bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Selection Methods for Autotetraploids. I. Theoretical1
Authors: Hill R. R. , Haag W. L.
Published: July 2010

The relative effectiveness of selfed progeny test, selfed family, polycross progeny test, polycross family, full‐sib family, and individual selection was compared theoretically. Initial gene frequency, level of environmental variance, and level of dominance were variables in the comparisons. The comparisons were based on theoretical changes in gene frequencies with one cycle of selection in two‐allele autotetraploid populations that were in random‐mating equilibrium.

Theoretical responses with selfed progeny test and selfed family selection were equal and always greater than the other methods. Polycross progeny test selection was the second most effective method, and polycross family selection was the least effective method. Full‐sib family and individual selection were intermediate between polycross progeny test and polycross family selection. Fullsib family selection was more effective than individual selection when environmental variance was large, but individual selection was more effective for some gene frequencies when environmental variance was small.
Comparison of Selection Methods for Autotetraploids. II. Selection for Disease Resistance in Alfalfa1
Authors: Haag W. L. , Hill R. R.
Published: July 2010

One generation of selection based on selfed progeny test, selfed family, polycross progeny test, polycross family, and individual phenotype was conducted for resistance to Uromyces striatus Schroet. var. medicaginis (Pass.) Arth., Phoma herbarum West var. medicaginis Fckl., and Stem. phylium botryosum Wallr. in alfalfa (Medicago sativa L.). Selected individuals from each method with each pathogen were intermated separately. The resulting populations were compared experimentally to evaluate relative effectiveness of the selection methods.

Each method of selection produced a significant increase in resistance to U. striatus. Selfed progeny test and selfed family selection gave similar responses and were the most effective methods. Polycross progeny test and polycross family selection also gave similar responses, but were the least effective methods for U. striatus resistance. Response with individual selection was intermediate to responses with selfed and polycross methods. Each of the progeny test and family methods produced similar and significant increases in resistance to P. herbarum. Individual selection for resistance to P. herbarum was not effective. No method of selection produced a significant increase in resistance to S. botryosum
Genetics of Flowering Response in Cotton. VI. Flowering Behavior of Gossypium hirsutum L. and G. barbadense L. Hybrids1
Authors: Kohel R. J. , Richmond T. R. , Lewis C. F.
Published: July 2010

The center‐of‐origin cottons (Gossypium spp.) are isolated from cultivated American cottons by their shortday flowering response, and an understandng of the inheritance of flowering response is important hi attempting to transfer genes from these primitive cottons. The genetic systems controlling flowering response in Gossypium hirsutum and G. barbadense cottons were studied in diallel crosses involving short‐day anl day‐neutral lines of each species. The G. hirsutum lines were Texas Marker‐1 and M‐ll (day‐neutral) and Texas 220 and Texas 371 (short‐day). The G. barbadense lines were ‘Pima S‐l’ and 3‐79 (day‐neutral) and ‘Lengupa’ (shortday). These lines were crossed in all possible combinations, and the F1, F2, backcrosses to both parents, and a testcross to Texas Marker‐1 were grown for each combination. Flowering response was recorded as percentage of flowering plants and the mean date of flowering for each line in the field at College Station, Texas. A failure to meet the preanalysis tests of assumptions prevented the analysis of these data by the Hayman‐Jinks diallel analysis. The data were analyzed by comparison of mean, performance. We concluded that G. hirsutum and G. barbadense, represented in this study, have nonhomologous systems controlling flowering response. Within G. barbadense, flowering response is recessive to nonflowering and under single‐gene control. In G. hirsutum, however, flowering response is under multigenic control, which is partially dominant or additive to nonflowering. In interspecific cross combinations, the segregation for flowering response follows a multigenic pattern.
Resistance in Sorghums to the Greenbug: Field Evaluation1
Authors: Teetes G. L. , Schaefer C. A. , Johnson J. W. , Rosenow D. T.
Published: July 2010

Field screening of several sorghum [Sorghum bicolor (L.) Moench] lines and F1 hybrids showed adult plant resistance to Biotype C Schizaphis graminum (Rondani). Sorghum lines IS 809, KS 30, and SA 7536‐1 in general were significantly less infested with greenbugs than susceptible lines Tx 7000 and Tx 2536. F1 hybrids of resistant ✕ susceptible lines showed similar results when compared with susceptible NB 505. Resistant sorghums appeared only to affect beneficial insect abundance by reducing the number of their prey. Greenbug populations found on resistant SA 7536‐1, PI 264453, KS 30, or IS 809 sorghums were not reflected in the amount of leaf damage. That is, these sorghums, especially KS 30 and IS 809, were not damaged as severely by greenbugs as Tx 7000 and Tx 2536. Resistant types did not influence nymphal duration; however, IS 809 did significantly influence fecundity.
Effect of Water Stress on Photosynthesis and Transpiration of Flag Leaves and Spikes of Barley and Wheat1
Authors: Johnson R. R. , Frey N. M. , Moss Dale N.
Published: July 2010

‘Dickson’ barley (Hordeum vulgare L.) and ‘Era’ wheat (Triticum aestivum L.) were grown in a growth chamber in 25‐cm diameter ✕ 29‐cm deep plastic pots. Starting 7 days after the spike emerged from the flag leaf sheath, water was withheld for up to 7 days, during which time flag leaf water potentals fell as low as −33 bars. Rates of net photosynthesis and transpiration of both flag leaves and awned spikes decreased linearly with decreasing flag leaf water potential. Net photosynthesis reached zero in the flag leaves and spikes of each species when the leaf water potentials reached −31 to −33 bars. Flag leaf transpiration reached zero at −28 bars in both barley and wheat, and linear regression equations predicted that spike transpiration would reach zero at −39 and −31 bars in barley and wheat, respectively. Barley spikes possessed a greater amount of awn tissue and had higher net photosynthetic and transpiration rates than did wheat spikes.

