bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of Male‐sterile Mutant Ms12 in American Pima Cotton1
Authors: Turcotte E. L. , Feaster Carl V.
Published: July 2010

A male‐sterile American Pima cotton (Gossypium barbadense L.) plant was found in the field in 1976. Genetic male steriles in cotton are useful as markers and in controlled crossing by providing male‐sterile stocks as female parents. In this study our objectives were to determine the inheritance of the genes conditioning the Pima male‐sterile trait and to detect possible linkage between Pima male‐sterile and other mutant genes in cotton. Crosses made between Pima male‐sterile and normally male‐fertile ‘Pima S‐5’ plants produced male‐sterile and male‐feritle F1 plants in a 1:1 ratio. BC1 progenies from sterile F1 plants crossed with Pima S‐5 fit a ratio of 1 sterile : 1 fertile. Fertile F1 plants crossed with Pima S‐5 produced only fertile progeny. These data show that the male‐sterile trait is conditioned by one dominant gene. We propose the name Male‐sterile‐ 12 and the gene symbol Ms12 for this trait. Linkage tests between Ms12 and 23 Gossypium mutant genes were negative. Relationships between Ms12 and other genetic male steriles in cotton are discussed.
Predicting Forage Yield from Morphological Traits in Reed Canarygrass1
Authors: Casler M. D. , Hovin A. W.
Published: July 2010

Yield components and morphological traits have been investigated as a means of more efficiently selecting for improved economic yield in many crop species. The objectives of this research were to develop equations for predicting forage yield from morphological traits of reed canarygrass (Phalaris arundinacea L.) and to determine the potential usefulness of these equations as selection indices in forage yield improvement. Ten parental clones and their topcross progenies were evaluated for 2 yr at four Minnesota locations for forage yield and two locations for morphological traits. Forage yield was predicted by multiple regression analysis from among the following traits of spaced plants and simulated solid‐seeded plots (microplots): leaf blade width, leaf blade thickness, specific leaf weight, leaf rigidity, culm diameter, tiller dry weight, tiller number or density, plant height, spaced‐plant area, and spaced‐plant circumference. Predictive equations were generated by screening models for high coefficient of determination (R2), low average relative influence (diagonal elements of the hat matrix), and low residuals. Of the 16 predictive equations developed (based on data for three harvests and means over harvests for spaced plants and microplots at two locations in 1979) and evaluated, only four had R2 ≥ 0.68. Of these, the equation developed from means over harvests on Rosemount spaced plants (RS‐M) had uniformly the best predictive value across both locations and years, the lowest average relative influence, and the lowest average residuals. Expected genetic gain for seasonal forage yield based on predicted yield from the RS‐M equation, which included leaf rigidity and tiller number, was 4.3% per cycle for 10% selection intensity and phenotypic selection compared with 4.6% per cycle for yield per se. Increasing the selection intensity to 5% would increase the expected response to 5.0% per cycle. We concluded that this equation appears to have application for yield selection in spaced plant populations of this reed canarygrass germplasm.
Relative Development of Basal, Medial, and Apical Ovules in Soybean1
Authors: Stelly David M. , Palmer Reid G.
Published: July 2010

Previous reports on ovule development of soybean [Glycine max (L.) Merr.] discordantly state that ovule development within each ovary is synchronous, or that it is asynchronous. We have studied immature ovules of soybean to determine if their development was synchronous, and, if not, to ascertain the order of their development, and the effect of asynchrony on fertility. Megasporogenesis and megagametogenesis were analyzed from archesporium formation to pollen‐tube entry by using hemalum‐stained sections of paraffin‐embedded specimens. Relative stages of development in basal, medial, and apical ovules were determined for triovulate ovaries. Relative stages of development differed significantly, and the medial ovule was the most advanced in development. All three ovules of triovulate ovaries reached maturity before anthesis. The degree of protogyny exceeded that of variation in development, allowing for full female fertility at anthesis, and indicating that protogyny is an important aspect of the self‐pollination mechanism in soybean. Protogyny also permits successful cross‐pollination 1 day before flowering (anthesis) without emasculation. Whether or not the variation in ovule development lowers the seeds‐per‐pod yield from cross‐pollinations is not known.
Yield Stability of Dry Bean Genotypes in the Dominican Republic1
Authors: Beaver J. S. , Paniagua C. V. , Coyne D. P. , Freytag G. F.
Published: July 2010

The seed yield and stability of performance of dry bean (Phaseolus vulgaris L.) genotypes grown in the Dominican Republic were measured using data from the 1981–1982 and 1982–1983 growing seasons. Genotype‐environment interactions were analyzed using regression techniques. Heterogeneity among regression coefficients accounted for a significant portion of the genotype‐environment interaction. The determinate red‐mottled genotypes that are grown widely in the Dominican Republic produced seed yields equal to or less than the mean of the tests, had an average yield response to environments of varying levels of productivity, and showed significant deviations from regression. On the other hand, indeterminate genotypes such as blackseeded ‘La Vega’ and white‐seeded 2W‐33‐2 produced greater than average mean seed yields, had an average or greater than average response to environments of varying levels of productivity, and possessed minimum deviations from regression during both growing seasons. These results suggest that the development of indeterminate red‐mottled genotypes might improve the yield level and stability of this bean class.
Inheritance of High Oleic Acid in Sunflower1
Authors: Urie A. L.
Published: July 2010

