bluuebunny/crossref_metadata_2025 huggingface dataset:
Preplant Tillage Effects on Population Dynamics of Soybean Insect Predators
Authors: Funderburk J. E. , Wright D. L. , Teare I. D.
Published: July 2010

Tillage operations modify soil habitats where many pests and their natural enemies reside at least during part of their life cycle. Bigeyed bugs (Geocoris spp.) and damsel bugs (Nabis and Reduviolus spp.) are common beneficial polyphagous insect predators in many crops. The objective of this research was to measure effects of tillage on population cycles and population size of those predators to aid in development of cultural IPM (integrated pest management) strategies for biological control of insect pests in soybean [Glycine max (L.) Merr.] double cropped with wheat (Triticum aestivum L). The four tillage regimes used were no tillage and disk tillage with and without in‐row subsoiling. Bigeyed bug nymphal and adult population cycles were similar for each tillage/subsoiling treatment. There were differences between years because in 1986 there was considerable overlap of generations, which was not observed in 1985. Disk tillage treatments had higher bigeyed bug nymphal and adult populations than the no tillage treatments in 1985 and 1986, but subsoiling did not influence population size. Damsel bug population cycles were also similar for all tillage/subsoiling treatments in both years. In 1985, populations of adult and nymphal damsel bugs were lower for no tillage without subsoiling than for disk tillage without subsoiling, disk tillage with subsoiling, or no tillage with subsoiling. Population sizes were similar for all treatments in 1986.
Screening Subterranean Clover for Persistent Hard Seed
Authors: Smith G. R.
Published: July 2010

Maintenance of hard seed through the summer is essential for reseeding of cool‐season annual clovers. ‘Mt. Barker’, Mississippi Ecotype, and 17 experimental lines of subterranean clover (Trifolium subterraneum L.) were evaluated for hard seed production and persistence over 3 yr. Initial hard seed level was measured 10 d after harvest. Persistence of hard seed was evaluated 50, 90, and 130 d after harvest under two storage treatments. The check (CK) treatment consisted of placing seed in a laboratory cabinet with temperature range of 23 to 26 °C. In the high diurnal fluctuating temperature (HDFT) treatment, seeds were placed in an incubator at 38 for 12 h, followed by a 12 h cool down to 24 °C. The HDFT treatment simulated summer soil surface temperatures. Line ✕ yr interactions had large effects on initial hard seed percentage. In 1984 and 1985, most lines produced more than 60% hard seed. In 1986, possibly due to high rainfall during seed maturation, many lines showed a sharp decrease in initial hard seed level. Persistence of subterranean clover seed stored under simulated summer soil surface temperatures (HDFT) was influenced by both production year and plant genotype. Seed production environment set the upper limit for hard seed level, but genotype determined rate of seed softening. Heritability of hard seed percentage measured 90 d after harvest under the HDFT treatment was 80.7%.
Soybean Cultivar Identification Using High Performance Liquid Chromatography of Chromatography of Seed Proteins
Authors: Buehler R. E. , McDonald M. B. , Van Toai T. T. , St. Martin S. K.
Published: July 2010

A substantial increase in the number of soybean [Glycine max (L.) Merr.J cultivars has occurred in recent years. Many of these are derived from a narrow genetic base, which makes traditional cultivar identification increasingly difficult. As a result, new techniques that detect minor biochemical differences need to be evaluated for their ability to differentiate among cultivars. This study examines the applicability of reversed phase high performance liquid chromatography (RP‐HPLC) for soybean cultivar identification. Salt soluble proteins of 14 cultivars were extracted from unimbibed seeds, eluted from a reversed phase C4 column with increasing concentrations of acetonitrile, and monitored at 280 nm. Seeds were obtained for study from three differing growing locations in Ohio. While no qualitative differences of elution profiles were detected within cultivars and locations, comparisons of quantitative RP‐HPLC seed protein profiles permitted separation of genetically diverse genotypes. Retention time ratios for selected peaks were not significantly different among cultivars, but peak area percentage showed that quantitative differences were useful criteria for distinguishing closely related lines. This study documents that RP‐HPLC analysis of soybean seed proteins can distinguish divergent soybean genotypes and suggests that peak area percentage of RP‐HPLC profiles is a superior method of cultivar analysis.
Restricted Index Selection for Total Alkaloids and Yield in Tobacco
Authors: Matzinger D. F. , Wernsman E. A. , Weeks W. W.
Published: July 2010

A negative genetic correlation between yield and total alkaloids (TA) in tobacco, Nicotiana tabacum L., populations causes decreases in yield when selecting for increased TA. A restricted selection index was employed in an ‘NC13’ ✕ ‘McNair 135’ population to increase TA and hold yield at the mean of the population. The genetic correlation in the base population was −0.67. After three cycles of full‐sib family selection, TA had increased 2.5% of the mean per cycle and there had been no significant change in yield. The increase in TA was about 58% of that expected from direct selection for increased TA, where there would be an expected decrease in yield of 1.9% per cycle. Selection for increased TA also led to a correlated decrease in the ratio of particulate matter in smoke to TA in spite of a positive genetic correlation between particulate matter and TA.
Crossability of Pearl Millet with Wild Pennisetum Species
Authors: Dujardin Michel , Hanna Wayne W.
Published: July 2010

