bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosomal Location of Male Fertility Restoring Genes in Six Lines of Common Wheat1
Authors: Bahl P. N. , Maan S. S.
Published: July 2010

A monosomic set of male‐sterile ‘Chris’ (Triticum aestivum L.) with T. timopheevi Zhuk. cytoplasm was used to determine the chromosomal location of Rf‐genes in six male fertility restoring lines (FR‐lines) of T. aestivum L. The six FR‐lines were: R1‐Lee (Nebraska 542437/T. aestivum ‘Lee’), R2‐Sonora 64 (T. timopheevi/2*T. aestivum ‘Marquis’//‘Sonora 64’), R3 (T. timopheevi/3*T. aestivum ‘Marquis’), R4 (amphidiploid T. timopheevi‐Ae. squarrosa/3*T. aestivum ‘Dirk’), R5 (T. Zhukovsky Men. and Er.,/3*T. aestivum ‘Justin’), and T. aestivum ‘Primepi’. The relative proportions of male‐sterile and male‐fertile plants in the F2 and F3 from monosomic F1 indicated that chromosomes 1A and 7D of R1‐Lee, R2‐Sonora 64, R3, R4, and R5 had Rf‐genes. R2‐Sonora 64 and R5 each had a third Rf‐gene on chromosomes 6B and 7B, respectively. Primepi had Rf‐genes on chromosomes 1B and 5D. The inheritance of fertility restoration in control crosses and in some of the noncritical crosses indicated that R1‐Lee, R2‐Sonora 64, and R5 each had three Rf‐genes, and R3, R4, and Primepi each had two. The deficiency of certain chromosomes influenced the penetrance and expressivity of the Rf‐genes in certain crosses.
The Relationship Between F2 and Selected F3 Progenies in Cotton (Gossypium hirsutum L.)1
Authors: Meredith William R. , Bridge R. R.
Published: July 2010

Yield, components of yield, and fiber determinations of five parental lines of cotton (Gossypium hirsutum L.) and their 10 F2 hybrids were made at Stoneville, Mississippi in 1968. These results were then related to the 1969 F3 performance at the same location of eight random, eight high yield, and eight high strength selections from each cross.

The linear correlation coefficient for the F2 and mean F3, yield was 48 and not significant. The F2 hybrids, therefore, gave little information regarding which cross to use when selecting for lint yield. However, high correlations between the F2 and F3 for lint percent, seed index, and fiber length, strength, and elongation were detected. The performance of F2 was a good indication of these traits.

Differences in yield, lint percent, seed index, fiber length, and fiber strength among the three selection types were observed. The yield selections produced 5.7% more lint than the random and strength selections. However, the increased yield was partially at the expense of fiber properties. The average length and strength of the fiber quality selections were slightly greater (1.0%) than the random entries. There was no significant difference in yield between the random and high strength selections.
Pollen Storage of Certain Agronomic Species in Liquid Air1
Authors: Collins F. C. , Lertmongkol Vatcharee , Jones J. P.
Published: July 2010

Viability of liquid air‐stored pollen from alfalfa (Medicago sativa L.), soybeans (Glycine max L. Merr.), cotton (Gossypium hirsutum L.), corn (Zea mays L.), oats Avena sativa L.), rye (Secale cereale L.), sorghum (Sorghum bicolor (L.) Moench), and wheat (Triticum aestivum (L.) em Thell) was measured by in vitro germination, staining with tetrazolium bromide, and pollination. Some stored pollen of alfalfa, soybeans, cotton, and rye germinated in vitro. Stored pollen of all eight species exhibited variable levels of viability when stained. Successful pollinations of soybeans and rye were obtained with stored pollen. Results of germinating in vitro and staining of fresh pollen compared favorably. The staining method was simpler and gave more consistent results than in vitro germination. In addition, staining can be used for species for which suitable artificial germination media have not been developed.
Path Coefficient Analysis of Seed Yield Components in Soybeans (Glycine max (L.) Merr.)1
Authors: Pandey J. P. , Torrie J. H.
Published: July 2010

Seven soybean [Glycine max (L.) Merr.] cultivars grown at three different seeding rates were studied in 1969, 1970, and 1971 to determine the influence of seeding rate on components of seed yield. A correlation and path coefficient analysis was made to determine the direct and indirect effects of seed components on seed yield. Pods per unit area and seeds per pod had the greatest effect on seed yield in five and four of the nine sets of data, respectively.

The soybean was found to have the ability to compensate for differences in stand. Compensation was accomplished primarily through number of pods per plant. In general, yield components were negatively associated with each other.
Evaluation of Wax Coatings for Improving Sugarbeet Storage1
Authors: Wyse R. E. , Dilley D. R.
Published: July 2010

The effect of paraffin and a commercial wax coating on the respiration rate and weight loss of large and small sugarbeet (Beta vulgaris L.) roots was determined.

Wax coatings on sugarbeets were most beneficial in reducing respiration rates under conditions where rates were high and gaseous diffusion became a dominant factor in regulating respiration rates. The respiration rate of the beet root was primarily a function of the internal oxygen concentration for a given size of beet.

The internal oxygen concentration reflects the resistance of the beet to gaseous diffusion and surface area. The sensitivity of the internal oxygen concentration to increased diffusion resistance makes surface coating appear to be a practical method of lowering internal 02 and thus reducing respiration losses.

