bluuebunny/crossref_metadata_2025 huggingface dataset:
Divergent Selection for In Vitro Dry Matter Digestibility in Switchgrass1
Authors: Vogel K. P. , Haskins F. A. , Gorz H. J.
Published: July 2010

The purposes of this study were to determine if phenotypic selection for in vitro dry matter digestibility (IVDMD) could be used to improve the IVDMD for switchgrass (Panicum virgatum L.) and to obtain heritability estimates of IVDMD in switchgrass. In 1973 a selection nursery of over 2,200 plants was established with transplanted seedlings of two similar Nebraska experimental strains. In 1974 about 800 plants that appeared to be agronomically superior were sampled for IVDMD. Single‐plant selectlons for high and low IVDMD were made in each of the nursery rows. In 1976, ramets from 25 of the high‐IVDMD selections and from 25 of the low‐IVDMD selections were transplanted to establish isolated high‐ and low‐ IVDMD polycross (PC) nurseries. Seed harvested from these nurseries in 1977 and from the same openpollinated (OP) clones in the selection nursery in 1976 was used in 1978 to establish a replicated seeded sward nursery in which the following strains were compared: high IVDMD PC, high IVDMD OP, ‘Pathfinder,’ low IVDMD OP, and low IVDMD PC. Forage yields and IVDMD were measured in 1978 and 1979. Over the 2 years the strains averaged 51.5, 50.0, 49.4, 48.3, and 48.1% IVDMD, respectively. The high IVDMD PC strain was significantly higher in IVDMD than the other strains in both years. Realized heritabilities for high and low IVDMD were 0.59 and 0.55, respectively. Strains did not differ significantly for forage yield in either year; thus, the gain in IVDMD by breeding was achieved without any yield loss.
Effects of Daylength Response and Semidwarfism on Agronomic Performance of Spring Wheat1
Authors: Busch R. H. , Chamberlain D. D.
Published: July 2010

Semidwarfism and daylength insensitivity have advantages for winter increase in southern latitudes and to allow wider potential use in breeding programs around the world. To determine if these traits have adverse effects in the upper Midwest, the progenies from a cross of ‘Justin,’ a tall daylength‐sensitive spring wheat (Triticum aestivum L.), by ‘Ciano 67,’ a semidwarf daylength‐insensitive cultivar, were separated into four phenotypic classes: tall‐insensitive (TI), tallsensitive (TS), semidwarf‐insensitive (DI), and semidwarf‐sensitive (DS). Each phenotypic class was represented by 28 F6 lines, randomly derived with the exceptions of their response to daylength and plant height. The lines were grown in three environments after normal time of seeding and one environment after late seeding to obtain information on the effects of semidwarfism and daylength‐insensitivity on various traits in different environmental conditions.

As expected, the insensitive classes headed earlier than the sensitive classes, while the tall classes and semidwarf classes headed similarly. The sensitive classes were slightly taller than the insensitive classes.

The tall classes yielded more than the semidwarf classes in the two environments where yields were highest but did not differ over all locations. The sensitive classes were superior to the insensitive classes in three of the four environments, but they did not differ following late‐seeding. Individual high‐yielding lines were observed in each phenotypic class, except in the TI class.

The DS class had considerably lower test weight than all other classes. However, reduced test weight did not appear to be closely associated with semidwarfism since the DI class had test weight equal to the mean of the two tall classes.

The DS class was lowest in protein percentage, but the DI class was equal to the TS class. Thus lower protein percentage did not appear closely related to the semidwarf trait.

Late seeding did not reduce the performance of the semidwarf or the insensitive classes relative to the other classes. The TS and DI classes represented parental types and apparently had higher frequencies of favorable gene combinations for yield. Consequently, for future studies, intercrossing may be beneficial to help distribute favorable gene combinations. Using these genetic materials, no severe deleterious effects were observed to be tightly associated with semidwarfism or daylength‐insensitivity.
Response of Soybean Strains to Artificial Inoculation with Nematospora coryli1
Authors: Keeling B. L. , Hartwig E. E. , Jackson E. L.
Published: July 2010

Pods on nine field‐grown soybean [Glycine max (L.) Merr.] strains were artificially inoculated with Nematospora coryli Peglion to determine if resistance to the yeast spot disease could be determined by this method. Reduced seed weight and thickness and visual appearance of seed were used as measures of response to inoculation. Significant differences in response to the yeast spot organism were obtained. PI 227687, IAC 74‐2832, PI 208785, PI 319526, and D72‐8879 were considered resistant and D75‐11041, ‘Forrest,’ ‘Hardee,’ and ‘Hill’ were susceptible.
Screening the USDA Glycine Soja Collection for Presence or Absence of a Seed Lectin1
Authors: Stahlhut R. W. , Hymowitz T. , Orf J. H.
Published: July 2010

The USDA Glycine soja Sieb. & Zucc. collection containing 559 accessions was screened for the presence or absence of a seed lectin. Nearly one‐half (49%) of the G. soja accessions were found to lack this seed lectin. The seed lectin from G. soja and the cultivated soybean [G. max (L.) Merrill] exhibited antigenic homology and migrated to identical positions in polyacrylamide gels. This suggests that the lectins of the two species are very similar or the same. Accessions of G. soja lacking seed lectin nodulated normally when compared with accessions containing seed lectin.
Lint Yield and Resistance to Pink Bollworm in Early‐maturing Cotton1
Authors: Wilson F. D. , George B. W. , Wilson R. L.
Published: July 2010