Wild relatives of cultivated species have genes that potentially could be used to improve crop cultivars. The objective of this research was to study the crossability of eight wild Pennisetum species with diploid and tetraploid pearl millet, P. glaucum (L.) R. Br. Twenty and 28 interspecific hybrids, respectively, were produced between diploid (2n = 14) pearl millet and P. orientate L. C. Rich. (2n = 36), and P. setaceum (Forssk.) Chiov. (2n = 27). Only three hybrids were produced between tetraploid (2n = 28) pearl millet and P. orientate. Three hundred thirty‐seven interspecific hybrids were produced when tetraploid pearl millet was pollinated with P. squamulatum Fresen., but no hybrids were produced when diploid pearl millet was used as the female parent. No interspecific hybrids were produced between diploid or tetraploid pearl millet crossed with P. ramosum (Hoschst.) Schweinf. (2n = 10), P. mevanum Leeke (2n = 32), P. macrourum Trin. (2n = 36), P. pedicellatum Trin. (2n = 54), and P. polystachion (L.) Schult. (2n = 54). Fertility of pearl millet ✕ P. squamulatum hybrids indicated partial homology between the pearl millet A genome and one or more genomes of P. squamulatum.
Agronomic and Botanical Components Associated with Seed Productivity of Kentucky Bluegrass
Authors: Ensign R. D. , Everson D. O. , Dickinson K. K. , Woollen R. L.
Published: July 2010

Kentucky bluegrass (Poa pratensis L.) is a genetically complex perennial plant and evaluation of early generation breeding material for potential seed productivity is difficult. Twenty eight agronomic and botanical components were studied for their association with seed productivity during a 6‐yr field experiment grown near Moscow, ID. The soil was a Latahco silt loam (fine silty mixed, frigid argiaquic Xeric Argialbollo). Using 15 diverse cultivars or experimental strains, our research indicated that several components of the bluegrass plant were important indicators of seed productivity. Seed weight/panicle and seeds/panicle were most highly correlated (r = 0.68 and 0.67) with seed yields. Components indicating early stages of maturity, vigor at anthesis, leaf blade length, panicle length, spikelets/panicle, number of panicles/plant, and harvest date were also highly correlated (r > 0.54) with seed yields. The magnitude of some correlations varied among years indicating environment‐specific associations. Path analysis for each of the 3 yr showed that full heading date, number of panicles, and seed weight/panicle accounted for 65% of the variation in a high seed‐yielding year. However, for drought stressed years, the model accounted for approximately 90% of the variation in seed yield.
Nitrate Inhibition of Root‐Nodule Symbiosis in Doubly Rooted Soybean Plants
Authors: Eaglesham Allan R. J.
Published: July 2010

Split‐root experiments have demonstrated that NO−3 inhibits nodule formation on legumes primarily as a root‐localized effect rather than as a function of whole‐plant N nutrition. The degree to which the root‐localized effect is coupled with the N status of the shoot is not well understood. To investigate this, doubly rooted soybean [Glycine max (L.) Merr.] plants were produced by layering stems in adjacent pots to induce the formation of adventitious roots; thus, the effects of N added to the entire original root could be examined in terms of nodulation on both the original and the adventitious roots. When NO−3 level was sufficiently high to completely suppress nodulation on the original root, there was profuse nodulation and significant nitrogenase (C2H2 reduction) activity on the adventitious root. This indicated that even when mineral N supply to the root was abundant there was an N deficit in the shoot. The apparent poor coupling of N status of the root with that of the shoot was confirmed when doubly rooted plants accumulated more N than did singly rooted plants. Stem nodules of sesbania (Sesbania rostrata Brem. & Oberm.) are analogous to adventitious root nodules of doubly rooted soybean in that they form on root primordia not in contact with added N; the adverse effects of applied NO−3 on nodule development and function were more pronounced on sesbania stems than on soybean adventitious roots. Therefore, the coupling of root‐N status with shoot‐N status may be particularly loose in soybean with potentially important implications for growth in N‐rich soils.
Fungicide and Nitrogen Effects on Winter Wheat under Low Foliar Disease Severity
Authors: Cox W. J. , Bergstrom G. C. , Reid W. S. , Sorrells M. E. , Otis D. J.
Published: July 2010

Fungicide utilization is expected to increase on winter wheat (Triticum aestivum L.) in response to registration of fungicides that control powdery mildew (Erysiphe graminis DC) and Septoria nodorum blotch [Phaeosphaeria nodorum (Müller)]. Field experiments were conducted in New York in 1985 and 1986 on a Honeoye silt loam (fine‐loamy, mixed, mesic Glossoboric Hapludalf) to examine the influence of N [67 kg ha−1 at Zadoks Growth Stage (GS) 25, and split‐application of 67 + 67 kg ha−1 at GS 25 and GS 31], and timing of fungicide application (0.28 and 1.8 kg ha−1 a.i. of triadimefon [1‐(4‐cholorphenoxy)‐3,3‐dimethyl‐1‐(1H‐1,2,4‐triazol‐1‐yl(‐2‐butanone] and mancozeb [zinc ion and manganese ethylene bisdithiocarbamate], respectively, at GS 31 or GS 55) on disease severity, CO2 exchange rate (CER) of the flag leaf, yield components, and grain yield. Moderately dry and warm conditions resulted in low foliar disease severity from GS 31 to GS 55, thereby providing limited secondary inoculum to infect the flag leaf (<8% disease severity at GS 75) during excessively wet grain‐filling periods. Fungicides did not influence flag leaf CER and kernel weight, which was reflected in the limited grain yield responses to fungicide applications at GS 31 and GS 55 compared to no fungicide treatment (5.90, 6.07, and 5.81 Mg ha−1, respectively). The split‐N application increased grain yield compared to the single N treatment (5.58 to 6.27 Mg ha−1), especially in 1985 (5.47 to 6.40 Mg ha−1) when kernels per spike were increased (26.5 to 30.2). The data suggest that high rates of N, split‐applied, have potential to increase yield of winter wheat and foliar disease severity in the northeastern USA. Fungicides, however, should not be applied as a preventive measure for mildew and leaf spot control if severity is low from GS 31 to GS 60.
Inheritance and Expression of Genes for Kanamycin and Chloramphenicol Resistance in Transgenic Cotton Plants
Authors: Umbeck Paul , Swain Will , Yang Ning‐Sun
Published: July 2010