The observation that wax coatings reduce desiccation and respiration rates suggests that spraying surface beets with a wax coating and then covering them with straw may prevent desiccation on the surface of commercial storage piles and thus reduce sucrose losses.
Relations Between Alpha‐amylase Activity and Growth of Rice Seedlings1
Authors: Williams John F. , Peterson Maurice L.
Published: July 2010

A study was made of possible relationships between alpha‐amylase activity (referred to as “activity”) and rice (Oryza sativa L.) seedling vigor, particularly as to stand establishment from water‐sown seeds. Relationships between activity and seedling weight (wt) during germination were noted for different cultivars and under different temperature and oxygen conditions.

The r values for activity ✕ wt for ‘IR‐8’ and ‘Italica Livorno’ were highly significant (0.99 and 0.96 respectively) from the 3rd through the llth days of germination. These two cultivars differed widely in seed weight, enzyme activity, and seedling weight increases. The r value among 20 cultivars was 0.60, significant at the 0.05 level. The range in activity units was from 121.2 (for Italica Livorno) to 16.2 (for ‘Colusa’). A comparison of activity units at 30 C on rice germinated on moist blotters, under water, and in a N2 atmosphere showed that submergence had little effect on activity but the oxygen‐free atmosphere cut AU in half. These same conditions greatly suppressed seedling weights. Low temperatures (18 C) severely reduced AU and weight. It was concluded that alpha‐amylase activity was not an important limitation to seedling development of water‐sown rice under cold‐water conditions.
Polyembryony in Soybeans1
Authors: Kenworthy W. J. , Brim C. A. , Wernsman E. A.
Published: July 2010

Twin seedlings were observed in the progeny of malesterile (ms1ms1) plants of Glycine max (L.) Merrill from natural crossing blocks. Of the seedlings observed, more than 4% were embryonic twins. Triplets and conjoined individuals were also found. Cytological examinations of root‐tip preparations revealed that most individual plants from twin sets were diploid (2n=40). However, diploid: haploid and diploid:triploid twin pairs were also identified. Genetic analysis of a marker trait in the twin seedlings and their selfed progeny indicated that diploid diploid sets originated primarily after cross‐fertilization. Evidence suggests that the mechanism underlying the development of these twins involves a cleavage of the zygote or the development and fertilization of multiple embryo sacs within an ovule.
Variability and Heritability of Perloline in Festuca sp., Lolium sp., and Lolium‐Festuca Hybrids1
Authors: Buckner R. C. , Bush L. P. , Burrus P. B.
Published: July 2010

Perloline (an alkaloid that may inhibit digestibility in ruminants) was determined in Lolium and Festuca sp. and in Lolium‐Festuca hybrids. Lolium sp. had less perloline than Festuca sp. L. multiflorum had the smallest amount of perloline and F. elatior the largest. Although highly significant genotype‐environment interactions were obtained for perloline quantity for a 3‐year period, broad sense heritability estimates varied from 0.57 to 0.80 among polycross progenies of three groups of genetic materials. Correlation coefficients of association between parents and progenies were positive and highly significant. The data suggest that genetic control of perloline may depend on relatively few genes and that progress can be made toward the development of Lolium‐Festuca populations that are either high or low in perloline content.
Breeding Methods for Improving Yield and Fiber Quality of Upland Cotton (Gossypium hirsutum L.)1
Authors: Culp T. W. , Harrell D. C.
Published: July 2010

In the introgression of Gossypium arboreum L. ✕ G. thurberi Tod. fiber strength to medium staple Upland cotton (G. hirsutum L.), we have been most successful with the pedigree method of hybridization and selection. Hybridization is required for the recombination of genes for high lint yield and fiber strength or length, and selection is necessary to locate the desirable recombinants in segregating populations.

In 25 years of selection within breeding lines after the F5 generation, only two highly desirable recombinants, Earlistaple‐7 and Pee Dee 4381‐54, have been found. Yield improvement in Earlistaple‐7 is attributed to fusarium wilt resistance rather than to recombination of genes for lint yield and fiber quality. We cannot rule out the possibility of intercrossing or outcrossing in the isolated seed increase of Pee Dee 4381 from which Selection‐54 was obtained.

Random intermating, backcrossing, and composite‐crossing also were tried as methods to improve yield and fiber quality of Upland cotton. A valuable breeding line (Q) was developed by three cycles of backcrossing to three G. hirsutum parents (with selection only for high lint percentage) and a composite‐cross of progenies from each of these backcross populations. No desirable recombinants were found with random intermating. Failure of this method was attributed to: 1) broad germplasm pools, 2) nonelimination of undesirable plants from the populations, and 3) study of small populations of 10,000 plants.

We believe that any breeding method that gives maximum combinations of genes for yield and fiber quality is desirable, and selection of promising recombinants in early generations is necessary to maintain populations of practical size.
Success in Hybridizing and Selfing Trifolium repens at Different Temperatures1
Authors: Gibson Pryce B. , Chen Chi‐Chang
Published: July 2010

Seasonal variation in successful hybridization of Trifolium repens L. (2n = 32) motivated this study on the effect of different temperatures on white clover seed yields from cross‐ and self‐pollinations.

Plants of a T. repens clone were grown at temperatures of 15, 20, 25, and 30 C. Self‐compatibility was determined at each temperature by rolling the heads between the thumb and fingers. Plants at each temperature were cross‐pollinated with pollen from a T. repens plant of a different genotype and with pollen from a 32‐chromosome, F1 hybrid from the cross T. uniflorum L. (2n =32) ✕ autotetraploid T. occidentale Coombe (2n = 32).

