bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Nuclear Genetic Resistance in Maize to Race T of Southern Corn Leaf Blight
Authors: Johnson G. R. 
Published: July 2010

Two maize (Zea mays L.) inbred lines, in Texas malesterile cytoplasm (Tcms), with high levels of nuclear genetic resistance to race T southern corn leaf blight (Helminthosporium maydis Nisikado and Miyake) were derived by selfing and selection from two open‐pollinatedcomposite sources. The lines were confirmed to be in Tcms and were utilized in crosses with an extremely susceptible Tcms line in two generation‐mean analysis experiments.Resistance was polygenic, and additive genetic effects accounted for most of the variation among generations. Dominance effects accounted for a small but significant portion of the genetic variance in both experiments.The results suggest that gene frequencies for resistance could be enhanced by recurrent mass selection. In a program for development of commercial hybrids, selection should be practiced in male‐sterile cytoplasm in two unrelated source populations. Lines would be extracted by inbreeding and crossed. Resulting hybrids would be evaluated for disease resistance, agronomic suitability, and yield.
Awned vs. Awnless Isogenic Winter Barley Grown at Three Environments1
Authors: Shannon J. G. , Reid D. A. 
Published: July 2010

Four pairs of homozygous winter barley (Hordeum vulgare L.) lines, isogenic for full‐awned and near‐awnless, and their respective recurrent parents were grown at Quantico, Md.; Hagerstown, Md.; and Tucson, Ariz. in 1973.The awned isogenic line showed a more consistent and significant yield advantage over the awnless isoline in each of the four genetic backgrounds under the irrigated, Arizona conditions than under Maryland conditions. At Hagerstown, where lodging was severe, and at Quantico where scald [Rhynochosporium secalis (Oud.) J. J. Davis] was present, the awned isogenic lines yielded more than their awnless counterparts in six of eight instances suggesting the importance of awns where photosynthesis is reduced due to lodging or disease.The advantage of the awned vs. awnless isogenic pairs was more consistently expressed in test wt/hl and kernel wt than in yield. The greatest advantage of awns for test wt and kernel wt was shown under the irrigated (Arizona) environment. In general the isogenic pairs did not differ in heads/unit area or kernels/spike.
Linkage and the Synthesis of Better Genotypes in Self‐fertilizing Species1
Authors: Bailey Theodore B. , Comstock R. E. 
Published: July 2010

The basic task of the breeder of self‐fertilized species is the aggregation of superior alleles in a single pure line or cultivar. This study focused on the model problem of collecting into one line all the favorable alleles present in one or the other of any pair of pure lines. Background theory and simulation data are presented. The breeding procedure investigated involved intra‐line selection during the formation of single seed descent lines from an F2, followed by selection among the derived lines. We also considered recurrent use of the procedure; two selected lines from one cycle being crossed to provide the F2 base for the next cycle. Simulation was used to investigate the effect of genetic linkage on response to selection as reflected by probabilities of fixation of favorable alleles. As was to be expected, our data show that those probabilities are decreased by repulsion but increased by coupling linkages among the superior alleles. It follows that the impact of linkage depends on the way in which the superior alleles present in one parent line but not in the other are distributed among and within linkage groups. Assuming this to be random, our results indicate that, when parent lines are about equal in genetic value, the balance between repulsion and coupling will be such that linkage will have little effect on the average probability of fixation. However when one parent line is substantially better than the other, there will be more coupling linkage and the average probability of fixation will be increased. Nevertheless the average genetic value of selected lines will be less than or, at best, little above the level of the superior parent lineWe conclude that the full genetic potential of a two line gene pool is not likely to be achieved by the selection system described. Two systems believed superior to the one on which this study was focused are discussed. Both require increases in the proportion of seed produced by cross‐pollination but this may be justified by the associated potential for genetic improvement.
Acid Invertase Activity in Kernels of Normal and Opaque‐2 Corn at Different Growth Stages through Maturity1
Authors: Fullerton S. G. , Svec L. V. 
Published: July 2010