A sunflower (Helianthus annuus L.) oil which is high in oleic acid could be used as a cooking oil for deep fat frying of potato chips and other snack foods. Individual half‐seed analysis was used to select for high oleic acid in the high oleic sunflower cultivar Pervenets which exhibited inter‐ and intra‐plant variation for oleic acid content of individual seeds. The plant selection Pervenets‐3 and progenies bred true, remained nearly temperature insensitive, and had an average oleic content of 875 g kg−1 in six diverse greenhouse and field environments. Pervenets‐3 progenies were crossed to P21, a line which varied from 110 to 710 g kg−1 oleic acid content depending on environment. The F1 data indicates that Pervenets‐3 progenies carry a dominant factor with essentially no maternal effects which conditions high oleic acid. However, 8.9% of F1 seeds in eight of fifteen crosses exhibited deviation below 700 g kg−1 oleic content, thus indicating the presence of modifiers. The high oleic character reacted as a single dominant factor in F2's and backcrosses involving two P21 lines. In F2's from a cross involving another P21 line, one population fit the expected ratio for a single dominant factor while two populations exhibited a reversal in dominance. Apparently, some P21 lines do and some do not carry major factors and/or modifiers causing deviation. This high oleic character may be transferred to inbred lines for use in production of high oleic sunflower hybrids but low oleic parents should be selected which do not carry factors causing deviation.
Trends in Winter Wheat Performance as Measured in International Trials1
Authors: Kuhr S. L. , Johnson V. A. , Peterson C. J. , Mattern P. J.
Published: July 2010

Multiple‐year testing periods of an International Winter Wheat Performance Nursery (IWWPN) were compared to identify a yield trend for modern winter wheats and to assess the genetic contribution to any predicted yield gain. Average grain protein concentration, plant height, and 1000‐kernel weight values of the most productive cultivar in each trial were examined to determine whether simultaneous trends for these traits could be established and/or correlated with yield performance. Data from a uniform set of sites over 12 test periods from 1970 to 1983 indicated yield advancement from 4075 to 5946 kg ha−1 for the most productive wheat (Triticum aestivum L.) cultivars. Of this gain, 57% was attributable to improvements in cultural techniques whereas 43% was due to genetic improvements. When data from all reporting test sites were used, predicted yields advanced from 4022 to 5326 kg ha−1 with 55% of the gain attributable to genetic improvement. A slowing in the rate of yield increase was not detected among the most productive wheat cultivars in this study. Generally, increased grain production levels are associated with reductions in grain protein concentration. However, the increased grain yields in the IWWPN were not associated with significant reductions in grain protein concentration. Relative to the long‐term check, ‘Bezostaya 1’, grain yields of the most productive cultivars in the IWWPN showed a significant increase from 1970 to 1983, while the grain protein concentration of these cultivars remained essentially constant. Since high yielding semi‐dwarf wheats succeeded many of the older standard‐height cultivars during the 1970s it was of interest to determine whether a correlated response between higher yields and reduced height would be apparent among the IWWPN cultivars. Plant height of the most productive cultivars was variable and not closely associated with grain yield per se. Although a trend toward shorter height of these cultivars was not apparent, more of the recently tested cultivars in the IWWPN have been short in stature. The average height of the three most productive cultivars per trial has shown a significant decline from 1970 to 1983. Kernel weight values were variable and not closely correlated with advances in grain yield.
Relationship Between Fatty Acid Composition of Vegetative and Reproductive Structures of Six Soybean Genotypes1
Authors: Martin B. A. , Rinne R. W.
Published: July 2010

The objective of this study was to determine if correlations exist between seed oil composition and lipid composition of other plant organs. Six soybean [Glycine max (L.) Merr.] genotypes, Williams, Wells, AS, A6, N782245 and PI 123440, were used to determine the effects of selection for seed oil composition on fatty acid composition of other plant parts and cultured cells. Analysis of fatty acid composition in the seedling stage would permit selection, prior to flowering, of parents for improvement of seed oil fatty acid composition in a breeding program. This would allow a breeder to select and intermate selections in the same season. Use of cultured cells could provide a more efficient means of selection of mutants in the fatty acid desaturase pathway. The results of the study showed no significant correlation between the relative content (mol %) of any fatty acid in the seed and that fatty acid in other tissues across all six genotypes. Significant differences in fatty acid composition were observed in roots, leaves and cultured cells between some genotypes. These differences were similar, though of lesser magnitude, to those observed in the seed. The A6 genotype had significantly higher stearic acid content in the polar lipid fraction from cultured cells and root tissue than other genotypes examined. The A5, A6, and PI 123440 genotypes, which had low linolenic acid in seeds, had low linolenic acid in the triacylglyceride fraction of roots and leaves. Another line, N782245, with low linolenic acid in its seeds, did not. Our results indicate that seed oil composition is developmentally controlled by mechanisms which are not consistently expressed in other tissues. Therefore selection for specific fatty acid composition in vegetative plant parts or cultured cells may not be an effective breeding method for altering final seed composition.
Modified XYZ System of Producing Hybrid Wheat1
Authors: Driscoll C. J.
Published: July 2010

