bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Floral Expression by Sugarbeet Seedlings under Continuous Incandescent Lighting and Moderate Temperatures1
Authors: Saunders J. W.
Published: July 2010

Continuous incandescent lighting (25‐35 μEm−2 sec−1) and moderate temperatures (20/14 C day/night) with 14 hour fluorescent lighting (350 to 550 μEm−2 sec−1) per day elicited flowering within 80 days in seedling populations of seven of eight sugarbeet lines tested in growth chamber experiments. The percentage of the plants that flowered ranged from 0 to 100 among lines. Shortest time to flower was 38 days. This method of rapid floral expression can lead to accelerated generation times for breeding purposes. It may also risk increasing the incidence of field bolting because of inadvertent selection for greater sensitivity to expressive factors unless conditions are optimized to permit flowering of the whole population.
Inheritance of Semolina Color in Six Durum Wheat Crosses1
Authors: Johnston R. A. , Quick J. S. , Hammond J. J.
Published: July 2010

Ten durum wheat (Triticum turgidum L. var durum) cultivars and experimental lines were crossed, and lines were generated for two genetic studies pertaining to the inheritance of semolina color. Experiment I included six crosses grown in a split plot arrangement of a randomized complete block design over three environments. Data on semolina color for P1, P2, F1, F2 F3, BCP1 and BCP2 generations were analyzed by using an unweighted least squares procedure to determine the relative importance of gene effects. An average of 82% of the genetic variability for semolina color was attributed to additive effects. In Exp. II, F3 lines and their corresponding F4 families were derived from five of the original crosses and grown in an augmented design with replicated checks at one location. Heritabilities were calculated for the five crosses and compared to realized heritabilities, revealing only slight differences. The realized heritabilities obtained for the five crosses were 69, 66, 31, 52, and 66%. There were only slight differences between the predicted and actual gains for each cross. Transgressive segregation for high color was found in four of the five crosses. Semolina color was a highly heritable trait controlled primarily by additive gene effects. The intensity of expression was influenced by environment, but improvement of color should be possible through early generation selection.
Inheritance of Spike Nodding Angle in Spring Barley1
Authors: Miller J. P. , Brinkman M. A.
Published: July 2010

The objective of this study was to evaluate the inheritance and gene action of spike nodding angle in spring barley (Hordeum vulgare L.). Spike nodding angle measurements were made on the basis of both individual plants and 1.5‐m rows of plants as the units of measurement. Individual plant measurements were made at Madison, Wis. in 1979 on F1, F2, and F3 plants from a diallel cross without reciprocals among six parents that had spike nodding angles ranging from erect to nodded during much of the postheading period of growth. Spike nodding angles were measured 30 d after heading. One analysis indicated that both additive and dominance gene effects were important, while another hadicated that general combining ability (additive gene effects) was more important than specific combining ability (nonadditive gene effects). Narrow‐sense heritabillty estimates on individual plant basis were low, ranging from 0.15 to 0.27. Because there was concern about the reliability of measuring spike nodding angles on an individual plant as the unit of measurement, parentoffspring regression analyses were conducted on 1.5‐m rows of plants as the unit of measurement. The row‐plot measurements were made at Madison and Arlington, Wis. in 1980 and at Madison in 1981. The F3–F4 generations were evaluated in 1980 and the F4–F5 generations were evaluated in 1981. In general, heritability estimates calculated by three methods were medium to high, ranging from 0.35 to 0.99. Although these heritability estimates may have been inflated by dominance gene effects, they are considered to be more meaningful than heritability estimates obtained on the basis of an individual plant. The nodded spike characteristic should be transferrable in barley breeding programs without unusual difficulty.
Nitrogen Fertilization Effects and Anatomical, Protein, and Amino Acid Characteristics of Yellow Berry in Triticale
Authors: Sharma G. C. , Paul A. D. , Bietz J. A.
Published: July 2010

We studied the effect of N fertilization on yellow berry (YB) triticale (✕ Triticosecale Wittmack) and the anatomical, protein, and amino acid differences between YB and normal kernels of several triticale lines. Some bread (Triticum aestivum L.) and durum (T. durum L.) wheats were also included for comparison. Increased fertilization significantly reduced YB incidence. Tritlcale lines differed significantly in YB incidence, implicating genetic factors in YB expression. Scanning electron microscopy revealed that normal kernels have a more dense endosperm protein matrix than do YB types. Endosperm and aleurone cells generally fractured around the starch granules and cytoplasm, respectively, in YB kernels. The total protein content of YB kernels was generally 1 to 1.5% lower than in normal kernels. The YB kernels contained significantly more lysine as percentage of protein, but less aspartic acid and glutamic acid than normal kernels
Growth‐Chamber and Field Reaction of Three Smooth Bromegrass Strains to Pyrenophora bromi (Died.) Drechsl1
Authors: Jessen D. L. , Carlson I. T. , Hodges C. F.
Published: July 2010