A significant linear relationship existed between ribulose 1,5‐diphosphate (RudP) carboxylase activity and flag leaf water potential for flag leaves and awns of both varieties. Photosynthetic rates decreased to zero at −33 bars while substantial RudP carboxylase activity remained in all tissues. If in vivo RudP carboxylase activities are comparable to the in vitro rates measured, this enzyme did not likely limit photosynthesis at low water potentials.

The rapid and severe stress imposed in this growth chamber experment similarly affected the potosynthetic process of both awned spikes and flag leaves of wheat and barley. The time course of the development of severe stress in plants growing in the field may be quite different, however, than for potted plants. Thus, if awned spikes have an advantage in drought situations in the field, it is probably related to their recovery or survival capability and not to differences in the way water stress affects photosynthesis in awns compared to leaves.
Contribution of Cotyledons to Growth of the Sainfoin Seedling1
Authors: Cooper C. S. , Fransen S. C.
Published: July 2010

We studied growth of the sainfoin (Onobrychis viciaefolia Scop.) seedling in three experiments designed to measure energy relationships during early seedling development and the photosynthetic contribution of the cotyledons.

Growth of the sainfoin seedling depends on stored substrates during the first 7 days of growth. Stored substrate, however, was not adequate for normal first‐leaf formation and expansion, which appeared to depend on cotyledonary photosynthesis. Once stored reserves have been used, cotyledon photosynthesis is of major importance to early seedling growth. Covering the cotyledon resulted in: (1) a greater proportion of accumulated dry matter being transported to leaves and stems at the expense of root growth; (2) a significant decrease in specific leaf weight of first leaves; and (3) a reduction in seedling growth of 36% at 18 days of age. Cotyledons provided all of the photosynthate when seedlings were 7 days old. A subsequent decrease in photosynthetic contribution of cotyledons was in proportion to the decrease in cotyledon area as a percentage of total photosynthetic area and was only 18% by the time seedlings were 19 days old.
Function of Peroxidase in Resistance of Soybean to Bacterial Pustule1
Authors: Urs N. V. Ramaraje , Dunleavy J. M.
Published: July 2010

Peroxidase activity of soybean [Glycine max (L.) Merr.] plants was determined to investigate its possible role in disease resistance. Activity of the enzyme was determined in mitochondrial and supernatant fractions obtained from roots of the near‐isogenic soybean cultivars ‘Clark’ and ‘Clark 63,’ susceptible and resistant, respectively, to bacterial pustule disease caused by Xanthomonas phaseoli var. sojensis. Peroxidase activity in both mitochondrial and supernatant fractions from roots of Clark 63 was greater than in those from Clark. Peroxidase activity was higher in the mitochondrial fraction than in the supernatant fraction from Clark 63.

Peroxidase activity of the mitochondrial fraction from Clark 63 was threefold greater than that of Clark. Peroxidase was partially purified from mitochondria from roots of both cultivars. The peroxidase preparation from Clark 63 had greater bactericidal activity in the presence of hydrogen peroxide than that of Clark. There was a highly significant correlation between peroxidase activity per mg protein in the root preparations and percent survival of bacterial cells. A correlation coefficient of ∓0.7112 was obtained when ascorbic acid was present in the bactericidal assay system, and a coefficient of ∓0.6141 was obtained when ascorbic acid was omitted from the system.
Windbreak Influence on Water Relations, Growth, and Yield of Soybeans1
Authors: Frank A. B. , Harris D. G. , Willis W. O.
Published: July 2010

Response of ‘Norman’ soybeans [Glycine max (L.) Merr.] to a shelter‐induced microclimate was studied under dryland and irrigated soil water regimes. Leaf water potential (Ψ1), xylem water potential (ΨX), stomatal diffusion resistance (rB), canopy temperature, dry matter accumulation, leaf area, leaf density, plant height, and yield components were measured to determine the effects of shelter influences on a soybean crop.

Plant water status, characterized by measuring Ψ1, ΨX, rB, and canopy temperature during selected days, was strongly affected by soil water regime and sheltered conditions. The treatment combination of shelter plus irrigation resulted in the most favorable plant water status. Under dryland, where soil water was limiting, plant water status of the sheltered and exposed treatments was similar.

Dry matter production, green leaf area, and plant height were generally increased under sheltered treatments if soil water was not limiting. Dryland sheltered treatments showed early vegetative stimulation when compared to exposed treatments, but the resulting depletion of soil water in the sheltered treatment restricted later growth. Both irrigated and dryland sheltered plants had a lower leaf density compared to exposed plants.