Self‐pollinations resulted in no seed at 15 and 20 C, a few at 25 C, and more at 30 C. Intraspecific and interspecific cross‐pollinations at 25 C resulted in the highest seed production.

Seed from the interspecific cross were planted and the plants classified cytologically for hybridity. Plants from seed produced at 15 and 20 C were all hybrids; plants from seed produced at 25 C were 80% hybrids; and plants from seed produced at 30 C were 17% hybrids. The higher temperatures, although favoring seed production, increased the probability of selfing.
Field and Greenhouse Selection for Phytophthora Root Rot Resistance in Alfalfa1
Authors: Frosheiser F. I. , Barnes D. K.
Published: July 2010

We developed a field nursery to screen for Phytophthora root rot resistance in alfalfa (Medicago sativa L.). The critical steps included scattering Phytophthora megasperma Drechs.‐infested soil over the area, leveling the soil before seeding, and irrigating the soil so that it remained wet for 2 to 3 weeks. In the greenhouse, we tested seedlings in inoculated steamed sand in tanks where the water levels were controlled by subirrigation. Disease severity in field and greenhouse tests was significantly correlated in two sets of comparisons (r = 0.990 and r = 0.949, 8 df). The degree of resistance was significantly correlated with both forage and root production in wet soil. An example of progress in breeding for resistance was the increase in resistant plants in a population from less than 10% to about 50% after 2 cycles of selection and to about 63% after 3 cycles of selection. Other populations have responded similarly.
Modification of the Variety Cross Diallel Model for Evaluating Cycles of Selection1
Authors: Hammond J. J. , Gardner C. O.
Published: July 2010

A general model for the analysis of variety cross diallels was modified for use when the populations represent different cycles of selection from one parent variety. The a and d parameters in the improved populations are functions of a and d in the parent variety assuming negligible mutation effects. The modified model permits the simultaneous estimation of a polynomial regression in a and in d. The regression equation in homozygous effects (a) is a direct measure of weighted average change in gene frequency, and the equation in heterozygous effects (d) is a measure of the approach to fixation of the favorable alleles. If favorable genes are dominant, the first derivative of the equation in heterozygous effects evaluated at zero gives the cycle at which the weighted average gene frequency will be 0.5.

A parent population and selected cycles of selection were generated on an IBM 360 computer to illustrate the theory. Crosses and related populations were generated according to the Gardner‐Eberhart model and estimates obtained were compared to known parametric values. From the idealized diallel and related populations, change in gene frequency was determined as well as time to fixation and expected response at the endpoint of selection, when gene frequencies are changing at a linear rate.
Regrowth of Alfalfa After Heat Stress1
Authors: Pulgar Claudio E. , Laude Horton M.
Published: July 2010

The extent and persistence of growth depression in alfalfa (Medicago sativa L.) following heat stress was established under controlled conditions by comparing stressed with unstressed plants of the same clone. Temperatures were used that simulated the periodic heat extremes of the field. Significant reduction in number and length of shoots in the regrowth was obtained within 7 days of stress. The period of depressed growth was extended as the intensity of stress was increased either by elevating temperature or lengthening exposure time. Measurable reduction in shoot numbers and size persisted up to 6 weeks following a stress which produced no visible evidence of tissue mortality.
Continuous Backcrossing to Transfer Prolificacy to a Single‐Eared Inbred Line of Maize1
Authors: Duvick D. N.
Published: July 2010

The prolificacy of C103, an inbred line of maize (Zea mays L.), was increased by crossing it to a highly prolific popcorn, backcrossing four times to the inbred with selection in each backcross population for signs of the incompletely recessive prolific trait, and then selfing to homozygosity while selecting for prolificacy. When three selections of the converted inbred were compared to the original in hybrid combinations at three rates of planting, they were more prolific but not higher yielding than the original inbred at low rates; and had less silk delay, were much less barren, and were much higher yielding than the original at high rates. These results agree with the hypothesis that prolific germplasm tends to reduce barrenness at high planting rates. They also demonstrate that continuous backcrossing can be used for rapid transfer of a quantitative trait, such as prolificacy, from exotic to adapted strains.
Developmental Studies on the Panicle Initiation in Sorghum1
Authors: Lee Kit‐wah , Lommasson Robert C. , Eastin Jerry D.
Published: July 2010

A study of the morphology and development of the sorghum (Sorghum bicolor (L.) Moench) panicle was made from photographs of fresh apices and from stained sections of fixed material. From periodic collections, the transition from vegetative to reproductive stages indicated an acropetal initiation of primary branch primordia. Higher orders of branch primordia are commonly found on lower branch primordia. Differentiation of spikelets in the panicle is basipetal and is marked by the appearance of glume primordia. Both fertile and sterile spikelets of a pair are morphologically similar during their early development, but the floret parts of the latter degenerate as the inflorescence matures. A developmental stage system evaluating the degree of panicle development is proposed.