A modification to the XYZ system of producing hybrid seed of wheat (Triticum aestivum L.) is proposed in which a selfed Vline replaces a Y‐line to maintain and increase the male‐sterile Z‐Iine. This modification removes the need of the X‐line, which in the original system, was needed to generate a large quantity of Y‐line. In turn, the requirements of the alien chromosome are eased, and an isochromosome can be used to carry the compensating male‐fertility gene, which has distinct advantages. The modified XYZ system has fewer stages than the XYZ system, and these are comparable to those of the cytoplasmic‐male‐sterility system; however, both of the special genetic components are in the female parent of the hybrid. The Cornerstone male‐sterile mutant provides a satisfactory Z‐line, and a 4α isochromosome of Triticum urartu Jakubz. and a 4HmL isochromosome of barley (Hordeum vulgare L.) are being tested as the second genetic component.
Genotype ✕ Environment Interactions in Peanut Multiline Populations1
Authors: Norden A. J. , Gorbet D. W. , Knauft D. A. , Martin F. G.
Published: July 2010

The stabilities of four peanut (Arachis hypogaea L.) multiline populations plus their component lines were determined over a 4‐year period, 1980‐1983, at two locations in Florida. The study was undertaken to provide information concerning the stability of both yield and market quality factors of multiline cultivars vs. the component lines which form them. Each multiline was obtained from a different cross, and was formed by compositing in equal proportions the seed from four early generation, phenotypically similar sib‐lines. The interactions of genotype (population) with environments was highly significant (P = < 0.01) for pod yield and five quality factors (percentage fancy pod, shelling percentage, weight per 100 seeds, percentage of extra large kernels and sound mature kernel yield) studied. Large differences in yield and market quality traits were not found between sib‐lines. However, differences were found in stability estimated from regression coefficients and deviation from regression of multilines compared to their component lines, possibly due to the buffering action resulting from greater genetic variability. Multilines did not have greater stability in all cases, but the difference between the multiline and its least stable component line was generally greater than the difference between the multiline and its most stable component line. This research indicates that the chance of improving the yield stability and market acceptibility of peanut cultivars is increased when the multiline approach is used.
Inheritance of Dhurrin Content in Mature Sorghum Leaves1
Authors: Gorz H. J. , Haskins F. A. , Vogel K. P.
Published: July 2010

Seedlings of both KS8 and N32 sorghum[Sorghumb bicolor (L.) Moench] were high in dhurrin [p‐hydroxy‐(S)‐mandelonitrile‐β‐ D‐glucoside] and thus in hydrocyanic acid potential (HCN‐p), but the HCN‐p of mature leaves from field‐grown plants of KS8 was only about one‐tenth as high as that of N32. A study of the inheritance of this large difference between KS8 and N32 revealed that a single major gene pair was responsible. There were no obvious maternal effects and Fl'S were generally intermediate in HCN‐p level betweent he two parents, indicating that neither high nor low HCN‐p was completely dominant. HCN‐p level was inttuenced by genetic background since mean values of the low and intermediate HCN‐pcl asses increased slightly as the proportion of genetic background ascribable to N32 was increased. A survey of 102 additional sorghums revealed that the gene for low HCN‐p carried by KS8 does not appear to occur widely because KS8h ad the lowest HCN‐pof all entries assayed.
Effect of Clipping Frequency and Maturity on the Yield and Quality of Four Pearl Millets1
Authors: Burton Glenn W. , Primo A. T. , Lowrey R. S.
Published: July 2010

The objective of this study was to determine how yield and quality of pearl millet [Pennisetum americanum (L.) Leeke] forage might be improved by breeding later maturing cultivars. Three near‐isogenic populations, A, B, and C and a synthetic D, requiring 73, 105, 160, and 194 days from planting to anthesis, respectively, were cut at 2, 4, 6, 8, 12, and 24 week intervals for 2 yrs. Only at 8, 12, and 24 week cutting intervals, did populations B, C, and D exceed A in height. Populations A, B, C, and D produced very few seed heads when cut every 2 weeks. All had headed when cut once after 24 weeks. Percent of plants in head for A cut every 4 weeks was 94, for B cut every 8 weeks was 90 and for C and D cut every 12 weeks was 77 and 50, respectively. Cut at 12 and 24 weeks, C yielded 40 to 60% more dry matter than A. Cut more frequently, yields of A, B, and C were similar. Extending the maturity date from 73 to 160 days gradually increased leaf percentages and leaf yields. Cut every 12 weeks, C produced twice as much leaf material as A. Generally dry matter percentages decreased as the maturity of populations A, B, C, and D increased. Population A had the lowest digestibility and C and D had the highest digestibilities at all cutting frequencies.Population A had lower protein concentration at all cutting frequencies than B, C, and D which did not differ. Breeding later maturing cultivars taking over twice as many days to anthesis as the 73‐day types generally sold today will not improve the seasonal distribution of the forage greatly but should increase animal performance particularly if they were grazed rotationally or fed as green chop and silage.
Pollinator Density Effects on Frequency and Randomness of Male‐Sterile Soybean Pollinations1
Authors: May M. L. , Wilcox J. R.
Published: July 2010