Soybean yields were increased from 20.4 hl/ha for the irrigated exposed treatment to 24.0 hl/ha for the irrigated sheltered treatment. Under dryland, the yields were 11.8 and 12.8 hl/ha for exposed and sheltered treatments, respectively.
Factors Affecting Pollen Movement and Natural Crossing in Pearl Millet1
Authors: Burton Glenn W.
Published: July 2010

Pollen from taller purple (PP) or red (RR) plants of pearl millet [Pennisetum americanum (L.) K. Schum., formerly P. typhoides (Burm.) Stapf and Hubb.] produced hybrids (Pp) (Rr) on green (pp) (rr) plants at distances up to 55 m but was responsible for only 3.7% of hybrids on green heads flowering at the same time within a radius of 1 m. In a field planting of ‘Tift 23’ germplasm pool D, purple and red plants of Tift 23 were responsible for only 0.88, 0.76, and 0.34% of hybrids at distances of 0.6, 1.2, and 1.8 m, respectively. This uniform flowering germplasm pool carrying 24 chlorophyll deficient (cd) mutants (each at a frequency of .005) showed 31.2% of inbreeding in 1972 and 18.1% in 1973. Natural crossing in these 2 years was 69 and 82%, respectively. Thus the 1,500 seeds on one head may contain germplasm from many males but a disproportionate amount of germplasm from the female parent. This fact, plus variations in height, anthesis date, and wind direction, makes it advisable to maintain natural (variable maturity) germplasm pools by sampling many plants as if each were a pure breeding entity and considering extra germplasm contributed by pollen movement as an uncertain bonus.
Response of Intersubspecific Peanut Hybrids to Photoperiod1
Authors: Wynne J. C. , Emery D. A.
Published: July 2010

Three peanut (Arachis hypogaea L.) lines tracing to three geographic areas of South America and representing Valencia, Virginia, and Spanish types and their three F1 hybrids with reciprocals were evaluated for response to short‐ and long‐day treatments in the North Carolina State Phytotron Unit of the Southeastern Environment Laboratories.

Lines and hybrids, when grown under a 9‐hour shortday photoperiod, were smaller but produced more fruit than when they were grown under a long‐day treatment produced by 9 hours of light plus a 3‐hour interruption of the dark period. The Valencia and Spanish lines flowered earlier and produced more flowers and fruit than the Virginia line.

Most hybrids showed greater heterotic response for fruit yield under short than under long days. All hybrids exceeded the midparent value for the yield of fruit for the short‐day treatment, while only two of the six crosses exceeded the midparent value for fruit yield under long days.

Reciprocal crosses involving the Spanish line showed significant differences for five of seven characters. Means were superior when the Spanish Hne was used as the female.
Performance of Original and Advanced Maize Populations and Their Diallel Crosses1
Authors: Genter C. F. , Eberhart S. A.
Published: July 2010

Six maize (Zea mays L.) breeding populations, 7 advanced populations developed from them by recurrent selection, diallel crosses among all 13 populations, and 9 check hybrids were evaluated in 17 environments during 1970 and 1971. The objective was to evaluate, under a wide range of environmental conditions, observed progress from three methods of recurrent selection and to estimate changes in genetic parameters obtained from a diallel of the original populations versus estimates from a diallel of the advanced populations. VCBS(S)C4 and VCBS(HT)C3 were about 20% higher yielding than VCBS; this improvement was expressed in their population crosses. Selection also increased the environmental response (b1) of these populations and their crosses. Very little improvement was detected for the other populations or their crosses. Source materials and environmental conditions under which recurrent selection trials are conducted may be as important as the selection method used.

Population and average heterosis effects explained most of the variation among entries. Hence, relative performance of the population crosses could be predicted reasonably well by population performance per se. Yields of the best population crosses did not differ significantly from yields of the hybrid checks. Extraction of inbred lines from VCBS(S)C4 or VCBS(HT)C3 to be used with lines extracted from BSSS(HT)C7 or PHWI(M)C9 should resuit in superior hybrids with a wide range of adaptation.
Anther Culture in Soybeans1
Authors: Ivers D. R. , Palmer R. G. , Fehr W. R.
Published: July 2010

To facilitate anther culture in soybeans [Giycine max (L.) Merr.], five bud stages from the cultivar ‘Hark’ are described. Combinations of bud length, corolla development, and anther development were indicators used to classify buds as stages 1 through 5, Stage 3 contained microspores that were predominantly individualized, uninucleate, and devoid of starch. Culture contamination, which ranged from 3.3% with buds from the winter greenhouse, to 100% with material from the field, was best controlled by treatment with 95% ethanol for 2 min, 5.25%N aOCfIo r 5 min followed by a sterile water rinse. Miller's and Nitsch's basic media are evaluated for callus growth and plantlet development, with addition of various levels of coconut milk, kinetin, iron, and auxins. No embryoids or plantlets were observed and. the callus formed was diploid.
Effectiveness of Visual Selection for Early Clonal Generation Seedlings of Potato
Authors: Tai G. C. C.
Published: July 2010

Random samples of 20 F1 potato (Solanum tuberosum L.)seedlings from each of 25 crosses were planted as single‐hill lots. Tubers were harvested, and each clone was planted again as a single‐hill lot and a 10‐hill lot. Seven selectors independently scored the dug tubers for acceptability and measurements were recorded for five important characteristics (maturity, tuber appearance, average weight of marketable tubers, number of marketable tubers, and number of small tubers) which were considered to have a causal effect on visual decision making. Analyses of data derived from the three experiments revealed that the correlation between experiments was low for visual scores of individual clones and moderate to high for mean visual scores of crosses. Two reasons were suggested to explain the poor efficiency of visual discrimination among individual clones: 1) the influential trait had poor correlations between experiments, and 2) the different pattern and degree of segregation of the influential traits among crosses caused the selectors to switch their attention to different traits when examining clones within different crosses. On a cross mean basis, tuber appearance and average weight of marketable tubers appeared to be more influential than other traits on the mean visual score of crosses.
Cotton Flowering and Fruiting Responses to Application Timing of Chemical Growth Retardants1
Authors: Thomas Robert O.
Published: July 2010

