bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlled Hybridization Technique for Switchgrass
Authors: Martínez‐Reyna Juan M. , Vogel Kenneth P.
Published: July 2010

Controlled hybridizations of plants are necessary for genetic studies, including those that use molecular markers. A hybridization technique for grass species such as switchgrass, Panicum virgatum L., with indurate floral bracts has not been previously reported. The objective of this study was to develop a technique for emasculating and hybridizing switchgrass. Emasculations were successful when the top of the stigmas could be seen through the translucent tips of the lemma and palea. Panicle branches containing 25 to 50 fertile florets were emasculated at this stage after removing excess panicle branches. Both sessile staminate florets and the fertile florets of a spikelet were emasculated because removal of the sessile floret damaged the upper fertile floret. Emasculations and hybridization were completed before natural pollen shed, which occurs after 1000 h in the greenhouse. Panicle branches with emasculated rioters were covered with glassine bags. Anthers from florets of male parents at a similar stage of development were collected in petri dishes and shaken to induce pollen shed. Pollen in petri dishes was applied directly to stigmas of florets emasculated previously the same morning. The average percentage of crossability [(seed/floret emasculated and fertilized) 100] for crosses that produced seed was 27%, with a range of 4 to 86%. The procedure was successfully used to make controlled crosses in a greenhouse between plants of ’Summer’, an upland tetraploid, and ‘Kanlow’, a lowland tetraploid switchgrass.
Imperfect Yellow Hilum Color in Soybean is Conditioned by II rr TT
Authors: Cober E. R. , Ablett G. R. , Buzzell R. I. , Luzzi B. M. , Poysa V. , Sahota A. S. , Voldeng H. D.
Published: July 2010

Hilum color is useful for identifying soybean [Glycine max (L.) Merr.] cultivars. Tawny‐pubescent yellow‐hilum genotypes are sometimes described with buff, light brown, or very light brown hila in Canada. This study was conducted to determine whether the yellow hila of tawny‐pubescent lines discolor more than grey‐pubescent lines, and whether therefore these yellow hila may actually be classified as brown rather than yellow. Seed of tawny‐ and grey‐pubescent yellow hila isolines in two genetic backgrounds grown in three or four seasons were scored(1, light, to 4, dark) for hilum color by soybean breeders and also classified by the Variety Verification Unit, Canadian Food Inspection Agency. Hilum color was scored darker and non‐yellow (2.9 score) for tawny‐pubescents lines compared with yellow ( 1.4 score) for grey‐pubescent lines. The effects of year and genetic background were also significant. Generally, non‐yellow and yellow hila were found in tawny‐pubescent lines while only yellow hila were found in grey‐pubescent lines. We propose recognition of a new hilum color, imperfect yellow, conditioned by II, rr, and TT. The hilum color imperfect yellow has been approved by the Soybean Genetics Committee. The color of imperfect yellow hila ranges from yellow to brown depending on the genetic background of the line and environmental conditions.
Importance of Canopy Attributes in Determining Dry Matter Accumulation of Pigeonpea under Contrasting Moisture Regimes
Authors: Nam N. H. , Subbarao G. V. , Chauhan Y. S. , Johansen C.
Published: July 2010

Variability in the yield of extra‐short‐duration (ESD) pigeonpea [Cajanus cajan (L.) Huth.] genotypes in drought environments is related to variation in crop growth rate (CGR) and total dry matter (TDM) production. Our investigation was aimed at assessing the importance of canopy attributes in determining the growth of ESD pigeonpea under contrasting moisture regimes. Using two automated rain‐out shelters (ROS), six genotypes were grown under well watered conditions or with water deficit imposed from flowering until maturity. Water deficit significantly decreased the cumulative intercepted photosynthetically active radiation (CIR). The relationship between biomass accumulation and CIR was linear and water deficit affected the slope of the relationship (i.e., radiation use efficiency, RUE) (b = 1.92 g MJ−1 for well watered vs. 1.43 g MJ−1 for water deficit). Genotypes differed in RUE under well watered (1.70 to 2.19 g MJ−1) and moisture deficit (1.30 to 1.66 g MJ−1) conditions. Genotypic variation in canopy attributes was significant. Leaf area duration (LAD) significantly correlated with CGR only under well watered conditions. Cumulative intercepted radiation and RUE accounted for nearly 99% of the genotypic variation in CGR under both moisture regimes, of which RUE alone contributed nearly 90%. Variation among genotypes in CIR alone did not explain the differences in dry matter accumulation under either moisture regime. Only RUE explained more than 90% of the genotypic variation in CGR and 70% in TDM under both moisture regimes. The results indicated that RUE is critical in determining pigeonpea productivity under well watered and moisture‐deficit regimes.
Corn Growth and Yield under Different Crop Rotation, Tillage, and Management Systems
Authors: Singer Jeremy W. , Cox William J.
Published: July 2010

