bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Variability for Mineral Elements in Reed Canarygrass1
Authors: Hovin A. W. , Tew T. L. , Stucker R. E. 
Published: July 2010

Genetic variability in forage crops for mineral concentration has not been exploited to correct mineral deficiency or imbalance in plants or feeds. The objectives of this study were to determine gene action for concentration of several major and minor elements and to obtain estimates of K/(Ca + Mg) ratio in reed canarygrass (Phalaris arundinacea L.).Twelve parent clones selected randomly from a broad genetic base and 30 two‐clone crosses of an incomplete diallel were evaluated in small field plots during each of 3 harvest years (one year for N) at two locations to determine genetic variability for mineral concentration. Concentrations of N, P, K, Ca, Mg, Zn, Cu, and Mn were determined in first regrowth forage. Also, the K/(Ca + Mg) ratio was calculated. Most genotypes contained less Ca and Zn than that required to meet the daily needs for a moderately producing dairy cow. The Mn concentration was higher than that usually reported as was the K/(Ca + Mg) ratio.General combining ability was detected (P < 0.01) for all characters, but specific combining ability only for Mn (P < 0.05). Additive genetic variance was present (P < 0.05) for all elements except N, while non‐additive genetic variance was observed only for Mn concentration. Narrow‐sense heritability estimates were moderately high except those for N concentration and K/(Ca + Mg) ratio.The estimated potential ranges of mineral concentration that could be reached through a few cycles of selection indicated that Ca and Zn concentrations could be brought up to the desired level. The K concentration could be reduced considerably barring genetic correlation between K and Ca. The phenotypic correlations involving K, Ca, and Mg were all positive. The K/(Ca Mg) ratio could be genetically maintained in a range of 3.0 ± 0.5 units.Concentrations of maior elements were negatively correlated with forage yield of parent clones and were generally larger than correlations computed for the crosses. Only N and P were significantly negatively correlated with yield in the crosses.
Relationship of Hydroxamate Concentration in Maize and Field Reaction to Helminthosporium turcicum1
Authors: Long B. J. , Dunn G. M. , Routley D. G. 
Published: July 2010

In 1959, the cyclic hydroxamate 2,4‐dihydroxy‐7‐methoxy‐l,4‐benzoxazin‐3‐one (DIMOBA) was first reported maize (Zea mays L.) and has since been implicated in resistance to several pathogens. In our study, 14 inbred lines of maize commonly used as parents of many hybrids in the United States, plus the genotypes BxBx and bxbx were utilized to test the relationship of concentrations of hydroxamates and resistance to Helminthosporium turcicum Pass. in the field. One set of the 16 inbreds was analyzed for hydroxamates nondestructively by a rapid procedure using steam tissue from seedlings 36 to 40 cm high. The same set of inbred lines was similarly analyzed at mid‐silking stage by Hamilton's procedure using leaf tissue. A second set of the 16 inbred lines was inoculated in the field with spore suspensions of H. turcicum and evaluated for resistance at mid‐silking stage using a visual rating scale.A highly significant correlation (r = 0.76, dr. = 43) was obtained between concentrations of hydroxamates in stem tissue from the seedlings and hydroxamate concentrations in leaf tissue at mid‐silking stage. A significant correlation (r = 0.57, dr. = 46) was obtained between concent.rations of hydroxamates in seedling stem tissue and resistance to H. turcicum. Similarly, a highly significant correlation (r = 0.64. df. = 43) was obtained between hydroxamate concentrations in leaf tissue of inbreds at mid‐silking stage and resistance to H. turcicum.
Seedling Growth of Smooth Bromegrass Measured in Five Environments1
Authors: Tan Geok‐Yong , Tan Wai‐Koon , Walton P. D. 
Published: July 2010