Improved screening procedures would aid in selection for resistance to brown leaf spot caused by Pyrenophora bromi (Died.) Drechsl. (Helminthosporium bromi Died.) in smooth bromegrass (Bromus inermis Leyss.). The objectives of this research were to use a growthchamber inoculation procedure to study variation in brown leaf spot reaction among and within three smooth bromegrass strains and to compare the results with field disease ratings. Reaction to brown leaf spot in the growth chamber was determined as the percentage diseased leaf area on the four youngest leaves on one tiller per plant. Average percentage diseased leaf area increased with an increase in leaf age. The wide range of variation in percentage diseased leaf area among plants within the three strains indicates that the growth‐chamber inoculation procedure would be useful for screening plants for brown leaf spot resistance. The association between repeated determinations on the same set of plants suggests that preliminary selection of resistant genotypes on the basis of rank performance in a single growth‐chamber trial would be reasonably effective. SB‐5, a fiveclone synthetic selected for brown leaf spot resistance in the field, was more resistant to infection in the growth chamber and field than SB‐C3, the population from which parent clones of SB‐5 were selected, and ‘Lincoln’, a susceptible cultivar. SB‐C3 and Lincoln were not significantly different in disease reaction in the growth chamber, but SB‐C3 was more resistant than Lincoln in the field.
Effects of Chemical and Physical Treatments on Germination of Freshly‐Harvested Kleingrass Seed1
Authors: Tischler Charles R. , Young Bruce A.
Published: July 2010

Freshly‐harvested kleingrass (Panicum coloratum L.) seed exhibit post‐harvest dormancy (approximately 10 to 20% germination) which is essentially lost following 6 months storage at room temperature. The purpose of this investigation was to determine if physical and chemical seed treatments can circumvent or alleviate this dormancy. For all experiments, total germination of seed was determined over a 35 d period (35/25°C, day/night temperature, 12 h light). Seed from several genotypes were included so that tests for treatment ✕ genotype interactions could be made. Sulfuric acid (H2SO4) treatments were most effective in promoting germination of freshly‐harvested seed (three separate experiments). As scarification requirements (for hard seed) do not disappear with time, our data suggest acid treatments either a) destroy a germination inhibitor, or b) modify the lemma and palea to allow inhibitors to diffuse out of the caryopsis. Several other treatments increased germination slightly. Untreated seed stored for 6 months at −20°C were essentially dormant after storage. This dormancy was greatly reduced by sulfuric acid treatments. Germination of untreated seed stored at room temperature for 6 months increased from 27 to 92%. Germination of the seed stored at room temperature was increased to a maximum of 96% by several treatments, although sulfuric acid treatments were no longer the most effective. This suggests different levels or mechanisms of dormancy exist even within seed from a specific genotype, so that as seed age, their response to various chemicals change. For all experiments, significant differences between genotypes and treatments were noted, and treatment ✕ genotype interactions were significant. Hence, use of a given chemical (i.e., sulfuric acid) on a bulk seedlot may differentially stimulate germination or injure certain genotypes present in the seedlot.
F4 Bulk Testing in Testcrosses of 27 Exotic Peanut Cultivars1
Authors: Isleib T. G. , Wynne J. C.
Published: July 2010

Peanuts (Arachis hypogaea L.) are potentially a genetically vulnerable crop in the United States because of their narrow genetic base. To broaden the base, breeders must identify exotic parents for inclusion in programs of hybridization and selection. Parental, F1, and/or F2 performance could be used as indices to predict performance of inbred lines derived from crosses of adapted by exotic parents. Twenty‐seven exotics representing five South American centers of diversity, Africa, and China were testcrossed to an adapted Virginia (ssp. hypogaea var. hypogaea) breeding line. The parents had been previously sorted into five morphological groups,. Parents, F1'S, and F2's were tested in 1979. Twenty F2 families per cross were bulked in the F4 and tested in 1981. Variation among bulks for pod and seed yield and other characters was due predominantly to differences among morphological groups. Exotics of ssp. hypogaea produced higher yielding bulks than those of ssp. fastigiata. Spanish (var. vulgaris Harz.) parents produced the hightest yielding fostigiata‐derived bulks. Variation among bulks within morphological groups was significant for pod and seed size parameters and meat content, but not for yield. Performance of parents per se and F2's were the best indicators of F4 bulk performance, based on product moment and rank correlations. F1 performance, heterosis, inbreeding depression, and epistatic effects were largely unrelated to F4 performance. It was proposed that exotics' performance per se could be used as a criterion for selection of parents for yield, although inclusion of F2 yields in a multiple‐variable index was more accurate in predicting F4 bulk means. Selection should be practiced within morphological groups of parents in order to retain parents from ssp. fastigiata.
Inheritance of Seedling Root Length and Relative Root Weight in Cotton1
Authors: Eissa A. M. , Jenkins J. N. , Vaughan C. E.
Published: July 2010