To fully evaluate and characterize the stability of traits transferred via Agrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic cotton (Gossypium hirsutum L.) plants (no. 1397, no. 1427, and no. 1438) for inheritance and expression of their foreign genes. Following regeneration from tissue cultures transformed using A. tumefaciens, primary regenerated plants were tested for expression of T‐DNA marker genes encoding the proteins neomycin phosphotransferase II (NPT‐II) and chloramphenicol acetyltransferase (CAT). To test for transmission of marker traits flowers were either self‐pollinated or crossed to the cotton cultivar Coker 312. Selfed progeny and backcrosses were germinated in vitro and selected on medium containing 50 mg L−1 kanamycin. At the three‐leaf stage of development, enzymatic activity of NPT‐II and CAT was measured on seedlings capable of germination and survival in the presence of kanamycin. Progeny derived from selfed and backcrossed pollinations of plants no. 1397 and no. 1427 both segregated 3:1 and 1:1, respectively, as expected for a single gene trait. No CAT activity was detected in these plants or their progeny. Southern blot analysis of regenerated plants, selfed progeny and backcrosses of no. 1397 and no. 1427 confirmed the inheritance of only the NPT‐II coding sequence portion of the T‐DNA. In plant no. 1438 and its backcross progeny, enzyme expression of both NPT‐II and CAT was detected. Segregation analysis of no. 1438 backcross progeny showed a 1:1 pattern of inheritance. Southern blot analysis of no. 1438 and its progeny showed that the entire T‐DNA coding region was present. Despite the presence and function of the CAT gene in backcross progeny of no. 1438 these plants did not display chloramphenicol resistance. Germination of seeds obtained from no. 1397, no. 1427, and no. 1438 on kanamycin‐containing (50 mg L−1) medium efficiently selected for transgenic seedlings expressing kanamycin resistance. Our data support the conclusion that the single gene insertion of foreign traits in cotton is inherited and expressed in a Mendelian fashion.
Shoot Regeneration of Callus Derived from Globular to Torpedo Embryos from 59 Sunflower Genotypes
Authors: Espinasse Anne , Lay Charles
Published: July 2010

Response of sunflower (Helianthus annuus L.) to in vitro culture has been shown to depend on medium, genotype and explant tissue. The objective of the present study was to evaluate the potential for shoot organogenesis from callus, of globular‐ to torpedo‐stage embryos (0.2–1.2 mm long), of 59 sunflower genotypes. Embryos were cultured on four modified Murashige and Skoog media (MS) varying in concentrations of NAA (naphthalene acetic acid) and BA (6‐benzylaminopurine). The MSO contained 1 mg/L NAA and 0.1 mg/L BA; MSI contained 2 mg/L NAA and 1 mg/L BA; MS2 contained 0.5 mg/L each NAA and BA; and MS3 contained 0.1 mg/L NAA and 1 mg/L BA. Frequency of embryo‐derived callus forming shoots was used to measure potential for plant regeneration. Five genotypes produced no callus or shoots from callus on any media, and both callus and shoot formation occurred on 5% or less of the plated embryos of eight genotypes. Three genotypes showed 80% or more callus formation with little or no shoot organogenesis; whereas, for four genotypes, more than 70% of the plated embryos developed shoots from callus on one or more media. One‐half of the genotypes showed 20% or more shoot‐forming callus. Effect of the medium varied in importance. All media were equivalent for callus formation, but MS3 had the most genotypes with a high frequency of shoot formation from callus. MS2 was second in promoting shoot organogenesis from callus. Because of a strong genotype ✕ medium interaction, the use of two MS media with different hormonal compositions is recommended to increase the frequency of sunflower genotypes regenerating shoots from callus derived from globular‐ to torpedo‐shaped embryos.
Osmotic Adjustment and Growth of Barley Genotypes under Drought Stress
Authors: Blum A.
Published: July 2010

Osmotic adjustment is receiving increasing attention as a probable component of drought resistance in crop plants, including barley (Hordeum vulgare L.). This work was done to study a possible association between osmotic adjustment and growth under drought stress. Twenty‐six diverse barley genotypes were grown in nutrient solutions in the growth chamber. Drought stress was imposed by adding polyethylene glycol 6000 to the nutrient solution producing a −0.54 MPa solution water potential as compared with controls of pure nutrient solution with a −0.02 MPa of solution potential. Percent growth reduction by drought stress was calculated from growth rates measured under stress and in the controls. Osmotic adjustment was calculated as the difference in osmotic potential at full turgor between stress and controls. Leaf water potentials of genotypes grown under drought stress ranged from −1.37 to −1.51 MPa, but did not differ significantly. For the same leaf water potential, genotypes differed significantly in osmotic adjustment which ranged from −0.17 to 0.46 MPa. Growth reduction by drought stress differed significantly among genotypes with a range of 78.1%. Growth reduction by drought stress was negatively associated with osmotic adjustment across genotypes (r = −0.80). The association was nonlinear, indicating that growth reduction decreased only as osmotic adjustment increased to about 0.2 MPa or more. These results suggest that induced osmotic adjustment under drought stress may be an important component of drought resistance in barley growth, and it should be evaluated when all genotypes are subjected to the same leaf water status.
Selection for Canopy Temperature Differential in Six Populations of Soybean
Authors: McKinney N. V. , Schapaugh W. T. , Kanemasu E. T.
Published: July 2010