The influence of several chemical growth modifiers on suppression of undesirable late fruiting and on yield of cotton (Gossypium hirsutum, L.) was studied in 1972 and 1973. Plant responses were critically dependent on timing of application. With application at first flower, two compounds had no effect on rate of flowering, but reduced boll retention from 3rd and 4th week flowers. A third compound reduced both flowering and boll retention during weeks 4 and 5. Yield was significantly reduced in each case. A fourth compound was evaluated at three dates of application: Jul. 23, Aug. 8 (peak of flowering), and Aug 23. Yield was reduced by treatment at the early and intermediate dates. Treatment Aug. 23 did not reduce yield significantly but effectively suppressed late boll set.

Comparisons of yield responses to growth retardants for both years revealed that the 1973 crop with generally higher yield, was the more sensitive to yield reduction. Application in early to mid‐August at peak of flowering reduced yield significantly in 1973, whereas application 2 weeks later did not. Boll weight was reduced somewhat in late opening bolls from plots sprayed at peak of flowering. Thus chemical growth retardants that suppress late boll set may also impair full development of the last bolls that mature. Therefore, application timing is a compromise between the desired earlier termination of fruit set and the possible loss in yield and quality of late‐opening bolls.
Herbivore Feeding on Cyanogenic and Acyanogenic White Clover Seedlings1
Authors: Miller J. D. , Gibson P. B. , Cope W. A. , Knight W. E.
Published: July 2010

Populations of white clover (Trifolium repens L.) seedlings consisting of 11% cyanogenic and 89% acyanogenic phenotypes were exposed in the field at four locations to test for selective elimination of phenotypes by herbivores (mainly insects and other small pests). No significant relationship was found between phenotypes and elimination of seedlings by the herbivores.
Inheritance of Hard Seed in Cotton1
Authors: Lee Joshua A.
Published: July 2010

The purpose of this study was to determine the inheritance of hard or impervious seed coat in cotton (Gossypium hirsutum L). A hard seed was defined as any that could resist water uptake for 24 hours at 27 C. The breeding line SP‐hard seed was crossed with the nonhard‐seeded variety ‘Carolina Queen’ and various backcross and filial generations were raised. Graphing the relative frequencies of hard and nonhard seed taken from individual plants in the various generations revealed evidence for two genes. Their concerted action determines the level of seed hardness noted in SP‐hard seed (i.e. from 50 to > 90%, depending on the environmental conditions under which the seed matured). Under the humid conditions of greenhouse growth, expression of hard seed appeared to be largely recessive than nonhard, but there was evidence that this condition is subject to reversal in an arid environment.
Genetic Studies of Induced Mutants in Melilotus alba. IV. Inheritance and Complementation of Six Additional Chlorophyll‐deficient Mutants1
Authors: Ronnenkamp R. R. , Gorz H. J. , Haskins F. A.
Published: July 2010

Six ethyl methanesulfonate‐induced chlorophyll‐deficient mutants of Melilotus alba Desr. were studied. Each of the mutants behaved as a monogenic recessive. Complementation analysis revealed that the genes from five of the mutants were nonallelic to each other and to the previously reported mutants ch4, ch5, ch6, and ch7. Proposed symbols for the five genes are ch8, ch9, ch10, ch11, and ch12. No linkage was detected between ch5 and ch7, ch7 and Mf (multifoliolate leaf), ch8 and ch4, ch8 and ch5, ch8 and ch6, and ch8 and ch7.
Correlation of Fusarium Wilt of Cotton in the Field and Greenhouse1
Authors: Kappelman A. J.
Published: July 2010

Cultivar expression of cotton (Gossypium hirsutum L.) to Fusarium oxysporum Schlecht f. vasinfectum (Atk.) Snyd. & Hans, was studied under field conditions where nematodes were present and under greenhouse conditions where only the wilt fungus was artificially introduced into the plant.

In greenhouse studies, seedlings were artificially inoculated with either mixtures or individual wilt isolates in the absence of nematodes. When a highly‐virulent isolate of fusarium was used for greenhouse inoculations, results were highly correlated with those obtained under field conditions where nematodes and wilt were both present. Isolates of fusarium obtained from resistant or susceptible varieties were not always of high or low virulence, respectively. Therefore inoculum of known high virulence must be used in greenhouse tests for symptom expression to be correlated with that obtained under field conditions.
Effect of Diseases on In Vitro Digestibility of Smooth Bromegrass1
Authors: Gross D. F. , Mankin C. J. , Ross J. G.
Published: July 2010

Disease epidemics reduce the forage yield of smooth bromegrass (Bromus inermis Leyss.) but little is known about their effects on in vitro dry matter digestibility (IVDMD). Thirty‐one gcnotypes infected with three pathogens through natural inoculation in the field were evaluated for incident foliar diseases and IVDMD percentages. IVDMD percent was negatively correlated (—0.64, significant at the 1% level) with disease percent. A 1% increase in diseased area on the leaf, and age of leaf (as measured by one leaf lower on the culm), decreased IVDMD 0.12% and 0.19%, respectively.