A perennial problem in cotton, Gossypium hirsutum L., involves obtaining a vigorous, uniform stand when planted early. Strains that grow roots longer and higher in relative root weight (mg/mm length) than currently used cultivars when temperatures are cool may help alleviate this. Using the standard cotton, cool temperature (18°C) germination test we determined root lengths and relative root weights for 124 day‐neutral composite F3 strains. Variability among lines was significant for each seed and seedling parameter. Fixed model diallel analyses of five strains indicated that among the five strains one would have difficulty in selecting for long roots with high relative root weight. Generation mean analysis indicated from one of two crosses that large amounts of additive, dominance, and additive by additive epistatic effects were present for the two primary root traits. One should thus be more successful if selection is delayed to the F3 to allow genetic recombination of additive and additive by additive epistatic genes to occur. Recurrent selection should be a useful method of breeding. The cross of strains 3822 ✕ 3851, involving accessions T‐214 and T‐225, respectively, should be useful for developing lines with root length equal or longer than ST 213 and relative root weight greater than ST 213. We speculate that plants with long roots and a high relative root weight should possess increased levels of resistance to seedling disease through a mechanical type of resistance; i.e., the plants should have more root tissue to slough off as diseased tissue and yet maintain a viable root system and a healthy plant than would plants with short roots with a low relative root weight.
Mass Selection for Tobacco Seedling Weight under Two Nutrient Regimes1
Authors: Van Sanford D. A. , Matzinger D. F.
Published: July 2010

Selection for increased weight of Nicotiana tabacum L. seedlings was conducted for 10 generations of recurrent mass selection in optimal and stress nutrient environments. Following the last cycle of selection, all cycles were evaluated on the nutrient level on which they were selected as well as on the alternate level. Selection response for both nutrient levels was significant when evaluated on either level; however, the responses were less than those predicted from estimates of genetic parameters in the base population. Maximum gains were obtained from selection on the optimum nutrient level whether final evaluation was made on either the optimum or stress level. Selection for increased seedling weight led to a correlated response of earlier germination. Only slight changes were obtained for a correlated change in root length, reflecting the compensation of genetic and maternal correlations of opposite sign.
Frequency and Stability of Tetraploids from 2X–4X Crosses in Red Clover1
Authors: Taylor N. L. , Giri N.
Published: July 2010

Crosses were made between 2X and 4X red clover (Trifolium pratense L.) plants under field cages by honey bees (Apis mellifera L.) to investigate the feasibility of producing autotetraploids by the mechanism of unreduced gametes. Clones from three cultivars and one experimental strain were used as female parents (diploids) and plants from a nitrous oxide‐derived tetraploid population of the cultivar ‘Kenstar’ were used as the male parents. Diploid parents yielding low amounts of seed produced a high percentage of tetraploids, but those yielding large amounts of seed produced very few tetraploids. High seed set apparently via pseudo‐self‐compatibility or 2X‐2X crosses from pollen contamination, interfered with the production of seeds via unreduced gametes in some cages. The frequency of tetraploids derived from diploid female parents in other cages where monoploid pollen was apparently excluded ranged from one per 1500 to 11000 flowers. About half of the apparent tetraploids were aneuploids that could not be distinguished from euploids except by chromosome examination. The frequency of univalents, bivalents, and multivalents at metaphase I of the unreduced gamete population was similar to that of the nitrous oxide‐derived population. In comparison to the colchicine‐derived material, there were more univalents and bivalents and fewer multivalents at metaphase I of the unreduced gamete population. Further research on the exact mechanism of nitrous oxide doubling and a comparison of the three methods is necessary.
Time of Physiological Maturity and Post‐Physiological Maturity Drying Rates in Wheat1
Authors: Clarke John M.
Published: July 2010

Field experiments were conducted in 1978 through 1981 to determine kernel moisture at physiological maturity and to study post‐physiological maturity drying rates in spring wheat (Triticum aestivum L.). Time of physiological maturity was taken as the date beyond which there was no significant increase in kernel dry weight. Yearly environmental conditions influenced kernel moisture at physiological maturity. Under low rainfall conditions, physiological maturity occurred at higher kernel moisture values than under wet conditions. Physiological maturity was probably induced prematurely by drought conditions. Cultivar ranking for kernel moisture at physiological maturity was reasonably consistent from year to year. Over cultivars and years, physiological maturity occurred at 32.4 to 43.6% kernel moisture. There was little difference among cultivars in rate of water loss after physiological maturity. Comparisons of drying rates are difficult in materials that reach physiological maturity on differing dates. Environmental conditions favoring rapid drying may have masked genotypic differences in drying rate.
Inheritance of a Short Petiole Trait in Soybean1
Authors: Kilen T. C.
Published: July 2010

A short‐petiole trait, found in a segregating F3 soybean [Glycine max (L.) Merr.] line, may have utility in narrow‐row culture. The objective of this study was to determine the inheritance of the trait. Crosses were made between short‐petiole and long‐petiole parents. Measurements of the top petioles of parental, F1, F2, and F3 populations indicate that the trait is controlled by a single recessive gene, lps.
Sequential Screening of Soybean Plants for Resistance to Phytophthora Rot and Brown Stem Rot1
Authors: Sebastian S. A. , Nickell C. D. , Gray L. E.
Published: July 2010

A greenhouse experiment was conducted to determine if soybean [Glycine max (L.) Merr.] plant reaction to Phialophora gregata Allington and Chamberlain (W. Gams) (Pg) is independent of a previous resistant reaction to Phytophthora megasperma Drechs. f. sp. glycinea Kuan and Erwin (Pmg). Reaction to Pg was independent of the previous reaction to Pmg. These results suggest that soybean plants can be sequentially screened for resistance to both Pmg and Pg without an interaction.
Growth Potential of the Axis as a Determinant of Seedling Vigor in Birdsfoot Trefoil1
Authors: Curtis K. , McKersie B. D.
Published: July 2010