Canopy temperature represents a quantitative measurement of a plant's response to heat and drought stress. Information is needed concerning the genetic variability for canopy temperature (Tc) in segregating populations if plant breeders are to effectively manipulate Tc. This study was conducted to characterize genetic variation for canopy temperature in six populations of soybean [Glycine max (L.) Merr.] and to assess the effectiveness of selection within the populations for canopy temperature. Parent plants, F1, and F2 individuals were space planted and a hand‐held infrared thermometer was used to monitor plants for Tc on 3 d during late vegetative and early reproductive growth in 1982. Advanced F3 and F3:4 lines from each population were monitored in unreplicated progeny rows for Tc following canopy closure in 1983 and the four warmest (HOT) and four coolest (COOL) F3:4 lines were selected for further study. Selected lines in the F3:6 generation were replicated in 1984 and monitored for Tc. Heritability estimates for seasonal mean canopy temperature differential ( = canopy temperature — air temperature) based on parent‐progeny regression ranged from 1 to 22% for F2 and F3 parent‐progeny regression; and 0 to 19% for F3:4 and F3:6 parent‐progeny regression. Rank correlations of F3:4 vs. F3:6 lines for were significant in three of the six populations. The mean of the HOT vs. COOL selections measured in 1984 were significantly different in three populations, indicating effective F3:4 selection. Early generation selection for was not successful in soybean due to low heritability. Manipulation of in unreplicated F4 progeny rows was effective in one‐half of the populations monitored, however, greater consistency and reliability would have to be achieved before a positive recommendation could be given to use this technology in soybean breeding.
Verification of Infection‐Type Data for Identification of Genes for Resistance to Leaf Rust in Some Hard Red Spring Wheat
Authors: McVey D. V.
Published: July 2010

Infection‐type data have been used to postulate the genes present in wheat (Triticum aestivum L.) cultivars conditioning resistance to wheat leaf rust (Puccinia recondita Rob ex Desm. f. sp. tritici). Conventional genetic studies confirmed the accuracy of the hypothetical resistance genotypes derived from infection‐type data. The objectives of this study were to: (i) postulate the genes for resistance to leaf rust in 10 hard red spring wheat and, (ii) confirm their postulated resistance genotypes by crossing them with appropriate leaf rust (LR) near‐isogenic line(s). Both phases of the study were based on leaf rust reactions of wheat seedlings in the greenhouse. Postulated resistance genotypes confirmed by the genetic study were: ‘Glenlea’ contained Lrl; ‘Era’ contained LrlO; ‘Alex’, ‘James‘, and ‘Waldron‘ contained Lr2a and LrlO; ‘Guard’ and ‘Marshall’ contained Lr2a; and MN7529 contained LrlO and Lrl6. In addition, it was postulated that Guard, ‘Len’, and Marshall also contained LrlO and that MN7529 contained Lrl based on the infection‐type data. The accuracy of postulated resistance genotypes indicates that infection‐type data can be used with confidence in selecting parents for making crosses to develop new genetic combinations for resistance.
Five Cycles of Replicated S1 vs. Reciprocal Full‐Sib Index Selection in Maize
Authors: Odhiambo M. O. , Compton W. A.
Published: July 2010

Five cycles of S1 per se (S1) and reciprocal full‐sib (RFS) selection were compared for the improvement of three maize (zea mays L.) populations and two population crosses. The replicated structure of the selection experiments allowed direct comparisons of selection methods together with measures of genetic drift. The selection criterion used was a multiplicative index involving yield, moisture, upright plants, and undropped ears and therefore the experiment measures the value of this type of index in selection studies. Populations and population crosses evaluated were Nebraska B. Synthetic (NBS), Nebraska Stiff Stalk Synthetic (NSS), Nebraska Krug open pollinated variety (NKS), NBS ✕ NSS, and NBS ✕ NKS. Improvement was measured in random mated, bulked inbred (S1) populations, and the population crosses. Both selection procedures were performed in three replicates. The entries for the evaluation study were derived from Cycle 0 and recombined replicate populations from Cycles 3 and 5. The evaluation trials were grown in 1985 and 1986 at Lincoln, NE. The S1 selection increased index values in the bulked inbred populations by 5.8% per cycle when averaged over populations. The RFS selection increased index values of inbred populations by 3.4% per cycle. Both methods were equally effective in improving index values of the random mated populations with average responses of 2.0% for S1 and 1.8% for RFS selection per cycle. The average index response in the population crosses was 3.6 and 2.9% per cycle for RFS and S1 selection, respectively. Genetic drift was observed to cause significant differences among the replicate populations for index and its components.
Genotype‐by‐Environment Interaction in Grain Sorghum. II. Effects of Temperature and Photoperiod on Ontogeny
Authors: Hammer G. L. , Vanderlip R. L. , Gibson G. , Wade L. J. , Henzell R. G. , Younger D. R. , Warren J. , Dale A. B.
Published: July 2010