Moderately early maturing breeding stocks and cultivars of cotton, Gossypium hirsutum L., grown at Tempe, Ariz. in plots untreated with insecticide yielded slightly less to substantially more lint by mid‐September than long‐season cultivars did by mid‐October. Seed damage percentages caused by pink bollworm (PBW), Pectinophora gossypiella (Saunders), were lower in the moderately early and the very early cottons than in the long‐season cultivars. The very early maturing cottons, however, had lower yield potential than the moderately early or long‐season ones. Because all cottons suffered losses in yield from PBW, earliness is viewed only as one factor in assisting cotton cultivars to escape damage. Earliness would have to be combined with other resistance characters to produce cultivars that possibly could be grown without protecting them from PBW damage with insecticide.
Heritability of Canopy‐Apparent Photosynthesis and Its Relationship to Seed Yield in Soybeans1
Authors: Harrison S. A. , Boerma H. R. , Ashley D. A.
Published: July 2010

Selection based on canopy‐apparent photosynthesis (CAP) may be a means of improving the effectiveness of selection for seed yield in soybeans [Glycine max (L.) Merr.]. The present study was undertaken to determine the heritability of CAP and to determine the relationship of CAP to seed yield in F3‐derived lines from two soybean crosses.

In 1977 and 1978, 34 F3‐derived soybean lines from each of the crosses, ‘Dare’ × ‘Forrest’ (Cross V) and ‘Tracy’ × ‘Davis’ (Cross VI), were planted in a randomized complete block design with three replications. Two CAP determinations/plot were made during the period of pod and seed development. Significant genotypic variation and transgressive segregation for CAP occurred at each measurement for both crosses. Heritabilities based on variance component estimates were 41% for CAP and 28% for seed yield in Cross V and 65 and 14% for Cross VI.

Seed yield and CAP were significantly related (r=0.55 and 0.54) in both crosses. The average yield improvement over the 2 years of indirect selection based on CAP rate, using a 15% selection intensity, was 79% of direct selection for yield in Cross V and 146% in Cross VI. Based on the 2‐year means, 6 of the 10 highest yielding lines in Cross VI were among the 10 lines with the highest CAP rates. With the techniques used in our experiment, the cost and time of measuring CAP greatly exceeded that for measuring yield. The value of selecting for increased CAP to increase seed yield will be determined by the adaptability of current and future technology to determine CAP on fieldgrown soybeans.
Evaluation of the World Safflower Collection for Resistance to Phytophthora1
Authors: Da Via D. J. , Knowles P. F. , Klisiewicz J. M.
Published: July 2010

The World Safflower (Carthamus tinctorius L.) Collection was tested 5 years in the field for resistance to root rot induced primarily by Phytophthora drechsleri Tucker, P. parasitica Dast., and P. cryptogea Pethyb. and Laff. Resistance of 1,547 entries of the World Safflower Collection obtained from 35 different countries was evaluated. Nurseries were planted on a heavy clay soil following a crop of rice (Oryza sativa L.). In order to maximize disease incidence, plants were stressed for water prior to flood irrigation. Disease readings were made 10 to 20 days after irrigation. Seeds (achenes) from individual open‐pollinated plants which appeared resistant were harvested and planted the following year. After 5 years of testing, 15 of the most resistant lines which had been originally obtained from the following countries were released: Turkey, five; Egypt, Afghanistan, and Iran, two each; Sudan, India, Iraq, and Australia, one each. The released genotypes were designated UC‐150 to UC‐164, respectively.
Vertical‐Pull Resistance of Maize Inbreds and Their Testcrosses1
Authors: Penny L. H.
Published: July 2010

Studies were conducted to determine the relationship between vertical root‐pull resistance of maize (Zea mays L.) inbreds and that of their testcrosses with two inbred‐testers as an evaluation of the extent to which differences among inbreds can be transmitted to crosses of those inbreds. Thirty‐three inbreds and their testcrosses were evaluated at two stages of growth in four environments. Wide differences for pull resistance existed among the inbreds and were repeatable in different environments with minor interactions. The differences were present at the tassel stage of plant development and were most pronounced at the milk stage. Differences shown by the inbreds themselves were also expressed in their testcrosses but at a lower magnitude. Correlation coefficients calculated from combined data from the four environments for the inbreds vs. the two sets of testcrosses were 0.85 and 0.69 (significant at the 0.01 level of probability) at the tassel stage and 0.78 and 0.73 (significant at the 0.01 level of probability) at the milk stage. It is concluded that pull resistance differences among inbreds can be used to predict their performance in crosses.
Influence of Boll Removal on Assimilate Partitioning in Cotton1
Authors: Peoples T. R. , Matthews M. A.
Published: July 2010

Field experiments with Upland cotton (Gossypium hirsutum L.) were initiated to determine the effect of boll removal on the distribution of 14C‐assimilates 24 hours following removal. The mainstem leaf subtending the sympodium supplied the first and second boll positions with assimilates. In the absence of bolls, assimilates in the mainstem leaf moved basipetally from the leaf subtending the first position. The majority of assimilates were translocated to the first position boll. Removal of the first position boll resulted in assimilate movement to the second position parts of the plant when the second position was 10 days old. The majority of the assimilates from the second position leaf, being further out on the sympodium, remained in the sympodium, as long as at least one fruiting body was present. Removal of all the bolls from the sympodium resulted in translocation primarily in a basipetal direction.
Breeding for Early Maturity and Verticillium Wilt Tolerance in Upland Cotton1
Authors: Cano‐Rios Pedro , Davis Dick D.
Published: July 2010

Inheritance of earliness of crop maturity and Verticillium wilt (Verticillium dahliae Kleb.) tolerance and the relationship between the two characters, was investigated using seven strains of cotton (Gossypium hirsutum L.). Maturity rank was consistent over the two locations used, Las Cruces, N.M., USA, and Matamoros, Coahuila, Mexico.