Seedlings which developed from large seeds of birdsfoot trefoil (Lotus corniculatus L.) cv. Leo elongated faster than seedlings from small seeds, and this has been associated in previous experiments with improved field emergence and forage yield in the year of establishment. The physiological basis for the difference in seedling elongation between large and small seeds and between the cultivars Leo and Empire was investigated. The increased rate of axis elongation in large seeds was associated with an increased rate of dry weight (DW) accumulation. Both endosperm and cotyledon reserves contributed to this growth. When grown on an agar medium, supplemented with nutrients but without hormones, the axes from large seeds accumulated more DW than axes from small seeds suggesting that differences in sink size are primarily responsible for the differences in growth rates. Seedlings of Leo elongated faster than those of Empire and this was associated with a greater increase in axis DW. Endosperm reserves were depleted similarly in both cultivars, but Leo had a greater quantity of cotyledon reserves and translocared more to the axis than Empire. When grown on agar medium, the Leo axes accumulated more DW than Empire. The data are interpreted as indicating that differences in the ability of the axis to accumulate DW (sink size) account for differences in seedling vigor between seed sizes and contribute to the differences in vigor between the cultivars Leo and Empire.
Identification and Characterization of the Gene Conditioning Powdery Mildew Resistance in ‘Amigo’ Wheat1
Authors: Lowry J. R. , Sammons D. J. , Baenziger P. S. , Moseman J. G.
Published: July 2010

‘Amigo’ wheat (Triticum aestivum L.), is a source of genetic resistance to greenbug (Schizaphis graminum Rondani) biotype C, and is reportedly resistant to powdery mildew (Erysiphe graminis D.C. ex. Merat. f. sp. tritici Em. Marchal). The objective of this research was to identify and characterize the gene(s) for powdery mildew resistance in Amigo wheat To verify that Amigo is resistant to powdery mildew, selected lines from a near‐isogenic series carrying genes conditioning powdery mildew resistance, and ‘Kavkaz’, Amigo, and ‘Chancellor’ wheats were inoculated with culture 3 of E. graminis tritici and observed for disease reaction. Kavkaz is mildew resistant and Chancellor is known to be susceptible to powdery mildew. Crosses were made between Amigo and Chancellor, and between Amigo and the lines from the near‐isogenic series and Kavkaz. Resulting F2 plants were inoculated with culture 3 of E. graminis tritici and rated for resistance. Results from the screening procedures confirmed that Amigo is mildew resistant and that resistance is conferred by a single dominant gene. The segregation ratios for the F2 populations of Amigo/isogenic series and Amigo/Kavkaz suggest the Amigo gene conferring mildew resistance is previously unreported. A possible linkage relationship between the genes for powdery mildew resistance in Amigo and ‘Asosan/8*Chancellor’ was tested. The F2 families of the cross Amigo/2/Asosan/8*Chancellor were inoculated with E. graminis tritici culture 3 and segregation ratios observed. Close linkage between the genes for resistance in Amigo and Asosan/8*Chancellor was confirmed.
Inheritance of Flowering Date in Cicer Milkvetch1
Authors: Towsend C. E.
Published: July 2010

Flowering date is an important characteristic of cicer milkvetch (Astragalus cicer L.) because of its potential relationship to forage yield. Therefore, cicer milkvetch was evaluated in a 10‐parent diallel cross for flowering score (profuseness of flowering) in the seedling year and for flowering date in the seedling year and in two growth periods of the 2nd year. The F1 progenies and their reciprocals were grown under irrigation. Significant differences occurred among crosses for all traits. The variance for these traits was partitioned into general combining ability, specific combining ability, and reciprocal effects. Each of these components was significant for all traits. When plants from late ✕ early flowering crosses were classified as either flowering or nonflowering in the seedling year, flowering (vernalization not required) was partially dominant to nonflowering (vernalization required). In the seedling year, 73% of all FI plants flowered while 98% flowered in each of the two growth periods of the 2nd year. In general, plant vigor over all growth periods was poorly correlated with flowering date. It will be possible, however, to select vigorous plants which flower early in all three growth periods.
Variance Components and Linkage Effects for Quantitatively Inherited Traits in Two Barley Crosses1
Authors: VandeLogt M. B. , Brinkman M. A. , Forsberg R. A.
Published: July 2010

The objective of this study was to evaluate components of genotypic variance and the effects of linkage for heading date, plant height, kernel brightness, test weight and grain yield in two barley (Hordeum vulgare L.) crosses, Bonanza/H279‐70‐1‐4 and Larker/H279‐70‐1‐4. In 1977, F4, F5, F6, and F7 generations of 49 families from each cross were grown in a split plot design with families as whole plots and generation lines as subplots. The experimental procedure was repeated in 1978 with the F5, F6, F7, and F8 generations. A hierarchal structure of the experimental material was used so that genotypic variances and covariances could be calculated. Least squares procedures were used to evaluate additive, dominance, and linkage effects. Additive genetic variance was an important component of the observed variances and covariances for all traits in both crosses. Dominance variance was present for heading date, kernel brightness, test weight, and grain yield, but dominance mean squares may have been inflated by linkage effects. There was couplingphase linkage for grain yield in both crosses and for heading date in Larker/H279‐70‐1‐4. The results indicated that breeding procedures which keep linked blocks of favorable genes intact should be utilized in crosses among adapted barley genotypes.
Nonrandom Mating in Experimental Populations of Maize1
Authors: Kahler A. L. , Gardner C. O. , Allard R. W.
Published: July 2010