Rotation effects on corn (Zea mays L.) growth have not been documented. Our objective was to evaluate dry matter (DM) and N accumulation of corn following corn, soybean [Glycine max (L.)Merr.], or wheat/red clover (Triticum aestivum L./Trifolium pratense L.) using moldboard plow, chisel, and ridge tillage under high (broadcast herbicides and 163 kg N ha−1) and low chemical management (banded herbicides and 95 kg N ha−1). In 1993, corn following soybean, compared with corn under high chemical management, had greater DM and N accumulation during vegetative development but similar N accumulation after silking (45 kg ha−1) and yield (7.6 and 7.2 Mg ha−1, respectively). In 1994, corn following soybean, compared with corn under high chemical management, had similar DM and N accumulation during vegetative development, but greater N accumulation (59 and 35 kg ha−1, respectively) after silking and yield (11.4 and 10.7 Mg ha−1). Corn following wheat/clover under both management systems, compared with corn following corn under high chemical management, had greater DM and N accumulation during vegetative development in 1994. Corn following wheat/clover under high chemical management had the greatest N accumulation after silking (79 kg ha−1) and yield (12.0 Mg ha−1), whereas the other two systems had the same N accumulation after silking and yield. Corn yield had linear responses to N accumulation after silking in 1993 (r2 = 0.47) and 1994 (r2 = 0.87). We conclude that N accumulation after silking influenced the yield response to rotation more than DM and N accumulation during vegetative development did.
Evaluation of Simple Methods for Estimating Broad‐Sense Heritability in Stands of Randomly Planted Genotypes
Authors: Smith S. E. , Kuehl R. O. , Ray I. M. , Hui R. , Soleri D.
Published: July 2010

Inexpensive estimates of broad‐sense heritability (BSH) may valuable in plant breeding. This research evaluated two methods for estimating BSH with data from stands of equidistantly spaced genotypes. Both methods depend on the assumption that genetic and environmental contributions to plot variance (plot = group of contiguous plants) change at different rates as plot size changes if genetic variation is distributed randomly. For the method proposed by V.J. Shrikhande, variances among plot means are computed and leastsquares regression used to estimate environmental and genetic variances and the change in a plot variance with changes in plot size. The other method involves the same approach, but uses a two‐parameter model suggested by G.H. Freeman but not previously used to estimate BSH. Both methods produce biased BSH estimates since genotypic and genotypic × environmental components of variation are inseparable. Our objectives were to: (i) develop software to calculate variances for the methods, and (it) compare BSH estimates generated using these methods with each other and with those from analysis of variance (ANOVA) of data from families grown in the same environment. Data were from a perennial herb, Sphaeralcea emoryi Torr. grown in Tucson, AZ. Shrikhande's method produced parameter estimates with large variances and BSH estimates that averaged 3.6 times larger than those from Freeman's method. Only BSH estimates from Freeman's method agreed well with those from ANOVA for most traits. Freeman's method may be useful for rapidly and inexpensively generating BSH estimates in a variety of situations, especially when traditional genetic analysis are difficult.
Comparison of Soluble Sugar Degradation in Soybean Seed under Simulated Tropical Storage Conditions
Authors: Locher R. , Bucheli P.
Published: July 2010

Storage of soybean [Glycine max (L.) Merr.] seed under tropical conditions can lead to deterioration that affects product taste and color. A study was designed to assess the effect of extreme storage conditions on the degradation of soluble sugars and to relate these changes to seed deterioration. Seed of six cultivars of soybean were stored for 9 mo. under control (4°C, 45% RH) and simulated tropical (30°C, 82% RH) conditions. Soluble sugar metabolism was monitored by high performance anion exchange chromatography coupled to pulsed amperometric detection (HPAE‐PAD). soluble sugar content was constant or only slightly affected under control conditions. However, substantial hydrolysis of stachyose, raffinose, and verbascose occurred under simulated tropical conditions. The resulting release of glucose and galactose, combined with the degree of hydrolysis of oligosaccharides, appears to be strongly linked to soybean seed quality as indicated by seed germination. Storage behavior was cultivar dependent, pointing to the importance of selecting cultivars for storability in tropical countries. Determination of glucose seems to be a sensitive analytical and practical tool for monitoring soybean seed quality and deterioration under extreme climatic conditions.
A Seed Specific Δ‐12 Oleate Desaturase Gene Is Duplicated, Rearranged, and Weakly Expressed in High Oleic Acid Sunflower Lines
Authors: Hongtrakul Vipa , Slabaugh Mary B. , Knapp Steven J.
Published: July 2010

The seed oils of wild‐type sunflower (Helianthus annuus L.) germplasm typically contain 140 to 350 g kg−1 oleic acid (18:1). Sunflower germplasm with 800 to 950 g kg−1 18:1 (high oleic germplasm) has been developed with a dominant mutation (Ol) originating from the cultivar ‘Pervenets’. We speculated that this mutation reduced the activity or expression of a Δ‐12 oleate desaturase (OLD) gene. This was tested by cloning OLD genes expressed in developing seeds and comparing nucleotide sequences, OLD transcript concentrations, and OLD restriction fragment lengths among wild‐type (low oleic) and backcross‐derived mutant (high oleic) lines fixed for ol or Ol alleles, respectively. An Arabidopsis thaliana L. OLD (At OLD) cDNA probe was used to isolate a full‐length cDNA clone (OLD‐7) from a developing seed cDNA library of sunflower. OLD‐7 was strongly expressed in developing seeds, but was not expressed in the other tissues sampled. The nucleotide sequences for OLD‐7 0RFs from partially isogenic low and high oleic acid lines (HA89 and HA341) were 100% identical. High oleic lines had substantially lower OLD‐7 transcript concentrations than low oleic lines. Restriction fragment analyses showed that OLD‐7 is duplicated and rearranged in mutant lines and linked to the Ol locus; thus, increased oleic acid content seems to be caused by DNA changes affecting OLD‐7 cis regulatory sequences. OLD‐7 RFLPs distinguish between Ol locus genotypes and can be used to accelerate the development of high oleic lines in sunflower.
Applications of Biotechnology in Turfgrass Genetic Improvement
Authors: Chai Benli , Sticklen Mariam B.
Published: July 2010