Acid invertase activity in the placento‐chalazal tissue of developing corn (Zea mays L.) kernels was measured from 23 to 49 days after pollination. Because sucrose, the transported saccharide in corn, is thought to be converted by acid invertase to glucose and fructose before passing into the developing endosperm, acid invertase activity of the placento‐chalazal tissue during kernel‐fill period may be a useful index of maturity and potential productivity, as well as an indicator of yield difference among genotypes.Ten single cross corn hybrids were grown in the field near Middletown, Del., in 1973, including five normal endosperm hybrids of varying relative maturity and their sister hybrids with opaque‐2 (o‐2) genotype. Daily high and low temperatures and rainfall were recorded for the growing period. At 23 to 49 days post‐pollination, kernel samples were harvested, lyophilized, and acid invertase activity of the placento‐chalazal tissue determined.Pioneer Brand hybrids 3570, 3516, and 3387 had significantly higher levels of acid invertase activity than did Pioneer Brand hybrids 3369 A and 3306, but no differences in acid invertase activity were found between normal and o‐2 hybrids. During the period from 23 to 37 days post‐pollination, acid invertase activity decreased, then the activity increased sharply from 37 to 39 days and decreased but more slowly during the 39 to 49 day period. The o‐2 hybrids had lower yields than did the normal genotype hybrids, even though the acid invertase activity was very similar in the paired comparisons. Acid invertase activity in the placental‐chalazal tissues did not appear to be limiting yield of these hybrids.
Combining Ability for Seedling Dry Weight and Forage Yield in Cicer Milkvetch1
Authors: Townsend C. E. 
Published: July 2010

Polycross progenies of plants from three selected populations of cicer milkvetch, Astragalus cicer L., were evaluate for combining ability for seedling dry weight in the greenhouse and for forage yield in the field. Parental plants were selected for high vigor, low vigor, or large seed. The large‐seeded group was average or above average for vigor. About 80 progenies were evaluated in the greenhouse and at two field locations. In another study 45 progenies were evaluated at one field location.Seedling dry weight of the progenies in the greenhouse ranged from 19 to 118% of the reference progeny which had been selected for high seedling emergence in the field. Only one progeny was significantly better than the reference and it was from the large‐seeded group. Of the 19 progenies that did not differ significantly from the reference, one was from the low‐vigor, five from the large‐seeded, and 13 from the high‐vigor population.In field studies the frequency of high‐yielding progenies was higher in the high‐vigor and large‐seeded populations than in the low‐vigor population through the second year. However, in one study that was conducted for 3 years, the performance of the low‐vigor population was much better in the third year while that of the large‐seeded population was relatively poorer. In general, genetic variation within cicer milkvetch for seedling dry weight and forage yield appeared sufficient to permit improvement of these characters.
Hypocotyl Diameter as a Predictive Selectin Criterion in Sugarbeet1
Authors: Doney D. L. , Theurer J. C. 
Published: July 2010

Investigations concerning sugarbeet (Beta vulgaris L.) seedling characters and field root yield suggested a relationship between seedling hypocotyl diameter and root yield. This report deals with the hypocotyl diameter character and its relation to root yield, its genetic characteristics and its use as a selection criterion.The hypocotyl diameter of 3‐week‐old seedlings was measured with a micrometer caliper (graduations of 0.01 mm). Seedlings were grown in vermiculite in growth chambers and watered daily with equal amounts of nutrient solution. Hypocotyl diameter measurements were significantly correlated with root yield (0.70, 0.73, and 0.76) in three separate field trials. Significant heterosis for this character was observed in 14 of 18 crosses. In a six‐female ✕ three‐male sib analysis, general and specific combining ability and estimates of the proportion of additive to non‐additive genetic variance were similar for root yield and hypocotyl diameter. Selection of individual plants in heterozygous populations significantly increased the hypocotyl diameter of 3‐week‐old seedlings. The expected rate of increasing root yield (relative selection efficiency) when selecting for this character was 1.46 relative to selecting for root weight of space‐planted beets. These data suggest that this character could be an effective selection criterion for increasing root yield in sugarbeet.
Genetic Variation in Stomatal Length and Frequency and other Characteristics in Bromus inermis Leyss.1
Authors: Tan Geok‐Yong , Dunn G. M. 
Published: July 2010