Eight enzyme loci were used to estimate the amount of outcrossing vs. self‐fertilization in two maize (Zea mays L.) populations, NHG(M)C‐21 and NHG(M)P‐16, that were developed recurrent mass selection for high yield and prolificacy, respectively. Single‐locus and multilocus estimates of outcrossing (t) and selfing (s = 1 − t) were made in selected (C‐21S and P‐16S) and unselected (C‐21 and P‐16) samples from each population. Single‐locus outcrossing values fluctuated widely from locus to locus in each of the four samples. The weighted mean single‐locus estimates of outcrossing were 0.91 ± 0.03, 0.94 ± 0.03, 0.88 ± 0.03, and 0.82 ± 0.03 (t = 0.89 ± 0.02) for C‐21, C‐21S, P‐16, and P‐16S, respectively; the multilocus (8‐locus estimate) outcrossing estimates were 0.81 ± 0.02, 0.88 ± 0.02, 1.00 ± 0.02, and 0.91 ± 0.02 (t = 0.90 ± 0.01). These results show that approximately 10% self‐pollination occurred in these populations, and that as a result the populations contain homozygotes in excess of mating expectations immediately after the mating cycle. However, in general, adult genotypic frequencies fit binomial square expectations which suggests that selection favoring heterozygotes occurred between seedling and adult stages of the life cycle.
Relationships between Soybean Yield in Narrow Rows and Leaflet, Canopy, and Developmental Characters1
Authors: Metz G. L. , Green D. E. , Shibles R. M.
Published: July 2010

Approximately 40 advanced generation soybean [Glycine max (L.) Merr.] lines within each of three maturity groups from each of two single‐cross populations were yield tested in 35‐cm rows. Seed yield was studied in relation to leaflet, canopy, and developmental characters measured in 3 years to determine if these characters 1) were related to seed‐yielding ability in narrow rows and 2) could be of use in a breeding program to improve soybean yield in narrow rows. All canopy and leaflet characters were measured at stage R5 (beginning of rapid seed‐filling phase). Maturity groups in each population were selected to differ by approximately 7 days in mean days to R7 (5% of pods are mature pod color). Generally, late‐maturing lines were larger and more vegetative than early lines. Significant genetic variances were found for most characters within each maturity group. In 1978, heritabilities of the characters (0.00 to 0.95) were generally high as or higher than heritability of yield (0.40 to 0.74). Small leaflet~size and low leaflet mass in the late‐maturity groups were most closely and consistently associated with high yield in both populations (r = ‐0.15 to ‐0.54). A low canopy rating, suggesting deep light penetration into the canopy, was also related to high yield in the late maturity group of one population (r = ‐0.24 to ‐0.45). Selection in both crosses for small leaflet size in the late‐maturity group in 1975 or 1977 improved seed yield an average of 4.9% over the group mean in 1978.
Inheritance of Feather Leaf and Plantain Leaf Characters in Sugarbeet1
Authors: Theurer J. Clair
Published: July 2010

F1 crosses and F2 progenies of normal ✕ abnormal leaf types were made and studied in the greenhouse to determine the inheritance of two foliar characters in sugarbeet, Beta vulgaris L. Plantain leaf (Pl2) a parallel veined lamina character in sugarbeet, was inherited as a simple dominant gene. This character phenotypically resembles another plantain character observed several years ago; however, the latter was governed by a single recessive gene. A feather leaf (ft) character was found to be controlled by a single recessive gene. Neither plantain leaf nor feather leaf genes were linked with genetic factors in the prominent Y‐R‐B linkage group in sugarbeet. Since these mutant characters have little or no detrimental effects on plant growth, the mutant plants could prove to be very useful marker stock for genetic and breeding experiments with sugarbeet.
Heritability of Tolerance to Phytophthora Rot in Soybean1
Authors: Walker A. K. , Schmitthenner A. F.
Published: July 2010

Heritability estimates would be useful in determining breeding strategies for tolerance to phytophthora rot caused by Phytophthora megasperma Drechs. f. sp. glycinea Kuan and Erwin in soybean [Glycine max (L.) Merr.]. The objectives of our study were to determine the heritability of tolerance to phytophthora rot in three soybean crosses and to determine what effect majorgene, race‐specific resistance has on tolerance. Parents and F3‐derived lines from three soybean crosses were evaluated for tolerance to phytophthora rot using the greenhouse, mycelium‐inoculum‐layer method. Also, each F3‐derived line was tested for race‐specific resistance. Herltability estimates for tolerance were determined for susceptible lines, resistant lines, and combined lines for each cross using the components of variance method. Heritability estimates ranged from 79 to 87% on an entry‐mean basis and from 49 to 63% on a plot basis. Herltability estimates were not affected by major‐gene resistance. However, lines carrying major‐gene resistance had a higher mean tolerance rating than lines which did not carry genes for race‐specific resistance. This suggested that major‐gene resistance and tolerance were not completely independent. The high heritability estimates indicated that considerable genetic gain should be expected from selection for tolerance in crosses where genetic variability is present.
Genotypic Variation for Duration of Seedfill in Soybean1
Authors: Egli D. B. , Orf J. H. , Pfeiffer T. W.
Published: July 2010