During the past two decades, substantial progress has been made in applying modern biotechnology in turfgrass genetic improvement. Applications of biotechnology have assisted turfgrass breeding programs in several different ways. This review article addresses the advances made in turfgrass biotechnology, which are categorized in the following areas: (i) applications of molecular markers to assist breeding practice, (ii) in vitro manipulations for regenerable tissue culture, (iii) genetic engineering by DNA transfer techniques, and (iv) the use of fungal endophytes to improve turfgrass performance. Further achievements in turfgrass biotechnology hold promise for solving problems that challenge the turfgrass industry.
Allelic Frequency Change of P1 Gene in Maize Population After Recurrent Selection for Grain Yield
Authors: Frascaroli E. , Landi P.
Published: July 2010

Full‐sib family recurrent selection for grain yield was conducted for four cycles in maize (Zea mays L.). The source population was the F2 of A632 (with red cob) ×195 (with white cob). Objectives of this research were to evaluate the change in allelic frequency at the P1 gene (determining cob color), to assess whether this change was due to random drift only, and to detect whether allelic frequencies were correlated with grain yield responses. The source and the four selected populations were crossed to two inbred lines with white cob (recessive trait). The frequency of red cob allele increased with selection following a highly significant linear trend (b = 0.066 cycle−1), suggesting the effect of directional selection. Correlation between allelic frequency and grain yield was significant for populations as S2 generation (r = 0.938), and as testcrosses (r = 0.886), and could be ascribed to fight linkage, to pleiotropy, or both.
Genetic Characterization of Glufosinate‐Ammonium Tolerant Summer Rape Lines
Authors: Kumar A. , Rakow G. , Downey R. K.
Published: July 2010

Weed control is an important factor for the successful production of canola [Brassica napus (L.) and B. rapa (L.) ] on the Canadian prairies. Traditionally, various pre‐and post‐emergent herbicides have been used to achieve the required level of weed control. Recently, B. napus has been genetically engineered to express tolerance to the broad‐spectrum, post‐emergent herbicide, glufosinate‐ammonium [2‐ amino‐4‐(hydroxymethylphosphinyl)butanoic acid]. This study was conducted to determine the genetics of glufosinate‐ammonium tolerance in a series of Agrobacterium‐mediated transgenic lines of B. napus carrying the phosphinothricin‐acetyl transferase (pat) gene from Streptomyces viridochromogens (Krainsky) Waksman and Henrici. Twenty R1:F2 and 19 R1:BCF1 populations derived from 20 R1 transformants were analyzed for the number of transgenic inserts on the basis of their segregation pattern for herbicide tolerance. Fifteen of the 20 transgenic lines had a single insertion of the pat gene which behaved in a Mendelian manner and five had insertions at two independent loci. Ten transgenics with single gene inserts crossed in a half‐diallel fashion were used to establish allelic relationships of transformants. The results indicated that the insertions had occurred at different loci within the plant genome with a possibility of an association between inserts in one case. It was concluded that transformants should be analyzed for number of transgene inserts and for genetic stability before they may be used in breeding programs for the development of glufosinate‐ammonium tolerant B. napus cultivars.
A Dominant Gene Decreases Erucic and Increases Dienoic Acid in the Seed Oils of Meadowfoam Subspecies
Authors: Knapp Steven J. , Crane Jimmie M.
Published: July 2010

Meadowfoam (Limnanthes alba Benth.) seed oil is a source of erucic acid (22:1 Δ13) and novel very long‐chain fatty acids. The fatty acid profiles of L. alba subspecies are distinctly different. L. alba ssp. versicolor produces significantly more erucic acid and significantly less dienoic acid (22:2) than L. alba ssp. alba. The L. alba ssp. alba profile is the standard for certain meadowfoam oil markets. Because changes in the profile could affect meadowfoam oil markets, we completed a study to elucidate the genetics of erucic and dienoic acid content differences in the subspecies. The fatty acid contents of F2 and F3 progeny from an L. alba ssp. alba × L. alba ssp. versicolor (P1 × P2) cross were assayed by gas chromatography. P1 produced 81 g kg−1 erucic acid and 297 g kg−1 dienoic acid, whereas P2 produced 242 g kg−1 erucic acid and 86 g kg−1 dienoic acid. There were two non‐overlapping erucic by dienoic acid phenotypic classes among 100 F2 progeny. The phenotypic distribution (79:21) was not significantly different from 3:1 (P = 0.48); thus, these progeny segregated for a dominant gene. This was verified by F3 progeny tests. Unless markets can tolerate the range of fatty acid compositions found in L. alba germplasm, cultivars with the L. alba ssp. alba fatty acid profile must be developed.
Crop Diversification in the Sahel through Use of Environmental Changes near Faidherbia albida (Del.) A. Chev
Authors: Payne W. A. , Williams J. H. , Moussa K. A. Maï , Stern R. D.
Published: July 2010

Pearl millet [Pennisetum glaucum (L.) R. Br.] is well adapted to the harsh environment of the West African Sahel but has relatively low genetic yield potential and market value. Crop diversification is desirable, but alternative crops generally cannot tolerate the harsh climate and soil conditions that pearl millet can. This study tested the hypothesis that alternative crops could be grown near Faidherbia albida (Del.) A. Chev. (syn. Acacia albida), a tree species of semiarid Africa, because of its ameliorating effects on the surrounding environment. Octants around trees were sown to pearl millet, maize (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], and cotton (Gossypium hirsutum L). Crop, soil, and climate measurements were made periodically during the growing season. Soil fertility and fine‐particle content decreased with distance from trees. Inside the canopy, irradiance was reduced by 0.5 to 1.0 kW m−2 and daytime soil temperature at a depth of 0.05 m was reduced by as much as 6°C. Improved conditions within the tree canopy were reflected by increased crop yield. Sorghum and maize tended to use less soil water than millet. Sorghum and maize yielded more than 120 g m−2 near the tree bole, whereas millet yielded ≈ 80 g m−2. Near the edge of the tree canopy, where pearl millet maintained yields of 40 g m−2, the other crops tended to fail. Faidherbia albida trees can be used to diversify cropping systems and increase yields in the Sahel, but adoption of this agroforestry system may be constrained by modern social factors which have disrupted traditional land husbandry practices.
Stand Persistence and Seedling Recruitment for Eastern Gamagrass Grazed Continuously for Different Durations
Authors: Aiken G. E. , Springer T. L.
Published: July 2010