Nine cultivars of smooth bromegrass (Bromus inermis Leyss.) were grown in four controlled environments in the greenhouse and growth room and one field environment. The four controlled environments were high light and high temperature, high light and low temperature, low light and high temperature, and low light and low temperature. Each environment was planted as complete blocks with nine cultivars assigned at random into each of the four blocks. Four harvests at 1‐week intervals were sampled at random within each cultivar with the first harvest commencing at the two‐leaf stage. The studies were confined to seedlings sampled within 2 months of seedingSignificant differences in tiller number, leaf number and area, seedling dry weight, specific leaf weight (SLW), shoot to root ratio (S/R), relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR) were found among bromegrass cultivars and environments. ‘Carlton’ and ‘Manchar’ generally produced the largest number of leaves and tillers, largest leaf area, greatest seedling dry weight, and greatest RGR and NAR among the nine cultivars. ‘Blair’ and ‘Lyon’, in most cases, were the poorest entries.Sed weight was correlated positively with leaf number (0.28 to 0.65), leaf area (0.48 to 0.78), and seedling dry weight (0.38 to 0.79) but was correlated negatively with SLW (—0.15 to —0.67) in all growth stages and environments. The results suggested that increasing seedling vigor at the early growth stage in smooth bromegrass can be achieved by screening breeding material on the basis of seed weight. Furthermore, the correlations between RGR and NAR were highly significant (in most cases, r > 0.90) and persisted throughout the environments studied indicating that cultivar differences in RGR were attributed more to NAR than LAR. Selection for high NAR at the later seedling growth stages (2 months old or more) is suggested as an important parameter in improvement of smooth bromegrass
Effect of Root Temperature on Dry Matter Distribution, Carbohydrate Accumulation, and Acetylene Reduction Activity in Alfalfa and Birdsfoot Trefoil1
Authors: Barta A. L. 
Published: July 2010

Although birdsfoot trefoil (Lotus corniculatus L.) is a legume better adapted to poor or marginal soils than is alfalfa (Medicago saliva L.), reduced carbohydrate storage in roots and increased susceptibility of trefoil to roots and crown diseases in warm climates results in poor persistence. The objective of this study was to examine the effect of high root temperature on carbohydrate content and acetylene reduction activity in alfalfa and trefoil during regrowth.A total of six samplings of each species grown at 16 and 30 C root temperatures were made at flowering and 2 weeks later during regrowth. Dry matter distribution, total nonstuctural carbohydrate (TNC) accumulation, N concentration, and acetylene reduction activity of roots were measured in plants grown in sand with nutrient solution.High root temperature resulted in significantly reduced total plant or root dry weight only in alfalfa at flowering. However, trefoil root TNC was significantly lower at 30 C at both growth stages and was only 4.3% on a dry weight basis 2 weeks after cutting. It appeared that trefoil root carbohydrate concentration is influenced by root temperature as well as air temperature, thus helping explain why trefoil often fails to persist in warm climates.Both total plant N and rate of acetylene reduction at flowering were much greater for alfalfa than for trefoil. Rates of acetylene reduction were significantly reduced by high root temperature only in alfalfa. Total plant N was affected much less than was acetylene reduction activity at 30 C in both species.
Seedling Growth of Cicer Milkvetch in Controlled Environments1
Authors: Townsend C. E. , Wilson A. M. 
Published: July 2010

Seedling growth of cicer milkvetch (Astragalus cicer L.) is relatively slow and must be improved before the species can become a valuable forage crop. Therefore, our objectives were (a) to determine the effects of temperature on seedling growth of a seed source with a broad genetic base, and (b) to determine the variability among polycross progenies for seedling growth measurements. Seedlings were grown in controlled environmental chambers at 20 C day and 15 C night temperatures (20‐15 C), at 25 C day and 20 C night temperatures (25‐20 C), or in the greenhouse.In the analysis of growth over a 42‐day period, seedlings at the two temperature treatments in the growth chambers differed significantly for relative growth rate (RGR), leaf area ratio (LAR), and net assimilation rate (NAR). Seedling growth was most rapid at the 25‐20 C treatment. Except for NAR at 25‐20 C, growth periods within both temperature treatments differed significantly for RGR, LAR, and NAR. Simple correlation coefficients between shoot weight, root weight, total weight, shoot height, leaf area, and number of leaves were significant and ranged from 0.91 to 0.99 for each treatment. This suggests that any one of the traits studied would be a reliable indicator of seedling vigor.Significant differences occurred among environments for height, weight, number of leaves, and multileaflet position for seedlings of 22 polycross progenies. Within most environments there also were significant differences among progenies for these traits. The two growth chamber treatments provided better environments for selection of seedling vigor than did the greenhouse. We believe that environmental growth chambers, along with field testing, can be used effectively to improve the seedling vigor of cicer milkvetch.
Genetic Control for Percentage Groat Protein in 424 Advanced Generation Lines From an Oat Cross1
Authors: Iwig M. M. , Ohm H. W. 
Published: July 2010