Three factors considered to be of importance in the control of yield, which are associated with the development of the inflorescence, are number of primary branch primordia, number of branches arising from each primary branch, and the timing of spikelet differentiation. Of these, the time sequence of acropetal differentiation of primary branch primordia followed by basipetal differentiation of spikelets may be the most important in controlling yield.
Effect of Cytoplasmic Male Sterility on Accumulation and Translocation of 14C‐labelled Assimilates in Corn1
Authors: Criswell J. G. , Hume D. J. , Tanner J. W.
Published: July 2010

A male‐sterile corn (Zea mays L.) hybrid and its fertile counterpart were grown under field conditions for 3 years. In each year one upper leaf of plants of both types was allowed to assimilate 14CO2 in photosynthesis at both tassel emergence and silking. The plants were harvested after either 1 or 8 days, and distribution patterns of 14C were measured. Less upper leaf assimilates were distributed to male‐sterile tassels than to fertile tassels. More of the labelled assimilates accumulated in developing ears and husks of male‐sterile plants. Increased tolerance in male‐sterile corn lines to stresses caused by high plant populations and other environmental factors appears to occur at least partly because of reduced intraplant competition for assimilates by tassels during early ear development.
Barley Yellow Dwarf Virus Resistance in Crosses with Pettis Oats1
Authors: Weerapat Praphas , Sechler Dale T. , Poehlman J. M.
Published: July 2010

Five oat (Avena sativa L.) cultivars, ‘Pettis,’ ‘Jaycee,’ ‘Florida 500,’ ‘Orbit,’ and ‘O5807,’ and F1, F2, and F3 progenies from crosses of Pettis to the other cultivars were inoculated with barley yellow dwarf virus (BYDV), strain Champaign 6. Observations were made on percentage leaf discoloration, plant height, number of panicle‐bearing tillers, and grain yield per plant. Pettis and Jaycee are resistant, Florida 500 is intermediate, and Orbit and 05807 are susceptible to BYDV. F1 and F2 means generally ranked in the same order as the respective Jaycee, Florida 500, Orbit, and 05807 parent means. Lines superior to the higher parent in grain yield were isolated from the crosses to Jaycee, Florida 500, and Orbit. When crossed with two susceptible tester cultivars, Pettis had combining ability superior to Jaycee for the characters studied. A high negative correlation was obtained for leaf discoloration vs the other characters. High positive correlations were obtained among plant height, panicle number, and grain yield. Percentage leaf discoloration provides a useful criterion for evaluation of BYDV resistance in preliminary screening tests and grain yield provides a quantitative measurement of the overall effects of the disease on productivity.
Correlations Among Chemical and Agronomic Characteristics in Certain Oat Cultivars and Selections1
Authors: Forsberg R. A. , Youngs V. L. , Shands H. L.
Published: July 2010

Correlations among several chemical and agronomic characteristics were determined in 1970 and 1971 for 10 Avena sativa L. cultivars and for 46 F4‐F6 backcross “N” lines derived from a complex interspecific cross involving a 6x amphiploid. In 1971, groat protein percentage was significantly and negatively correlated with yield in both series, but in 1970 a nonsignificant positive r of 0.37 existed in the A. sativa series. A strong negative association existed between groat protein percentage and kernel weight in the A. sativa and 46 “N” line series in 1971 (−0.71** and −0.28*, respectively), when kernel weights were considerably higher than in 1970. Correlation coefficients between groat protein and lipid percentages were negative, though nonsignificant, for the A. sativa series in both years, but were near zero or positive in the “N” series. ‘Dal’ was high in both groat protein and lipid percentages, illustrating that departures from the general relationship exist. Lines such as ‘Lodi,’ with higher lipid and lower protein percentages, contribute strongly to a negative association.

The correlation between lipid percentage and grain yield was significant and positive only in 1971. While r values between lipid percentage and kernel weight were significantly positive in the A. sativa series in both years, the relationship in the “N” series was significant and negative in 1970 and near zero in 1971. Groat protein percentages varied more from year to year within selections than did lipid percentages.

The association between groat protein percentage and four of the six fatty acids differed in the A. sativa series from that in the “N” series. The relationship between lipid percentage and the fatty acids were considerably more in agreement for the two series. Lipid percentage was positively associated with percentages of stearic and oleic acids, but negatively correlated with myristic, palmitic, and linoleic acids.
Variation in Protein Percentage in Different Portions of Peanut Cotyledons1
Authors: Tai Y. P. , Young C. T.
Published: July 2010

Six varieties of peanuts (Arachis hypogaea L.) were studied for variation in percent protein by macro‐Kjeldahl analysis of small sections from four consecutive segments (I, II, III, and IV) of the two cotyledons, with section IV at the embryonic end of the individual seeds. The distribution of percent protein in the cotyledon was significantly different within each variety. Four small‐ and medium‐seeded varieties showed slightly higher protein in both end sections (I and IV) of the seeds than in the middle sections (II and III). High correlation coefficients were obtained between the protein percent of each section and that of the whole cotyledons except for section IV of the ‘Argentine’ variety. However, the combined sample from sections I and II produced less variability and gave an accurate estimate of percent protein for the whole cotyledons. All three seed parts of the six peanut varieties showed a significant difference in percent protein. The embryonic axis and the cotyledon had about the same amount of protein, but each had a much higher protein percent than did the seed coat.
Genetic and Environmental Effects on Quantity and Quality of Alfalfa Nectar1
Authors: Walker A. K. , Barnes D. K. , Furgala Basil
Published: July 2010