Only general combining ability effects (GCA) were significant for either character. The strains Nectariless and Stahmannh ad the largest GCA effects for crop earliness, indicating that these cottons are potentially useful sources of germplasmin earliness breeding programs. Yugoslavian and ‘Deltapine 16’ exhibited the largest GCA effects for Verticillium wilt tolerance.

Yugoslavian and Stahmann showed the largest GCA effects for lint yield, suggesting that these strains could have value in developing wilt tolerant cultivars with good fiber yields. The strong association between wilt tolerance and lint yield at Las Cruces suggested that selecting for wilt tolerance among progenies stemming from these cottons on wilt‐infested soil might also increase lint yield.

Simultaneous selection for earliness of crop maturity and wilt tolerance, using Stahmannas a donoro fearliness, could be accomplished using the pedigree method of breeding.
Effects of Different Types of Sand and Vermiculite Grades on the Test Tube Method for Evaluating Preinoculated Seed1
Authors: Schoen J. F. , Kramer N.
Published: July 2010

Combinations of two types of sand and two grades of vermiculite in test tubes (25 × 200 mm) were evaluated for growth of seedlings with root nodules at 21 days of age. Rhizobium‐inoculated alfalfa seeds were planted two per test tube. Each type of sand was suitable for testing provided it was washed free of fine particles. Seedlings grown in substrate combinations which included the vermiculite having smaller (0.32 cm) particle sizes produced fewer nodules regardless of the sand type.
Cell Dynamics in Leaf Meristems of Contrasting Tall Fescue Genotypes1
Authors: Volenec J. J. , Nelson C. J.
Published: July 2010

Leaf elongation rate is a factor associated with yield per tiller and rate of canopy development. Elucidation of the mechanism by which leaves elongate may assist plant breeders and crop managers in optimizing agronomic performance. Our objectives were to locate the leaf intercalary meristem of tall rescue (Festuca arundinacea Schreb.) and to assess the relative contribution of cell division, cell elongation rate, and mature cell length to leaf elongation rate. Both cell division and elongation occurred in an intercalary meristem located with a lignin‐sensitive stain in the basal 30 mm of the elongating leaf. Growth rates within the elongation zone were ascertained by placing equispaced ink dots on the epidermis of the exposed meristem region and then measuring their displacement after 24 hours of growth. Growth occurred between dots placed 2 mm above the point of the previous leaf's attachment and those placed 13 and 26 mm above in genotypes exhibiting low (LYT) and high (HYT) yield per tiller, respectively. Maximum elongation rate occurred from 6 to 7 mm and from 9 to 14 mm above the point of the previous leaf's attachment in the LYT and HYT genotypes, respectively. In these regions, elongation rate of leaf tissue of the LYT genotype averaged 1.0 mm mm‐1 day ‐1, which was 40% higher than that of the HYT genotype.

Microscopic measurement of epidermal cell lengths throughout the elongation zone, and measurement of leaf elongation rate (LER), permitted an assessment the relative contribution of both cell division and elongation. The LER of 26 mm day‐1 of the HYT genotype was 44% higher than that of the LYT genotype. The HYT genotype also had a 100% longer cell elongation zone and produced 185 epidermal cells day ‐1 cell column‐1 which was 24% more than that produced by the LYT genotype. The 145 µm length of mature epidermal cells of the HYT genotype was 22% longer than those of the LYT genotype. The elongation zone of the HYT genotype contained 509 epidermal cells which was 94% more than the LYT genotype, but each epidermal cell expanded at a rate that was 20% slower. This resulted in a duration of elongation of 2.8 days cell‐1 for the HYT genotype, which was 56% longer than that of the LYT genotype. The large number of cells and long duration of cell elongation in the HYT genotype overcame the slow rate of cell elongation. This resulted in more and larger matured cells which led to the more rapid LER and high yield per tiller characteristic of the HYT genotype in comparison with the LYT genotype.
Breeding Potentials of Noncultivated Cottons. V. Productivity of Cultivars, Race Stocks, and F1 Hybrids among Them in Long‐ and Short‐Day Environments1
Authors: Wilson F. D. , George B. W.
Published: July 2010

Twelve primitive race stocks of cotton (Gossypiura hirsutum L.), four Upland cultivars, and 24 race stock ✕ cultivar F1 hybrids were grown in three replicated tests in the summer at Phoenix, Ariz. and in the winter at Isabela, Puerto Rico. Objectives of this research were to compare productivity, to study hybrid expression of agronomic properties, and to determine the effects of cultivar ✕ race stock and genotype ✕ environment interactions on parents and their F1 hybrids when grown in long‐ and short‐day environments.

Six of the 12 race stocks produced no bolls at Phoenix and few boils at Isabela. Hybrids of four of the six also produced no boils at Phoenix, but produced more bolls than either parent at Isabela. The other six race stocks, representatives of race latifoliura (from which Upland cotton was derived) produced from 2 to 29 bolls/plant at Phoenix. Five of the latter six produced more bolls at Isabela than at Phoenix; two of these five produced more bolls than the cultivars at the Puerto Rican location. None of the latifolium race stock ✕ cultivar hybrids produced more boils than the cultivars at Phoenix, but 5 of the 12 produced a larger number at Isabela.

