bluuebunny/crossref_metadata_2025 huggingface dataset:
Sucrose Metabolism Related to Growth and Ripening in Sugarcane Internodes
Authors: Lingle Sarah E. , Smith Robert C.
Published: July 2010

Sucrose concentration is an important component of yield in sugarcane (Saccharum spp. hybrids). To further understand the relationship of sucrose biochemistry to growth and sucrose accumulation in sugarcane, sugars, sucrose synthase (SS), acid and neutral invertases, pyrophosphate:fructose 6‐phosphate 1‐phosphotransferase (PPi‐PFP), fructose 2,6‐bisphosphate (F26BP), and adenosine triphosphate: fructose 6‐phosphate, 1‐kinase (ATP‐PFK) were extracted from the top eight internodes of greenhouse‐grown ‘CP 70‐321’ sugarcane plants. Internode 1 was defined as that subtended by the topmost leaf with exposed dewlap. Internodes 2 and 3 had the highest elongation rates; Internodes 5 to 8 were fully elongated. The rate of sugar accumulation, especially sucrose, increased rapidly after elongation ceased. The activity of SS was associated with elongation and may be related to sink strength of elongating internodes. Acid and neutral invertase activities were more generally distributed. When unstimulated by F26BP, the activity of PPi‐PFP was similar to that of ATP‐PKF. Addition of 1 µM F26BP stimulated PPi‐PFP activity up to 60‐fold. The concentration of F26BP extracted from all internodes was sufficient to fully stimulate PPi‐PFP. There was no clear relationship between developmental stage, F26BP concentration, and the activity of PPi‐PFP or ATP‐PFK. Further investigations on the role of SS in sugarcane development seem warranted.
Dinitrogen Fixation, Nitrogen Transfer, and Productivity of Forage Legume‐Grass Communities
Authors: Heichel G. H. , Henjum K. I.
Published: July 2010

The extent of N2 fixation in legume‐grass mixtures grown in the northcentral USA and the importance of legume to grass N transfer are not well understood. The objective of this 4‐yr field experiment was to determine seasonal N2 fixation and N transfer by stable isotope methods in swards of alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.), and ladino white clover (T. repens L.) with reed canarygrass (Phalaris arundinacea L.). Alfalfa in mixture with grass fixed the most N2 per season (82 to 254 kg N ha‐1) and ladino white clover the least (1 to 20 kg N ha‐l). For all mixtures except birdsfoot trefoil grass, N2 fixation was greatest during Year 2 of the stands. The proportion of legume N from symbiotic fixation increased progressively from Year 1 through 4 and averaged >93% for all legumes in Year 4. Legume to grass N transfer was greatest in Year 2 of the stands and averaged ≈36% of grass N across all mixtures. On a land area basis, N transfer in Year 2 ranged from 29 to 53 kg N ha‐1 and was greatest for the ladino white clover‐grass mixture. The decline in N transfer in Years 3 and 4 was associated with a loss in sward legume content, reduced whole‐plant dry matter accumulation in legume and grass, and large losses in root‐plus‐crown dry matter accumulation by grass in Year 4. The results indicate that forage legumes in mixture with grass are virtually self‐sufficient for N and can concurrently transfer appreciable N to the companion grass.
Standard Errors and Confidence Interval Estimators for Expected Selection Response
Authors: Bridges W. C. , Knapp S. J. , Cornelius P. L.
Published: July 2010

Expected selection response (R) is widely used in plant breeding to compare populations and selection schemes, but methods have not been described for estimating variances or confidence intervals of R, or, if they have, their validity is uncertain. In this paper, we describe an exact and approximate standard error of R and normal‐approximation intervals of R. We used simulation to test the validity of these intervals by comparing realized coverage probabilities to stated coverage probabilities for different experiment sizes, stated coverage probability values, and values of family‐mean heritability (H). Coverages of the normal‐approximation interval estimated using the exact standard error (interval R1) ranged from 0.874 to 0.922 and 0.932 to 0.966 for stated coverages of 0.90 and 0.95, respectively. Coverages of the normal‐approximation interval estimated using the approximate standard error (interval R2) ranged from 0.880 to 0.940 and 0.934 to 0.980 for stated coverages of 0.90 and 0.95, respectively. Both R1 and R2 are valid interval estimators for R if the usual assumptions of the analysis of variance are met.
Selection for Seed Set in a Wheat Population Treated with a Chemical Hybridizing Agent
Authors: Kofoid K. D.
Published: July 2010

Production of hybrid seed is an important component of hybrid wheat (Triticum aestivum L.) utilization. A recurrent selection program was initiated using gridded mass selection to select for increased seed set on individual plants that had been treated with a chemical hybridizing agent (CHA). Four cycles of selection with recombination were completed using the spring wheat random‐mating population NDPI. To determine the effectiveness of this selection procedure, 32 random half‐sib selfed families from both the CO and the C4 cycles of selection, 32 random inbreds from the original NDP1 population, and 32 inbred lines from several wheat breeding programs were compared for both fertile seed yield (no CHA) and hybrid seed yield (0.6 kg ha−1 CHA) in replicated tests at two locations in 1986. Differences were found among entries for all traits when averaged across treatments. A significant rate ✕ entry interaction was found only among the inbred lines for grain yield, test weight, grain protein concentration, kernel weight, and kernels per spike. The families from the mass‐selected population had a 20% greater seed set than the families from the original population and a 73% greater seed set than the inbred lines when treated with the CHA. Inbreds developed from the population had a 45% greater seed set than the conventional inbreds when treated. The increased hybrid seed production was associated with longer spikes and an increase in the number of spikelets per spike. When not treated with the CHA, the mass‐selected group also had grain yield greater than the original population. The results indicate that outcrossing ability can be improved in wheat either directly through selection or indirectly through the use of random‐mating populations.
Source‐Sink Manipulation as a Postanthesis Stress Tolerance Screening Technique in Wheat
Authors: Bruckner P. L. , Frohberg R. C.
Published: July 2010