Greenhouse inoculation of 33 genotypes with Drechslera bromi (Died.) Shoem. produced a significant decrease in IVDMD. Inoculation with bromegrass mosaic virus did not significantly reduce in vitro digestibility. Greenhouse inoculation of the same genotypes with Rhynchosporium secalis (Oud.) Davis. resulted in significant differences between IVDMD of inoculated and uninoculated plants; linear regression showed that the effects of increasing disease lesions by 1% would decrease IVDMD by only 0.04%. Since low levels of infection did not appear to have a large effect on digestibility as measured by IVDMD, a medium degree of resistance to foliar diseases should be sufficient for a smooth bromegrass cultivar for pasture use.
Evaluation of Alfalfa for Stem‐Nematode Resistance1
Authors: Elgin J. H. , Evans D. W. , Faulkner L. R.
Published: July 2010

An improved laborsaving technique for evaluating stem‐nematode [Ditylenchus dipsaci (Kühn) Filipjev] resistance in alfalfa (Medicago sativa L.) was developed. To demonstrate the technique, seedlings of three resistant and three susceptible varieties were inoculated by watering with nematode suspensions at seeding and again at 2, 4, and 6 weeks and were rated 16 weeks after seeding. Resistant varieties ‘Apalachee,’ ‘Lahontan,’ and ‘Washoe’ averaged 90.1, 67.8, and 63.7% resistant plants, respectively. Susceptible varieties ‘Saranac,’ ‘Vernal,’ and ‘Ranger’ averaged 34.9, 15.1, and 12.2% resistant plants. Because of its ease of application and its ability to differentiate clearly between resistant and susceptible varieties, this method should appeal to many workers.
Stomatal Size and Frequency in Soybeans1
Authors: Ciha A. J. , Brun W. A.
Published: July 2010

The stomatal frequency of 43 soybean [Glycine max (L.) Merr. genotypes varied significantly. The mean frequency on the adaxial surface was 130 (range: 81 to 174); on the abaxial surface, it was 316 stomata/mm2 (range: 242 to 345). The mean guard cell lengths were 21.9 and 20.4 µ for the adaxial and abaxial surfaces, respectively.

Stomatal frequency and leaf area were measured on the terminal leaflet of the third trifoliolate of soybeans grown at 18, 24, and 30 C and at 19,300 and 32,300 lux. Stomatal frequency significantly decreased with temperature on the abaxial surface, but there was no effect on the adaxial surface. Stomatal frequency significantly increased with light intensity on both surfaces. Leaf area increased with temperature and decreased with light intensity. Stomatal number/leaflet did not vary significantly with light or temperature treatments.

Water‐stressed, field‐grown plants had significantly greater stomatal frequency and smaller leaf area than nonwater‐stressed plants. Stomata/leaflet surface were significantly lower on water stressed plants than nonwater‐stressed plants.
Genotypic and Phenotypic Variances and Correlations in Peas1
Authors: Pandey Shivaji , Gritton E. T.
Published: July 2010

Eight lines of peas (Pisum sativum L.) and all possible Fl's among them were grown in five environments to study the genotypic and phenotypic variances and correlations among eight traits. Genotypes and environments had highly significant effects on all traits. Parents exhibited highly significant genotype × environment interactions but Fl's were remarkably stable.

Plant height was often positively correlated with pods/plant, seeds/plant, and yield/plant, indicating superior yielding ability of taller plants. However, indeterminate growth is unacceptable in peas for canning because of the range in maturity of peas borne at the different nodes and the excessive vine growth which interferes with harvesting. Correlations of percentage seed protein with the different traits were variable, but generally positively correlated with increased yield. There was some indication of lower protein with heavier seeds. Strong positive genotypic and phenotypic correlation coefficients obtained between pods/plant and seeds/plant, seeds/pod and seeds/ plant, and between those two traits and yield/plant, indicate that selection for either or both of these traits would result in superior yield. The genotypic correlation between weight/seed and yield was high, but the phenotypic association was low.
Yield Performance of Nonprolific and Prolific Maize Hybrids at Six Plant Densities1
Authors: Prior C. L. , Russell W. A.
Published: July 2010

Grain yield response of nonprolific and prolific Corn Belt maize (Zea mays L.) single‐cross hybrids to plant densities from 20,500 to 72,000 plants/ha were investigated. Four types of hybrids, each type including seven hybrids, were grown at six plant densities in eight environments (two locations in four years). The hybrid types were: type 1, elite, nonprolific; type 2, first‐cycle, prolific; type 3, second‐cycle or elite, prolific; and type 4, crosses between elite, nonprolific, and first‐cycle, prolific parental lines. Types 1 and 3 had the highest average yields (86.5 and 89.7 q/ha, respectively) over all densities and environments and were not significantly different. Type 2 (76.3 q/ha) and type 4 (80.0 q/ha) yielded significantly less than types 1 and 3. Elite, prolific hybrids (type 3) yielded more uniformly over the range of densities (b1 = 0.33) than did the elite, nonprolific hybrids (type 1, b1 = 2.00). Types 2 and 4 were intermediate in response (b1 = 1.08 and 1.73, respectively). The extent of prolificacy at the various densities probably was the most important factor in explaining responses of the types.
Inheritance of Resistance to Rhizoctonia Root Rot in Sugarbeet1
Authors: Hecker R. J. , Ruppel E. G.
Published: July 2010

