bluuebunny/crossref_metadata_2025 huggingface dataset:
Leaf Area and CO2‐exchange Rate as Determinants of the Rate of Vegetative Growth in Soybean Plants1
Authors: Kaplan Stuart L. , Koller H. R.
Published: July 2010

The purpose of this experiment was to examine the interrelationships between CO2‐exchange rate (CER) and certain growth analysis variables in soybean [Glycine max (L.) Merr.] plants.

Soybean plants representing 16 cultivars were grown in a controlled environment chamber. At 22 and 29 days after planting, leaf area and dry weights of the leaves, supporting tissue, and roots were measured for each plant. From these data, the rate of vegetative growth (GR) was determined for each cultivar as well as leaf area growth rate (LAGR), specific leaf weight (SLW), and other growth analysis variables.

At 28 days after planting, the CER per unit leaf area of the terminal leaflet of the second trifoliolate leaf was measured. The resistance to CO2 diffusion was partitioned into boundary layer, stomatal, and mesophyll components. Gas exchange was measured independently for each leaf surface.

Growth rate was negatively related to CER and SLW and positively related to LAGR. Furthermore, CER was positively and negatively related to SLW and LAGR, respectively. As the leaves increased in SLW and CER across the cultivars, their rate of area expansion decreased. Since GR was positively correlated with LAGR and negatively correlated with CER, it appears that increases in CER did not compensate for decreases in LAGR; consequently, differences in GR among the cultivars were detected.
Recurrent Mass Selection for Improved Seed Yields in Intermediate Wheatgrass1
Authors: Knowles R. P.
Published: July 2010

The first cultivars of intermediate wheatgrass (Agropyron intermedium Host., Beauv.), released in North America had poor seed yields. At Saskatoon a breeding program of recurrent mass selection was carried out from 1955 to 1971 to develop more fertile strains. In each cycle of selection, 1,000 plants were evaluated visually for seed filling, and 50 of the most desirable plants were harvested. Seed of those with best seed yields and good seed quality was used to plant the nursery for the next cycle of selection. Open‐pollination (OP) seed was used for propagation in early cycles and controlled‐pollination (CP) seed was used in later cycles.

The rate of seed yield improvement per cycle was 10.2% for OP propagation and 20.3 for the CP method. Slight concurrent improvements were made in forage yield, resistance to lodging, and seed quality. Herbage quality of selected lots was generally below that of the ‘Ree’ check cultivar but without a consistent trend.

A single cycle of polycross breeding gave somewhat greater improvement than a single cycle of mass selection, but required more years to complete.

Although selection was confined to a single station, the improvements obtained were noted regionally.
Influence of 2,4‐D, Pronamide, and Simazine on Dry Matter Production and Botanical Composition of an Alfalfa‐grass Sward1
Authors: Triplett G. B. , Keuren R. W. Van , Walker J. D.
Published: July 2010

Pronamide [3,5‐dichloro (N‐l,l‐dimethyl‐2‐propynyl)‐benzamide], simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine], and 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] were evaluated for management of species composition in established swards of alfalfa (Medicago sativa L.) which had become colonized by orchardgrass (Dactylis glomerata L.), Kentucky bluegrass (Poa pratensis L.), and dandelion (Taraxicum officinale Weber). Dormant application of 2,4‐D ester reduced seedling dandelions, but did not affect mature dandelions, alfalfa stands, or yields. Simazine did not affect total yield or botanical composition of forage in this study. Pronamide application reduced bluegrass and total forage yield in the first harvest. The alfalfa component of the forage and total yield of alfalfa increased with pronamide treatments. Total forage yield for the season was the same for all treatments.