Success in developing wheat (Triticum aestivum L.) cultivars with improved postanthesis stress tolerance has been limited. Because stress environments are inherently erratic in nature, screening techniques that can be applied in low‐stress environments would be valuable. Postanthesis source limitation was evaluated as a screening technique for postanthesis stress tolerance, under conditions of low plot replication and low within‐plot sampling, in a set of 20 wheat genotypes that were previously shown to vary in postanthesis stress tolerance. Sink size reduction treatments, consisting of a 70% postanthesis surgical reduction of kernel number per spike, were applied in 1982 and 1983 at Fargo and Prosper, ND. The relative increase in kernel weight associated with kernel number reduction treatments, as compared with control treatments, was used to estimate the degree of postanthesis source limitation (SR). Significant variation in SR occurred among environments and among genotypes, but genotype ✕ environment interaction was nonsignificant. Kernel growth was limited an average of 16.4% (genotypic range 7.1–41.5%) by postanthesis source. Variability associated with the technique was high, perhaps due to confounding genotypic effects independent of any stress response. Degree of postanthesis source limitation to kernel growth was not correlated to postanthesis stress tolerance indices determined for this set of genotypes. Determination of postanthesis source limitation does not appear to be a usable technique for routine screening of diverse wheat germplasm for postanthesis stress tolerance due to poor precision, relatively high resource allocation requirements, and a poor association of source limitation and stress tolerance across a wide range of genotypes.
Identification of Four Gossypium sturtianum Monosomic Alien Addition Derivatives from a Backcrossing Program with G. hirsutum
Authors: Rooney William L. , Stelly David M. , Altman David W.
Published: July 2010

Alien chromosome addition lines provide means to distinguish effects of specific alien chromosomes, to detect homoeologies between chromosomes of different species, and to conduct chromosome‐specific introgression. Over the last few years, numerous monosomic addition (MA) stocks were derived from interspecific backcrosses of Gossypium sturtianum J.H. Willis (2n = 2x = 26, C1 genome) with G. hirsutum L. [2n = 4x = 52, (AD), genome] as recurrent parent. Using 10 MA plants of varied pedigrees from this project, our objectives were to (i) identify and characterize different MA stocks, (ii) determine the phenol) pic effect of each addition chromosome, and (iii) estimate the frequency of (AD)1‐C1 recombination. We identified 4 distinct G. sturtianum MA types among the 10 analyzed, and have temporarily designated these as C1‐A, C1‐B, C1‐C, and C1‐D. The C1‐A, C1‐B, and C1‐D MA stocks differed phenotypically from the recurrent parent, while the C1‐C MA stock was phenotypically indistinguishable from the recurrent parent. None of the MA chromosomes was pollen transmissible, but all were ovule transmissible in vivo. Frequencies of ovule transmission from the MA chromosomes ranged 13.7% for C1‐B to 77% for C1‐A. Cytogenetic analyses of the parental stocks and their backcross progenies revealed low but nonetheless increased frequencies of abnormal meiotic chromosomal configurations, possibly due to previous intergenomic recombination, the meiotic disturbances, or both. Genetic data to substantiate recombination have not yet been obtained, but chiasmata were observed at a frequency of 1.7% per meiotic C1 chromosome in the MA stocks, indicating that recombination with chromosomes of G. hirsutum is occurring, albeit infrequently. The establishment and characterization of these four MA stocks will facilitate development of dispersed repetitive genomic probes for the C1 genome, analysis of interspecific C1‐to‐(AD)1 genomic introgression, and the derivation of additional C1 MA stocks.
Growth and Yield Performance of Potato Grown at Three Elevations in Hawaii: II. Dry Matter Production and Efficiency of Partitioning
Authors: Manrique L. A. , Bartholomew D. P.
Published: July 2010

Field data on the growth and yield of potato (Solanum tuberosum L.) are needed for the validation of models of potato growth in tropical environments. A potato genotype ✕ environment experiment was conducted on Mt. Haleakala, Maui, Hawaii, in 1985 at elevations of 91, 282, and 1097 m, and in 1986 at elevations of 91, 640, and 1097 m. The objective was to collect basic data on the effects of environment (primarily temperature) on the patterns of dry matter production and partitioning of the standard north‐temperate cultivats Katahdin, Desiree, Kennebec, and Norchip and the heat‐tolerant clones LT‐I, C14‐343, and CI‐884. Dry weight of plant components and total dry weight per plant (TOT) were measured tuber initiation (T1), T1 + 20 d (T2), and T1 + 40 d (T3). temperatures at 91 m hastened development such that, at T1, TOT was almost 2.0 and 4.0 times greater than at 1097 m for 1985 and 1986, respectively. Overall, tuber dry weight (TU) increased significantly at T2 and T3 as temperature decreased with increasing elevation. Dry matter partitioning to tubers (TU/TOT) generally was highly and significantly correlated with temperature. At T2, 54, 59, 65, and 80% of the variation in TU/TOT for Norchip, Kennebec, Katahdin, and Desiree, respectively, was explained by average minimum temperature from T1 to T2. For the later‐maturing clones LT‐1 and C1‐884, >80% of the variation in TU/TOT also was explained by some measure of temperature during the period T1 to T2, T2 to T3, or both.
Simulation Model for Studying Dynamics of Water Flow and Water Status in Plants
Authors: Fernández C. J. , McCree K. J.
Published: July 2010