Eastern gamagrass (Tripsacum dactyloides L.) is a warm‐season perennial grass with significant forage potential. Grazing must be carefully managedfo r this grass to persist. A 3‐yr study was conducted to evaluate the persistence of eastern gamagrass with stocking rates designed to graze eastern gamagrass to a height of 30 to 38 cm and then deferring grazing for the remainder of the season. The experimental site was on a Leadvale silt‐loam soil (fine‐silty, silceous, thermic Typic Fragidult). Pastures were stocked at different rates to impose the following treatments: (i) long duration continuous stocking at a light stocking rate (LDLS; 3.0 steers ha−1), (ii) intermediate duration continuous stocking at a moderate stocking rate (IDMS; 4.9 steers ha−l), and (iii) short duration continuous stocking at a heavy stocking rate (SDHS; 7.4 steers ha−l)). Length of grazing averaged 142 ± 6 (± SEM) d for LDLS, 110 ± 8 d for IDMS, and 85 ± 7 d for SDHS. New seedlings of eastern gamagrass emerged each spring at similar densities in all three treatments. Some of these plants survived and increased plant densities over the 3 yr for LDLSa nd IDMS, but not for SDHS. Concentrations of nitrogen (N) and total nonstructural carbohydrates (TNC) stored in proaxes were similar among the three grazing treatments in April at the initiation of spring growth, and in October just before the onset of winter dormancy. Ungrazed plants had higher TNC than grazed plants in October, but the grazed plants had sufficient reserves to retain their vigor for 3 yr. Eastern gamagrass can persist under a variety of stocking rates if grazing is deferred for the remainder of the growing season when canopy height falls to 30 to 38 cm.
Nondestructive Assessment of Sinapic Acid Esters in Brassica Species: II. Evaluation of Germplasm and Identification of Phenotypes with Reduced Levels
Authors: Velasco Leonardo , Möllers Christian
Published: July 2010

The seed of Brassica spp. contain high levels of sinapic acid esters (SAE). Because of their antiquality nature, the presence of SAE limits the use of Brassica meal as a source of high‐quality protein. The objective of this study was to search for material with reduced SAE content in Brassica spp. A collection of 1487 accessions of 21 species of Brassica and a set of 1361 samples of breeding material of rapeseed (B. napus L.) were analyzed for SAE content by using a previously calibrated near infrared reflectance spectroscopy (NIRS) instrument. The accessions of the germplasm collection showed an average SAE content of 9.4 g kg−1, ranging from 1.7 g kg−1 in an entry of B. tournefortii Gouan to 15.5 g kg−1 in an entry of B. carinata A. Braun. Low levels of SAE were found in B. barrelieri (L.) Janka, B. oxyrrhina Coss., B. souliei (Batt.) Batt., and especially in B. tournefortii, with an average SAE content of 4.1 g kg−1 in 31 accessions. Breeding material of B. napus ranged from 5.0 to 17.7 g kg−1. The samples with the lowest SAE content from both the germplasm collection (n = 112) and the breeding material (n = 75) were further analyzed by the laboratory reference method, with the low levels being confirmed. The SAE content was positively correlated with oil content, and negatively correlated with protein and glucosinolate contents. Because of the observed correlations, simultaneous selection for low SAE, low glucosinolate and high oil contents should be performed. The use of B. tournefortii germplasm having low SAE content in breeding programs can potentially reduce these compounds in cultivated Brassica oilseeds.
Comparison of Seedling and Cuttings for Evaluating Winter Hardiness in Alfalfa
Authors: Brouwer D. J. , Duke S. H. , Osborn T. C.
Published: July 2010

Studies of the genetic control of winter hardiness (WH) in alfalfa (Medicago sativa L.) require the replication of specific genotypes in the field. Clonal propagules would provide worthwhile information in replicated trials if seedlings and cuttings give similar genotype rankings. In this study, we compared seedlings with genetically identical cuttings for WH, fall dormancy (FD),and freezing tolerance (FT), and evaluated the relationships among these traits. Seventy‐two plants each from 15 genotypes, covering a broad range of FD, were clonally propagated and transplanted to the field as seedlings and cuttings in a randomized complete block design. For all traits, genotype was a highly significant (P < 0.001) source of variation, but the genotype × establishment method (seedlings vs. cuttings) interaction was not significant (P > 0.05). Winter survival was significantly correlated with freezing sensitivity (r = −0.92, P < 0.01) and FD (r = −0.66). Our results suggest that alfalfa plants established from cuttings will faithfully represent seedling‐established plants for the purpose of evaluating winter hardiness.
Forty Years of Forage Quality Research: Accomplishments and Impact from an Animal Nutrition Perspective
Authors: Fahey G. C. , Hussein H. S.
Published: July 2010