The quantity of nectar per floret and the principal nectar sugars of four alfalfa (Medicago sativa L.) clones were studied under two controlled temperature regimes. One regime was a constant 25 C and the other was an alternating diurnal temperature regime ranging from 18 to 32 C. Clones varied significantly in volume of nectar per floret, percent total nectar sugar, and ratios of suerose: fructose and glucose:fructose. Temperature regimes significantly affected quantity of nectar per floret, percent total nectar sugars, and the ratios of sucrose: fructose and sucrose:glucose. Time of day did not affect any nectar trait. Samples taken between early morning and midafternoon appeared to be least affected by environmental factors.
Yield Stability of Single Crosses and Three‐way Hybrids of Grain Sorghum1
Authors: Patanothai Aran , Atkins R. E.
Published: July 2010

Replicated yield trials were conducted during 3 years in Iowa to compare the responsiveness of parental lines and different types of sorghum (Sorghum bicolor L. Moench) hybrids to a range of environmental conditions. Fertile single crosses and three‐way hybrids gave equivalent mean yields over nine environments, and both hybridtypes yielded significantly more than male‐sterile single crosses and parental lines. Estimates of parameters that describe stability of performance over environments indicated that the three‐way hybrids as a group were slightly more stable for grain yield than were the fertile single crosses. Deviations from regression were smaller for the three‐way hybrids, and their average regression coefficient on an environmental index was closer to 1.0. Considerable variation for these parameters was evident among the individual hybrids, suggesting that stability of performance may be attainable with either single or three‐way crosses.
Production of Inhibitory Compounds in Corn Inbreds with Monogenic and Multigenic Resistance to Helminthosporium turcicum1
Authors: Calub A.G. , Long B. J. , Dunn G. M.
Published: July 2010

Utilizing the drop diffusion technique the sixth or seventh leaf of corn (Zea mays L.) seedlings was inoculated with drops of a spore suspension of Helminthosporium turcicum Pass. in a humid chamber at 100% RH, 21C, and 3230 lux. Drops of the suspension were then withdrawn from 1 to 6 days after inoculation and centrifuged. The supernatant or diffusate, then free of spores and germ tubes, was mixed with a drop of fresh spore suspension. Diffusates that inhibited spore germination or delayed the growth of germ tubes were assumed to contain a phytoalexin or other inhibitory substance.

Percent leaf infection was determined within 6 to 9 days from seedlings inoculated at the third leaf stage and left in the humid chamber at 100% RH for 18 hours.

Multigenic lines produced inhibitory substances similar in effect but in significantly larger amounts than monogenic inbred lines. Percent leaf infection was also significantly lower on multigenic than on monogenic inbred lines. Percent spore germination in bioassays was significantly correlated with percent leaf infection. The addition of monogenic (Ht) resistance to two multigenic resistant inbreds diluted their ability to produce inhibitory substances.
Mass Selection and Mating Systems in Cereals1
Authors: Redden R. J. , Jensen N. F.
Published: July 2010

Responses to two cycles of mass selection under two mating systems were compared in the F2 and F3 generations of one cross each of spring wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). The number of green tillers prior to head emergence was used as the critical character. Additional characters, time from sowing to flowering and fertility number at maturity, were measured also in the evaluation of selection response for green tillers. The mean response for increased tillring, evaluated at two sites against unselected control generations, was higher in the wheat at 10.3%cycle than in the barley at 6.3%/cycle. Broad sense hentability estimates for tillering were between 10 and 25% for each cross.

In both species the selection responses were greater in the hybrid than in the selfed selection series. The hybrid series was obtained by random mating among the selections in each cycle. The respective responses in barley realized over two selection cycles, were 17.1% with outbreeding and 8.7% with inbreeding at site 1, and 13.9% with outbreeding and 10.3% with inbreeding at site 2. In wheat at site 1, the responses were 22.6% with outbreeding and 18.5% with inbreeding. (Site 2 of the wheat had poor establishment.) Since the same F2 selection generated the hybrid and selfed series, the differences in response were attributed to the second cycle only. Asso. ciated selection responses for time to flowering and tiller number at maturity were detected only in the wheat.

The results showed that mass selection with concurrent random mating could be a useful breeding stratcgy in self‐pollinated crops.
Genetic and Environmental Effects on Production of Inhibitory Compounds in Corn Resistant to Helminthosporium turcicum1
Authors: Calub A. G. , Dunn G. M. , Routley D. G. , Couture R. M.
Published: July 2010

By utilizing the leaf drop diffusate technique, seedling leaves of corn (Zea mays L.) were inoculated with a spore drop suspension of Helminthosporium turcicum Pass, in a humid chamber at 21 C and light intensity of 3,230 lux. The drop suspensions were then withdrawn from 1 to 7 days after inoculation and centrifuged. The supernatant or diffusate, now free of spores and germ tubes, was mixed with a drop of fresh spore suspension. Diffusates which inhibited spore germination or delayed growth of the germ tube were assumed to contain phytoalexin or other inhibitory substances.