Models are useful for visualizing the many complex interactions that occur in plants, and for investigating effects of morphological and physiological attributes on plant performance. Plant Water Dynamics simulates the dynamic variations of plant water status that occur while a plant interacts with the environment. The modeling approach was based on the idea that plant water status depends on the balance of three fluxes: uptake of water from soil, storage of water in plant tissue, and loss of water by transpiration. All three fluxes are calculated directly or indirectly as functions of plant water status, as defined by leaf water potential. At any given time, the sum of all water fluxes is balanced to zero. The model is based on water transport theory and uses the concepts of capacitance, effective leaf area, and morphological homeostasis to calculate the change in organ water fraction per unit change of organ water potential, the leaf area that effectively intercepts radiation, and the increase in xylem cross‐sectional area in proportion to the increase in effective leaf area, respectively. Stress responses control the flow of water through the plant by affecting the conductances of roots, xylem, and leaves. These stress responses are triggered as the water status of soil and plant deteriorate. Original features of the model include the introduction of a storage term into the flux balance, the inclusion of stress effects on xylem as well as root conductances, and the ability to modify stress responses as the plant osmotically adjusts. A sample run simulating transpiration and leaf water potential data for sorghum plants [Sorghum bicolor (L.) Moench] during a single water deficit cycle under controlled environmental conditions showed that the model is a reliable simulation tool. Analysis of each of the model's new features demonstrated that the approach used in Plant Water Dynamics is an improvement over previous models.
Leaf Gas Exchange and Related Leaf Traits among 15 Winter Wheat Genotypes
Authors: Morgan Jack A. , LeCain Daniel R.
Published: July 2010

Many investigations have been conducted during the past few decades to understand the nature of photosynthetic differences among Triticum spp. and related species, yet only limited information on photosynthetic and water use efficiency differences is available among wheat (Triticum aestivum L.) genotypes. The epurpose of this preliminary study was to examine leaf‐gas exchange related leaf traits among winter wheat genotypes in the field to characterize genotypic‐related variation in photosynthesis water‐use efficiency. Fifteen winter wheat genotype, 13 developed in the central and southern Great Plains of the USA and 2 from the USSR, were planted into a Nunn clay loam (fine, montmorillonitic, mesic Aridic Argiustoll) near Fort Follins, CO, in September 1987. Leaf‐gas exchange measurements were performed appoximately weekly on flag leaves of all genotypes from 27 May (early heading stage) through 20 June 1988. Significant genotypic effect were found for photosynthetic rate per leaf area (CER), leaf conductance), (g5leaf water‐use efficiency( WUE8 = CER/g5), the ratio of intercellular [CO2]/ambient[CO2], specific leaf weight, and chlorophyll concentration. Among the genotypes with the lowest water use efficiencies were the two old, large‐leaved Soviet genotypes and the two oldest Great Plains genotypes surveyed ‘Vona’ and ‘Sturdy’. Negative associations of leaf size with CER and WUE8 were mostly due to differencens in leaf size and CER between the relatively small‐leaved Great Plains genotypes and the large‐leaved Soviet genotype. Significant variation for WUE8 among the winter wheat genotypes was due to genotypic‐related differences in both photosynthetic capacity and gs.
Seed Germination in Polyethylene Glycol Solution: Effects of Filter Paper Exclusion and Water Vapor Loss
Authors: Emmerich W. E. , Hardegree S. P.
Published: July 2010

Seed germination under controlled water potentials is commonly investigated in petri dishes containing polyethylene glycol (PEG) solution‐saturate filter paper. Filter paper exclusion of PEG and water vapor loss from unsealed container change the solution water potential from the initial PEG solution potential. The influence of water potential change attributable to PEG exclusion and vapor loss were evaluated with sideoats grama [Bouteloua curtipendula (Michaux) Torrey], buffelgrass [Cenchrus ciliaris L.], Lehman lovegrass [Eragrostis lehmanniana Nees], and kleingrass [Panicum coloratum L.]. Exclusion of PEG by filter paper substrate significantly influenced total germination and germination rate for three of the four species. The absence of a measurable effect on Lehmann lovegrass was attributed to low germination lower water potentials. Oscillating substrate water potentials originating from water vapor losses and subsequent additions produced significantly greater total germination and faster germination rate when compared to a constant water potential. Polyethylene glycol filter‐paper exclusion and water vapor loss from PEG solutions are significant influences that must be considered when conducting seed germination investigations.
Genetic Markers to Locate and Transfer Heterotic Chromosome Blocks for Increased Pearl Millet Yields
Authors: Burton Glenn W. , Werner B. K.
Published: July 2010