A population of 424 advanced generation lines from an oat (Avena spp.) cross between high and low protein parents was developed in a hierarchy of families and lines with certain genetic relationships. Genotypic variances were estimated and partitioned into components due to additive, dominance, and additive X additive genetic effects for several traits.Additive genetic variance was significant for heading date, plant height, percentage groat protein (groat protein), seed yield, and groat weight. Dominance was not significant for any of the traits. Additive ✕ additive genetic variance was significant for groat protein and seed yield. Within several F2‐derived families, large differences in F6 were shown between F3‐derived families and between F4 lines within F2‐derived families for groat protein and seed yield. These large differences may be due to cytological abnormalities occurring when A. sativa L. gennplasm is crossed with A. sterilis L. germplasm causing large intact segments of chromosomes to segregate intead of random recombination.Small but significant correlations of 0.21, 0.15, −0.27, 0.23, 0.10, and −0.34 were shown between heading date and plant height, heading date and groat protein, heading date and groat weight, plant height and groat protein, plant height and groat weight, and seed yield and groat protein, respectively. Several agronomically desirable lines were identified from the population of 424 lines. These lines demonstrated that the negative correlation between seed yield and groat protein can be broken to some degree. Some genes for high groat protein from A. sterilis appear to have been transferred into good yielding, agronomically acceptable lines.
Genetic Control of Hypocotyl Pigmentation among White‐Flowered Soybeans Grown in Continuous Light1
Authors: Palmer R. G. , Payne R. C. 
Published: July 2010

Seedlings of 64 white‐flowered soybean (Glycine max L. Merr.) plant introductions, cultivars, and genetic lines were grown in continuous light of 505 μEm−3S−1. Tawny (T _ Td _) pubescent genotypes (22 samples) and light‐tawny (T _ td td) pubescent genotypes (20 samples) had bronze pigmentation on the hypocotyl shortly after emergence. Gray (t t Td _ or t t td td) pubescent genotypes (22 samples) had no detectable bronze pigmentation.Reciprocal F1 hybrids of tawny pubescent plants and gray pubescent plants had bronze hypocotyl color and tawny pubescence. In the F2 generation, plants with bronze hypocotyl color invariably had tawny pubescence, while all plants with green hypocotyls had gray pubescence. The T locus has a pleiotropic effect on hypocotyl color and on pubescence color which was detected in white‐flowered soybeans. This relationship was constant in all tested populations and suggests a simple, rapid, and inexpensive method of detecting certain off‐types in whiteflowered soybean populations at the seedling stage.
Divergent Mass Selection for Ear Length in Maize1
Authors: Cortez‐Mendoza Hernan , Hallauer A. R. 
Published: July 2010

Mass selection for increased and decreased ear length was conducted in ‘Iowa Long Ear Synthetic’ of maize (Zea mays L.) for 10 generations. Evaluation trials of the selected populations were conducted in five environments, and measurements were made for ear length and eight other plant and ear traits. The objectives of the study were to determine the direct and correlated responses for 10 cycles of divergent mass selection for ear length in Iowa Long Ear Synthetic.Direct response to 10 cycles of divergent mass selection for ear length was asymmetrical. The predicted and realized responses for increased ear length were nearly the same. Realized response for decreased ear length, however, was twice as great as for increased ear length. It seemed that unequal gene frequencies and directional dominance of genes affecting ear length were responsible for the asymmetry observed for ear length.The correlated responses of grain yield per plant, ear diameter, kernel depth, ear height, and days to silking also were asymmetrical. Selection response for increased ear length was not accompanied by a correlated response in grain yield per plant. Selection response for decreased ear length, however, was accompanied by a significant response for decreased grain yield per plant. A significant decrease in kernel depth with selection for increased ear length caused the lack of yield response with selection for increased ear length. Other correlated responses to selection for increased ear length were taller plants, later silking, and decreased diameter. Selection for decreased ear length resulted in shorter plants, but there was no change in days to flower, ear diameter, and kernel depth. Selection for increased ear length was not effective for increasing yield.
Relative Efficiencies of Population Improvement Methods in Corn: A Simulation Study1
Authors: Choo T. M. , Kannenberg L. W. 
Published: July 2010