The length of the seed filling period is related to yield in soybean [Glycine max (L.) Merr.] and may be useful as a selection criterion in cultivar development programs. Genotypes from the World Soybean Germplasm Collection were grown in the field at Lexington, Ky. to estimate the genotypic variation in seed filling period that is available and to compare methods of estimating the seed filling period. Nine (1980), 14 (1981), and 59 (1982) genotypes were grown in four‐row plots 6 m long with 0.76 m between rows with two replications using conventional cultural practices. The length of the seed filling period was estimated from whole plant growth stages (R4 to R7 and R5 to R7) and from the effective filling period (EFP) determined from individual seed measurements. Significant genotype differences were found each year for all estimates of the filling period; however, genotypes with filling periods significantly longer than the longest filling period of a check cultivar were identified only in 1982. There was a significant genotype ✕ year interaction for 13 genotypes in the test for 2 years. The interaction seemed to result from the differential effects of moisture stress on the seed filling periods of the unadapted genotypes. There was a consistent relationship between the growth stage estimates of seed filling period and EFP over all genotypes and across 2 years; however, late maturing check cultivars (MG IV and V) showed longer filling periods, based on growth stage estimates, than MG III check cultivars; but there were no significant differences in EFP. The genotypes with long filling periods could be useful in developing higher yielding soybean cultivars, even though significant genotype ✕ year interactions frequently occur.
Response of Rice to Solar Radiation and Temperature Estimated from International Yield Trials1
Authors: Seshu D. V. , Cady F. B.
Published: July 2010

Experimental yields from cooperative rice (Oryza sativa L.) trials of the International Rice Testing Program network are related to major weather variables during reproductive and ripening stages. Based on the grain yield data from irrigated rice variety trials conducted in 40 environments during 1976–1981, regression models were developed and tested for predicting rice yields from total solar radiation and temperature data. The test sites were from eight countries in Asia, two from Latin America and one each from Africa and Oceania. Trials were conducted under conditions of good water control, optimal fertility and adequate plant protection and on sites with no appreciable soil stresses. Estimation of standard errors and evaluation of predictive ability of the formulated models are stressed. Among the models evaluated, a prediction equation based on radiation (RAD) and minimum temperature (MINT) during the ripening stage of 30 days after flowering demonstrated predictive ability. The environments ranged from 17.4 to 29.2°C for MINT and 315 to 637 mWh cm−2 for RAD. Predicted yield increased 0.41 t ha−1 (standard error of 0.092) for an additional 100 mWh cm−2 of total solar radiation, or an increase of 0.47 t ha−1 for an additional 100 langleys. For temperature, the change in predicted yield depended on the value of MINT. The rate of change in predicted yield was estimated as −2.10 + 0.075 MINT, i.e., the predicted yield change decreased 0.075 (0.0068) t ha−1 for each degree increase in MINT. Rates of changes in predicted yield were estimated at −0.68 (0.047), − 0.38 (0.025), and − 08 (0.024) for 19, 23, and 27°C, respectively. Model parameters were estimated by weighted least squares utilizing prior knowledge that yield predictions should decrease throughout the range of MINT from 18 to 28°C. Yield predictions are graphically summarized by yield response curves and isoquant plots.
Genetic Shifts in Mixed Bean Populations. II. Effects of Regeneration1
Authors: Roos Eric E.
Published: July 2010

Seed storage is the most commonly accepted form of long‐term germplasm preservation. Maintenance of the genetic integrity of seed populations during both seed storage and regeneration is an important aspect of this preservation process. Seeds of mixed and pure‐line populations of eight snap bean (Phaseolus vulgaris L.) cultivars were artificially aged and grown in the field to determine potential genetic shifts in the populations. After three cycles of seed regeneration the composition of unaged populations gradually shifted in favor of three cultivars (‘Black Valentine’, ‘Tendercrop’, and ‘Cherokee Wax’); while artificially aging seeds for 6 weeks at 32°C, 90% relative humidity, resulted in the total elimination of three cultivars (‘Kinghorn Wax’, Tendercrop, and ‘White Seeded Tendercrop’). Averaged over 3 years, Black Valentine had the highest seed yield/plant followed by Tendercrop and Cherokee Wax with ‘Bountiful’ having the lowest yield. Computer simulation of the effects of repeated cycles of regeneration of unaged seed populations predicted that Bountiful would be eliminated from the population after 5 cycles, assuming a sample size of 64 seeds for each cycle. Kinghorn Wax, ‘Spartan Arrow’ and ‘Landreth's Stringless Green Pod’ would be eliminated after 9, 10, and 15 cycles, respectively. Simulation of the combined effects of seed aging (to 50% viability) and regeneration resulted in a prediction that only two cultivars (Black Valentine and Cherokee Wax) would survive 15 cycles.
Inheritance and Anatomy of a Narrow Leaflet Trait in Alfalfa1
Authors: Brick M. A. , Barnes D. K. , Dobrenz A. K.
Published: July 2010