In sorghum [Sorghum bicolor (L.) Moench], genotype‐by‐environment interaction effects on ontogeny can be caused by differing responses to temperature and photoperiod. We conducted glasshouse and field experiments to develop predictive models of ontogeny for old and new sorghum genotypes. New genotypes are considered better adapted to more tropical environments. In the glasshouse studies, 10 genotypes were grown at two temperatures (20 and 25 °C) and six planting dates (photoperiod 10 to 15 h). At photoperiods greater than about 13 h, duration of emergence to floral initiation (GS1) was lengthened about 5 d for all genotypes at both temperatures. Genotypes differed in duration of GS1 by up to 10 d at both temperatures. Hybrids responded like their earlier parent, indicating earliness to show some form of dominance. Photoperiod had little or no effect on duration of floral initiation to anthesis (GS2), and hybrids differed by about 3 d. Field experiments with 12 hybrids were conducted at sites in Australia and USA covering latitudes from 16 to 39 °C. Durations of GS1 and GS2 ranged from 17 to 128 d and 24 to 85 d, respectively. Daily rate of development was modeled using functions of air temperature and photoperiod. Development rate of all hybrids exhibited a curvilinear response to temperature in both phases. Old and new hybrids differed in their temperature responses in GS1 but were similar in GS2. New hybrids had slower rates of development at all temperatures, but the difference was greater at higher temperatures (>25 °C). All hybrids had similar short‐day photoperiodic response in GS1, with a critical photoperiod 13.2 h. The models were tested on a separate data set covering a similar broad range of environments and performed well.
Alfalfa Autotoxic Fraction Characterization and Initial Separation
Authors: Hall M. H. , Henderlong P. R.
Published: July 2010

Alfalfa (Medicago sativa L.) has been reported as having autotoxic or autoallelopathic characteristics, but the plant fraction containing the autotoxic material and the responsible compound have not been isolated or identified. Greenhonse and laboratory studies were conducted to: (i) determine if ‘Vangard’ alfalfa exhibits autotoxicity, (ii) determine which plant fraction contains the autotoxic material, and (iii) separate the autotoxic fraction using paper chromatography procedures. In greenhouse studies, alfalfa plant material reduced alfalfa emergence by an average of 87 and 62% in a Kokomo silty loam soil (fine, mixed mesic, Typic Argiaquoll) previously cropped with alfalfa and corn (Zea mays L.), respectively. Incubating the soil and plant material under two contrasting moisture regimes did not alter the inhibitory activity. However, autoclaving the soil and plant material negated the autotoxic response. Laboratory studies indicate that the autotoxic compound was contained within the water‐extractable alfalfa fraction, and was not the direct result of microbial activity, although microbial activity may increase the dissipation of the compound. Ascending paper chromatographic separation indicated that the autotoxic compound had an Rf characterization similar to phenolic acid; however, phenolic‐absorbent polyvinylpolypryrrolidone did not affect the autotoxic response. The results indicate that alfalfa contains a water‐soluble autotoxic compound that has characteristics indicative of a phenolic compound.
Somatic Embryo Ontogeny in Suspension Cultures of Orchardgrass
Authors: Conger B. V. , Hovanesian J. C. , Trigiano R. N. , Gray D. J.
Published: July 2010

Orchardgrass (Dactylis glomerata L.) is the only known grass or cereal species in which somatic embryos fully develop to a germinable stage directly in a single liquid medium. The objectives of the present investigation were to document and detail the developmental pattern of these embryos and to compare their size and structure to zygotic counterparts. Suspension cultures were initiated and mainrained in Schenk and Hildebrandt medium containing 30 μM dicamba (3,6‐dichloro‐o‐anisic acid) and 3 g L−1 casein hydrolysate. The suspension was passed through a 120‐μm sieve resulting in a culture composed of single cells and small cell masses. Somatic embryos that were identical in structure and size to zygotic embryos occurring in mature caryopses developed from these cells directly in the liquid maintenance medium. The developmental pattern was indirect embryogenesis. Embryos differentiated and were released from clumps of embryogenic cells (proembryonal complexes). This pattern is analogous to that in suspension cultures of certain dicotyledonous species, e.g., carrot (Daucus carota L.). Fully developed embryos were germinated and resulting seedlings grown to mature plants.
Extrusion of Protoplasm and Protein Bodies through Pores in Cell Walls of Pea, Bean, and Faha Bean Cotyledons during Imbibition
Authors: Spaeth Stephen C.
Published: July 2010

Several processes contribute to leakage of intracellular substances from legume seeds during imbibition. This study was conducted to determine whether protoplasm and protein bodies also leak from cotyledonary cells by a process analogous to pressure‐driven extrusion from multicellular blisters. The effects of soaking, and air‐drying or fixing excised cotyledons and intact seeds of field‐grown bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), and faba bean (Vicia faba L.) were investigated using scanning electron microscopy. When dissolution and dispersion of intracellular substances were minimized by removing cotyledons from water, cells of excised ‘OSU 605’ pea cotyledons provided direct evidence for cellular pressure‐driven extrusion. Streams of intracellular substances from OSU 605 ranged from 0.2 to 1 μm in diameter. Similar extrusion streams were not found in situ on cotyledons of other genera, cultivars, or treatments; however, projections from protoplast surfaces, pores through cell walls, and orifices and protein bodies in intercellular spaces were consistent with cellular extrusion. The path for cellular extrusion probably was pores through contact cell walls (regions of cell wall in contact with adjacent cells), and then channels along the middle lamella to orifices at intercellular spaces or cotyledonary surfaces.
Oligosaccharide Metabolism and Accumulation in Developing Soybean Seeds
Authors: Lowell Cadance A. , Kuo Tsung Min
Published: July 2010