Many important advancements have been made during the past 40 yr as regards forage quality and its effect on ruminant animal nutrition. In the early days of this 40‐yr period, forage quality was considered as a product of digestibility and intake, with intake being the more important of the two processes. Factors affecting each of these processes were heavily studied. At the same time, analytical methodology and developed that had relevance to animal nutrition. Examples include the two‐stage Tilley and Terry in vitro procedure and the Van Soest detergent system of forage analysis. On the pasture side, definition of plant‐animal interrelationships influencing output per animal and per hectare of pasture was a key goal. In more recent years, significant accomplishments have occurred in a number areas including (i) development of near infrared reflectance spectroscopy (NIRS) for forage quality determination; (ii) forage conservation procedures; (iii) role of crop residues in feeding systems; (iv) minerals and secondary plant compounds that affect forage plant digestion, metabolism, and health; (v) digestive kinetics and nutrient availability at different points in the ruminant digestive tract; (vi) development of modeling and systems approaches to the study of forage digestion and to pasture and forage management feeding; (vii) forage supplementation strategies; and(viii) developing an understanding of microbial and animal limitations to fiber digestion and utilization.
Cell Wall Structural Foundations: Molecular Basis for Improving Forage Digestibilities
Authors: Hatfield R. D. , Ralph J. , Grabber J. H.
Published: July 2010

Forages play an important role in the world wide animal industry. The fiber (cell wall) portion makes up 300 to 800 µg g−1 of forage dry matter and represents a major source of nutritional energy for ruminants, but, unfortunately, less than 50% of this fraction is readily digested and utilized by the animal. Significant progress has been made in the past 30 to 40 yr towards understanding cell wall structure and function and developing mechanistic models that explain limitations to structural polysaccharide degradation and utilization by ruminants. In grasses, it is now clear that wall bound ferulates play a key role in cross‐linking xylans to each other and to lignin, resulting in less degradable walls. Much has been accomplished in advancing our understanding of the lignification process in plants, particularly the genes and enzymes involved in the monolignol biosynthesis. The application of molecular techniques to this area has advanced our understanding of the metabolic process while providing tools for further exploration of wall structure and function and providing direction as to possible avenues to improve forage digestibility.
Heritability of Hull Percentage in Oat
Authors: Ronald P. S. , Brown P. D. , Penner G. A. , Brûlé‐Babel A. , Kibite S.
Published: July 2010

Low hull percentage has long been recognized as a valuable measure of grain quality in oat, Avena sativa L.; however, reliable selection for low hull percentage has been impeded by a lack of understanding of its heritability. The objective of this study was to investigate the heritability of hull percentage in three oat crosses, involving the cultivars Cascade, Robert, and AC Marie, which have 30, 25, and 23% hull, respectively. Populations F2‐deriveF4 through F7 lines were grow in replicated or unreplicated trials at several locations in western Canada from 1992 to 1995. Heritability estimates were calculated based on hull percentage data determined by mechanically dehulling 2‐g kernel mixtures or samples of 50 primary kernels. Primary kernel hull percentage data, collected from replicated trials at multiple locations, were used to evaluate the effect of genotype × location interaction on phenotype. Broad‐sense heritability estimates by parent‐offspring regression ranged from 0.35 to 0.72 for hull percentage of 2‐g kernel mixtures, and 0.80 to 0.90 for hull percentage of 50 primary kernels. An evaluation of variance components showed highly significant genotype and location effects for primary kernel hull percentage. Genotype effects had a greater influence than location on primary kernel hull percentage, whereas the effect of genotype × location interaction was relatively less important. High broad‐sense heritability estimates for hull percentage support the use of early generation selection for reduced hull content in oat.
Cotton Seedling Root Growth Responses to Light Reflected to the Shoots from Straw‐Covered versus Bare Soil
Authors: Kasperbauer M. J.
Published: July 2010

Poor seedling establishment can severely impact cotton(Gossypium hirsutum L.) when grown in a double‐crop sequence following wheat(Triticum aestivum L.). My objective was to determinw whether the light spectrum reflected from wheat straw to the cotton seedlings could be a contributing factor. Cotton was planted in 3 L pots of loamy sand which was screened to remove old plant residue. Pots were arranged in groups of five and covered with 122‐ by 122‐ by 2‐ cm polystyrene foam insulation panels which had 5 ‐cm holes centered over each pot. Panels were covered with fresh wheat straw, weathered straw, or bare soil so that different far‐red to red( FR/R) light ratios were reflected. Insulation maintained the same soil temperature (±0.5) in all pots regardless of surface cover. Each pot was thinned to a single seedling that emerged on the same day. Leaf area and stem length were measured on seedlings cut at the soil surface 1 wk after emergenc. Roots were washed free of soil, spread on paper, covered with transparent plastic, and photocopied. Root lengths were measured on the photocopies. Stems, leaves, and roots from each plant were dried and weighed. The fresh wheat straw reflected the highest FR/R ratio and resulted in seedlings with the least root length, lowest root weight, longest stems, and lowest root/ shoot weight ratio. This 2‐yr glasshouse study show that the spectral environmen over fresh straw can contribute to modified seedling morphology and suggests that it should be considered when developing management practices for no‐till double‐crop cotton.
Inheritance of Reduced Stearic and Palmitic Acid Content in Sunflower Seed Oil
Authors: Miller J. F. , Vick B. A.
Published: July 2010