Genetic variation in stomatal length and frequency was investigated in 10 single crosses of a half‐diallel cross involving five bromegrass (Bromus inermis Leyss.) genotypes.The diallel analyses revealed much higher general combining ability (GCA) than specific combining ability (SCA) for all characters. The SCA was not significant for any character. Relatively high narrow‐sense heritability estimates were obtained for stomatal length (0.69) and frequency (0.85) and for other leaf characters. General combining ability effects of the parental clones were also estimated for all characters. Negative genotypic correlations were obtained between stomatal length and stomatal frequency of the same leaf. The phenotypic and genotypic correlations obtained between stomatal characters and other traits showed that stomatal length was positively while stomatal frequency was negatively correlated with leaf length, width, area, and tiller dry weight. These data indicated that selection for larger and fewer stomata should tend to result in longer and wider leaves of larger areas and greater tiller dry weight. None of the characters under study was associated with the spaced plant yield.
Timing of Glyphosate for Conversion of Bermudagrass Turf to Tall Fescue1
Authors: Johnson B. J. 
Published: July 2010

Renovation of bermudagrass [Cynodon dactylon (L.) Pers.] turf to tall rescue [Festuca arundinacea Schreb. ‘Kentucky 31’] is a major problem since soil fumigation is usually necessary to completely kill the existing turf. This study was conducted to determine if bermudagrass could be controlled with a fall application of glyphosate [N‐(phosphonomethyl) glycine] and the turf successfully reestablished by over‐seeding with tall rescue without disturbing the soil surface. Herbicidal treatments were applied 0, 1, 5, or 10 days before overseeding, and 1, 5, or 7 days after overseeding.Bermudagrass ground cover was reduced most after 1 year where glyphosate was applied any time before overseeding in fall 1973 (1 to 4% ground cover), and l0 days before overseeding in fall 1974 (6% ground cover). After the second growing season, bermudagrass ground cover ranged from 9 to 18% cover. Glyphosate treatments did not injure tall rescue either year when applied 1, 5, or 10 days before overseeding. Glyphosate applied as a single treatment significantly reduced bermudagrass ground cover, but did not give complete control.
Effects of Recurrent Selection for Crushing Strength on Morphological and Anatomical Stalk Traits in Corn1
Authors: Chang H. S. , Loesch P. J. , Zuber M. S. 
Published: July 2010

Twelve morphological and anatomical traits were evaluated in two synthetics of corn, Zea mays Lo, which had undergone selection for high and low crushing strength. The two synthetics were represented by third cycle selections designated ‘MoSQ A‐High,’ ‘MoSQ A‐Low,’ and ‘MoSQ B‐Low.’ The study was conducted to determine whether selection for stalk strength resulted in corresponding changes in one or more anatomical traits. Most of the traits evaluated were affected by selection. Significant differences, however, were not detected among the four sub‐populations for rind density. Multiple regression coefficients indicated that stalk density and rind density were relatively less important than rind weight and area of rind in predicting rind crushing strength. The area of vascular bundles, the area of lignification, and the we;.ght of rind and stalk section were correlated with rind crushing strength responses to selection.MoSQ A and MoSQ B were similar in stalk strength, but derived their essentially equal strength in different ways. MoSQ A had greater number of vascular bundles than MoSQ B, and vascular bundle number was greater for the high than for low selections. MoSQ B had more lignification per vascular bundle than MoSQ A, and the lignified area in the rind was correlated with crushing strength. We concluded that populations may differ in the particular array of anatomical traits that contribute to stalk strength. Nevertheless, strength in this study appeared to reside principally in the rind tissue.
Inheritance and Interrelationships of Grain Yield and Selected Yield‐Related Traits in a Hard Red Winter Wheat Cross1
Authors: Sidwell R. J. , Smith E. L. , McNew R. W. 
Published: July 2010