The introgression of exotic germplasm by conventional breeding procedures to promote greater heterosis and yield within adapted hybrid cultivars often is a difficult and lengthy process. As part of long‐term investigations, the objectives of this study were to evaluate and use nonlethal genetic markers to locate heterotic chromosome blocks (HCBs) in exotic pearl millet [Pennisetum glaucum (L.) R. Br.] lines, develop methods to use the markers to transfer in the future the selected HCBs to inbred T383, and to increase the yield of ‘Tifleaf 2’ (T85A ✕ T383). The nonlethal dominant R gene for red plant color was used to screen 129 pearl millet near‐isogenic populations for high‐yielding HCBs by measuring height and weight of at least 50 red and 50 green spaced plants in each population. In 27 populations, HCB heterosis [(green — red plant wt)/red plant wt) ✕ 100] ranged from 18 to 61% (P < 0.01). The nonlethal tr gene for the trichomeless condition was used to screen 91 pearl millet populations for HCB heterosis = [(Tr ‐ tr plant wt)/tr plant wt) ✕ 100]. In 52 of these populations, HCB heterosis ranged from 17 to 44% (P < 0.01). The best HCBs are being transferred to inbred T383, the male parent of Tifleaf 2, using the genetic markers R and tr to follow the HCBs during the backcross transfer. The design calls for completing three to four backcross generations per year. When top‐yielding HCBs identified by R and tr become a part of the gene complex of T383, T85A ✕ T383 HCB can be expected to outyield T85A ✕ T383. Plant height measurements were of no value in screening exotic lines for high yielding HCBs.
Leaf Expansion Rate Effects on Emergence and Juvenile Plant Growth in Early‐Maturing Maize
Authors: Cross H. Z.
Published: July 2010

Good stand establishment and vigorous growth in the early spring are attributes desired in most maize (Zea mays L.) hybrids. This field research sought to determine if selecting for higher average leaf expansion rates (ALER) in early maize could improve seedling emergence and juvenile plant growth rates. Two independent groups (GI and GII) of 16 lines were selected from S2 lines previously rated using the formula ALER = (leaf number ✕ leaf length ✕ leaf width ✕ 0.75)/(d to pollination). Within GI and GII, eight lines with high ALER ratings (HER) were paired by source population, year of evaluation, and silking date with eight lines with low ALER ratings (LER). Sets of hybrids were produced by crossing lines from GI with lines from GII so as to represent a 2 ✕ 2 factorial arrangement of ALER hybrid types (HER ✕ HER, HER ✕ LER, LER ✕ HER, and LER ✕ LER). There were 16 hybrids (four hybrids in each of four sets) representing each hybrid type. Combining abilities of S2 lines with differing ALER values were estimated for number of seedlings emerged, vigor ratings and leaf emergence 25 d after planting, and height of juvenile and mature plants. General combining abilities averaged across seven environments indicated that for GI, HER parents were superior to LER parents for all traits. In GII, the HER parents produced hybrids with more emerged leaves and taller juvenile plants than LER hybrids. Significant SCA appeared to be related to maternal differences for number of plants emerged, emerged leaves, vigor rating, and juvenile plant height. Results indicated that using ALER as selection criterion would produce small increases in percent emergence, early vigor ratings, and juvenile plant growth in the populations studied.
Comparison of Three Selection Procedures for Development of Early‐Maturing Soybean Lines
Authors: Byron D. F. , Orf J. H.
Published: July 2010

Northern‐latitude soybean [Glycine max (L.) Merr.] breeders are interested in breeding procedures that will efficiently extract high‐yielding Maturity Group (MG) 0 and MG I genotypes from crosses involving MG II and III parents. The objective of this research was to compare the efficiency of three selection procedures: pedigree, single‐seed descent, and single‐seed descent with early‐maturity selection for extraction of MG 0 and I genotypes. Four populations derived from crosses of parents of MG 00 and 0 with parents of MG II and III were used to evaluate the selection procedures. Twenty‐seven F5 lines of MG I or earlier were selected for each procedure in each population and were evaluated for yield, maturity, plant height, lodging, seed weight, and lengths of the reproductive (R1–R7) and seed filling (R4–R7) periods. No consistent yield advantages were evident for any breeding procedure when the mean yield of all lines, or the top three yielding lines from each maturity set were compared. In addition, no consistent differences were apparent among the selection procedures for maturity, height, lodging, seed weight, or lengths of the R1‐R7 and R4‐R7 periods. Because it required the least resources, the SSDE procedure emerged as the most cost‐effective procedure.
Regulation of Nodule Development in Supernodulating Mutants and Wild‐Type Soybean
Authors: Lee S. H. , Ashley D. A. , Boerma H. R.
Published: July 2010

Nodulation of soybean [Glycine max (L.) Merr.] is regulated factors both internal and external to the plant tissues. This greenhouse study was conducted to further characterize the regulating phenomena originating in the shoots and roots. Grafts were made among three genotypes, wild‐type ‘Bragg’ and two supernodulating (nitrate‐tolerant symbiotic: nts) mutants (nts 382 and nts 246) showed smaller root and shoot growth and greater nodulation than Bragg. In I‐shaped grafts, one shoot of each genotype was grafted onto one mainstem of 7‐d‐old plants of each of the different root genotypes. In Y‐shaped grafts, all possible two‐way combinations of the shoots of the three genotypes were grafted onto two lateral branches of Y‐shaped plants that developed after trimming the shoot apex. Varying the shoot genotypes in the I‐shaped grafts resulted in significant (P < 0.05) differences in shoot dry weight, root dry weight, nodule number, nodule dry weight, and specific nodule activity, but varying the root genotypes had no effect. There were significant (P < 0.05) effects of shoot genotype on the plant dry weight and nodulation characters, and significant (P < 0.05) effects of root genotype on the nodule number in Y‐shaped grafts. In both I‐shaped and Y‐shaped grafts, Bragg shoots increased partitioning of dry matter to the root tissue, whereas nts mutant shoots increased partitioning of dry matter to the nodule. A directional response of nodulation was present in Y‐shaped grafts with greater nodulation occurring on the half of the root system corresponding to the supernodulating nitrate‐tolerant shoots vs. Bragg shoots.
Lipid Concentration and Composition of Soybean Zygotic Embryos Maturing In Vitro and In Planta
Authors: Dahmer M. L. , Collins G. B. , Hildebrand D. F.
Published: July 2010