Soluble sugar composition of developing soybean seed (Glycine max L. Merr.) vary with cultivar. This study was conducted to determine the relation between soluble sugar accumulation and associated enzyme activities in developing seed of two soybean cultivars, Williams 82 and Wolverine. Activities of sucrose synthase, invertase, galactinol synthase, and α‐galactosidase were compared to soluble sugar content (hexoses, galactinol, myo‐inositol, oligosaccharides) at seven different reproductive growth stages. A twofold higher dry matter content in mature seeds of Wolverine corresponded to a larger seed size and longer linear seed fill. Increases in sucrose synthase and alkaline invertase activities in both cultivars corresponded to accumulation of 90% total dry matter. Acid invertase activity remained below 45 nmol glucose seed−1 min−1 during seed development. Initial raffinose and stachyose formation occurred at beginning maturity in Williams 82 and full seed in Wolverine. This change in sugar partitioning during late seed development was accompanied by twofold and threefold increases in galactinol synthase activity and galactinol content, respectively, and a substantial decrease in the substrate for this enzyme, myo‐inositol. Highest levels of galactinol synthase activity at the end of linear seed fill in both cultivars, however, preceded the accumulation of the highest stachyose levels by two growth stages. Activity of α‐galactosidase increased linearly in both varieties with time. Relatively high activities of sucrose synthase and alkaline invertase during the accumulation of the majority of dry matter in both cultivars suggest that these enzymes may be associated with this process in soybean seeds. Regulation of raffinose oligosaccharide accumulation in developing soybean seeds also may depend on galactosyl transferase activity.
Drought Stress Effects During Seed Fill on Soybean Seed Germination and Vigor
Authors: Dornbos D. L. , Mullen R. E. , Shibles R. E.
Published: July 2010

Environmental stress exerts a substantial effect on leaflet productivity and yield, but its effect on germination and vigor is poorly understood. The objective of this study was to relate drought stress intensity during soybean [Glycine max (L.) Merr.) seed fill to reductions in seed yield, mass, germination, and vigor. Drought was imposed on pot‐grown plants (cv. Gnome) in the greenhouse by applying differing volumes of water during seed fill. Stress intensity was measured by summing stress degree days (SDD), the daily difference between the leaf and air temperature, measured using an infrared and shielded thermometer, respectively. As SDD values increased from 46.2 to 141.2, leaf resistance increased 68%, transpiration decreased 44%, and apparent photosynthesis decreased 71%, verifying that severe drought had been imposed. Seed yield was linearly reduced 38 and 58% by drought in 1985 and 1986, primarily because few seeds were produced. Seed germination and vigor decreased as SDD increased. The effect of drought on germination and vigor was substantially less than that on yield and was inconsistent across years. Drought reduced standard germination percentage and seedling axis dry weight 5 and 12%, respectively and increased single‐seed conductivity 19%. Seed quality loss was correlated with reduced single‐seed mass. Severe drought that occurred throughout seed fill reduced yield and seed number at a faster rate than seed mass, germination, or vigor, and maintained the development of at least some viable and vigorous seeds.
Potential for Increasing Cotton Yields Through Enhanced Partitioning to Reproductive Structures
Authors: Meredith William R. , Wells Randy
Published: July 2010

Yield increases in cotton (Gossypium hirsutum L.) have been primarily through changes in partitioning dry matter from vegetative to reproductive structures. The objective of this study was to determine if yield increases would likely continue through continued changes in dry matter partitioning. Five obsolete cultivars, five popular and high yielding cultivars from five cotton breeding organizations, and 15 advanced strains from five cotton breeding organizations were used for yield and growth analyses at three environments, two in 1985 and one in 1986. Obsolete cultivars averaged 24% less lint than the 20 more modern genotypes and showed greater investment of dry matter into vegetative rather than reproductive structures. There was no major difference in mean yield or growth characteristics detected between the five currently used cultivars and the 15 strains. However, these 20 genotypes showed significant (P < 0.05) genetic variability for yield and most growth characteristics. Plant height and stem wt. to total dry wt. ratio showed strong negative genetic correlations with yield (r = −0.44 to −0.80). Strong positive genetic associations with yield were found for boll wt. to total dry wt. ratio (r = 0.86) and the late sampling of reproductive‐vegetative ratio (r = 0.91). This study suggests that yield increases through the use of conventional breeding methods are likely to be achieved through continued partitioning of dry matter from vegetative to reproductive structures.
Inheritance of Palmitic and Stearic Acid Mutants of Soybean
Authors: Bubeck D. M. , Fehr W. R. , Hammond E. G.
Published: July 2010