Reducing the saturated fatty acid content of sunflower (Helianthus annuus L.) oil would benefit the sunflower industry through increased consumer preference for a low saturated sunflower product. This study was conducted to determine the inheritance of low stearic and low palmitic acid content found in three sunflower mutant lines treated with two mutagens, N‐nitroso‐N‐methylurea (NMU) and ethyl methanesulfonate (EMS) at rates of 1 and 2 g kg−1. The fatty acid content of approximately 6800 M5 lines was analyzed by gas chromatography. Two M5 lines, HA 821 LS‐1 and RHA 274 LS‐2, had lower stearic acid content (41 and 20 g kg−1), and one M5 line, RHA 274 LP‐1, had lower palmitic acid content (47 g kg−1) than their respective parental lines. Segregation ratios of F2 and testcross progeny indicated that the low stearic acid content in HA 821 LS‐1 was controlled by one gene, designated fas1, with additive gene action. The low stearic acid content in RHA 274 LS‐2 was controlled by two genes with additive gene action. The first gene was designated fas2, and the second gene was temporarily designated fasx. The allele fap1 was identified in RHA 274 LP‐1 to control low palmitic acid content with additive gene action. The combination of the alleles for low stearic and low palmitic acid content identified in this study could reduce the total saturated fatty acid content of oil in sunflower from 130 g kg−1 to less than 80 g kg−1.
Inheritance of Cytoplasmic‐Virescent cyt‐V and Dense‐Glanding dg Mutants in American Pima Cotton
Authors: Percy Richard G.
Published: July 2010

Morphological mutants of cotton (Gossypium spp.) have been used extensively in genetic mapping studies and in several instances have proven useful in agronomic improvement efforts. This investigation was conducted to determine the inheritance, allelism, and linkage associations of two spontaneous mutants found in plants of American Pima (G. barbadense L.) cotton. The two mutants were crossed to the normal phenotype cultivar PS‐6 and to several genetic marker stocks. Appropriate F1, F2, and BC populations were created for analyses of inheritance and linkage studies. Analyses of F1 and F2 populations of a virescent mutant indicated that it is inherited as an extranuclear factor. Expression of the mutant is transient, being strongest in the first true leaf after germination and fading by the fourth or fifth true leaf. It is proposed that the mutant be designated cytoplasmicvirescent and be assigned the gene symbol cyt‐V. Analyses of F1, F2, and BC populations of a second, juvenilely expressed, densely glanded mutant indicated that it is inherited as a single, recessively expressed gene. Tests for association of the dense glanding trait with 13 other mutant markers produced no evidence of linkage. Linkage tests with two markers, T1 and ms13, were inconclusive. Expression of the dense glanding mutant is confined to expanding leaves and internodes, and to bracteoles. Expression is strongest in the first and second apical leaves, and fades by the fourth or fifth leaf. The designation denseglanding and gene symbol dg are assigned to the mutant.
Genetic Control of a Photoperiod‐Sensitive Response in Sorghum bicolor (L.) Moench
Authors: Rooney W. L. , Aydin S.
Published: July 2010

Photoperiod‐sensitive (PS) sorghums (Sorghum bicolor L. Moench) are not uncommon, but the production of a PS hybrid from two photoperiod insensitive (PI) lines is unusual. The inbred line EBA‐3 is PI, but F1 hybrids of EBA‐3 with most other PI inbreds are PS and will not initiate floral development until daylengths are <12 h and 20 min. The objective of this study was to determine the inheritance of the PS response. Ten PI inbred lines were crossed as females with EBA‐3 by hand emasculation and pollination. F1 and F2 populations were evaluated for photoperiod response as indicated by flowering date in plantings at College Station and Halfway, TX. F2:3 progeny for two of the crosses plus two testcrosses were used to confirm F2 segregation data. Nine of ten F1 progeny were strongly PS. Plants in nine F2 populations segregated for photoperiod response. Segregation in eight of the F2 populations fit a 9:7 PS/PI ratio, indicating that two independent gene loci were interacting in complementary dominant epistasis. Evaluation of crosses between EBA‐3 and maturity standards for the Ma1, Ma2, Ma3, and Ma4 loci indicated that the loci responsible for this photoperiod sensitivity are different from previously characterized loci. The gene symbols proposed for these two loci are Ma5 and Ma6.
Yield and Quality of Soymilk and Tofu Made from Soybean Genotypes Grown at Four Locations
Authors: Bhardwaj H. L. , Bhagsari A. S. , Joshi J. M. , Rangappa M. , Sapra V. T. , Rao M. S. S.
Published: July 2010

Soyfoods are becoming popular among American consumers because of potential health benefits. However, specific information about the kind of soybean [Glycine max (L.) Men.] seed desirable for soyfoods preparation is limited. The objectives of this study were to compare soymilk and tofu prepared from 12 soybean genotypes grown at four locations in the southern USA during 1995 to identify genotypes suitable for soymilk and tofu manufacture and to determine effects of seed traits on yield and quality of soymilk and tofu. Location effects were significant only for soymilk solids and tofu strength. Soymilk yield with a mean value of 5.1 mL g−1 seed was not affected by soybean genotype. Significant genotypic effects were observed on tofu yield, which varied from 0.82 to 0.91 g mL−1 of soymilk. Tofu yield was significantly correlated to seed size (+0.31), seed oil (+0.74), rate of water absorption after 1 and 16 h of soaking (+0.38 and +0.56, respectively), and seed protein (−0.82). Seed protein content, seed size, and soymilk solids were significant determinants of tofu yield (R2 = 0.80). Two variables, soymilk index (SI) and tofu index (TI), were calculated to compare overall suitability of soybean genotypes for soymilk and tofu production. SI was calculated by summing yield, total solids, protein content, and whiteness index of soymilk. TI was calculated by summing yield, protein, whiteness index, and strength of tofu. Seed oil content and size were significant determinants of SI (R2 = 0.41), whereas soymilk color, seed size, and seed protein content were significant determinants of TI (R2 = 0.52). The SI and TI values indicated BARC‐9 to be a desirable genotypes for soymilk and for tofu preparation.
Plant Density‐Dependent Variation in Density, Frequency, and Size of Watermelon Fruits
Authors: Duthie James A. , Roberts B. Warren , Edelson Jonathan V. , Shrefler James W.
Published: July 2010