Reliable methods of culturing isolated immature soybean embryos under stringent environmental controls are available, but have not been used to study factors affecting soybean seed lipid biosynthesis. This study compared the changes in lipid composition during seed maturation in planta and in two in vitro culture systems and evaluated both culture systems for studying the developmental regulation of lipid biosynthesis. Immature soybean [Glycine max (L.) Merr. cv. McCall] embryos from three developmental stages (seed length = 2–3, 5–6, or 8–9 ram) were cultured for 5, 15, or 45 d in LSG (modified Linsmaer‐Skoog salts, 50 g kg−1 sucrose) or SHGM (Schenk‐Hildebrandt salts, 10 g kg−1 sucrose) liquid culture media. Lipid concentrations of the cultured embryos ranged from 10 to 179 g kg−1 dry wt. and were consistently lower than that of mature seed (185 g kg−1 dry wt.). Regardless of stage at excision, the mole percent (mol %) of palmitic and linolenic acids declined and the mol % linoleic acid increased when embryos were cultured in LSG. This pattern is consistent with that observed during maturation in planta. In contrast, the mol % of palmitic and stearic acids increased when embryos were cultured in SHGM and the resulting fatty acid profiles bore little resemblance to those of mature seed. Immature embryo culture in LSG medium provides a viable system for examining lipid biosynthetic processes and, with discriminant function analysis of storage lipid composition, can provide a useful estimate of embryo maturation.
Method to Evaluate Ease of Pericarp Removal on Lime‐Cooked Corn Kernels
Authors: Serna‐Saldivar S. O. , Almeida‐Dominguez H. D. , Gomez M. H. , Bockholt A. J. , Rooney L. W.
Published: July 2010

A simple and effective method to evaluate the ease of pericarp removal on lime (CaO)‐cooked corn (Zea mays L.) has been developed. Corn kernels placed in perforated nylon bags are lime‐cooked for 20 min at 98 to 100 °C and then stained in a solution containing methylene blue and eosine Y. We evaluated 11 corn hybrids grown at seven locations in 1989. The relative ease of pericarp removal was affected by hybrid and by growth environment, with hybrid differences being most important. The method requires a small sample, is rapid, and is ideally suited for ease of pericarp removal in screening large numbers of samples in breeding programs.
Detection of Isoflavones in Seedling Subterranean Clover
Authors: Gildersleeve Rhonda R. , Smith G. R. , Pemberton Indre J. , Gilbert C. L.
Published: July 2010

Reproductive disorders in sheep (Ovis ones) have been linked to ingestion of subterranean clovers (Trifolium brachycalycinum Katzn. & Morley, T. subterraneum L., and T. yanninicum Katzn. & Morley) containing high levels of the phytoestrogenic isoflavones formononetin (7‐hydroxy‐4‐methoxyisoflavone; FM), genistein (5,7,4‐trihydroxyisoflavone; GE), and biochanin A (5,7‐dihydroxy‐4‐methoxyisoflavone; BA). Breeding programs involving subterranean clovers should include selection for low isoflavone concentrations. Our objective was to develop a seedling assay that would predict field levels of FM, GE, and BA in subterranean clover. Five subterranean clover cultivars were grown in the field at Overtoil, TX, over a 3‐yr period (1985, 1986, and 1987); leaf samples were analyzed for FM, GE, and BA. The same cultivars were used to test potential seedling assays. Six seedling growth stages were used: ungerminated seed (UGS), swelled seed (SWS), seedlings after 48 h germination with testa removed (2DAYS), seedlings grown in distilled water for 8 d (8DAYS), seedlings grown in the greenhouse for 42 d (42DAYS), and regrowth harvested 21 d later (REGRO). Tissue samples were extracted with methanol (7 d at 5 °C) and analyzed using high performance liquid chromatography HPLC techniques. Field‐grown samples of each of the cultivars were consistent with previously known values for FM, GE, and BA. Only trace amounts of isoflavones were detected in the UGS and SWS treatments. The 2DAYS and 8DAYS seedling treatments were highly variable and inconsistent in regard to isoflavone content compared with field data for the cultivars. Regression equations using the 42DAYS and REGRO treatments were accurate in their prediction of FM, BA, and total isoflavones in field‐grown subterranean clover. The 42DAYS and REGRO treatments for determining isoflavone content of subterranean clover seedlings could be used to rank germplasm for potential phytoestrogen effects.
Restriction Fragment Length Polymorphisms Can Differentiate among U.S. Maize Hybrids
Authors: Smith J. S. C. , Smith O. S.
Published: July 2010

Previous methods to differentiate U.S. maize hybrids using biochemical data have been criticized on the basis that the genome has been inadequately sampled. The objective of this study was to utilize an additional set of highly polymorphic genetic markers (restriction fragment length polymorphisms; RFLPs) to establish the degree to which these data discriminate among 78 elite maize (Zea mays L.) U.S. hybrids selected with a bias toward including hybrid pairs previously undifferentiated by biochemical data. Thirty‐eight probes revealed 288 RFLP variants across all hybrids. RFLP and biochemical data clustered most hybrids into similar groupings. For those hybrids of known pedigree, distances between hybrids on the basis of pedigree showed a correlation of r = 0.91 with RFLP distances. Where available, field performance data gave identical groupings of hybrids as were shown by RFLP data. These data show that RFLPs can provide a practical means of differentiating hybrids.
Effectiveness of Early‐Generation Selection for Tillering Capacity in Spring Wheat
Authors: Hucl P. , Baker R. J.
Published: July 2010