Genetic variability among the hybrids was caused by differences among the race stocks. Lack of cultivar ✕ race stock interactions suggested that the genetic variability may be attributed largely m additive effects. Numerous instances of heterosis, however, also suggested the presence of nonadditive genetic effects. for hybrids from 8 of the 12 race stocks, location ✕ race stock interactions were significant for all six agronomic characters studied, indicating the inconsistency of hybrid performance for those traits between the two locations. For the other four hybrids, however, the location ✕ race stock interaction was significant only for lint yield/plant, but not for its components. Significant location ✕ cultivar interactions were much more infrequent than location ✕ race stock interactions. Positive heterosis for F1 vs. cultivar comparisons was shown by 26% of all hybrid/character combinations at Isabela and by 9% of those combinations at Phoenix. Several race stocks, potentially useful for specific characters, were noted for future breeding efforts.
Genetic Variability and Heritability of Certain Forage Quality and Mineral Constituents in Lolium‐Festuca Hybrid Derivatives1
Authors: Buckner R. C. , Burrus P. B. , Cornelius P. L. , Bush L. P. , Leggett J. E.
Published: July 2010

Breeding tall fescue (Festuca arundinacea Schreb.) cultivars with high digestibility and high nonstructural carbohydrate content and the proper balance of potassium (K), calcium (Ca), and magnesium (Mg) may overcome many of the seasonal problems of cattle grazing the species. The objective of this paper is to present estimates of genetic variability and heritability of digestibility, water‐soluble carbohydrates, K, Ca, Mg, and the K/(Ca + Mg) ratio and their association in selected Lolium‐Festuca hybrid derivatives. Twenty‐eight parental clones were evaluated in a spaced plant nursery, and their polycross progenies (pep) in seeded rows in Madison County, Kentucky. Additionally, the pcp were evaluated in sod plots in Fayette County, Kentucky. A combined analysis of variance of parents and pep at both locations for forage quality and mineral constituents showed highly significant differences for these characteristics among selections, generations, years, and their interactions. Broad sense heritahility estimates among parental clones were high for all constituents, indicating that a considerable portion of the total variability was genetic. Heritability estimates obtained from regression of pcp on parents were relatively high when parents and pcp were grown in close proximity for all constituents except K and the K/(Ca Mg) ratio. When parents and pcp were grown in widely different environments, the heritability estimates were low for all constituents. Thus, breeding materials should be evaluated for forage quality and mineral constituents in a minimum of two locations with widely different environments. Predictions of response to selection were disappointingly small for all characters. The data suggest that progress in breeding for low tetany potential in these materials, while possible, may require considerable time and effort.
Agronomic Performance of Soybeans with Differing Levels of Iron Deficiency Chlorosis on Calcareous Soil1
Authors: Froechlich D. M. , Fehr W. R.
Published: July 2010

There are marked differences among soybean [Glycine max (L.) Merrill] cultivars for susceptibility iron deficiency chlorosis on calcareous soils. Our objective was to determine the relationship between agronomic performance and the amount of iron deficiency chlorosis that soybean cultivars sustain. Fifteen cultivars ranging from highly resistant to highly susceptible to iron chlorosis were tested on calcareous and noncalcareous soils in five Iowa environments during 1978 and 1979.

There was a significant linear relationship between percentage yield reduction and visual chlorosis scores. The average percentage yield loss increased by 90% for each unit increase in chlorosis score. There also was a significant linear relationship between percentage yield reduction and percentage height reduction, with a 1.6% yield loss for each 1% reduction in height. Because of the reduction in height, lodging was reduced as chlorosis symptoms increased. Maturity was delayed for cultivars that had severe chlorosis symptoms. Seed weight and protein and oil content were not significantly influenced by chlorosis expression. The results should facilitate the assessment of potential yield reduction from iron deficiency chlorosis for planning appropriate control measures.
Anthracnose Resistance Increases Alfalfa Yields1
Authors: Elgin J. H. , Barnes D. K. , Busbice T. H. , Buss G. R. , Clark N. A. , Cleveland R. W. , Ditterline R. L. , Evans D. W. , Fransen S. C. , Horrocks R. D. , Hunt O. J. , Kehr W. R. , Lowe C. C. , Miller D. A. , Offutt M. S. , Pickett R. C. , Sorensen E. L. , Taliaferro C. M. , Tesar M. B. , Van Keuren R. W.
Published: July 2010

Development of high levels of anthracnose (Colletotrichura trifolii Bain) resistance in alfalfa (Medicago sativa L.) in the early 1970's stimulated interest in obtaining estimates of the increased productivity associated with resistance. This paper reports the results of forage yield trials established at 24 locations in the eastern, midwestern, and western United States. Each trial included four pairs of anthracnose‐susceptible and anthracnose‐resistant bioindicator strains: 1) Glacier and Beltsville 1‐An4, 2) Saranac and Beltsville 2‐An4, 3) Vernal and Beltsville 3‐An4, and 4) Team and Arc. Forge yields were recorded for 3 years at 18 locations and for 2 years at six locations. Average annual forage yields were significantly higher for the resistant strains than for the susceptible strains at 15 of the 24 locations, averaging 1.1 mt/ha/year (10%) greater for the resistant than for the susceptible strains. A 0.8 mt/ha/year (7%) yield advantage of resistant strains over susceptible strains was obtained over all 24 locations. These results clearly indicate the value of anthracnose‐resistant alfalfa cultivars to U,S. agriculture.
A Whole‐plant Indicator of Soybean Physiological Maturity1
Authors: Gbikpi Pascal J. , Crookson R. Kent
Published: July 2010