The four homozygous combinations of the genes Ht and Bx were bioassayed plus the heterozygote HthtBxBx. The HtHtBxBx genotype, treated with drops of distilled water only, served as control. Greatest to least inhibition was produced by the double dominant HtHtBxBx, followed by the single dominant genotypes and then the double recessive hthtbxbx. Both Ht and Bx had a significant inhibitory effect. A significant amount of inhibition occurred within 24 hours after inoculation, increased to a maximum on the second or third day following inoculation, and continued at this high level until the sixth day. Inhibition was decreased significantly by leaf detachment, low spore concentration, and high preconditioning temperature.
Cytogenetics and Breeding Behavior of a Hexaploid Agrotricum Immune from Wheat Streak Mosaic Virus1
Authors: Wong Raymond Sze‐Chung , Wells Darrell G. , Gardner Wayne S.
Published: July 2010

A breeding line of spring wheat, C.I. 15092, selected from Triticum aestivum L. em Thell./Agropyron intermedium (Host) Beauv. bred true for immunity from wheat streak mosaic virus (WSMV). F1 hybrids of C.I. 15092/T. aestivum ‘Fletcher’ had 20 paired and 2 unpaired chromosomes of unequal size at metaphase I of meiosis in pollen mother cells. Apparently C.I. 15092 had one Agropyron chromosome pair carrying genes for immunity from WSMV substituted for a homoeologous wheat chromosome pair. Immunity from WSMV was completely dominant in hybrids. Inheritance data indicated that the Agropyron chromosome was transmitted through 27% male and 21% female gametes of the F1 hybrid C.I. 15092/Fletcher. A small number of immune F2 and F3 plants were comparable to control plants in seed set, indicating that the whole Agropyron chromosome added to the wheat complement was not strikingly harmful in some plants, at least, not to self‐fertility.
Fiber Elongation and Dry Weight Changes in Mutant Lines of Cotton1
Authors: Kohel R. J. , Quisenberry J. E. , Benedict C. R.
Published: July 2010

Genetic variation in fiber elongation and secondary cell wall deposition in cotton (Gossypium hirsutum L.) was studied using three monogenic mutant lines (Ligon lintless, Pilose, and immature fiber) and two genetically diverse normal lines (Z2557 and Texas Marker‐1). Because it has been shown that secondary cell Wall deposition can begin before fiber elongation ceases, this experiment studied the genetic variability and interrelations between these two features of fiber development. The fiber development of these lines demonstrated that it is possible to alter, through genetic manipulation, either elongation or dry weight increase of the fibers without appreciably changing the other, thus demonstrating that fiber elongation and secondary cell‐wall deposition are not necessarily controlled by the same genetic factors.
Heterosis, Inbreeding Depression, and Combining Ability in Diallel Crosses of Cigar‐Wrapper Tobacco1
Authors: Dean C. E.
Published: July 2010

Seven varieties and breeding lines of cigar‐wrapper tobacco (Nicotiana tabacum L.) and the 21 possible hybrids between them, excluding reciprocals, were evaluated in terms of 8 important characters. Heterosis above the midparent was observed for number of 40‐cm (16‐in) leaves, total leaf number, lateral vein angle, yield, No. 1 string, grade index, crop index, and blue mold index. One hybrid, 1128✕5058, yielded significantly more than the highest‐yielding parent, ‘Florida 20.’ Inbreeding depression was observed for number of 40‐cm leaves, lateral vein augle, yield, crop index, and blue mold Peronospora tabacina Adam) index.

Estimates of general combining ability were significant for all characters investigated; specific combining ability was significant for number of 40‐cm leaves, total leaf number, and lateral vein angle. The data indicate the predominance of additive genetic variance in the material investigated, but also suggest that nonadditive components may be important, especially for certain leaf characteristics. Inferences from the data are that development of pure lines from segregating material would, in general, be preferable to the development of F1 hybrids as a breeding procedure to produce commercial varieties. If F1 hybrids are to be used commercially for any reason, intensive development of inbreds for specific contributions to particular F1 hybrids and evaluation of combining ability could result in superior hybrids for specific situations.
Variation of Soluble Proteins in Alfalfa, Sainfoin, and Birdsfoot Trefoil1
Authors: Gutek L. H. , Goplen B. P. , Howarth R. E. , McArthur J. M.
Published: July 2010

Soluble protein concentration was measured at different stages of growth in alfalfa (Medicago sativa L.), which does produce ruminant bloat, and in sainfoin (Onobrychis viciaefolia L.) and birdsfoot trefoil (Lotus corniculatus L.), which do not produce ruminant bloat. Optimal sampling procedures for more effective selection of a low soluble protein (nonbloating) alfalfa in a plant breeding program was studied. Alfalfa showed no significant diurnal variation in soluble protein content. Highest levels were found in the top (10 cm) leaves and stems. In general, highest soluble protein concentrations occurred in prebud and up to the middle to late bud stage. There was significant variation due to seasonal effects. In sainfoin all of the fraction I protein was precipitated by tannins at all stages of growth. In birdsfoot trefoil accumulation of tannins resulted in decreasing soluble protein levels with advancing maturity. The development of a nonbloating, high tannin alfalfa variety was discussed.
Equations for the Rate of Dark Respiration of White Clover and Grain Sorghum, as Functions of Dry Weight, Photosynthetic Rate, and Temperature1
Authors: McCree K. J.
Published: July 2010

Equations were designed to be used in computer models of photosynthesis and respiration in crops. They were developed from new experimental data on the rates CO2 exchange of whole plants grown under constant conditions. The dark respiratory rate was separated into two components. The “maintenance” component was taken to be the efflux of CO2 after more than 48 hours in the dark at constant temperature. This component was proportional to the dry weight of the plant (W), and was a strong function of temperature (T). The proportionality constant (c) was about twice as great for clover (Trifolium repens L.) as it was for sorghum (Sorghum bicolor L.), at the same temperature. The “growth” component was taken to be the difference between the “maintenance” component and the total efflux during a normal night period (N). This component was proportional to the total influx during the previous daytime period (D), and the proportionality constant (k) was independent of species and temperature. The values of c and k were in good agreement with values calculated by Penning de Vries, using the principles and equations of biochemistry.