The tillering process is one of the major determinants of grain yield in wheat (Triticum aestimm L.). A restricted tillering (oligoculm) ideotype has been proposed for maximizing grain yield. This study was conducted to estimate the heritability and effectiveness of selection for tillering capacity in oligoculm and nonoligoculm spring wheat crosses. Eight populations derived from crosses among high tillering ('Neepawa', ‘Ingal’), low tillering (‘Ko Fong’, ‘Siete Cerros’), and oligoculm (M1417) parents were evaluated at Saskatoon, SK. The F1, F2, and the F2‐derived F3, F4, F5, and F6 lines were tested under dryland conditions. The 10 highest‐ and 10 lowesttillering F7 lines from each of the oligoculm crosses were grown under irrigation at Saskatoon and Outlook, SK. Tiller production of F1 hybrids did not differ significantly (P = 0.05) from their midparent values in 16 of 18 hybrid‐environment combinations. Heritability estimates for tillers per plant were, on average, much higher for the oligoculm crosses. At commercial seeding rates, high‐ and low‐tillering F4 lines differed significantly in spikes per square meter in eight out of nine populations. High‐ and low‐tillering selections in oligoculm F4 populations differed, on average, by 19% for spikes per square meter, compared with 12% in nonoligoculm crosses. Limited May and June precipitation during the evaluation of the F, and F6 generations resulted in few (4 of 16) significant differences in spikes per square meter between high‐ and low‐tillering groups. Averaged across 2 yr (1987,1989), the low‐tillering selection group in oligoculm crosses yielded 7% less than the high‐tillering group. Early‐ generation divergent selection for tillering capacity was more effective in oligoculm than in nonoligoculm crosses.
Near Infrared Reflectance Spectroscopy for Analysis of Sugarcane from Clonal Evaluation Trials: I. Fibrated Cane
Authors: Berding Nils , Brotherton G. A. , le Brocq D. G. , Skinner J. C.
Published: July 2010

Determination of quality components is important in assessing the economic merit of clones in sugarcane (Saccharum spp. hybrids) evaluation trials. Laboratory throughput is limiting and analytical costs are high. This research aimed to assess near infrared reflectance (NIR) spectroscopy for analyzing fibrated cane to resolve these problems. A replicated trial provided samples of cane. Quality components were analyzed by routine laboratory methods. Samples of fibrated cane were scanned, using a Technicon 450R NIR spectrophotometer to provide reflectance data (log I/R). Sampling analyses indicated all routine lab determinations were performed with high accuracy relative to plot‐to‐plot variation and subsampling was annecessary. Correlation coefficients (r) obtained for the prediction test for fibrated cane were: Brix (0.91), commercial cane sugar (0.91), conductivity (0.20), fiber (0.89), moisture (0.92), polarimetry reading (0.96), and parity (0.60). Regressions for moisture and pol reading were significantly skewed. The NIR and routine lab analyses did not differ significantly for any component. Precision of NIR analysis compared with routine lab analysis was inferior for all components except purity. Error ratios ranged from 1.3to 3.4. Sampling analyses of spectrophotometer readings (as log 1/R) revealed inadequate sample fibration, mixing, and presentation as potential major sources of error. Analysis of fibrated cane is promising, but insufficiently accurate for advanced selection stages. The substantial operational advantages of fibrated cane analysis warrant further research to resolve the problems described.
Dry Matter Production and Radiation Interception of Potato
Authors: Manrique L. A. , Kinry J. R. , Hodges T. , Axness D. S.
Published: July 2010

The quantification of radiation‐use efficiency (RUE), the amount of dry matter produced per unit of intercepted photosynthetically active radiation, is important for yield modeling and determination of yield potentials in different environments. This study was conducted to determine the mean RUE value of potato (Solanum tuberosum L.) and its stability across diverse environments. Radiation use efficiency was computed with growth analysis data from a field experiment with four cultivars conducted in Hawaii at four elevations, from field experimentation in Washington and Oregon, and from field experiments described in the literature for seven other locations. Radiation‐use efficiency values in Hawaii varied from 2.2 g MJ−1 at 91 m elevation to 2.8 g MJ−1 at 1097 m. Genotype means in Hawaii varied from 2.2 to 2.5 g MJ−1. Comparisons across locations indicated RUE was significantly related to mean daily temperature (r2 ‐ 0.34, n = 12, P < 0.05), vapor pressure deficit (VPD) (r2 = 0.63, n = 12, P < 0.01), and mean total solar radiation (TSR) (r2 = 0.74, n = 11, P < 0.01). Inclusion of either a VPD effect or a solar radiation effect in models of potato growth should improve dry weight predictions.
Light Source and Nutrient Regime Effects on Fiber Composition and Digestibility of Forages
Authors: Jung H. G. , Russelle M. P.
Published: July 2010