Gene marker traits often provide opportunities to learn about the genetic and morphological properties of a species. An alfalfa (Medicago sativa L.) plant with narrow leaflets was observed in a field of ‘Hayden’ alfalfa. The objectives of this investigation were to determine the mode of inheritance for this trait and to compare anatomical features between narrow leaflet and normal leaflet phenotypes. The F1, F2, and F3 generations were studied to determine the inheritance of the narrow leaflet trait. Segregation data fit a single tetrasomic recessive gene (nrl) hypothesis. Cross‐sections of mature leaflets from normal and narrow leaflet plants were compared for anatomical differences. Histological investigations revealed that the narrow leaflet phenotype had thinner leaflets, fewer palisade cells, and an enlargement of the leaflet at the outer margin. The narrow leaflet trait may be useful for investigating the relationships between leaf morphology and physiological characteristics. However, it will have limited usefulness in a breeding program because the homozygous recessive genotypes are completely female sterile and have indehiscent anthers.
Probable Genes for Leaf Rust Resistance in Several Hard Red Spring Wheats1
Authors: Statler G. D.
Published: July 2010

Reaction to different Puccinia recondita f. sp. tritici cultures was used to determine probable genotypes for seedling resistance in several hard spring wheat (Triticum aestivum L.) cultivars grown in North Dakota. Many of the cultivars studied can be combined into groups on the basis of sharing the same genes for resistance. Several cultivars probably have Lr2a and/or Lrl0 and a few contained Lrl. It is likely that most of these cultivars have genes in addition to those determined by this method as well as genes for adult plant resistance.
Multiple Insect Resistance in Several Soybean Genotypes1
Authors: Lambert Lavone , Kilen T. C.
Published: July 2010

Three commercial soybean [Glycine max (L.) Merr] cultivars and two breeding lines were evaluated for levels of resistance to four insect species. ‘Centennial’, ‘Forrest’, and ‘Tracy‐M’ and the advanced breeding lines D75‐10169 and D75‐12035 were compared to the insect resistant plant introduction (PI) 229358 for levels of resistance to velvetbean caterpillar (Anticarsia gemmatalis Hübner), soybean looper [Pseudoplusia includens (Walker)], tobacco budworm [Heliothis virescens (Fabricius)], and corn earworm [Heliothis zea (Boddie)]. Three tests were conducted in two environments. Average weights of lepidopteran larvae reared on leaves from the five genotypes were greater than those reared on leaves from PI 229358 by 6.3, 24.4, 43.3, 73.6, and 92.7% for D75‐10169, D75‐12035, Tracy‐M, Forrest, and Centennial, respectively. Each plant genotype showing resistance to one of the insect species also showed resistance to the other three species evaluated. Thus, the development of cultivars from PI 229358 with resistance to several insect species may be possible without the costly and time‐consuming process of screening each insect species at each selection stage in a breeding program. The use of cultivars with intermediate levels of resistance as adapted parents in crosses with resistant germplasm may facilitate the development of highly resistant and agronomically desirable soybean genotypes.
Influence of N Fertilization on Wheat Milling and Baking Quality1
Authors: Johnson J. W. , Hargrove W. L. , Touchton J. T. , Yamazaki W. T.
Published: July 2010

The role of time and rate of N fertilization in influencing milling and baking quality of ‘Oasis’ soft red winter wheat (Triticum aestivum L.) was studied for 1 year at one location and years at a second location. The N fertilizer treatments were combinations of fall (0, 11, 22, 33, and 44 kg N ha−1) and spring (0, 22, 44, 66, and 88 kg N ha−1) N rates. Location‐years were found to have a major influence on milling and baking quality. In 1978, the grain protein content and flour protein was 1 to 3% units higher than in 1979. Fall N application rates above 33 kg ha−1 resulted in detrimental effects on milling and baking scores. Milling and baking scores were significantly lowered in only one of the three location‐years at the Georgia recommended spring N rate (66 kg ha−1). Specifically, spring N rates affected baking quality by the increase of flour protein. The correlation coefficients between flour protein and AWRC and cookie diameter were 0.79 and −0.80, both highly significant, respectively. The trend toward higher rates (above 88 kg ha−1) of N could result in higher protein content which would lower baking quality.
Inheritance of Tannins in Birdsfoot Trefoil1
Authors: Dalrymple E. J. , Goplen B. P. , Howarth R. E.
Published: July 2010

Condensed tannins appear to prevent bloat by acting as protein precipitants, preventing the formation of foams. The objective of this study was to determine the genetic basis for the production of condensed tannins in the forage of birdsfoot trefoil (Lotus corniculatus L.). Results from controlled crosses of high and low tannin plants showed that tannins in birdsfoot trefoil were controlled by a single dominant gene. The F2 and backcross generations gave disomic ratios, consistent with an allotetraploid interpretation. The gene symbol T is proposed for the gene for tannin control in birdsfoot trefoil.
Dinitrogen Fixation, Herbage Yield, and Rhizobial Preference of Selected Alfalfa Clones1
Authors: Heichel G. H. , Hardarson G. , Barnes D. K. , Vance C. P.
Published: July 2010