The experimental data were best fitted by the following equations:

For clover at 30C: N = 0.14 D + 0.0143W

For sorghum at 30C: N = 0.14 D + 0.0054W

Temperature dependence of maintenance coefficient:

cT = c30 (0.044 + 0.0019 T + 0.0010 T2)

where N = night total of CO2 evolved in g•12h‐l•plant‐1,

D = daytime total of CO2 taken up in g•12h‐1•plant‐1,

W = CO3 equivalent of dry weight in g•12h‐1•plant‐1,

T = temperature in °C.
Comparative Degradation of Coastal Bermudagrass, Coastcross‐1 Bermudagrass, and Pensacola Bahiagrass by Rumen Microorganisms Revealed by Scanning Electron Microscopy1
Authors: Akin Danny E. , Burdick Donald , Amos Henry E.
Published: July 2010

Leaves of the cultivars Coastal bermudagrass and Coastcross‐1 bermudagrass (Cynodon dactylon (L.) Pets.) and Pensacola bahiagrass (Paspalum notatum var. saurae Parodi) were investigated to delineate the relationship between microanatomy and rumen microbial degradation. Leaf sections of each forage were incubated in vitro with rumen microorganisms for 6, 12, and 72 hours and examined for the ease and extent of tissue degradation using a scanning electron microscope. Tissues of Coastcross‐1 bermudagrass were degraded faster than comparable tissues of Coastal bermudagrass. The extent of degradation after 72 hours appeared to be equal in the bermudagrasses. The rate of total tissue degradation in bahiagrass appeared to be between that of the bermudagrass cultivars. Results indicated that microanatomy effected differences in rumen microbial degradation between the two forage species. However, the rate of degradation between the cultivars of bermudagrass appeared to be due to inherent differences in the cell wall organization or composition of degradable tissues. Improvement in the digestibility of these forages may be possible by plant breeding to reduce microanatomical obstructions to digestibility or by breeding or processing techniques to modify structural limitations to digestibility in the cell walls.
Selection for Leaf Angle in Maize and Its Effect on Grain Yield and Other Characters1
Authors: Ariyanayagam R. P. , Moore C. L. , Carangal V. R.
Published: July 2010

Four generations of bidirectional phenotypic selection for leaf angle was practiced in a maize (Zea mays L.) variety using two leaf‐angle determinations; one method estimated the angle in the immediate vicinity of the culm, the other the angle to the tip of the leaf blade. Regression coefficients of 3.82 and 10.18° over selection cycles were found for the two angle measurements. Average change in leaf angle was 10 to 12% per cycle in each direction. Leaf blade and midrib thickness, but not leaf length and width, were associated with angle. Erect leaf types were generally shorter in plant height, later in maturity, higher in lodging resistance, and higher in light transmissibility. Relative leaf angle remained constant over stages of growth and position on the plant. Grain yield variations attributable to leaf angle differences were small and statistically insignificant at planting densities from 40,000 to 80,000 plants/ha.
Variation in Oat Kernel Characteristics Within the Panicle1
Authors: Youngs V. L. , Shands H. L.
Published: July 2010

Oat (Avena sativa L.) investigations are of current interest because of the high quality protein present in the oat groat. In this study, groats were analyzed individually from single panicles selected from three replicates each of ‘Dal,’ ‘Froker,’ and ‘Orbit’ oats grown in the nursery and in the greenhouse. Grain weight, groat weight, groat percent, protein percent, and protein content per groat were determined, and relative position on the panicle was recorded. Within a panicle, groat weight decreased and groat percent increased from primary to secondary to tertiary kernels. Protein percent varied only slightly between primary and secondary groats, but was less in the tertiary of Dal and Froker. About 60% of the total protein was in the primary groats of Dal and Froker. Orbit contained many doubles in which the primary groat was not formed; hence the primary groats contained only about 45% of the total protein. Position of the groat on the oat panicle had an effect on the kernel characteristics. Correlations between groat distance from the panicle base and kernel weight, groat weight, and protein weight were positive and highly significant. Between groat distance from the base and protein percent, the relation was negative and generally highly significant.
Gamma Radiation Effects on Pearl Millet Pollen1
Authors: Hanna Wayne W. , Young John R.
Published: July 2010

Gamma irradiation of pollen from pearl millet [Pennisetum americanum (L.) K. Schum. (formerly P. typhoides)] inbreds at doses of 0.2 to 16 kR indicated, based on seed set, that inbreds ‘Tift 23DB’ and ‘Tilt 186’ were significantly more sensitive to irradiation than inbred ‘Tift 239DB.’ Average seed set obtained by irradiating pollen of these inbreds was reduced about 50% at doses between 1.2 and 3 kR. No seed set was obtained when pollen was irradiated at 16 kR. Pollen irradiated at 3 kR produced the highest frequency (11%) of semisterile plants. Seed set on semisterile plants (generally 20 to 60%) was adequate to make the translocations useful cytological stocks.
Fertility Restoration in Confectionery Sunflowers1
Authors: Fick G. N. , Zimmer D. E.
Published: July 2010