Loss of green color from the pod has been suggested as an indication of physiological maturity for individual soybean [Glycine max (L.) Merrill] seeds. In this study, we evaluated the usefulness of green pod color loss as an indicator of the physiological maturity of an entire soybean plant. We also studied the relationship of this visual change to other stages of whole‐plant soybean development and maturity already in use or described in the literature. The study was conducted in 1978 and 1979 at St. Paul, Minn. on a well‐drained Waukegan silt loam (sandy‐skeletal, mixed mesic Typic Hapludolls). The 1st year, cvs. ‘McCall’ (Group 00) and ‘Hodgson 78’ (Group I) were used. In 1979, ‘Altona’ (Group 00) and ‘Steele’ (Group I) were added. Seed dry weight was measured at 1‐week intervals for 8 weeks which spanned the maturation phase. The calculated date of physiological maturity was then related to a variety of visual plant changes.

Loss of green pod color was found to be the most reliable indicator of physiological maturity across years, cultivars, and maturity groups. Stage R7 according to Fehr and Caviness (occurs when one normal pod on the main stem has reached its mature color) was next most reliable, but occurred before physiological maturity and interacted with years. The ‘all pods brown’ stage occurred midway between physiological maturity and harvest maturity (harvest maturity = average seed moisture at 13%). On the average, early maturing seeds reached physiological maturity 11 days before late maturing seeds. Seed moisture content averaged 44% when the entire plant was physiologically mature. Color of petioles and stems, and color or senescence of leaves were not reliable indicators of physiological maturity.
Cytogenetic Relationships Between Paspalum jurgensii and P. intermedium, P. vaginatum, and P. setaceum var. ciliatifolium1
Authors: Burson Byron L.
Published: July 2010

Paspalum jurgensii Hackel, 2n = 2x = 20, was crossed with P. intermedium Munro ex Morong, 2n = 2x = 20, P. vaginatum Swartz, 2n = 2x = 20, and P. setaceum Michx. var. ciliatifolium (Michx.) Vasey, 2n = 2x = 20. The hybrids were studied cytologlcally to determine their genomic relationships. Three P. jurgensii ✕ P. intermedium hybrids were produced. Each had a chromosome number of 2n = 2x = 20. Meiosis was irregular with a mean chromosome association of 16.48 univalents and 1.70 bivalents per cell. These findings indicate that P. jurgensii and P. intermedium have different genomes which are designated as JJ and II for the respective species. Twelve P. jurgensii ✕ P. vaginatum hybrids were studied cytologically and all had a chromosome number 2n = 2x = 20. Meiosis was very irregular with a mean chromosome pairing behavior of 18.22 univalents and 0.88 bivalents per ceil. Minimal chromosome pairing in these hybrids indicates the two species are not closely related. One hybrid was recovered from the P. jurgensii ✕ P. setaceum var. ciliatifolium cross. It had 20 chromosomes with a mean pairing behavior of 17.73 univalents and 1.14 bivalents per cell at metaphase I. This indicates these species have different genomes. Based on these and previous findings genomic formulas of DD and SS were proposed for P. vaginatura and P. setaceum var, ciliatifolium.
Aspects of Glycerolipid Metabolism in Developing Soybean Cotyledons1
Authors: Wilson Richard F.
Published: July 2010

The metabolism of glycerolipids (GL) labeled with palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2), or linolenic (18:3) acids was studied with unsliced soybean [Glycine max (L.) Merr. cv. Dare] cotyledons harvested at 30 days after flowering. An inhibitor of lipoxygenase, n‐propylgallate, was required in the incubation media to prevent the peroxidation of the exogenous 18:2 and 18:3 substrates by the soybean tissues. Phospholipids (TPL) accounted for greater than 75% of the glycerolipid radioactivity incorporated from each of the acyl‐substrates. The distribution of radioactivity in phospholipid molecular species was determined by assaying the diacylglycerol (DG) molecular species prepared from the phospholipid fraction by phospholipase C hydrolysis. The predominate phospholipid molecular species synthesized from the respective substrates were: SD, [1‐14C] 16:0 or [1‐14C]18:0; SM and MD, [1‐14C]18:1; SD and DD, [1‐14C]18:2; and DT and TT, [1‐14C]18:3; where S= 16:0 or 18:0, M = 18:1, D = 18:2, and T = 18:3. The predominate triacylglycerol (TG) molecular species synthesized from the respective substrates were: S2M, S2D, and SD2, [1‐14C]16:0 or [1‐14C]18:0; M2D and MD2, [1‐14C]18:1; SD2, D3, and D2T, [1‐14C]18:2; and DT2 and T3, [1‐14C]18:3. Stereospecific analysis of the radioactivity present in phospholipid, DG, and TG indicated a preference for unsaturated fatty acid incorporation at the sn‐2 position of each class. The observed acylincorporation patterns supported the precursory interrelation of phospholipids in soybean TG biosynthesis, and also established the nature of soybean TG molecular species biosynthesis from specific acyl‐substrates. The method described has general application for preparing specifically labeled DG molecular species with high specific radioactivity and for determining the biochemical nature of TG biosynthesis in experimental soybean lines selected for altered fatty acid composition.
Associations Among Pod Dimensions and Seed Weight in Soybeans1
Authors: Frank S. J. , Fehr W. R.
Published: July 2010

Selection for seed weight among soybean [Glycine max (L.) Merr.] genotypes can be accomplished by indirect selection for width of mature pods. Our study was designed to evaluate additional variables that could influence the effectiveness of indirect selection for seed weight. The objectives were to determine the influence of number of seeds per pod on pod length, width, and thickness; to determine if measurements on full‐size green pods were as effective for selection as measurements on mature pods; and to determine which pod dimensions would be most effective for indirect selection. Data were obtained on F4 plants and their progeny from six populations in three Iowa environments.