The parents, F1, F2, and backcrosses derived from two hard red winter wheat (Triticum aestivum L. em Thell.) cultivars were studied in a field experiment grown on the Agronomy Research Station at Stillwater, Okla., during the 1971‐1972 crop season. Data were taken on individual plants to estimate gene action, heritability, and interrelationships of grain yield and selected yield‐related traits. Characters studied were 1) grain yield, 2) tiller number, 3) kernel weight, 4) kernels/spike, 5) spikelets/spike, and 6) kernels/spikelet. The direct and indirect effects of characters 2, 3, and 4 on grain yield were also studied.Additive and dominance variances were much smaller than the environmental variance for each character except kernel weight. Kernel weight, tiller number, and spikelets/spike displayed rather high broadsense herRabilities while kernel weight was the only character to display a high narrow‐sense estimate. Other heritability estimates ranged from intermediate to low. On the basis of gene action and heritability estimates, direct selection to improve a trait, should be more effective for kernel weight than for any of the other traits.Tiller number had a high positive phenotypic correlation and an intermediate genetic correlation with grain yield. Phenotypic correlations of kernel weight and kernels/spike with grain yield were intermediate and low, while their genetic correlations were low and intermediate, respectively. Negative associations observed between kernel weight and tiller number and between kernel weight and kernels/spike suggests that simultaneous improvement of these characters will be difficult. Large positive phenotypic and genetic correlations were observed between kernels/spike and spikelets/spike and between seeds/spike and kernels/spikelet.Path coefficient analyses at the phenotypic level indicated that the direct effect of tiller number on grain yield was large while the direct effects of kernel weight and kernels/spike were intermediate and low, respectively. At the genetic level, the direct effect of each component was intermediate and about equal in magnitude. This implies that the large direct effect of tiller number at the phenotypic level was due largely to nonadditive genetic or environmental effects or both.The results of this study indicated that selection for kernel weight in early generations is the most important factor in a breeding program for increasing grain yield. Tiller number makes a greater contribution toward grain yield but is much more difficult to improve by selection in early generations.
Association of Genotype ✕ Environment Interactions with Performance Level of Soybean Lines in Preliminary Yield Tests1
Authors: Baihaki Achmad , Stucker R. E. , Lambert J. W. 
Published: July 2010

This study was conducted to determine the relationship of genotype ✕ environment interaction to yield level (high, medium, or low) of preliminary yield test materials. Forty‐four soybean (Glycine max L. Merr.) breeding lines and four cultivars were tested at three locations in each of 2 years and were categorized into high, medium, and low‐yielding groups. Genotype ✕ environment interactions were estimated within each group and over all lines. Stability parameter estimates were computed for the lines as an assessment of stability of each group.About 50% of the total genotype ✕ environment interaction for yield was contributed by the low yielding group, 25% by the medium yielding group and 25 by the high yielding group.The regression of stability parameter estimates (b values) on mean yield of the lines was positive and highly significant (r2 = 0.26). In general, the medium‐yielding group of lines was the most stable and the low‐yielding group was the least stable.Selecting the best one‐third of the lines in any of the single‐environment tests identified 11 of the top 16 lines based on means from all tests. Further, in each environment four or five of the five highest yielding lines (over all environments) were identified. We conclude that single environment preliminary yield tests can be used without serious risk of discarding outstanding lines.
Inheritance of Resistance to the Wartelle Race of Root‐knot Nematode in Soybeans1
Authors: Boquet D. , Williams C. , Birchfield W. 
Published: July 2010