Fertility restoration of male‐sterile cytoplasm was discovered in two inbred lines from the confectionery sunflower (Helianthus annuus L.) variety, ‘Sundak’. Limited data suggested that two independent, complementary, dominant genes were required for restoration. Crosses of the two restorer lines with several different cytoplasmic male‐sterile lines produced F1 hybrids that were resistant to rust and highly desirable agronomically.
Inheritance of Protein and Sulfur Content in Seeds of Chickpeas1
Authors: Sandhu Shabeg S. , Keim W. F. , Hodges H. F. , Nyquist W. E.
Published: July 2010

Seeds of 33 genotypes of chickpeas (Cicer arietinum L.), were assayed for total protein and one aspect of protein quality, sulfur content. Since the sulfur‐containing amino acids in protein of chickpea are first limiting in human dietary requirements, a barium sulfate turbidimetric method was developed for rapid determination of sulfur content. Using five genotypes, a coefficient of determination of 0.89 was obtained between the total‐sulfur content determined by this turbidimetric method and sulfur‐containing amino acids as percent of protein determined by an amino‐acid analyzer. Evaluation of these 33 genotypes over 2 years for 8 morphological, agronomic, and protein characters revealed significant genotypic effects and highly significant year‐by‐genotype interactions for all variables. Percent protein ranged from 14.5 to 28.9 with a mean of 21.8. A highly significant negative phenotypic correlation (r = —0.57) was determined between percent protein and 100‐seed weight. To avoid the pseudosuperiority of small, sometimes shrivelled, unfilled seeds, protein weight per seed was calculated. Protein weight per seed was positively correlated (P < .01) with sulfur as percent of protein and 100‐seed weight. Broadsense heritability estimates based on the phenotypic variance of means of genotypes over years ranged from 0.51 to 0.74 for the eight variables. Protein weight per seed revealed a value of 0.70, with percent sulfur and sulfur as percent of protein values of 0.64 and 0.51, respectively. Highly significant general and specific combining ability effects in F1 and F2 populations were evident for 100‐seed weight, percent protein, and protein weight per seed. Less definite results were obtained for percent sulfur and sulfur as percent of protein. Heterosis values were calculated comparing F2 with midparental values.
Correlation of Seed Oil Content in Sunflowers with Other Plant and Seed Characteristics1
Authors: Fick G. N. , Zimmer D. E. , Zimmerman D. C.
Published: July 2010

Studies of open‐pollinated and hybrid sunflower (Helianthus annuus L.) varieties showed a positive correlation of seed (achene) oil content with days to 50% flowerng, plant height, and test weight, and a negative correlation with rust reaction under moderate to severe rust conditions. No association of oil content with seed yield or seed weight was apparent. Oil content of inbred lines was negatively correlated with seed weight, but showed no correlation with 50% flowering, plant height, rust reaction, plant leafiness, head diameter, or head inclination. No differences in oil content were detected among individual F2 plants with different genotypes for fertility restoration, resistance to rust, or resistance to downy mildew. Fertility restoration and resistance to rust and downy mildew are traits introduced from wild sunflowers with relatively low oil content, and the lack of association suggests that these traits can be readily incorporated into high‐oil genotypes. An increase in oil content of about 2.5% was noted for seed from branched F2 plants, as compared to single‐headed types.
Relationship of Mitochondrial Efficiency to Forage Yield in Alfalfa1
Authors: Schneiter A. A. , McDaniel R. G. , Dobrenz A. K. , Schonhorst M. H.
Published: July 2010

The utilization of a physiological variable to determine yield potential could serve as a valuable tool for plant breeders. The object of this study was to determine if a relationship existed in ratios of adenosine diphosphate (ADP) to oxygen (mitochondrial efficiency) and forage production in alfalfa (Medicago sativa L.).

Significant differences in ADP:O among mitochondria isolated from 5‐day‐old seedlings of several lines of alfalfa were found. When ADP:O means of the seedlings were compared to forage yields obtained from field studies, significant positive correlation coefficients were found. Correlations were highest during cooler portions of the growing season (spring, fall) when yields are normally highest and lower during the summer months when forage production/harvest is low.

It would appear that the laboratory determination of ADP:O ratios may have potential as a physiological tool for the selection of high yielding alfalfa genotypes when grown under optimum conditions. When factors such as physical environment, insects, or diseases are the yieldlimiting variables the relationship may not be as valid.
Recurrent Restricted Phenotypic Selection Increases Forage Yields of Pensacola Bahiagrass1
Authors: Burton Glenn W.
Published: July 2010

Recurrent restricted phenotypic selection (RRPS), modified form of mass selection, was evaluated as a breeding technique for improving the forage yield of Pensacola bahiagrass (Paspalum notatum var. saure ‘Parodi’), a sexual diploid. Selection was based on single green weights of spaced plants at the end of the first season and spring yield the following year. Four cycles of RRPS increased forage yield of this grass 17.7% over that of the commercial check. The rate of progress per 2‐year cycle in a previously selected narrow‐gene population (NGP) was about 2%/cycle. In an unselected wide‐gene population (WGP), rate of progress was 6%/cycle. Variances and coefficients of variability (CV's) for yield spaced plants of the original and fourth‐cycle populations compared in the same test were similar for the NGP but were reduced substantially to the NGP level in the WGP. RRPS increased the frequency and yield of high‐yielding plants. Increasing seeding rates from 3 to 27 kg/ha in methyl bromide treated soil increased firstyear forage yields 76%, but had no effect on the relative yields of the commercial check and the fourth‐cycle populations. The data suggest that rate of progress could be doubled by use of a 1‐year cycle and the saving of 3 to 4 rather than 5 of the best plants in each 25‐plant block.