Number of seeds per pod had a significant effect on pod length, but was of no practical importance on pod width or thickness. Selection for pod length or width based on measurements of full‐size green pods was as effective as selection based on mature pod dimensions. Selection for pod length or width was more effective than for pod thickness. Use of pod length or width alone was as effective for selection as evaluation for pod area or volume. Pod width was considered the most efficient character to use for indirect selection because it can be measured without regard to number of seeds per pod and is faster to measure than pod length.
Selection for Agronomic Characters in Hill and Row Plots of Soybeans1
Authors: Garland M. L. , Fehr W. R.
Published: July 2010

The objectives of the study were to compare the effectiveness of selection for yield, maturity, height, lodging, and phenotypic score among soybean [Glycine max (L.) Merr.] lines in hill and row plots and in random and nonrandom complete‐block designs. Progeny from 50 random S3 plants of Maturity Group II were grown in two‐row, unbordered plots with 69 cm between rows within the plot and 102 cm between plots and in single, unbordered hill plots spaced 102 ✕ 102 cm. A randomized complete block design was used for the row plots, and both randomized and nonrandomized complete‐block designs were used for the hill plots.

There was no difference in the effectiveness of selection for yield between random and nonrandom hills. The hill and row plots were equally effective in selecting the top two lines. Actual genetic gain was 2.5 q/ha for random hills, 2.8 q/ha for nonrandom hills, and 3.0 q/ha for row plots with a 10% selection intensity. Considering possible differences in the selection differential and number of years per cycle between hill and row plots, the predicted genetic gain per year was 0.6 q/ha for random hills compared with 0.4 q/ha for rows.

Selection for maturity, height, lodging, and phenotypic score was similar in effectiveness for the three plot arrangements. Genotypic correlations of line performance between random and nonrandom hills had coefficients of 0.99 to 1.02 for the four characters. The genotypic correlations between hills and rows ranged from 0.89 to 0.99. Hill plots were as effective as rows for phenotypic selection of agronomically desirable genotypes.

Evaluation of yield, maturity, height, lodging, or phenotypic score can be done effectively in single, unbordered hill plots. The primary advantages of hills are the reduction in number of years required for cultivar development or recurrent selection by eliminating the need for a generation of seed increase and the larger number of lines that can be tested. Nonrandom hill plots may be useful in cases where randomization prevents efficient discarding of inferior lines before harvest.
Use of Substitution‐Monosomics to Determine the Chromosomal Location of Genes Conditioning Stem Rust‐Resistance in Langdon Durum1
Authors: Salazar G. M. , Joppa L. R.
Published: July 2010

All of the available D‐genome substitution‐monosomics of ‘Langdon’ durum wheat (Triticum turgidum L.) were corssed with the stem rust susceptible cv. ‘Marruecos‐9623,’ and the chromosomal locations of some of the genes for stem rust (Puccinia gramminis f. sp. tritici Ericks and E. Henn) resistance in Langdon were determined. Substitution‐monosomics (13”+2’) and normal (14”) F1 plants were identified by microscope examination of pollen mother cells. Critical crosses were detected by differences between the segregation of F2 progenies from 13” + 2’ and 14” F1 plants. Landgon has one gene for resistance to culture Or9e on chromosome 7A, and three genes for resistance to culture 111‐SS2 located on chromosomes 2B, 3B, and 7A. The gene for resistance to culture Or9e on chromosome 7A is linked to one of the genes for resistance to 111‐SS2 with a recombination value of 8.5%. A gene for resistance to culture GB121 was located on chromosome 4A. The Landgon substitution‐monosomics were used for the first time in this study, and their usefulness for locating genes on chromosomes was demonstrated. They were more fertile, more vigorous, and had higher frequencies of substitution‐monosomics in their progenies than durum monosomics lacking a compensating homoeologous chromosome from the D‐genome.
Fruit Temperature, Growth Rates, and Yield of Peanuts1
Authors: Dreyer J. , Duncan W. G. , McCloud D. E.
Published: July 2010

This experiment was conducted to test our hypothesis that the number of fruits established per plant should be inversely proportional to the growth rates of the individual fruits. Peanuts (Arachis hypogaea L.) were chosen as the test plant because their peculiar growth habit enabled us to vary fruit growth rates in a field experiment by cooling or warming the small soil volume occupied by the growing fruits with minimal effects on foliage and root temperatures.