The relative selection gains per year of three breeding methods (mass, modified ear‐to‐row, and S1 selection) for corn (Zea mays L.) population improvement were simulated for additive and complete dominance genetic models. The character was assumed to be controlled by 20 major (genotypic value of A = 2) and 20 minor (A = 1) genes with half of the genes of each type at an initial frequency of 0.5 and half at a frequency of 0.1. Genes were independently assorted. Selection intensities of 0.05 and 0.25 (or equivalent), and heritabilities of 0.2 and 0.6 were used~ The population size was 400. The half‐sib families in modified ear‐to‐row selection were evaluated in a four‐replication trial, and the S1 progenies were tested in a 10‐plant plot with four‐replications.Our studies indicated that S1 selection would be more efficient than the other two methods, provided that a winter nursery is used to shorten the cycle to 2 years. At the high heritability (0.6), mass selection was more effective than modified ear‐to‐row selection, but the latter was more effective under the low heritability. Genotypic variances decreased in all cases as selection proceeded, but the decrease was most rapid under S1 selection. About 14 cycles of S1 selection exhausted the genotypic variance at the high heritability and high selection intensity. The results also suggested that an S1 progeny evaluation trial with 10‐plant plots and four replications is adequate for improving population performance.
Cold Tolerance of Maize Inbred Lines Adapted to Various Latitudes in North America1
Authors: Mock J. J. , McNeill M. J. 
Published: July 2010

We evaluated cold‐tolerance responses [measured by percentage emergence (30 days after planting), emergence index (an estimate of emergence rate), and seedling dry weight (sampled 42 days after planting)] of 34 maize (Zea may L.) inbred lines adapted to various latitudes in North America. Evaluations were performed in field experiments planted in early April at Ames and Algona, Iowa, in 1974 and 1976. Objectives of our study were: i) to assess genetic variability and breeding potential for improvement of cold tolerance within maize germplasm adapted to North America, ii) to study associations of cold‐tolerance traits with other plant traits (including grain yield), and iii) to examine relationships between geographical locations of origin and cold‐tolerance responses of inbred lines adapted to North America.We observed large amounts of variability for each of the three cold‐tolerance traits. Means ranged from 27.5 to 82.9% for percentage emergence, 20.0 to 24.0 days for emergence index, and 0.33 to 1.16 dg for seedling dry weight; respective heritability estimates were 0.85 ± 0.06, 0.72± 0.06, and 0.80 ± 0.06. Genotypic correlations among the three traits were high, suggesting selection for improved cold tolerance (as an aggregate of the three traits) should be possible. Environments and genotype ✗ environments mean squares were highly significant; therefore, evaluations of cold tolerance of maize inbred lines should be conducted in more than one environment.Correlations of all three traits with juvenile plant height and leaf number (measured in early July), 50% silk emergence, mature plant height, and grain yield usually were low. Thus, seedling cold tolerance was not associated with vegetative vigor of juvenile plants, flowering date, or mature plant height. Seedling dry weight, however, was significantly correlated with grain yield (r = 0.48**), indicating good seedling vigor was related to high grain yield.Cold‐tolerance response generally was not related to geographical location of adaptation; however, 9 of the 10 best inbred lines were adapted to the central latitudes of the U.S. Corn Belt. Inbreds from the northern and southern regions ranked average or lower for cold tolerance. The three best cold‐tolerant inbreds were B73, (V3 x B14)‐2‐1 (both from Iowa), and Mo 17 (from Missouri). Breeding populations developed from the best inbreds in our study should contain gene complexes for good cold tolerance, plus variable flowering dates, plant heights, and grain yields.
Inhibition of Chlorophyll Synthesis by Pseudomonas glycinea1
Authors: Gulya T. , Dunleavy J. M. 
Published: July 2010