The negative correlation between signification of forage plant cell walls and digestibility bas been confounded with growth stage, plant age, or comparison across species. Growth environment was manipulated to alter cell‐wall development in forages to produce experimental materials of the same age for the study of cell‐wall composition effects on digestibility of fiber. Birdsfoot trefoil (Lotus corniculatus L.) and orchardgrass (Dactylis glomerata L.) were grown in sand culture under fluorescent‐incandescent or low pressure sodium (LPS) lamps. Nutrient solution treatments (total, high NH+4:NO−3, high NO−3:NH+4, and low S) were imposed on each forage in each light regime. Four‐week regrowth of leaf and stem plant parts was harvested, lyophilized, and analyzed for detergent fiber components, cell‐wall neutral sugars, uronic acids, esterified and etherified p‐coumaric and ferulic acids, Klason lignin, and lignin nitrobenzene oxidation products. In vitro degradation by a rumen fluid inoculum of detergent fiber components after 48 h of fermentation was determined. Exposure to LPS lamps caused small changes in neutral sugar proportions of the forage cell walls, and in birdsfoot trefoil, plant parts composition of core and noncore lignin shifted. The LPS lamp treatment resulted in higher in vitro degradability of detergent fiber components in birdsfoot trefoil, but depressed degradability of orchardgrass fiber. Nutrient regime caused changes in cell‐wall composition, but these were inconsistent and resulted in minor effects in fiber degradability. Detergent fiber analysis was less sensitive to treatment differences than individual component analysis, and gave different concentration estimates of the same cell‐wall fractions. Explanation of the changes in cell‐wall degradability was not possible based on the compositional data, but rather may require cell‐wall structural analysis.
Kernel Weight Response to Source‐Sink Changes in Spring Wheat
Authors: Blade S. F. , Baker R. J.
Published: July 2010

Field trials were used to investigate the hypothesis that yield of some cultivars of spring wheat (Triticum aestivum L.) may be limited by potential seed size. Eight cultivars, varying in kernel weight from 32 to 46 mg were tested in replicated experiments under dryland growing conditions at Saskatoon in 1985 and 1986. Plot thinning at the six‐leaf stage or at heading was used to increase the supply of photosynthate to developing spikes. Spikelet redaction, by severing spikes between spikelets 10 and 11 at anthesis or 8 or 18 d after anthesis, was used to increase the supply of photosynthate to the remaining spikelets. Flag leaf blade removal at anthesis or 8 or 18 d after anthesis was used to reduce the supply of photosynthate to developing kernels. Significant interaction between cultivar and spikelet reduction treatment in both years indicated that some cultivars were limited in kernel weight because of limited sink size. It was not clear whether greater sink capacity was associated with larger kernels or with semidwarf stature. Yield limitations due to sink capacity are expected to occur rarely under dryland growing conditions.
Selection for Resistance to Aphanomyces euteiches in Red Clover
Authors: Tofte J. E. , Smith R. R. , Grau C. R.
Published: July 2010

Red clover (Trifolium pratense L.) is known to be a moderate host for Aphanomyces euteiches Drechs. Recently, an isolate of A. euteiches (Ae‐572) was observed to be highly virulent on red clover. This research was conducted to determine inheritance of, and select for, resistance to A. euteiches in red clover using an inoculated seedling assay. Resistant and susceptible red clover plants were intercrossed to study the inheritance of resistance. Frequency distributions of resistant and susceptible F1 plants indicated that resistance to A. euteiches is inherited as a quantitative trait. Three cycles of selection for resistance to A. euteiches in red clover resulted in significant improvement in resistance from the original selected population (Cycle 0 = 3.64 mean disease severity index (DSI); Cycle 3 = 2.43 mean DSI). Narrow‐sense heritability estimates were high enough ((h2n = 51% for Cycle 3) to assure that a recurrent selection program utilizing family selection could be used to improve red clover populations for resistance to A. euteiches.
Characterization of Autotetraploid Russian Wildrye Produced with Nitrous Oxide
Authors: Berdahl J. D. , Barker R. E.
Published: July 2010

Poor seedling vigor is a major factor limiting widespread use of Russian wildrye [Psathyrostachys juncea (Fischer) Nevski] (2n 2x = 14) as complementary pasture. Induced polyploidy has been shown to increase plant vigor, particularly seedling vigor, of other diploid species. Objectives of this study were to produce autotetraploids in Russian wildrye using the N2O technique and to ascertain meiotic stability and seedling vigor of induced autotetraploids. Spikes were hand emasculated, pollinated, and treated with N2O at 0.5 MPa pressure from 20 to 44 h after pollination. Putative diploid and autotetraploid progeny were identified from measurements of stoma length, stoma frequency, and pollen grain diameter. Ploidy classification was verified by chromosome counts from microsporocytes. Fifty‐two progeny were obtained from nine crosses, but only 21 were autotetraploid. One plant was aneuploid, with 29 chromosomes. An average of 0.47 trivalent and 1.96 quadrivalent chromosome configurations were observed per cell at metaphase I, indicating the absence or inactivity of genetic factor(s) conditioning bivalent pairing. Seed set averaged 30 and 27% for diploids and autotetraploids, respectively. Emergence from a 5.0‐cm planting depth in a greenhouse test, a measure of seedling vigor, averaged a significant (P ≤ 0.01) 13% higher for autotetraploids than diploids. Nitrous oxide treatment of Russian wildrye resulted in meiotically stable autotetraploid selections with progenies that were superior in seedling emergence to diploid checks.
Heritability of Resistance to Seed Shattering in Kleingrass
Authors: Young Bruce A.
Published: July 2010