Genetic male‐sterility has been used to facilitate intermating in the recombination phase of soybean [Glycine max( L.) Merr.] breeding programs. Insect vectors of pollen do not move at random in these intermating blocks and this may restrict random pollination. This study was initiated to assess the amount of cross pollination to male‐sterile plants as affected by different proportions of pollinators in the intermating population. Seeds of ‘Century’ and CX602‐107‐1‐2 pollinators, both with tawny pubescence, were individually blended at 0, 20, 40, and 80% levels with F2 seeds of a gray‐pubescent population segregating for male sterility (ms2ms2). Two replications of the intermating blocks were grown each of 2 years in the field at Lafayette, Indiana. Seeds were harvested from male‐sterile plants in each treatment and the numbero f tawny(Tt) and gray (tt) pubescent plants developing from these seeds were recorded. Effects of years and interactions of years on pollinators and pollinator densities were not significant in the analyses. The incidence of tawny pubescent progeny from male‐sterile plants was linearly related to the amount of seed of tawny pubescent pollinators planted in the intermating blocks. The proportion of tawny progeny from individual male‐sterile plants was consistent irrespective of the numbero f seeds producedo n the male‐sterile plants. The data suggest that cross‐pollinations in recombination blocks using males teriles is directly related to the frequency of each pollinator genotype in the population. The data further suggest that foreign genes could readily each pollinator genotype in the population. The data further suggest that foreign genes could readily be introgressed into an intermating population containing male steriles by simply blending seeds of the foreign germplasm with those used to produce the intermating population.
Photosynthate and Dry Matter Distribution in Effectively and Ineffectively Nodulated Alfalfa1
Authors: Cralle Harry T. , Heichel G. H.
Published: July 2010

Ineffectively nodulated alfalfa (Medicago sativa L.) grown with combined N [In(+N)] was compared with symbiotically‐grown, effectively‐nodulated alfalfa (Sar) to determine whether ineffective nodulation had correlated effects on photosynthate partitioning into dry matter. Ineffectively nodulated alfalfa grown with [In( + N)] and without [In( − N)] combined N were compared to determine the effects of N stress on photosynthate partitioning. Either the topmost or lowest fully‐expanded, intact green leaf on the main stem was labeled with 14CO2 in pulse‐chase experiments. After a 24 h chase period, the plants were divided into source leaf, main stem, unexpanded leaves and shoot apex on the main stem, other fully‐expanded leaves on the main stem, shoots growing from axillary buds on the main stem, shoots growing from crown buds, crown, nodules, and root. The 14C partitioning was measured as relative specific activity (RSA) and percent of total plant recovered radioactivity (%TPR). The dry mass, %TPR, and RSA of aerial organs were similar in In( + N) and Sar. However, the dry mass and %TPR of the belowground organs (roots + crown + nodules) were 46% and 25% less, respectively, in In(+N) than in Sar. This differential partitioning of dry matter and photosynthate to roots and crowns between the populations indicates that the single recessive gene for ineffective nodulation may have correlated effects on growth or development. The allocation of photosynthate from the topmost and lowest fully‐expanded leaf was significantly (P<0.05) different to all organs except nodules and roots. The topmost fullyexpanded leaf was the primary supplier of photosynthate to the unexpanded leaves and shoot apex on the main stem, the main stem, and fully‐expanded leaves on the main stem. The lowest fully‐expanded leaf was the primary supplier to the shoots growing from axillary buds on the main stem, the shoots growing from crown buds, and the crown. The dry mass, RSA, and %TPR of the main stem, shoots growing from axillary buds on the main stem, fully‐expanded leaves on the main stem, and shoots growing from the crown were less in the In(−N) than in the In(+N). The converse was true for the unexpanded leaves and shoot apex on the main stem, crown, roots, and nodules. The carbon exchange rate of the topmost fully‐expanded leaf was reduced 45%, but the export of photosynthate significantly increased, under N stress. The dry mass, %TPR, and RSA of the nodules were greater by 19‐, 36‐, and 6‐fold, respectively, in In(−N) than in In( + N). These results indicate that the nitrate inhibition of nodulation and photosynthate partitioning to alfalfa nodules is unrelated to rhizobial effectiveness or to the functioning of the bacteroids.
Nonstructural Carbohydrates in Stem Base Components of Tall Fescue During Regrowth1
Authors: Volenec J. J.
Published: July 2010