Counts of alfalfa plants per m2 were made for individual plots and multiple regression analysis was used to determine the association of percent alfalfa composition of the first harvest and plant density with alfalfa yield. In pronamide treated plots as few as 10 to 20 alfalfa plants per m2 utilized resources made available by reduction of other species and produced acceptable yields. These results contrast to the 50 to 60 plants per m2 commonly considered necessary for productive stands and suggest the possibility that herbicides may be used to extend the productive life of swards containing alfalfa.
Effects of Plant Water Status on Stomatal Activity, Photosynthesis, and Nitrate Reductase Activity of Field Grown Cotton1
Authors: Ackerson R. C. , Krieg D. R. , Haring C. L. , Chang N.
Published: July 2010

The effects of varying degrees of water stress on stomatal activity, photosynthesis, and nitrate reductase activity were examined in field grown cotton (Gossyplum hirsutum L., cv ‘Dunn 56C’). A relationship between plant water status and activity of each measured physiological parameter was established.

Slight increases in leaf diffusive resistance were observed as leaf water potentials decreased although complete stomatal closure due to water stress was not generally observed. In many cases, visibly wilted leaves with zero turgor potentials exhibited minimal diffusive resistances. Morning and afternoon values of leaf diffusive resistance were distinctly different even though no correlation between leaf water potential and diffusive resistance was evident.

Water stress substantially reduced photosynthesis in both vegetative and reproductive leaves of cotton. Photosynthetic rates of each leaf type responded differently to declining leaf water potentials. The data suggest that the photosynthetic reduction could not be attributed to stomatal closure.

The activity of nitrate reductase was adversely affected by declining leaf water potentials. The nocturnal activity of nitrate reductase (respiratory linked) was also reduced by severe water stress. However, the reduction from maximum daily activity to minimum night time activity was similar in both stressed and non‐stressed plants. These data suggest that inhibition of nitrate reductase activity could be due to long term water stress effects rather than temporal changes in plant water status.

The data presented indicate that stomata of field grown cotton are relatively insensitive to water stress, at least within the range of leaf water potentials observed in this study. Measurement of stomatal activity may not be a good criterion for assessing plant water status of cotton. The measurement of one or more physiological processes may prove a better index of plant water status as well as providing sensitive selection criteria for breeding more drought tolerant varieties.
New Genes for Resistance to the Brown Planthopper in Rice1
Authors: Laksminarayana A. , Khush Gurdev S.
Published: July 2010

The inheritance of resistance to brown planthoppers (Nilaparvata lugens Stal.) was studied in 28 rice (Oryzasaliva L.) cultivars in the greenhouse. Seven‐day‐old seedlings were infested with second and third‐instar nymphs of brown planthoppers and seedling injury was recorded at 7 to 8 days after infestation.

Single dominant genes that are allelic to Bph 1 condition the resistance in ‘Balamawee’, ‘CO 10’, ‘Heenukkulama’, ‘MTU 9’, ‘Sinnakayam’, ‘SLO 12’, ‘Sudhubalawee’, ‘Sudurvi 305’, and ‘Tibiriwewa’. Single recessive genes that are allelic to bph 2 govern resistance in the cultivars ‘Anbaw C7’, ‘ASD 9’, ‘Dikwee 328’, ‘Hathiel’, ‘Kosatawee’, ‘Madayal’, ‘Mahadikwee’, ‘Malkora’, ‘M.I. 329’, ‘Murungakayan 302’, ‘Ovarkaruppan’, ‘Palasithari 601’, ‘PK‐1’, ‘Seruvellai’, ‘Sinna Karuppan’, and ‘Vellailangayan’. A single dominant gene also conveys resistance in ‘Rathu Heenati’, but it segregates independently of Bph 1 and is designated as Bph 3. Similarly, a single recessive gene conveys resistance in ‘Babawee’ but it segregates independently of bph 2 and is designated as bph 4. The resistance in ‘Ptb 21’ is controlled by one dominant and one recessive gene. The allelic relationships of these two genes to other genes are not known.
Genetic Analysis of Crosses among Corn Strains Divergently Selected for Percent Oil and Protein1
Authors: Dudley J. W. , Lambert R. J. , de la Roche I. A.
Published: July 2010

All possible crosses, excluding reciprocals, among the nine strains [Illinois high oil (IHO), reverse high oil (RHO), switchback high oil (SHO), low oil (ILO), reverse low oil (RLO), high protein (IHP), reverse high protein (RHP), low protein (ILP), and reverse low protein (RLP)] in the Illinois long term selection experiment for percent oil and protein in corn (Zea mays L.) were grown to measure their performance and to study; 1) the effects of oil and protein percentage on grain yield and other agronomic traits, 2) the effects of selection for percent protein on components of percent protein, 3) the relationship of percent oil and protein to calorie production, and 4) the importance of genetic effects for several traits.