Soybean [Glycine max (L.) Merr.] cultivars with increased levels of palmitic or stearic acid in the seed oil could reduce the need for chemical modifications during processing for some vegetable oil products. Mutants with altered levels of the fatty acids were developed by artificial mutagenesis with ethyl methane sulfonate (EMS). Four of the mutants had 128 to 182 g kg−1 palmitic acid compared with 90 to 100 g kg−1 in their parents, and four mutants had 132 to 301 g kg−1 stearic acid compared with 33 to 51 g kg−1 in their parents. The objective of this study was to determine the inheritance of palmitic or stearic acid in the seed oil of the eight mutants. Reciprocal crosses were made between each mutant and the cultivar Coles, among three of the palmitic mutants, and between the high‐stearic acid line A6 and the four stearic mutants. Fatty acid analysis of the parents and F1, F2, and F3 generations indicated that the allele controlling low palmitic and low stearic acid in Coles exhibited partial dominance to the alleles in PA1, PA2, PA3, ST1, ST2, ST3, and ST4 and no dominance to the allele in PA4. The crosses between A6 and the stearic mutants indicated that the alleles controlling high stearic acid in ST1, ST3, and ST4 occurred at the same locus as the fasa allele in A6 and that the allele in ST2 may occur at a different locus. Significant maternal and cytoplasmic effects on palmitic and stearic acid content were not confirmed in any of the mutants.
Association between Resistances to Anthracnose (Race 1) and Verticillium Wilt in Alfalfa
Authors: Viands D. R. , George S. R.
Published: July 2010

Because most alfalfa (Medicago sativa L.) cultivars in North America are bred for multiple disease resistance, it is important to know if breeding for resistance to one disease will alter the level of resistance to another disease in the same plant population. A cultivar susceptible to anthracnose, Race 1 (caused by Colletotrichum trifolii Bain) yielded more forage than did two resistant cultivars under field conditions when Verticillium wilt (caused by Verticillium albo‐atrum Reinke & Berth.) was severe in the field stands. Suspected negative association between resistances to these two diseases prompted two experiments under environmentally controlled conditions to explore this hypothesis. In an alfalfa population with variability for both disease resistances, no relationship was found (r = −0.07, P > 0.05) between resistances to the two diseases evaluated independently on different ramets of 58 replicated clones from stem cuttings. In a second population having more variability for resistance to anthracnose than the first population, no relationship was detected (r = −0.05, P > 0.05) among 75 half‐sib progenies. Selecting the most resistant plants for one disease usually did not significantly alter the resistance level to the second disease. Therefore, breeders need not be concerned about these inadvertent changes if population size is sufficient to avoid genetic drift. Because the Verticillium wilt resistance in both populations was derived from ‘Vertus’, this conclusion should not be generalized for all sources of resistance.
Characteristics of Ammonia Volatilization from Spring Wheat
Authors: Morgan Jack A. , Parton William J.
Published: July 2010

The gaseous exchange of NH3 between plants and the atmosphere is important in the N budgets of agricultural cropping systems, yet the physiological bases underlying plant NH3 fluxes remain obscure. The objective of this study is to describe NH3 fluxes from shoots of well fertilized growth‐chamber grown wheat (Triticum aestivum L.) plants from early vegetative growth through maturity. Effects of developmental stage and photorespiration on shoot NH3 and CO2 exchange were investigated with a steady‐state, whole‐plant gas exchange cuvette. Ammonia compensation points were also determined during the grain‐filling period. Volatilization (loss) of NH3 from wheat shoots at ambient [NH3] was consistantly observed throughout the study. Plant CO3 exchange rates and NH3 volatilization rates were strongly influenced by leaf area, although trends for exchange of the two gases were dissimilar when expressed on a leaf area basis. Photorespiration was only modestly associated with level of NH3 volatilization. The highest rates of NH3 volatilization occurred during grain filling, with two bursts of high activity after anthesis and prior to maturity. Ammonia compensation points rose as plants approached maturity. Increased potential for NH3 volatilization during later developmental stages is attributed to ontogenetic changes in plant N metabolism that elevate tissue [NH+4] from concentrations occurring in younger, vegetative tissue.
Mechanism of Dormancy in Pensacola Bahiagrass
Authors: West S. H. , Marousky F.
Published: July 2010

The rationale for this study was to characterize the dormancy factors that contribute to slow germination and poor stand performance in Pensacola bahiagrass (Paspalum notatum Flugge). Several dormancy releasing treatments were ineffective. The importance of the lemma was established by excising parts of the seed covers. Removing the second glume and sterile lemma did not reduce dormancy. Removing the palea resulted in significantly improved germination but still not as rapid nor as complete as removing the lemma. Germination was observed to occur by the coleorhiza protruding through an opening in the lemma caused by the separation of fibers immediately above the embryo. Aging the seed increased germination and the number of seed with visible, separated fibers. A dormancy mechanism is proposed in which water uptake and the expansion of the embryo are restricted until an opening occurs in the lemma.
Seasonal Application of Ethephon, Flurprimidol, Mefluidide, Paclobutrazol, and Amidochlor as they Affect Kentucky Bluegrass Shoot Morphogenesiscky
Authors: Diesburg K. L. , Christians N. E.
Published: July 2010