Nonstructural carbohydrates in stem bases are important for regrowth of tall fescue (Festuca arundinacea Schreb.). The objectives of this study were to i) examine changes in concentration of nonstructural carbohydrates in individuals tem base tissues during regrowth; ii) evaluate the relationship between leaf elongation rate (LER) and concentration of nonstructural carbohydrates; and iii) estimate the degree of polymerization (DP) fructans in tissues during regrowth. Plants were grown in a controlled environment chamber at 23°C with a photosynthetic photon flux density of 650 µmol m−2 s−1 during a 14‐h photoperiod. Plants were sampled immediately following defoliation and 2, 4, 7, 10, 14, 17, 21, and 24 days later. Reducing sugars, nonreducing sugars, starch, and fructan in intact stem bases declined to approximately 50% of initial concentrations by Day 4, and returned to original concentrations by Day 24. Initial concentrations of starch and fructan were higher in younger (inner) sheaths,when compared to older sheaths.Concentrations of nonreducing sugars in all sheaths declined following defoliation, while concentrations of reducing sugars and starch did not change markedly. Fructan concentrations on Day 24 were 19 and 77% of initial concentrations in the oldest and youngest sheaths, respectively. Nonstructural carbohydrates accumulated in newly formed sheaths and were not restored in older sheaths. Nonreducing sugars and fructan in elongating leaf bases declined to approximately 30% of initial concentrations by Day4. Maximum LER of 16 mm day−1 occurred between Days 2 and 7, which indicates that carbohydrates may not normally limit LER. The DP of fructan in old sheaths initially averaged 19 and decreased during regrowth, while the DP of 15 of young sheaths remained constant. The DP of fructan in bases of elongating leaves was less than 6 during rapid growth. Bases of elongating leaves may be more appropriate than intact stem bases as indicators of the availability of nonstructural carbohydrates for regrowth because of their responsiveness to defoliation.
Defining the Seed‐filling Period in Soybeans to Predict Yield1
Authors: Nelson Randall L.
Published: July 2010

The duration of seed fill has been shown to be related to seed yield in soybean [Glycine max (L.) Merr.]. However, several different growth stages have been used to delimit the seed‐filling period (SFP). This study was conducted to determine which growth stages delimit the SFP most highly correlated with yield. Twenty‐eight indeterminate accessions, 14 from each of Maturity Groups II and III, were selected from the USDA Soybean Germplasm Collection. These lines were selected for differences in length of SFP and similarities in other agronomic traits. Field experiments were grown in a Flanagan silt loam (Aquicarguidoll) and a Catlin silt loam (Typic Argiudoll) in 1980 and 1981, respectively. Data collected included the date of all reproductive (R) stages and seed yield. Genotypic and phenotypic correlation coefficients were determined for various reproductive or seedfilling periods and seed yield.Phenotypic correlation coefficients demonstrated a positive relationship between the duration of seed fill and seed yield but could not define the most appropriate seed‐filling period to predict yield. The genotypic correlations between various SFPs and seed yield provide evidence that supports the use of R4 or R5 as estimates of the beginning of seed fill and R7 as the termination. These data suggest that the currently defined R‐stages of soybean reproductive growth can provide reasonable estimates of the duration of seed fill and the seed‐filling periods so defined had a high correlation with seed yield among the lines in this experiment.
Diploid‐Tetraploid Comparisons in Rye. II. Forage Quality1
Authors: Pfahler P. L. , Barnett R. D. , Luke H. H.
Published: July 2010

Autotetraploids differ from their diploid counterparts in many vegetative, reproductive, and ecological traits. The effect of tetraploidy on the forage quality of rye (Secale cereale L.) grown in the lower latitudes was examined in this study. Six populations consisting of three diploid (2×) cultivars (‘Florida Black’, ‘Gator’, ‘Explorer’) and their autotetraploid (4×) derivatives were grown in two late fall‐winter‐early spring seasons (1979–1980, 1980–1981) at Gainesville (29°40′N Lat) and Quincy (30°35′N Lat), Florida. Two forage quality traits (in vitro organic matter digestion or IVOMD, crude protein or CP) were measured at a total of 16 clippings (Gainesville—four dates in each season, Quincy—three dates in 1979–1980 and five dates in 1980–1981). Over all clippings and genetic backgrounds, the IVOMD and CP of the tetraploids. No significant genetic background ✕ ploidy level interaction for either trait was present suggesting that autotetraploidy per se was the prime factor. Highly significant interactions for ploidy level ✕ cliping within season and location were found for both IVOMD and CP. The diploid‐tetraploid differences were more pronounced at the later clippings within each season and location but considerable variation in this pattern was observed among the various season‐location combinations. The genetic background ✕ ploidy level ✕ clipping within season and location (GB✕PL✕C/SL) interaction was significant for IVOMD but not CP. Regression analysis indicated that ploidy level altered the environmental stability of IVOMD but not CP. In general, the results of this study showed that the tetraploids, regardless of their genetic background, had a higher IVOMD, higher CP and a more uniform environmental response than their diploid counterparts.
An Analysis of Changes in Dominance‐Associated Gene Effects under Intrapopulation and Interpopulation Selection in Maize1
Authors: Hanson W. D. , Moll R. H.
Published: July 2010