Improvement of N2 fixation in forage legumes requires development of methods for the identification of genetic variability in this trait and measurement of its expression in the field. Our objective was to investigate the N2 fixation of clones of alfalfa (Medicago sativa L.) initially selected from adapted germplasm, over 4 years of growth in the field, with evaluation of the rhizobial preference of the clones in specific years. Dinitrogen fixation in the field was measured by the 15N isotope dilution method. Rhizobial preference was established by serology or by use of antibiotic resistant mutants. While rates of N2‐fixation varied substantially among clones in each year, three clones consistently ranked high across years, and three clones ranked low. Performance of the remaining five clones showed considerable variation with year of growth. Dinitrogen fixation was highly correlated (r = 0.70‐0.99) with herbage yield within each year and across years. There were significant differences in nodulation among the clones in 1978 and in 1979. Nodule number per plant was correlated with milligrams of N2 fixed per plant in both years (r = 0.63*, 0.65*) (*Significant at the 0.05 level) with herbage yield (r = 0.66*, 0.83*). Use of antibiotic resistant rhizobial strains, but not serology, showed significant differences among clones in preference for indigenous strains and for one mutant strain. However, both methods showed that most of the nodules were formed by indigenous strains. These results suggest that the capability for N2 fixation of some clones derived from adapted alfalfa germplasm can be reproducibly determined in the field by the 15N isotope dilution method, even when specific knowledge of rhizobial preference of the host is unavailable. This may facilitate the identification of plant material potentially useful in breeding forage legumes for improved N2 fixation capability.
A Diallel Study of Bract Surface Area/Lint Weight per Boll Ratio in Cotton1
Authors: Bowman D. T. , Jones J. E.
Published: July 2010

A seven parent diallel study was conducted to determine the inheritance of the ratio bract surface area per lint weight per boll in cotton (Gossypium hirsutum L.). Experiments were performed in the field at Alexandria and Baton Rouge, LA in 1978 and 1979, and included the seven parents, their 21 F1's and their 21 F2's. Inbreeding depression and F2 deviations were insignificant, suggesting that epistasis and dominance were not as important as additive effects. Partial failure of the assumptions of no epistasis, no multiple allelism, and independent gene distribution was observed in the three general tests. Epistasis and multiple allelism were specifically tested and found to be negligible. Genotype‐environment interaction assumptions were specifically tested, and the additive and dominance effects were found to deviate among environments. A significant year‐array interaction indicated that dominance relationships among parents were not constant between years, suggesting that one needs to test over years. Partial dominance was expressed at most loci where dominant alleles effected the bract surface area per lint weight per boll ratio, and these dominant alleles were effecting smaller ratios. Narrow‐sense heritability estimates ranged from 0.20 to 0.92 and averaged 0.47, indicating that nearly one‐half of the heritability was additive in nature.
A Theory to Explain the Relationship Between Corn Population and Grain Yield1
Authors: Duncan W. G.
Published: July 2010

The objective of the paper is to add to development of a better understanding of the nature of competition among corn (Zea mays L.) plants in planting patterns. Competition is hypothesized to consist of two components, crowding and the effect of crowding on grain yield. Crowding within a planting pattern is the sum of the independent crowding attributed to each plant as a function of its distance from the target plant. The effect of crowding on yield is a function of genotypes and environment. The theory explains the precise mathematical relationships previously observed between corn grain yield and plant population and why corn grain yield per unit area goes through a maximum as plant population increases. Relative grain yields that are independent of genotype and environment are given for a wide range of row widths and plant populations.
Relationships Between Enzyme Marker Loci and Morphological Traits in Two Mass Selected Maize Populations1
Authors: Pollak L. M. , Gardner C. O. , Parkhurst A. M.
Published: July 2010

Although enzyme loci have been shownto be associated (either directly or through linkage) with quantitative traits in several specific maize (Zea mays L.) populations, it is not known whether these associations occur in all maize populations. If they do occur generally in maize, it is not known whether the associations can be exploited for maize improvement. for the purpose of determining whether plants with different enzyme genotypes also had different morphologicacl haracteristics, 20 morphological traits were measured on individual field‐grown plants in two maize populations, one of which was mass selected for prolificacy [NHG(M)PI7] and the other for grain yield [NHG(M)C22]. Genotypes at eight and nine enzyme loci, respectively, were determined for the same individual plants. Discriminant analysis was used to discriminate between enzyme genotypes at a particular locus using as discriminating variables the morphological traits remaining after stepwise selection. if discrimination was achieved,t he associations between genotypes and morphological traits were determined. Discriminant functions were associated with yield, maturity, and leaf variables at the acid phosphatasel (Acpl) locus in both populations. Total grain yield, the selection criterion in C‐22, was correlated with the first discriminant function which accounted for 61.1% of the variance in the discriminating variables. In P‐17, the second discriminant function was correlated with yield of the top ear on the mains talk relative to number of ears and plant size. In total, in these particular populations in one specific environment, 15 of the 17 pairs of genotypes or groups of genotypes at a particular locus could be discriminated using morphological traits at a probability level less than 0.05. Information from more populations and environments is necessary before the feasibility of using enzyme loci in plant improvement is known.