the crosses. Data from F2 seeds of the cross M‐24 ✕ Bay indicated that linolenic acid content in M‐24 was controlled by an allele at a single locus with no dominance effects. In the cross of M‐24 ✕ KL‐8, F2 segregation indicated that linolenic acid content in M‐24 and KL‐8 was controlled by two different alleles at the same locus. Fort he M‐5 ✕ M‐24 cross, F2 segregation patterns and the segregation of F3 seeds from individual F2 plants indicated that M‐5 and M‐24 mutants have alleles at different independent loci that control linolenic acid content. Therefore, the allele in M‐24 is designated as fanxα (M‐24) to distinguish it from those of fan (M‐5) and fanx (KL‐8). The segregate with the fanfanfanxα fanxα genotype can be considered as an important germplatsm that can reduce the linolenic acid content in soybean oil.
Protein, Oil, and Yield of Soybean Lines Selected for Increased Protein
Authors: Helms T. C. , Orf J. H.
Published: July 2010

Soybean breeders need to evaluate alternative strategies for increasing yield, protein, and oil content. The correlated response for yield when selection is conducted for increased protein among unreplicated plant rows is unknown. Our objective was to evaluate selection for increased protein content at an intensity of 50% using unreplicated plots to determine the correlated response for yield, gross value per hectare, oil content, and the direct response for protein content. Ten populations that included 30 lines each were evaluated for yield, protein, and oil content at each of seven environments. Lines were selected solely for high protein content with one replicate at each of three selection environments and based on the average of two replicate in three selection environments. Additionally, selection was conducted on the basis of the population mean in the selection environment(s). Selected and unselected lines were evaluated in four validation environments that were not the same as the selection environments. Selection among individual lines solely for increased protein content decreased yield 70 kg ha−1 and increased protein content 7 g kg−1, when lines were selected on the basis of the mean of two replicates and three environments. Selection among populations for increased protein content, decreased yield 110 kg ha−1 and increased protein content 5 g kg when selection was based on the population mean averaged across two replicates and three environments. On average, selection for increased protein content resulted in decreased yield.
Salt Gland Ion Secretion: A Salinity Tolerance Mechanism among Five Zoysiagrass Species
Authors: Marcum Kenneth B. , Anderson Sharon J. , Engelke M. C.
Published: July 2010

Need for salinity tolerant turfgrasses is increasing because of government mandates requiring use of low quality secondary water sources for turfgrass irrigation. This study was done to elucidate salinity tolerance mechanisms of the Zoysia genus (zoysiagrass), which includes a number of important turfgrasses. Research objectives were to (i) determine the range in salinity tolerance among and within five zoysiagrass species, (it) determine if salt secretion via leaf salt glands is an important salinity tolerance mechanism within the Zoysia genus, and (iii) determine if salinity tolerance is associated with the rate, efficiency of leaf salt gland secretion. Fifty‐seven zoysiagrass accessions and cultivars, representing five interfertile species, were grown in hydroponic tanks in a glasshouse. Salinity of treatment tanks was gradually raised prior to data collection to a final treatment level of 400 mM NaCI. Relative salinity tolerance was determined by changes in percent leaf firing and percent leaf dry weight relative to control plants. Relative percent leaf firing varied from 19 to 80% among entries, indicating a wide range in relative salinity tolerance. Bicellular leaf salt glands were observed in all species, lying recumbent to the leaf surface in parallel rows atop intercostal ridges. Relative salinity tolerance was negatively correlated with leaf sap Na+ concentration and positively correlated with leaf salt gland Na+ secretion rate and leaf gland density. This indicates that salinity tolerance in the Zoysia genus is associated with shoot saline ion exclusion via leaf salt gland secretion, which, in turn, is related to leaf salt gland density.
Rapid Prediction of Mating System of Vicia Species
Authors: Zhang X. , Mosjidis J. A.
Published: July 2010

Maintenance and use of germplasm collections of Vicia species is difficult because of limited information on their mating systems. Polymorphism of seven enzyme systems in 31 accessions of 12 Vicia species were measured by isoelectric focusing to infer their mating system. To compare variability within and among accessions and between species, polymorphism indices were calculated by means of isozyme bands. All enzymes studied had polymorphic banding patterns. Twenty‐eight accessions were variable for at least one of the seven enzymes, whereas three other accessions were uniform for all seven enzymes. Within‐accession variation was larger than that among accessions in V. villosa Roth and V. villosa ssp. varia (Host) Corbière, whereas within‐accession variation was smaller than that among accessions of V. articulata Hornem., V. benghalensis L., V. cracca L., V. ervilia (L.) Willd., V. lutea L., V. narbonensis L., V. pannonica Crantz, V. peregrina L., and V. sativa L. The results agreed with field tests which demonstrated that V. villosa and V. villosa ssp. varia are predominantly cross‐fertilizing species, whereas the other species are mainly self‐fertilizing. The use of isozyme bands to determine mating system proved to be accurate. In addition, this method is convenient because it utilizes a small seed sample and is inexpensive and easy to perform.