Genetic relationships among maize (Zea mays L.) populations resulting from intrapopulation and interpopulation selection for grain yield were evaluated using information from a diallel mating design. The objective was to evaluate the nature of divergence associated with dominant gene effects following 8 and 10 cycles of full‐sib (F) and reciprocal recurrent (R) selection for grain yield within two base populations, Jarvis (J) and Indian Chief (I). Representation in reduced dimensions was based on the principal component analysis with an adjustment for experimental error. The theoretical development for this adjustment was presented. With continued cycles of selection, dominance‐associated gene effects played an increasingly greater role in both selection programs. Under both F selection and R selection, populations diverged from their base populations with respect to dominance‐associated gene effects. However, a corresponding divergence between the JF vs. JR populations and the if vs. IR populations did not occur. Similar changes in gene frequencies must have occurred at some loci under the two selection programs. Further, complementing dominant gene interactions were identified in two different populations under two different selection regimes. The pattern of divergence between JR and IR populations was not the response expected if overdominant locus effects predominated. Therefore, the results supported the concept that increasing the frequency of genes having favorable dominance‐associated effects was more important than increasing the frequency of heterozygous loci (overdominance) for high‐yielding, population hybrids.
Food Reserve Storage, Low‐Temperate Injury, Winter Survival, and Forage Yields of Timothy in Subarctic Alaska as Related to Latitude‐of‐Origin1
Authors: Klebesadel L. J. , Helm Dot
Published: July 2010

Timothy(Phleum pratense L.) is a valuable forage grass in cool, humid climates. However, the availability of genetic material within the species from over a broad geographic and latitudinal range, and the generally marginal winterhardiness of the species in Alaska has lent uncertainty to optimum germplasm sources for use in this northernmost state. Five experiments compared cultivars from diverse latitudinal sources for characteristics affecting winter survival and forage production in southcentral Alaska. Cultivars from Norway, Iceland, and Finland were more winter hardy than those from North America. In general, winter survival in Alaska was correlated with latitude of cultivar origin, with northernmost cultivars superior to those of more southern origin. ‘Engmo’, a cuitivar of extreme northern origin (69 to 70°N Lat), was more tolerant of freeze stress, stored higher levels of food reserves, had higher concentration of dry matter in crown tissues, and survived winters at this location (61.6°N Lat) markedly better than ‘Climax’, of intermediate latitudinal origin (ca. 45°N Lat), which in turn surpassed ‘Clair’ in these respects, a cultivar of more southern origin (38 to 39°N Lat). Northern‐adapted cultivars were more dormant in autumn after second forage harvest than mid‐temperate‐adapted cultivars. Timothy cultivars from North America, when well established and not winter‐injured, produced forage yields equivalent to Scandinavian cultivars and other extremely winter‐hardy, non‐timothy grasses, including ‘Polar’ bromegrass (predominantly Bromus inermis Leyss. ✕ B. pumpellianus Scribn.), ‘Garrison’ creeping foxtail(Alopecurus arundinaceus Poir.), ‘Nugget’ Kentucky bluegrass (Poa pratensis L.), and ‘Arctared’ red fescue (Festuca rubra L.). After sustaining sub‐lethal winter injury, timothy plants displayed a remarkable ability to recover during the growing season and produce second‐cutting forage yields comparable with hardier cultivars. The proportion of total‐season forage yield produced in the first cutting differed with origin of cultivars in the following ranking: Norway = Iceland = Finland > Sweden > Canada > USA. Snow cover in the field greatly enhanced winter survival of marginally winter‐hardy cultivars. Rhizomatous grass species survived the more stressful winters better than timothy. Apparently the more exposed, superficial position of the overwintering tissues of timothy crowns renders even the most winter‐hardy cultivars more susceptible to winter injury than hardy grasses with subterranean overwintering parts.
Effects of Genotype and Seed Size on Speed of Emergence and Seedling Vigor in Nine Spring Wheat Cultivars1
Authors: Lafond G. P. , Baker R. J.
Published: July 2010

Rapid seedling establishment is an important attribute for successful crop production in short‐season areas. A study was done to determine the role of seed size, speed of emergence and rate of plant development in seedling vigor of nine spring wheat, Triticum aestivum L., cultivars. Six field studies, comprised of three seeding dates in each of 2 years, were conducted. Each study included nine spring wheat cultivars divided into two seed sizes arranged in a randomized complete block design with four replications. Logistic curves were fitted to emergence data expressed as percentage of final number of seeds emerged in a 46 cm row length. Each curve was characterized by median emergence time, the most useful measurement for speed of emergence, and maximum rate of emergence. Cultivar differences were observed in both years for speed of emergence, Haun stage, and seedling shoot dry weight. The average number of growing degree‐days (GDD) required for emergence in 1982 and 1983 were 109 and 103, respectively. With respect to Haun stage, approximately 68 GDD were required per phyllochron (interval between the appearance of successive leaves). ‘Potam’, ‘Siete Cerros’, and ‘Glenlea’ were found to require significantly fewer GDD per phyllochron interval on the third seeding date of 1983. The relative performance of cultivars was similar for speed of emergence, Haun stage and seedling shoot dry weight. Plants grown from small seeds emerged faster but accumulated less shoot dry weight than plants grown from large seeds. There was no cultivar by seed size interaction observed for speed of emergence and seedling shoot dry weight. Seed size, speed of emergence, and Haun stage all contributed to differences between cultivars in seedling vigor. Seed size accounted for approximately 50% of the variation in seedling shoot dry weight. It was concluded that selecting for seedling vigor could be done by selecting for seed size, speed of emergence and/or rate of plant development.
Introgression of Unadapted Germplasm into Adapted Spring Wheat1
Authors: Eaton D. L. , Busch R. H. , Youngs V. L.
Published: July 2010