Segregating populations from crosses of rhizoctoniasusceptible and resistant strains of sugarbeet (Beta vulgalls L.) were studied for 3 years to determine the inheritance of resistance to root rot caused by Rhizoctonia solani Kuehn. Broad‐sense heritabilities were increased by intensity of infection and ranged from 0.07 to 0.65 in the F2's. The degree of infection in inoculated field experiments was continuous, but was rated into eight disease index classes for purposes of measurement. Groupings into discrete classes (e.g., susceptible, intermediate, or resistant) were not possible. The partitioning method of genetic analysis was used to study the genetic control of resistance. A somewhat different gentic model was determined to be most descriptive in each of the 3 years. The majority of the variation in the segregating populations could not be assigned to one gene, but two genes did account for most of the variation. All three models involved two loci and two or three alleles. We concluded: i) two loci accounted for the majority of the expression of resistance; ii) resistance was partially dominant at the major loci in all but one instance; iii) year Χ genotype interactions affected resistance, but their magnitude was not practically important; iv) there was evidence that the two resistance parents did not have exactly the same genotypes for resistance; v) epistatic interactions appeared to affect resistance; and vi) minor or modifying genes probably were involved in resistance.
Survival and Cold Hardiness of Winter Wheats During Partial and Total Ice Immersion1
Authors: Andrews C. J. , Pomeroy M. K.
Published: July 2010

Seedlings of winter wheats (Triticum aestivum L.) of contrasting cold hardiness were only slightly damaged by partial immersion in ice at −1C for up to 6 weeks, whereas during 1 week total ice immersion survival was reduced considerably. Survival varied with the cultivar, and increased in each cultivar with increasing period of cold hardening before ice exposure. The cold hardiness of plants thawed after 1 week partial ice immersion was similar to cold hardiness of nonimmersed plants, while hardiness of plants surviving after total ice immersion was reduced by 8 to 12 C. Plants with or without ice treatments showed greatest hardiness after 7 weeks cold hardening. Survival was reduced more rapidly with decreasing ice temperature, but cultivars with the greatest resistance to total ice immersion at −1C were not superior in their survival at −7 C. Thawing of the ice during the course of protracted total ice immersion at −1 and −3 C increased the survival of the immersed plants.
Genetic Variability for Chemical Composition of Alfalfa. I. Mineral Elements1
Authors: Hill R. R. , Jung G. A.
Published: July 2010

A series of four‐parent diallel crosses was constructed with patents randomly selected from ‘Saranac’ alfalfa (Medicago sativa L.). The single crosses and parents were evaluated in small field plots during each of 2 harvest years to determine genetic variability for mineral concentration. Quantitative genetic analyses were conducted for concentrations of phosphorus, potassium, calcium, magnesium, manganese, iron, copper, boron, aluminum, zinc, sodium, and Ca/P in first‐harvest forage.

Significant additive genetic variance was observed for all traits, except Cu, Al, Zn, and Na concentrations. Except for digenic genetic variance for Cu concentration, nonadditive genetic variances were not significant. At the soil fertility levels of our experiment, clones from Saranac alfalfa contained less P, Cu, Zn, and Na, more K and Ca, and a higher Ca/P ratio than recommended for a moderately producing dairy cow. Deviations from the recommended levels of the remaining elements were minor and considered unimportant. Estimated potential ranges of mineral concentrations that could be achieved through plant breeding showed that i) the P‐deficiency could be corrected, ii) correction of the Zndeficiency and the excessive Ca/P ratio would be possible, but difficult, and iii) deviations from dairy cow requirements for Cu, Na, K, and Ca could not be corrected through plant breeding without alteration of soil fertility levels.

Genotypic correlations were significant for the following pairs of traits: P and K, P and Fe, K and Fe, Ca and Mg, Ca and Fe, Ca and the Ca/P ratio, and Mg and Fe. All these genotypic correlations were positive.
Low Temperature‐induced Floret Sterility in Rice1
Authors: Lin Shiow Shong , Peterson Maurice L.
Published: July 2010

Sterility of 296 rice breeding lines grown in the field at Davis, Calif., ranged from 3.6 to 96.8%. Mean sterility was 30.1% from an April 28 seeding and 35.2 for a May 7 seeding. A large part of the variability was caused by differential tolerance to cool night temperature at the young microspore stage of pollen development (10 to 15 days before heading). Higher sterility from the later seeding was probably associated with cooler temperature during this critical period. Growth chamber trials indicated that percent sterility increased in almost direct relation to cool‐temperature exposure. No difference was found between cool‐temperature treatments only during the dark and cool temperature during both dark and light so long as the total length of exposure was the same.