Quantitative analyses of the continuous response of components of the biomass of fruits of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] to variation in plant density could provide insight into the mechanisms underlying effects of plant density on marketable yield. Per unit area, the linear response of fruit biomass to plant density recently has been shown to explain the linear response of marketable yield. In the current study we quantify plant density‐dependent variation in the size, density (no. per unit area), and frequency (no. per plant) of watermelon fruits. In single‐row plots, at least 3.7 m apart, plant density varied from 0.4 to 4.1 plants m2 (1000–9000 plants ha−1). In each experiment, the linear effect of plant density explained more than 80% of the variation in fruit density. Fruit density increased at linear rates of 0.6 to 1.1 thousand fruits ha−1 per thousand plants ha−1. The plant density‐dependent response of the size of fruits varied considerably among experiments but the frequency of fruits responded consistently. In four experiments, there was no evidence of an effect of plant density on fruit size but in three experiments, fruit size decreased at a curvilinear rate of approximately 2.0 (kg−1 fruit−1 per thousand plants−1 ha−1)(plants ha−1)2. Frequency of fruits decreased with plant density at curvilinear rates of 0.8 to 2.8 (fruits plan−1 per thousand plants ha−1)(plants−1 ha−1)2. The response of size of fruits and frequency of fruits, respectively, probably measured an environment‐dependent and an environment‐independent effect of intraspecific competition.
Cutting Frequency and Nitrogen Fertilization Effects on Yield and Nitrogen Concentration of Switchgrass in a Short Season Area
Authors: Madakadze I. C. , Stewart K. A. , Peterson P. R. , Coulman B. E. , Smith D. L.
Published: July 2010

Adapted warm season grasses have potential for both summer forage and biomass production in eastern Canada. A field study was conducted in 1995 and 1996 to determine the response of switchgrass (Panicum virgatum L.) cv. Cave‐in‐Rock, Pathfinder, and Sunburst to nitrogen (N) fertilization at 0,75, or 150 kg ha−1 and three harvest schedules in a short season area. The grass was harvested at 4‐ or 6‐wk intervals or left uncut until the end of the season. These treatments were combined in a split‐plot design in each of three blocks on a St. Bernard sandy clay loam (Typic Hapludalf). Herbage yield and herbage N concentration were determined at each harvest for the cutting schedules. Herbage yields revealed a cultivar × N × harvest schedule interaction in 1996, while in 1995 only the two‐way interactions between cultivar × harvest schedule and N × harvest schedule were evident (P < 0.05). Total yield ranking for the harvest regimes was uncut > 6‐wk > 4‐wk with their respective mean yields being 11,10, and 8 Mg ha−1 for Cave‐in‐Rock; 10,8, and 6 Mg ha−1 for Pathfinder and 11,8, and 7 Mg ha−1 for Sunburst. Nitrogen concentrations increased with fertilization and varied with harvest and year, but not with cultivar. Mean N concentrations were 12.4, 13.9, and 15.4 g kg−1 dry matter (DM) for the 0, 75, and 150 kg ha−1 N levels, respectively, under the 4‐wk system. Corresponding values were 10.1, 11.6, and 12.9 g kg−1 for the 6‐wk system. End of season N concentrations for the uncut regime averaged 5.4, 6.0, and 7.6 g kg−1 DM in increasing order of N fertilization. The results indicate that switchgrass has potential in both grazed or hay forage systems in eastern Canada.
Trichomes on Pigeonpea [Cajanus cajan (L.) Millsp.] and Two Wild Cajanus spp
Authors: Romeis J. , Shanower T. G. , Peter A. J.
Published: July 2010

Trichomes have been modified in a number of crops to develop insect‐tolerant genotypes. Pigeonpea, Cajanus cajan (L.) Millsp., is often heavily damaged by insect pests, and trichomes provide a potential insect resistance mechanism. The following study was conducted to identify and characterize the distribution of trichomes on pigeonpea and two wild species, C. platycarpus (Bentham) van der Maesen and C. scarabueoides (L.) Thours. Three glandular (Types A, B, and E) and two nonglandular (Types C and D) trichome types were identified with light and electron microscopy. Types A, B, C, and D were found on leaves, pods, and calyxes of all three Cajanus spp., except for Type A, which was not found on pods and calyxes of most C. scarabaeoides accessions examined. Because of their small size and rarity, Type E trichomes were not considered in this study. Pods of C. scarabueoides were the most densely pubescent, followed by pods of C. cajan and C. platycarpus. Trichome density on pods varied significantly among pigeonpea genotypes and different accessions of C. scarabaeoides. Differences across seasons and in greenhouse versus field‐grown plants were also significant. Leaves of C. platycarpus possessed the fewest trichomes, while C. cajan and C. scarabaeoides had highly pubescent leaves. The resistance of C. scarabaeoides pods to Helicoverpa armigera (Hübner) larvae reported in an earlier study is due to the high density of nonglandular trichomes. This wild species may thus be an important source for developing insect resistant pigeonpea.
Using a Subsample of the Core Collection to Identify New Sources of Resistance to White Mold in Common Bean
Authors: Miklas Phillip N. , Delorme Richard , Hannan Richard , Dickson Michael H.
Published: July 2010