Inconsistent efficacy has limited the use of turfgrass growth retardants. A 3‐yr field study was conducted to determine if the spring reproductive, summer vegetative, and fall reproduction‐inductive growth phases of Kentucky bluegrass (Poa pratensis L.) influence its response to turfgrass growth retardants. Amidochlor { N‐[(acetylamino)‐methyll‐2‐chloro‐N‐(2,6‐diethylphenyl) acetamide} and mefluidide N‐{2,4‐dimethyl‐S‐[[(trifluoromethyl)sulfonyllamino] phenyl}acetamide were fast acting and most effective in spring with nearly complete growth restriction during the second and third weeks after application. Paclobutrazol [(2RS, 3RS)‐1‐(4‐ chlorophenyl‐4,4‐dimethyl‐2‐(1H‐1,2,4‐triazol‐l‐yl)pentan‐3‐ol] and flurprimidoi {α‐(l‐methylethyl)‐α‐[4‐(trifluoromethoxy)phenyl]‐5‐ pyrimidine methanol} were slow acting, with an average of 16% growth reduction, which peaked 5 and 10 wk after treatment, respectively. Ethephon [(2‐chloroethyl)phosphonic acid] effects were continuous throughout the 10‐wk measurement periods, restricting growth an average of 30%. Flarprimidol was most effective in summer, whereas ethephon and paclobutrazol had similar effectiveness across seasons. Mefluidide prevented spring heading completely while amidochlor reduced heading by 79%. Mefiuidide was the only chemical to reduce turf quality severely. Ethephon was the only chemical to stimulate internode elongation. Measurement of individual phytomers within shoots from two sampling dates provided a continuous record of plant growth response to treatment over a 6‐wk period. Blade growth was affected more strongly than sheath growth by all growth retardants except paclobutrazol. Consistent differences in seasonal plant response to treatments in spite of yearly climate variations support the hypothesis that unique combinations of season with growth phase influence the response of Kentucky bluegrass to turfgrass growth retardants.
Evaluation of S2 Maize Lines Reproduced for Several Generations by Random Mating within Lines. II. Comparisons for Testcross Performance of Original and Advanced S2 and S8 Lines
Authors: Carlone M. R. , Russell W. A.
Published: July 2010

An alternative to the use of highly inbred lines to produce maize hybrids (Zea mays L.) would be to use lines that have been only partly inbred, selected in early generation testing for their combining, ability, and maintained by randomating within lines (sib‐mating). Our objective was to compare the testcross performance of original S2 lines with their maintained S2‐1ine counterparts and S2‐line derivatives to determine if changes have occurred in the S2 lines after several generations of sib‐mating or S8 lines after further inbreeding.

We evaluated the performance of 14 original S2 lines; each S2 line maintained by using 10 and 20 plants generation −1, four lines also maintained by using mild selection for agronomically desirable traits, and their Ss line derivatives in testcrosses with two unrelated testers. Significant (P < 0.05) or highly significant (P < 0.01) differences among groups were observed for 8 of the 14 traits evaluated; grain yield differences were nonsignificant. Individual comparisons between each original S2 line and its maintained S2‐1ine counterparts showed that significant differences occurred in both the positive and negative directions for many traits, thus indicatingenetic changes. Testcrosses of S2 lines maintained by using 10 plants generation −1 generally tended to be less stable than if they were maintained by using 20 plants. For grain yield, only one maintained S2 line differed significantly from its original S2‐line counterpart, whereas three S8 lines showed a significant change. Thus, maintaining S2 lines by sibmating by using 10 or 20 plants, or mild selection, had small effects on the combining ability of the individual S2 lines.
Combining Ability for Resistance in Corn To Fall Armyworm and Southwestern Corn Borer
Authors: Williams W. Paul , Buckley Paul M. , Davis Frank M.
Published: July 2010

Both the fall army worm, Spodoptera frugiperda (J.E. Smith), and the southwestern corn borer, Diatraea grandiosella Dyar, feed extensively on the leaves of corn, Zea mays L., in the southern USA. Their feeding can cause serious yield reductions. Several germplasm lines with resistance to leaf feeding by these two insect pests have been developed and released; however, only limited information is available on the inheritance of this resistance. No previous information on the relationships between resistance to fall armyworm and southwestern corn borer has been reported. The current investigation was undertaken to obtain information on the relative importance of general and specific combining ability in the inheritance of resistance to fall armyworms and southwestern corn borers and to compare the responses of the two insects to a diallel cross among inbred lines with varying degrees of resistance. Larval survival and growth were used to quantify levels of resistance. General combining ability was a highly significant source of variation among hybrids, but specific combining ability was a nonsignificant source of variation. Fall armyworm larval survival and weight on hybrids with varying levels of resistance were highly correlated with southwestern corn borer survival and weight on the same hybrids. This suggests that selecting for resistance to one of these insects should increase resistance to both.
Heterosis for Embryo Size and Source and Sink Components of Maize
Authors: Djisbar A. , Gardner F. P.
Published: July 2010

Assimilate source and sink components controlled by genotype and environment determine grain yield of maize (Zea mays L.). Field experiments were conducted in 1986 and 1987 at Gainesville, FL (29° 38′ N) on a Lakeland sand (hyperthermicoated Thermic Quartzipsamment) to assess heterosis for vegetative and yield components. In order to equalize leaf area index and light interception, parent inbred lines B73, MO17, MS71, and VA22 were planted at normal plant populations density (PPD) of 55 000 and also at 110 000 plants ha‐1, while three F1 hybrids from these inbreds were planted at 55000 and 27 500 PPD. In hybrid seeds, embryo size was associated with seed size. At common seed size (8 ram), lengths embryo and embryo axis of hybrids were greater than those of midparent and inbred line means, manifesting heterosis for embryo size. At common PPD, all biomass and grain yield source and sink components were significantly greater for hybrids than for inbreds. At common LAI and light interception achieved by doubling inbred PPD, hybrids produced significantly more biomass and kernel yield, kernel growth rate and weight, and grain‐filling duration, but kernel number for hybrids and inbreds was similar at common LAI. We conclude that hybrids as compared with their parent inbreds express heterosis in source components, including embryo size, as well as sink components, all contributing to higher biomass and grain yields of maize.