Floret and pollen sterility were highly correlated, whereas cool‐temperature‐treated plants fertilized with pollen that was not cool treated were equal in sterility to self‐pollinated, cool‐temperature‐treated plants. Comparisons of plants exposed to various light and darkperiod temperatures showed least sterility at 28 to 24 C and most at 36 to 16 C. Proposed procedures for screening rice germplasm for tolerance to temperature extremes are discussed.
Average Gene Frequency Estimates in Two Open‐Pollinated Cultivars of Corn1
Authors: Goodrich C. L. , Stucker R. E. , Compton W. A.
Published: July 2010

The purpose of this study was to obtain information on average gene frequency in two corn (Zea mays L.) populations. A design I mating system consisting of 100 males crossed to three females was developed in each of two open pollinated cultivars, ‘Golden Jewel’ and ‘Osterland's Yellow Dent.’ In addition, the male plants of the design I in each cultivar were selfed and crossed to females of the other cultivar. The intra‐population progenies, the inter‐population progenies, and S1 progenies from each cultivar were evaluated at two locations for yield, ear moisture, stalk lodging, and ear height. Days to flower was evaluated at one location only.

Ratios of estimated genetic components of variance and covariance were compared with corresponding theoretical ratios computed for various gene frequencies and levels of dominance. From these comparisons, approximate ranges of the gene frequencies in the two cultivars and relative magnitudes of gene frequencies were obtained.

The average frequency of favorable genes for yield appeared to be greater than 0.5 in both cultivars. There was some indication that the frequencies of favorable genes were lower for the other traits than those for yield. The ratios of variances among S1 progenies and covariance of S1 progenies with intra and inter‐cultivar crosses did not appear to add new information on gene frequencies, but supported the information gained from the comparison of the ratio of additive to dominance variance, the ratio of intra to inter‐cultivar variance, and the ratio of covariance of intra‐cultivar crosses with inter‐cultivar crosses. The average gene frequency for yield appeared to be higher in Osterland's Yellow Dent than in Golden Jewel.
Heritability Estimates of Percentage Seed Protein and Available Methionine and Correlations with Yield in Dry Beans1
Authors: Kelly J. D. , Bliss F. A.
Published: July 2010

Individual plant measurements of parental, F1, F2, BCP1 and BCP2 populations, F3, and F4 progenies of three crosses involving four bean strains (Phaseolus vulgaris L.) were used to determine inheritance of percentage protein, percentage available methionine, available methionine as percent of protein, and the correlations among these traits and with seed yield. Broad‐sense heritability estimates for populations grown in Wisconsin ranged from 0.32 to 0.71, 0.43 to 0.56, and 0.38 to 0.60 for percentage protein, percentage available methionine, and available methionine as percent of protein, respectively.

Narrow‐sense heritability estimates calculated by the standard unit regression analyses of F3 and F4 family means on F2 and F3 parental values, respectively, ranged from 0.63 to 0.79, 0.82 to 0.89, and 0.81 to 0.85 in the F3 generation and from 0.32 to 0.61, 0.52 to 0.87, and 0.51 to 0.81 in the F4 generation for the three traits. The moderately high heritability estimates and the apparent additive gene action indicated that selection within genetically variable populations should be effective.

A low negative correlation (r = −0.30) between seed yield and percentage protein suggested that selection should be made initially for high yield. Within high‐yielding families, plants having the highest percentage protein should be identified for further selection and intermating. Absence of correlation between seed and yield and percentage available methionine indicated that selection for either trait could be made without adversely affecting the other, while the positive correlation (r = 0.33) between percentage protein and percentage available methionine suggested that both characters could be improved simultaneously.
Combining Ability Analysis of Near‐homozygous Lines Derived from a 12‐parent Diallel Cross in Oats1
Authors: Stuthman D. D. , Stucker R. E.
Published: July 2010

Twelve oat (Arena sativa L.) genotypes, chosen primarily for high grain yield, were crossed in all combinations (except two) to determine the relative magnitude of general (GCA) and specific combining ability (SCA) as well as additive (δ2 Δ) and epistatic (δ2) genetic variance. Single seed descent was used to advance the material from F2 to F4. The test material consisted of 10 random F4‐derived lines from each of 64 crosses and was evaluated in the F6 and F7 generation at St. Paul, Minn., in 1972 and 1973. An analysis of variance for grain yield was computed to obtain among crosses and among lines‐in‐crosses sums of squares for individual and combined year data. The among crosses sums of squares was partitioned into general and specific combininga bility using least squares analysis.

All sources of variation involving crosses including interactions with years were highly significant. Regarding estimates of genetic components of variance δ2 Δ and δ2 ΔΔ, only the estimates of δ2 ΔΔ exceeded twice their respective standard errors. Confidence intervals of δ2 Δ and δ2 ΔΔ did overlap, however. Several criteria based on halfsib family performance were compared to parental pexformance; the associations provedt o be of little use. The relatively large amount of epistatic variance is a likely explanation for these poor associations. If these results are representative of other oat breeding populations, prediction of superior crosses from only parental performance data will not be useful.
Comparison of Different Hill‐plot Designs for Evaluating Quantitative Response to Oat Crown Rust1
Authors: Patanothai Soontree , Michel L. J. , Simons M. D.
Published: July 2010

Four hill‐plot field designs and a rod‐row design (plan 5) were compared for evaluation of the quantitative responses of five oat (Avena sativa L.) cultivars to two races of crown rust (Puccinia coronata Cda.) each at two levels of infection. In hill‐plot plan 1, test hills were planted in rows in a solid block. In plan 2, test hills were planted in rows alternating with rows of susceptible rust‐spreader hills. In plan 3, test hills were surrounded by barley (Hordeum vulgare L.) hills. In plan 4, single oat plants were grown in barley hills.