As predicted by the hypothesis, slower growth rates per fruit obtained by cooling the soil of the fruiting zone 4 C below the average ambient soil temperature of 27 C caused more fruits to be established. Warming the soil of the fruiting zone 3, 7, and 10 C above the ambient soil temperature had much less effect on fruit growth rates and consequently only the highest temperature caused a significant reduction in the number of fruits established. When harvest was delayed, as necessary to allow slower growing fruits to mature, average fruit weights were nearly the same for all except the warmest soil treatment. Thus the lower soil temperature resulted in a higher fruit yield because more fruits developed to nearly the same average weight but a longer filling period was required. The highest temperature produced the lowest yield because fewer and somewhat smaller fruits were produced.
Incorporation of Carbon‐14 into the Indigestible Fraction of Timothy Herbage1
Authors: Balasko J. A. , Knievel D. P. , Smith Dale
Published: July 2010

A better understanding of the nature of herbage‐quality deterioration of forages as they mature may aid in making crop management and crop improvement decisions. The purpose of this study was to follow the incorporation of carbon‐14 into the indigestible fraction of timothy (Phleum pratense L.) herbage at initiation of stem elongation, ear‐emergence, and anthesis. Plants grown in cans outdoors were exposed to 14C‐labeled CO2 and then harvested at intervals of 1, 3, 8, 32, and 168 hours following initial exposure at each growth stage. Herbage was divided into leaf blades, leaf sheaths, and stems at each sampling time. In vitro dry matter digestibility of each tissue fraction was determined, and the residue from each fraction was analyzed for 14C concentration. Rates of decrease in digestibility were greatest between ear‐emergence and ear‐emergence plus 168 hour growth stages for all tissue fractions. Proportions of whole tissue 14C remaining in the undigested residue of leaf sheaths and stems also were greater at ear‐emergence than at anthesis. Results suggest that rate of incorporation of 14C into indigestible fractions of timothy herbage is greater near ear‐emergence than near initiation of stem elongation or anthesis. Results also suggest that radioisotope studies can be effectively used to obtain a better understanding of plant tissue chronology, cell wall polysaccharide formation, and forage digestibility.
Selecting for Grain Protein and Yield in Sorghum Random‐Mating Populations1
Authors: Ross W. M. , Kofoid K. D. , Maranville J. W. , Voigt R. L.
Published: July 2010

Grain protein and grain yield relationships were studied in six sorghum [Sorghum bicolor (L.) Moench] populations tracing to the same base but developed with different objectives. Two cycles of selection for high and low grain protein in NP7BR were evaluated in Nebraska with 200 S1 progenies each that arose from intermating mass‐selected fertile plants. Means, variance components, heritabilities, genetic and environmental correlations, and expected correlated responses were determined. The same information was collected on 150 S1 progenies each from the related populations, NP7BR and NP9BR, selected for grain yield in Nebraska and for drought tolerance in Arizona, respectively.

Change from the first selection cycle to the second selection cycle was significant by mass selection for both high and low grain protein percentage in NP7BR. The 0.4% gains in either direction were about one‐half of those predicted, and protein and grain yield had strong negative genetic correlations (− 0.42 to − 0.65). Populations selected for grain yield produced more protein per ha (protein yield) than did populations selected for protein. In all populations, the expected correlated response of protein or of yield was negative when the other trait was selected. Protein percentage showed little correlated response with selection for protein yield except in NP7BR. Selection for protein yield would be expected to result in yield advances equal to selection for yield per se without drastic decreases in grain protein, but high environmental correlations between grain yield and protein yield would exist.
Preflowering Levels of Phytohormones in Sorghum II. Quantitation of Preflowering Internal Levels1
Authors: Dunlap J. R. , Morgan P. W.
Published: July 2010

Levels of free and bound indole‐3‐acetic acid (IAA), abscisic acid (ABA), and gibberellin‐like (GA‐like) compounds were determined over a 25‐day period prior to flowering in the above ground portions of an intermediate (60M) and a late (90M) maturing genetic line of Sorghum bicolor (L.) Moench.This was an initial effort to learn something about the hormone status of these lines on a whole shoot basis and there is no specific inference to the mechanism of photoperiodism. Following purification of the plant extract, IAA and ABA were analyzed with high performance liquid chromatography (HPLC); GA‐like substances were assayed with the lettuce hypocotyl elongation bioassay. The preflowering levels of GA‐like activity did not differ significantly between the two sorghum genotypes; however, the preflowering levels of both free IAA and ABA consistently increased with age in the later maturing genotype (90M). Increasing levels of free IAA and ABA relative to GA‐like activity may partially account for the delayed flowering characteristic of 90M. The differences in phytohormone levels in closely related genotypes differing in photoperiod requirement for floral initiation suggest the need for a detailed examination of the phytohormone status of the sorghum maturity genotypes relative to the mechanism of photoperiodism.
Preflowering Levels of Phytohormones in Sorghum III. Photocontrol1
Authors: Dunlap J. R. , Morgan P. W.
Published: July 2010

Indole‐3‐acetic acid (IAA), abscisic acid (ABA) gibberellins (GAs) were determined in two different maturity genotypes of Sorghum bicolor (L.) Moench as function of lighting conditions. Phytohormone levels were determined in bulked samples of preflowering shoot tissue from 28‐day‐old plants grown in a controlled environment and sampled during the day, night and after exposure to far red radiation (FR) (710‐730 nm). Levels of both IAA and ABA were highest in the later flowering genotype (90M) when sampled just prior to the beginning of darkness. The high tissue levels of both phytohormones in 90M declined during the night by 200 ng/g dry weight to levels near the lower limit of detectability. A similar trend was noted for levels of the same phytohormones in an earlier maturing genotype, 60M, but the magnitude of change was substantially less. In contrast to IAA and ABA, there was a net increase in the level of GA‐like activity during the night. Exposure of plants to 5 min of FR, a treatment known to accelerate flower initiation in sorghum (9, 19), had no effect on levels of IAA or ABA. The level of GA‐like compounds, particularly GA3‐like activity, increased in both sorghum genotypes after treatment with FR. The decline in IAA and ABA levels during the night in both genotypes as well as the increase in GA‐like activity, especially in the relatively early genotypes (60M), produce an apparent shift in hormone balance which may favor floral initiation.
Tissue Culture Initiation and Plant Regeneration in Hexaploid Species of Oats1
Authors: Rines H. W. , McCoy T. J.
Published: July 2010