The inheritance of root‐knot nematode (RKN) [Meloidogyne incognita (Kofoid and White) Chitwood] resistance in soybeans [Glycine max (L.) Merr.] was studied in the F1, F2, and F3 generations of a cross between resistant D69‐6344 and susceptible D69‐8178.Resistant and suspectible parents gave a consistent reaction to RKN regardless of inoculum density. F1 plants, however, were moderately resistant under low RKN densities, moderately susceptible under medium densities, and highly susceptible at higher inoculum densities. These data indicated that susceptibility to RKN was partially dominant. Frequency distributions of segregating populations indicated inheritance of resistance to RKN was a qualitative character conditioned by one major gene with at least one modifying gene.
Environmental Stability and Adaptation of Several Cotton Cultivars1
Authors: Bilbro J. D. , Ray L. L. 
Published: July 2010

We studied the stability, adaptation, and yields of several diverse cotton (Gossypiutn hirsutum L.) cultivars that had been grown at several locations in one or more of three, 3‐year periods of testing. We used as environmental indexes the mean lint yields of three “standard” cultivars that were common to all tests. The yields of the remaining cultivars were regressed upon these indexes. The regression coefficients (6 values) were used as measures of adaptability, and the coefficients of determination (r2 values) were used as measures of stability. Analyses of variance of lint yields also were computed.In comparison with the three standards, most of the other cultivars were adapted to all environments (b = 1.0), and all but one were stable. However, there were several significant yield differences among the cultivars within each of the three periods of testing. Thus, yield level was the most divergent parameter measured, adaptation was next, the stability was the least divergent. Because we found significant differences among commercial cultivars in both adaptation and stability, we believe that the use of these two parameters in conjunction with yield would be of significant benefit in breeding material evaluation.
Effects of Puccinia sorghi Rust on Yield and Several Agronomic Traits of Maize in Hawaii1
Authors: Kim Soon Kwon , Brewbaker James L. 
Published: July 2010

Ten paired doublecross hybrids of maize (Zea mays L.), genetically similar except for the gene Rp‐d conferring resistance to Puccinia sorghi Schw., were studied under natural rust epiphytotics in an area with continuous corn production in Hawaii. Data on eight agronomic traits are summarized from April and November plantings, including grain yield, plant weight, ear length and diameter, 1,000‐kernel wt, plant and ear height, and days to silk. Rust was severe in both seasons, and slightly more so in winter (6.0 vs. 5.2 on a seven‐point scale). In this area, winter corn yields are characteristically about half those of summer, due to reduced light intensity and daylength.The rust affected all traits significantly when data combined over the two seasons were considered. Average reductions caused by rust were 35% for grain yield, 27% for fresh plant weight, 11% for ear length, 10% for kernel wt and ear diameter, and less than 5% for plant and ear height and days to silk. Highly significant interactions of season with treatment (resistant vs. susceptible hybrids) were detected in grain yield and plant height, with the rust effect generally enhanced in the winter planting. Grain yield reductions by rust were best correlated with changes in kernel weight (r = 0.78), but clearly reflected major effects on ear lengths and diameters as well. In areas of continuous corn production, uncontrolled P. sorghi rust can be a serious disease affecting essentially all components of yield.
Inheritance of Harves Index and Related Traits in Oats1
Authors: Rosielle A. A. , Frey K. J. 
Published: July 2010

Harvest index of cereals is the ratio of grain to total plant yield. Harvest index and its components, plant weight and grain yield, and heading date, plant height, and 100‐seed weight, were studied in 15 crosses among 30 oat (Arena sativa L.) lines. F2‐derived lines from each cross, parents, and 10 check cultivars were tested in hill plots in 3 experiments. One experiment contained F2 derived lines tested in both F3 and F4, enabling direct comparisons between the two generations.Dominance was not of major importance in the inheritance of heading date, plant height, and 100‐seed weight. These traits showed small deviations of cross means from midparental values, little change of means and variances from F3 to F4, and no appreciable skewness. Plant weight and grain yield showed substantial dominance, as indicated by large deviations of cross means from mid‐parental values, large reductions in means and variances from F3 to F4 and negative skewness. Harvest index showed primarily additive gene action, although this conclusion was complicated by the occurrence of negative skewness. Crosses between parents that were both high in harvest index tended to show small phenotypic variation for harvest index and other traits.