Evaluation of response to rust was based on how the performance of rusted plots compared with the performance of corresponding unrusted control plots. Rust severity was highest in plan 1; intermediate in plans 2, 3, and 5; lowest in plan 4. A combined analysis of data from plans 1, 2, and 3 showed that cultivars, plans, rows, and levels of infection all significantly affected both yield and seed weight in terms of reduction due to rust infection. The plan ✕ cultivar interaction was significant for reduction in seed weight, but not for reduction in yield. However, in the four hill‐plot plans and the rod‐row plots, the cultivars ranked the same in order of reduction in seed weight. All correlation coefficients among the different plans for yield and seedweight reductions were significant. Coefficients of variation for these traits were lowest for the rod‐row plots; intermediate for plans 1, 2, and 3; and highest for plan 4. Plan 1 was most desirable for general use.
Genetics and Breeding of 42‐Chromosome Triticale. II. Relations Between Chromosomal Variability and Reproductive Characters1
Authors: Gustafson J. P. , Qualset C. O.
Published: July 2010

F2 plants from two hybrid populations of 42‐chromosome triticale (X Triticosecale Wittmack) in which one or more of the D‐genome chromosomes had been substituted for a corresponding number of rye chromosomes were analyzed for their meiotic stability (number of univalents at metaphase I). F2‐derived F3 lines were evaluated in field tests. Genetic variability was detected in both populations for grain yield and heading time, and in one of the two populations for spikelets/spike, pollen viability, and percentage fertility. Correlations with the number of rye chromosomes indicated that substitutions had no effect on meiotic stability or any of the agronomic characteristics analyzed. Correlations of the number of univalents with fertility and other characteristics were low, indicating that measurement of meiotic stability is apparently of little value as a selection criterion to improve either meiotic stability or fertility. The use of pollen viability would also be of limited value for selection for fertility or yield because the correlations were generally low and nonsignificant. However, differences between populations in amount of genetic variability for pollen viability indicated that this character might be useful in some populations though not in others.
Inheritance of Resistance to Cowpea Chlorotic Mottle Virus (Soybean Strain) in Soybeans1
Authors: Boerma H. R. , Kuhn C. W. , Harris H. B.
Published: July 2010

Four soybean, Glycine max (L.) Merr., crosses between resistant and susceptible cultivars were used to study the inheritance of resistance to cowpea chlorotic mottle virus (soybean strain). From greenhouse inoculation tests performed on the F1 F2, and F3 generations, resistance was shown to be conditioned by an allele at a single locus, designated as Rev, which exhibited complete dominance under the conditions of this study.
Phytophthora Root Rot in Seeding‐year Alfalfa as Affected by Management Practices Inducing Stress1
Authors: Pulli Seppo K. , Tesar Milo B.
Published: July 2010

Root rot (Phytophthora megasperma Drechs.) on alfalfa (Medicago sativa L.) in the seeding year is associated with soil excessively wet for ten days or longer. The objective of this experiment was to determine the incidence of Phytophthora root rot (PRR) in October of the seeding year on tiled, well‐drained loam soil at East Lansing, Michigan. Samples were obtained on all combinations of the following: early (April 27) and late (May 19) seeding, irrigation (two 5‐cm applications) and no irrigation, Vernal and Saranac cultivars, two and three cuttings, and seven seeding rates — 2.2, 4.5, 9.0, 13.5, 18.0, 22.5, and 36.0 kg/ha.

In this test, irrigation of 5 cm on July 29 and on August 15 increased Phytophthora root rot in alfalfa roots. The natural precipitation between April 1 and October 31 was 56 cm, 4.5 cm above normal. The cultivars Vernal and Saranac were similar in susceptibility to root rot under all treatments. Increasing cutting frequency from two to three cuttings in the seeding year resulted in more PRR under all conditions of seeding date or irrigation levels. Alfalfa seeded at below‐normal seeding rates of 2.2 and 4.5 kg/ha was significantly less diseased than at normal (9.0 or 13.5 kg/ha) or higher seeding rates. Most comparisons indicated a trend of more PRR in alfalfa seeded late on May 19 than earlier on April 27. Incidence and severity of Phytophthora root rot was increased by a combination of stress factors including high soil moisture levels, frequent cutting, high seeding rates, and late spring seeding.
Chromosome Pairing in Triploid F1 and Hexaploid F1, F2, and F3 Generations of Gossypium Hirsutum L. ✕ G. Sturtianum Willis1
Authors: da Silva E. P. , Endrizzi J. E. , Stith L. S. , Muramoto H.
Published: July 2010

Chromosome pairing was studied in the triploid F1 and the hexaploid F1, F2, and F3 generations of Gossypium hirsutum L. (AD genome) ✕ G. sturtianum Willis (C genome) hybrid. Pairing in the hexaploid forms in each generation was essentially homogenetic indicating that the transfer of agronomic characters between genomes by conventional breeding methods for cotton improvement would be difficult.
Natural Crossing in Guar, Cyamopsis Tetragonoloba (L.) Taub.1
Authors: Stafford R. E. , Lewis C. R.
Published: July 2010

Detectable natural crossing between 21 glabrous breeding lines of guar grown with two pubescent breeding lines ranged from 0.3 to 4.4%. Maximum crossing probably approaches 9%, if undetected natural crossing within glabrous and pubescent lines is also considered. Natural crossing of this magnitude must be considered in maintaining genetic purity of breeding lines and in maintaining varietal purity of seed increases.