Seed shattering and nonuniformity of seed ripening in kleingrass, Panicum coloratum (L.), reduce the quantity of harvestable seed and contribute to diminished seed quality. In this study two populations were derived from an accession of kleingrass (PI 410177) that has superior seed retention. The objective was to determine the heritability of seed retention and the feasibility of developing improved germplasm from these populations. Variation for seed retention (SR) was demonstrated in these populations using a laboratory procedure for measuring SR. Calms were excised from field‐grown plants after pollination, placed in water, and brought to a greenhouse to allow the seed to mature. After 35 d the intlorescences were uniformly agitated and the degree of SR determined. The heritability of SR was measured using parent‐offspring regression. Narrow‐sense heritabilities were similar and low in both populations (0.38 and 0.40), and genotype ✕ environment interactions were a large component of the total variation. This suggests that improvement of seed shattering resistance will be slow and will require replicated testing in multiple environments per cycle of recurrent selection.
Morphological and Agronomic Variation in North African and Arabian Alfalfas
Authors: Smith S. E. , Al‐Doss A. , Warburton M.
Published: July 2010

A long history of cultivation in desert regions of the Middle East has led to the evolution of diverse ecotypes of very nonwinterdormant alfalfa (Medicago sativa L.). However, relatively little is known about variation among alfalfa ecotypes from different regions of the Middle East. Relationships between extant Middle Eastern ecotypes and elite nondormant alfalfas are also not well understood. Both of these factors confound the use and conservation of this germplasm resource. The objective of this study was to develop and use practical numerical analysis procedures to describe variation in representative Middle Eastern alfalfa ecotypes and improved nondormant germplasm. Agronomic and morphological data were collected in southern Arizona over a 2‐yr period from 25 ecotypes from North Africa and the Arabian Peninsula and seven elite cultivars or populations bred in North America using primarily Middle Eastern germplasm. Data were taken on forage yield, stem elongation rate, maturity, response to salinity, aphid population, frost damage, leaf area and shape, internode number and length, and stem and leaf pubescence. These data were subjected to principal components and average linkage cluster analysis. This resulted in classification of the populations evaluated into six phenotypically distinct geographical groupings: northeastern Africa (including all elite populations), the central portion of the Arabian Peninsula, Oman, Yemen, southwestern Saudi Arabia, and the Siwa Oasis in Egypt. Eight country or regional clusters were resolved in further analysis. Significant regional variation was observed within the germplasm evaluated but ecotypes from neighboring countries were generally closely associated. All elite germplasm fell within one cluster and significant divergence from the phenotype common in elite nondormant cultivars and North African ecotypes was observed in germplasm from more isolated regions, especially in southern Arabia. This suggests that only a relatively small portion of the range of variability in Middle Eastern alfalfas has been used in formal breeding.
Genetics of Resistance of CI 15160 Durum Wheat to Biotype D of Hessian Fly
Authors: Weller S. J. , Ohm H. W. , Patterson F. L. , Foster J. E. , Taylor P. L.
Published: July 2010

A genetic study was conducted using the durum wheat (Triticum durum Desf.) Cl 15160 because of its resistance to Biotypes C, D, E, and L of the Hessian fly, Mayetiola destructor (Say). This resistance to Biotypes E and L, currently prevalent in regions in the eastern USA, is potentially useful in the development of resistant cultivars. The objectives of this study were to determine the number of genes conferring resistance to Biotype D in Cl 15160, establish the allelic relationships or independence of these genes to 11 of the named genes that confer resistance to Biotype D, and determine the allelic relationship between the resistance genes in Cl 15160 and those in six durum introductions. A controlled environment chamber was used during infestation. Analyses of progeny rows from random selfed backcross plants, D6647*2/CI 15160, indicated that one, and possibly two genes, control resistance to Biotype D. One of these genes confers a high level of resistance expression, while the second gene may have a low degree of expression. These genes differ from the named genes H5 and H9 through H18 as determined by testcross analysis, but at least one gene may be linked to H16 and possibly H10. The resistance genes in CI 15160 also differ from those in five durum introductions, including H19. At least one gene, however, is either allelic or very tightly linked to a resistance gene in CI 15161. The highly expressed gene in Cl 15160 may be a useful new source of resistance to the Hessian fly.
Strain Specificity of Soybean Mosaic Virus Seed Transmission in Soybean
Authors: Bowers G. R. , Goodman R. M.
Published: July 2010

Seed is a major source of primary inoculum for soybean mosaic virus (SMV) in soybean [Glycine max (L.) Merr.]. Although resistance to SMV seed transmission is known, it is not known if resistance is SMV‐strain specific. Field studies were conducted near Urbana, IL, to determine (i) if differences exist among SMV strains in their ability to be seed transmitted and (ii) whether resistance to seed transmission of one SMV strain holds for all strains. The first study used the soybean lines ‘Midwest’, PI 86146, and PI 181549 (known seed transmitters of the SMV‐G2 strain) and strains SMV G1 to G7 to test whether strains varied in their ability to affect seed transmission, seed coat mottling, seed weight, or seedling emergence. There were no differences among strains for seed weight or seedling emergence. Plants infected with the G5 strain produced seed with a lower incidence of virus transmission than plants infected with the other strains. A soybean line ✕ SMV strain interaction was found for incidence of seed coat mottling. In the second study, ‘Manchu 2204’, ‘Mukden’, and ‘Merit’ (putatively resistant to seed transmission of SMV‐G2) were inoculated with seven SMV strains to determine whether resistance to seed transmission is strain specific. Soybean line ✕ SMV strain interactions were found for seed transmission, seed coat mottling, and seedling emergence. Data indicate that resistance to SMV seed transmission is strain specific and must be considered in breeding programs.