Tissue cultures were initiated and plants regenerated from three hexaploid oat species ‐ the cultivated oat, Avena sativa L., and two wild oats, A. sterilis L. and A. fatua L. This is the first known description of plant regeneration from tissue cultures in the latter two species. Various types of tissue cultures were initiated from immature embryos with ‘regenerable‐type’ cultures being characterized by organized chlorophyllous primordia present in compact, yellowish‐white, highly‐lobed callus. Embryo size, species, genotype, conditions in which donor plants were grown, and 2,4‐D concentrations in the culture initiation medium all influenced the frequency with which regenerable‐type cultures were produced. Among 23 A. sativa cultivars tested, ‘Lodi’ and 2 Lodirelated lines consistently gave the highest frequencies of regenerable‐type cultures. This frequency was as high as 80% for Lodi in 1 test. Of 16 A. sterilis lines tested, only three produced regenerable‐type cultures, and these all were at a frequency of less that 20%. Seven of 32 A. fatua lines tested produced regenerabletype cultures at frequencies greater than 45%. In all 3 species there were tissue cultures capable of plant regeneration after more than 12 months in culture (9 to 10 subcultures). Since genotype influences culture initiation frequency and culture type, screening of genotypes and selection among segregating populations should be a fruitful approach in the improvement of cell culture capabilities in oats.
Release od Soluble Protein and Nitrogen in Alfalfa. III. Influence of Shading1
Authors: Walgenbach R. P. , Marten G. C.
Published: July 2010

Changes in leaf anatomy, morphology, and chemical composition due to different amounts of solar radiation could affect the apparent bloat potential of alfalfa (Medicago sativa L.) mediated via release of soluble protein into rumen fluid in the presence of ample available carbohydrates. Our objectives were to determine whether shading during growth would influence production characteristics as well as concentration of several N fractions and total nonstructural carbohydrates (TNC) released from alfalfa.

Alfalfa was shaded with saran shades [0 (control), 47, and 73% shade] from 12 May to 1 June [Period (P)l], 30 June to 7 July (P2), and 9 to 16 August 1978 (P3). Total nitrogen (TN), total soluble N (TSN), soluble nonprotein N (SNPN), soluble protein N (SPN), total nonstructural carbohydrates (TNC) were determined.

The 73% shade reduced yields 42% for P1, 30% for P2, and 24% for P3, while the 47% shade reduced yields 29% for P1, 22% for P2, and 10% for P3 compared to the respective control yields. In P1 (20 days of shade), concentration of SNPN in herbage was 10.1 mg/g dry wt for control, 10.5 mg for 47% shade, and 11.5 mg for 73% shade, while that of SPN was 14.8 mg for control, 13.8 mg for 47% shade, and 12.6 mg for 73% shade.

In P2 (7 days of shade), concentrations of TN, TSN, and SNPN in herbage increased as shade increased. Shade did not significantly influence the herbage concentrations of SPN in P2. In P3 (7 days of shade), shade did not significantly affect herbage concentrations of any of the N fractions. Shade of 73% reduced the TNC concentrations in herbage 16% for P1, 44% for P2, and 19% for P3, while shade of 47% recuded TNC 8% for P1, 28% for P2, and 10% for P3, compared to that in control herbage.

Reduced apparent bloat potential of alfalfa, as estimated by SPN release, occurred only in plants grown under low solar radiation for a continuous 20‐day period. However, both short and long periods of decreased solar radiation caused decreased TNC concentrations in herbage. Because an abundant supply of TNCis essential for the microbial activity that leads to gas production in the rumen, even relatively short periods of shade could be considered as potentially bloat suppressing. We conclude that the usual incidence of cloudy weather is not likely to be a major mediator of bloat incidence in ruminants that graze alfalfa, although periods of high solar radiation maybe considered bloat‐promoting rather than bloatsuppressing.
Selection for Winterhardiness in Wheat. III. Screening Methods
Authors: Fowler D. B. , Gusta L. V. , Tyler N. J.
Published: July 2010

Thirty‐four biochemical, physiological, and morphological characters of winter wheat (Triticum aestivum L.) were evaluated to determine their usefulness in winter survival prediction tests. Differences among cold acclimated plants from genotypes with a range of cold hardiness potential were significant for most of the characters evaluated. Close linear associations were found among many of these characters indicating that there are a number of possible screens which could be utilized as a supplement to field survival trials. However, at best, they are very coarse screens and, for differences of practical concern, size of experimental errors become a major limitation to their usefulness in selecting for field survival potential. Estimates of field survival (FSI) and LT50 had the smallest relative experimental errors and the highest heritability values. Crown LT50 estimates also gave the highest correlation with FSI. However, because LT50 is a destructive test which requires a large number of plants, it is limited to nonsegregating populations, Tissue water content and LT50 explained similar variability in FSI. Because tissue water content was not measured with as great a precision as LT50, it would appear to be less useful as a screen. However, when combined with a measure of plant erectness, tissue water content provided nearly as much information on FSI as did LT50. Both leaf water content and plant erectness can be measured without sacrificing entire plants and therefore they should be helpful winter hardiness screens for use by plant breeders.