Few sources of physiological resistance to the fungal pathogen Sclerotinia sclerotiorum (Lib.) de Bary, causal organism of white mold disease in common bean (Phaseolus vulgris L.), have been found and exploited by breeders. Our objective was to screen a subsample of the core collection of P. vulgris accessions representing the active USDA National Plant Germplasm System collection of 1698 accessions from Central and South America for reaction to white mold using a greenhouse straw test. White mold reactions were rated for 89 accessions from 1 = no disease symptoms to 9 = total plant collapse. Eleven core accessions, Pis (plant introductions) 152311, 207136, 207154, 290990, 290995, 293353,313850, 415886, 415906, 415913, and 415936, with scores <5 were identified as having putative physiological resistance to white mold. An expanded screening among 35 accessions from the active collection which had similar passport data to the resistant core Pis 207136, 290990, and 313850 revealed 20 resistant accessions with disease scores <5. A similar expanded screening of 18 accessions with similar passport data to core Pis 310674, 313608, and 415954 that had scores >6, revealed only four accessions with scores <5. These results indicated that a subsample of the core collection was useful for identifying ranges of accessions within the active Phaseolus collection that possessed a high incidence of putative physiological resistance to white mold.
Wear Tolerance, Shoot Performance, and Spectral Reflectance of Seashore Paspalum and Bermudagrass
Authors: Trenholm L. E. , Duncan R. R. , Carrow R. N.
Published: July 2010

Seashore paspalum (Paspalum vaginatum Swartz) displays wide intraspecific diversity and exhibits tolerance to numerous abiotic stresses. In addition, comparatively low fertility requirements and high quality growth characteristics of many ecotypes render this grass a prospective candidate for use on golf courses, athletic fields, and landscaped areas in warm climates worldwide. The objectives of this research were to evaluate the relative growth, quality, and wear tolerance of seashore paspalum and bermudagrass. This research was conducted in two consecutive field trials during 1997 under wear and non‐wear conditions on seven seashore paspalum ecotypes and three hybrid bermudagrass (Cynodon dactylon L. × C. transvaalensis Burtt‐Davy) cultivars established on a native Appling sandy clay loam (clayey, kaolinitic, thermic typic Kanhapluduit) at the University Georgia Experiment Station at Griffin, GA. We found that two paspalum ecotypes, Temple 1 and SIPV‐2, ranked as high or higher than ‘Tifway’ and ‘Tifsport’ for visual quality, shoot density, shoot growth, and amount of verdure tissue under non‐wear conditions. In addition, these two paspalum ecotypes showed the most favorable spectral reflectance data responses, indicating greatest utilization of intercepted light, and also showed rates of recovery from wear which were equal to or greater than those of the bermudagrass entries. Paspalum ecotypes Temple 1 and SIPV‐2 appear to be suitable for use in areas where a high quality, traffic‐tolerant turfgrass is required. Paspalum ecotypes with lower shoot densities were less wear tolerant.
Marker‐Assisted Best Linear Unbiased Prediction of Single‐Cross Performance
Authors: Bernardo Rex
Published: July 2010

Predicting the performance of untested single crosses is important in hybrid breeding programs. The objective of this study was to compare the effectiveness of best linear unbiased prediction based on trait data alone (T‐BLUP) and trait and marker data combined (TM‐BLUP). The simulation procedure involved creating founder and recombinant inbreds in each of two heterotic groups, determining genetic and phenotypic values of 3025 single crosses, randomly partitioning the single crosses into 500 tested and 2525 untested hybrids, and calculating the correlation between the true and predicted performance of untested single crosses. The T‐BLUP correlations ranged from 0.74 to 0.84, with n = 10, 50, or 100 quantitative trait loci (QTL) and trait heritability of 0.4 or 0.6. The advantage of TM‐BLUP over T‐BLUP decreased as n increased. With n = 50 or 100, the TM‐BLUP correlations exceeded the T‐BLUP correlations by 0.00 to 0.03, even when all QTL were tightly linked to flanking markers. The usefulness of TM‐BLUP is doubtful, not only for predicting single‐cross performance, but also for predicting breeding values of individuals within populations. The TM‐BLUP procedure is useful when few QTL control a trait, or when genetic gain is sought only at a limited subset of QTL.
Mass Selection for Improvement of Grain Yield and Protein in a Maize Population
Authors: Bletsos Eleftherios A. , Goulas Christos K.
Published: July 2010

Increasing grain protein concentration in maize (Zea mays L.) has not been a major focus of most breeding programs, which mainly focus on yield, maturity, and resistance to stress. The objective of this study was to evaluate the effectiveness of three cycles of mass selection to improve simultaneously yield and grain protein in the maize population GR‐OP‐319, derived from the F2 generation of the single‐cross hybrid PX‐95. The two‐step selection procedure involved a stratified mass selection system that included check plants for environmental control. In the first step, plants having grain yield higher than 80% of the check‐plant mean and protein concentration greater than the check‐plant mean were selected. In the second step, the four plants within each selection grid having the highest protein concentration were selected, which resulted in a final selection intensity of 5%. Three cycles of selection were completed during 1991 to 1995. Response to selection was evaluated during the selection process and by direct field evaluation of the C0, C1, C2, and C3 populations in 1995 and 1996. The average response during the selection was 5.1% cycle−1 for yield, 0.8 g kg−1 cycle−1 for protein concentration, and 7.0% cycle−1 for protein yield. No measurable differences among cycles were observed in the direct field evaluation even though the trends in the means of the cycles followed the trends shown during selection. After three cycles, the mass selection system studied did not appear to be particularly effective.