Soybean (Glycine max L.) cotyledons treated with toxin extracted from culture filtrates of Pseudomonas glycinea formed significantly less chlorophyll and aminolevulinic acid (ALA), a precursor of chlorophyll, than control cotyledons. The toxin induced a comparable reduction in the percentage of ALA and chlorophyll, which suggests that chlorosis produced by P. glycinea toxin results from an inhibition of some step at, or prior to, ALA synthesis.Toxemia‐affected trifoliate leaves of infected soybean plants were chlorotic and smaller than similar leaves of control plants. The toxin‐affected leaves did not differ significantly from control leaves in percentage of pheophytin, a chlorophyll degradation product, nor in the chlorophyll a:b ratio. Thus, chlorosis in toxemia‐affected leaves appears to be due to an inhibition of chlorophyll synthesis rather than an accelerated rate of chlorophyll degradation.
Effects of Powdery Mildew on Yield and Quality of Isogenic Lines of ‘Chancellor’ Wheat1
Authors: Johnson J. W. , Baenziger P. S. , Yamazaki W. T. , Smith R. T. 
Published: July 2010

The effect of powdery mildew (Erysiphe graminis DC. f. sp. tritici E. Marchal) infection on yield, and milling and baking quality was determined under natural field conditions. Near‐isogenic lines of ‘Chancellor’ wheat (Triticum aestivum L.), involving at least seven independent genes for resistance to powdery mildew, were grown at College Park and Queenstown, Md. in 1974 and 1975. A regression equation was determined to predict the effects of disease severity on yield.The severity of powdery mildew infection varied among years and locations. Chancellor yielded 34% less than the average yield of the resistant lines. Yield was negatively correlated with percent powdery mildew on the whole plant and on the flag leaf (r = ‐0.78** and −0.80**, respecively). The regression equation of yield in q/ha (Ŷ) on percent powdery mildew on the flag leaf was Y = 33.4 − 0.18 X, r2 = 0.65**. The gene in ‘Michigan Amber’ and the three Pm 3 genes were highly effective in reducing infection.The isolines differed significantly for percent flour protein, cookie diameter, and adjusted cookie diameter when grown under severe powdery mildew infection. The lines with the highest disease rating also had the lowest flour protein content. Percent flour protein was negatively correlated with percent powdery mildew on the whole leaf and the flag leaf (r = −0.77** and −0.80**, respectively). However, severe powdery mildew infection did not adversely affect the over‐all baking quality. Milling quality (flour yield and flour ash percent) was not affected by the severity of powdery mildew infection.
Root and Shoot Formation from Callus Cultures of Tall Fescue1
Authors: Lowe Karen W. , Conger B. V. 
Published: July 2010

The objectives of this study were to: i) initiate and maintain callus cultures of tall rescue (Festuca arundinacea Schreb. cv. Ky 31); ii) determine the frequency of root and shoot formation after different periods of subculture, iii) establish actively growing plants from these cultures. Calli were initiated from mature embryos on a modified Murashlge and Skoog (MS) medium containing 9 mg/liter of 2,4 dichlocophenoxyacetic acid (2,4‐D). After 28 days, the calli were transferred to a fresh MS medium containing 5 mg/liter of 2,4‐D and incubated for another 28 days before subculturing and testing for root and shoot formation. At this time, each callus was divided and one piece maintained on MS medium with 5 mg/liter of 2,4‐D and another piece placed on a medium with 0.5 mg/liter of 2,4‐D to test for root and shoot formation. This procedure was repeated for two additional subcultures at 28‐day intervals.Results based on more than 800 calli showed that the frequency of calli forming roots was about 45% regardless of number of subcultures. The frequency of calli forming shoots, however, decreased with increasing number of subcultures from 9.6% for the first subculture to 3.1% for the third subculture. A similar decrease was also noted for caili exhibiting both shoot and root formation. The identity of each callus was maintained throughout the entire period from initial plating of the embryo to the final subculture. Of 150 individual calli forming shoots, only 14 did so during more than one subculture period. Only one callus source exhibited shoot formation on all three subcultures. Plantlets and actively growing plants were easily established from calli with shoot formation.