The introgression of unadapted germplasm into adapted germplasm is one method of increasing useful genetic variability. In hard red spring wheat (Triticum aestivum L.) more information on methods of incorporation would be useful, especially for breadmaking quality traits, which are important for cuitivar release. Three populations were developed from two unadapted and three adapted wheat genotypes. The objective was to evaluate the agronomic and breadmaking quality traits of lines derived from types of crosses differing in the amount of unadapted germplasm. The four types of crosses evaluated were single cross, three‐way cross, and one and two backcrosses to the adapted parent. Twenty F2‐derived lines from each type of cross for each population were evaluated in three field environments. Although the means of the types of crosses did not differ significantly for yield, the mean of lines derived from the single cross were generally lowest and this cross produced the fewest high yielding lines and fewest lines with both high yield and good breadmaking potential. The first backcross and the three‐way cross produced similar numbers of high yielding lines. The second backcross produced no more high yielding lines than the first backcross or three‐way cross and required an additional generation to develop. Means of types of crosses for quality traits tended to approximate the mean of the parent contributing the largest percentage of germplasm to the cross. Genetic variation for grain yield and wheat protein concentration were similar for most types of crosses, except BC2, which had less variation. The relative proportions of the higher performing parent appeared as important as the type of cross used for development of lines.
Identifying Heterotic Blocks on Pearl Millet Chromosomes with Chlorophyll Deficient Mutants1
Authors: Burton Glenn W.
Published: July 2010

Chlorophyll deficient mutant stocks of pearl millet [Pennisetum americanum (L.) Leeke] were crossed with ‘Tift 23’ normal inbred to study the effect of the mutants on the yield of S1 spaced plants grown in the field. They were also used to identify heterotic blocks on the chromosomes of five pearl millet inbreds that might be used to increase the yield of an F1 hybrid. Measurements of the 717 S1 spaced plants from the cross Tift 23 (G/G) ✕ T664 (g/g) showed that when homozygous, the g allele was associated with a golden leaf color and a reduced plant height, plant yield, and seed yield per head of 92, 59, and 64% of the homozygous (G/G) plants, respectively. These heterotic differences (P<0.01) were probably due the interaction of the T664 genes linked to g with the genes on its Tiff 23 counterpart. Thus, the g allele identified and is included in a heterotic block on one segment of one pearl millet chromosome. The remaining blocks would have been equally distributed in the G/g and G/G groups resulting in essentially equal frequencies for all genes except those linked with the g locus. At least 86% (6/7) and probably 93% (13/14) of the genome would have segregated independently. Fourteen recessive chlorophyll deficient mutants (cd is the general symbol for any chlorophyll deficient mutant and Cd is its normal allele) induced in Tift 23 pearl millet were used to identify heterotic blocks in Sx populations of crosses with normal (Cd/Cd) Tift 23 and normal (Cd/Cd) inbreds 13, 18, 104, 166, and 186. The average spaced plant yields of the Cd/Cd and Cd/cd populations from the 14 Tift 23 Cd/cd mutant stocks crossed with the normal Tiff 23 Cd/Cd inbred were 916 and 893 g, respectively, and were not different statistically. Among the 69 S1 progenies of Tiff 23 Cd/cd ✕ the five normal inbreds Cd/Cd, the heterozygotes were heavier than the homozygotes in 53 cases, 15 of which were significantly heavier (P<0.05 or 0.01). A Tiff 23 mutant stock such as M5 that identified a high yield heterotic block in Inbred 104 (+ 1510**) identified a very low yielding heterotic block (+ 122) in Inbred 186. Thus, it should be possible to increase yields of Tilt 23 ✕ 186 by transferring heterotic block M5 from Inbred 104 to Inbred 186 by backcrossing or by biotechnology at some future date.
Respiration Rates of Soybean Cultivars1
Authors: Kishitani Sachie , Shibles Richard
Published: July 2010

Dark respiration rates of soybean [Glycine max (L.) Merr.] plants and organs, grown in the glasshouse, were measured by infrared gas analysis at several stages of development. Two early maturing cultivars, Hodgson (high yielding) and Chippewa (low yielding), not differ significantly in respiration rates on either a plant or a dry weight basis for any organ at comparable stages of development. Two late maturing cultivars, A3127 (high yielding) and Wayne (low yielding), differed significantly in root, but not shoot, respiration on a plant basis. The difference was entirely due to A3127 having a smaller root system, because the cultivars did not differ in respiration rate on a dry weight basis. A3127 showed 21% (1982) and 43% (1983) less root respiration than Wayne at all stages of development. Distribution of respiratory C efflux by whole plants also differed significantly for these two cultivars, with A3127 showing a greater proportion of its efllux coming from stem tissue in compensation for a lesser proportion from the root. For a l‐week period during early flowering, respiratory C losses amounted to 36% of C assimilated. Respiration rates on a dry weight basis diminished with plant development for all organs. The organs' respiration rates correlated significantly with their N concentrations.
Influence of Ammonia Vapors on the Dry Seeds of Soybean, Corn, and Peanut1
Authors: Woodstock Lowell W. , Hensin Tsao
Published: July 2010

The toxic effects of ammonia (NH3) on dry seeds of soybean [Glycine max (L) Merr.], corn (Zea mays L.), and peanut (Arachis hypogaea L.) were assessed in this study. Soybean seeds were killed after a 24‐h exposure at 15 mg L−1, whereas corn seeds were killed at only 1.5 mg L−1. The toxic effects of NH3 became more severe with exposure duration, e.g., in soybean, 15 mg L−1 NH3 killed seeds after 24 h, but not after a 2‐h exposure. Injury response of seeds to ammonia in the cold (5°C) was less severe than that at 25°C. Conductivity tests of steep water detected the injurious effects of toxic levels of NH3 on seeds. However, nontoxic levels of NH3 also increased leachate conductivity. It is concluded that levels of NH3 like|y to be encountered in refrigerated warehouses following a leak (0.015 to 0.15 mg L−1, i.e., 20 to 200 ppm) are unlikely to have an adverse effect on the germination or growth of soybean, peanut, or corn seeds.
Soybean Seed Size Influences Expression of the Impermeable Seed‐Coat Trait1
Authors: Hill H. J. , West S. H. , Hinson K.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seeds with the impermeable seed‐coat trait have been shown to retain quality better than typically, permeable seeds. Impermeable seeds, however, become permeable and imbibe water after different periods of soaking even when seeds are from the same genotype or plant. These differences in response demonstrate variation in the expression of this character. The purpose of this study was to determine if seed size was associated with the variation in expression within soybean breeding lines. Seeds of nine lines were grown in each of 2 yrs and separated into three size classes based on seed diameter. Seed permeability was determined for each size class by soaking seeds in water for 2, 4, 8, 24, and 72 h. Smaller seeds exhibited the impermeable response at a higher frequency than larger seeds after each soak in both years. Differences in seed permeability among size classes increased as soaking time increased. When data were averaged over years and lines, each decrease in seed size class was associated with a 17% increase in impermeable seed expression, after a 72 h soak. Although there were significant differences among lines in impermeable seed percentage, seeds within all lines exhibited a negative relationship between size and impermeable seed expression in at least 1 of 2 yrs, seven lines exhibited this relationship in both years. Results obtained indicate that variation in the impermeable response of seeds within an impermeable‐seed line is associated with seed size. Smaller seeds expressed the impermeable response in a higher frequency than larger seeds.
Effects of Rust on Yield and Quality of Pearl Millet Forage1
Authors: Monson W. G. , Hanna W. W. , Gaines T. P.
Published: July 2010

Rust (Puccinia substriata var. indica) occurs on pearl millet [Pennisetum americanum (L.) Leeke] in most years. Visual effects of the rust are severe, ranging from death of young plants from early infection to premature desiccation and/or death of leaves with later infection. There is a lack of quantitative data on the effects of rust on yield and quality of pearl millet. This study was initiated to assess the effect of rust on yield and quality of individual resistant and susceptible plants. Comparisons of 205 resistant with 173 susceptible plants showed significant reductions in dry matter (DM) concentration, DM yield, and in vitro dry matter digestibility (IVDMD) in diseased plants. The combined effects of lower yields and lower IVDMD led to a mean 51% reduction in digestible dry matter yield from the infected plants. The yield of leaves was reduced less by rust than was the yield of stems, but the opposite was true for IVDMD concentrations. Total sugars in the forage of infected plants were 64% less than in forage of resistant plants. Crude protein concentration was slightly higher in diseased plants. The results clearly demonstrated the benefits to be derived from incorporation of rust resistance into existing or new cultivars of pearl millet.
Development of a Cotton Plant with Glandless Seeds, and Glanded Foliage and Fruiting Forms1
Authors: Dilday R. H.
Published: July 2010

Pigment glands in cotton (Gossypium spp.) contain gossypol and related terpenoid aldehyde compounds and these glands are found throughout most aboveground parts, including seeds. These glands protect the plant from insect pests, but gossypol in the embryo of the seed is undesirable because it is toxic to nonruminant animals. The objectives of the present study were to identify a hexaploid cotton plant that possessed glands in most of the aboveground parts, except the seed, and initiate the transfer of this trait into a tetraploid cotton. A fertile hexaploid (2N= 78) plant from an interspecific cross of tetraploid (2N=52) Gossypium hirsutum L. ✕ diploid (2N=26) G. sturtianum Willis showed a phenotype having glandless seed, and glanded foliage and fruiting forms. This phenotype had flowerbud and seed gossypol percentages of 0.29 and 0.02, respectively. Fertile pentaploid F1 plants from crossing the hexaploid and the tetraploid G. hirsutum Texas marker‐1 (TM‐1) stock appeared to produce as much seed cotton as the tetraploid Texas marker‐1 at Brownsville, TX. However, the F1 plant produced 0.31% flowerbud and only 0.02% seed gossypol. The flowerbud and seed gossypol percentages of TM‐1 were 0.58 and 1.29, respectively. These results show that fertile hexaploid germplasm in cotton has been developed that possesses the unique characteristic of storing gossypol in glands in the vegetative foliar and fruiting plant parts but not in the embryo of the seed.