Results obtained suggest that; 1) grain yield is negatively correlated with percent oil and percent protein, 2) percent protein in the kernel is primarily determined by percent protein in the endosperm, 3) calories per g dry matter are largely determined by percent oil while calories per kernel or ha are largely determined by kernel weight or grain yield, 4) the sum of squares (s.s.) due to heterosis accounted for only 5 and 7%, respectively, of the entry s.s. for percent oil and percent protein but over 50% of the entry s.s. for yield of grain and protein, and 5) evidence was obtained of dominance for both high and low percent oil.
Interspecific in Trifolium L. Sect. Trifolium Zoh. II. Fertile Ployploid Hybrids Between T. medium L. and T. sarosiense Hazsl1
Authors: Quesenberry K. H. , Taylor N. L.
Published: July 2010

Interspecific hybrids of Trifolium medium L. ✕ T. sarosiense Hazsl. and reciprocal hybrids were produced by hand pollinations in a greenhouse. Hybrids of T. medium ✕ T. sarosiense were normal green and intermediate betweenthe two parents for morphological traits, but the reciprocal hybrids showed chlorophyll deficiencies including mottling and chimeras. Seed set from interspecific crosses was lower than from intraspecific crosses, but the small reduction in seed set represents only a minor isolation barrier between the species. All hybrids and both parents were self‐incompatible.

Hybrids of T. medium 2n=72 ✕ T. sarosiense 2n=48 and the reciprocal hybrids had 2n=60 chromosomes except for two plants which had 2n=58 chromosomes. Meiotic analysis of chromosomes of T. medium and T. sarosiense revealed mean frequencies of 7.40 I, 32.30 II and 1.34 I, 23.33 lI respectively per PMC at metaphase I of meiosis. The hybrids (2n=60) of T. medium ✕ T. sarosiense and reciprocal exhibited mean frequencies ot 5.30 I, 27.29 II and 4.68 I, 27.66 II, respectively, per PMC at metaphase I. However, the two 2n=58 hybrids had a reduction in bivalents to 25.96 and 26.00, respectively. Mean pollen stainabillty of the two parents was greater than 95%, whereas mean stainability of all hybrids was 89%. Other lines of T. medium were later identified with 2n=64, 68, 70, 72, and 80 chromosomes. The 2n=64 and 80 lines showed mostly 32 II and 40 II, respectively, but cytotypes with 68, 70, and 72 chromosomes had 32 II and an increasing number of univalents. Although the complexity of ploidy level in the T. medium taxa complicates any conclusions concerning phylogenetic relationships, our results indicate strong evolutionary links between T. sarosiense and T. medium.
Grafting as a Tool in Soybean Breeding1
Authors: Kiihl R. A. S. , Hartwig E. E. , Kilen T. C.
Published: July 2010

Grafting of soybean [Glycine Max (L.) Merr.] from different maturity groups was studied to determine its feasability for simplifying crossing. When grafted on early flowering genotypes, scions of later flowering genotypes flowered 21 to 50 days after grafts were made. About 95% of the grafts were successful.

The grafting technique appears to be an excellent method of inducing earlier flowering on late genotypes to permit their use in a crossing program. It is also a means of producing seed on genotypes that otherwise flower too late for seed production in a particular geographical area.
Repeatability of the Stability‐variance Parameter in Oats1
Authors: Eagles H. A. , Frey K. J.
Published: July 2010

Mean yields and stability variances were calculated for grain and straw yields of 80 F9‐derived lines of oats (Avena sativa L.) grown in 24 field environments. The repeatability of these parameters was investigated by correlating arrays of average phenotypic values obtained from subsets of the 24 environments arranged by random, stratified, and extreme methods. Correlations between arrays of mean yields from different subsets ranged from 0.78 to 0.85 for grain yield and 0.81 to 0.86 for straw yield, which shows good repeatability for means of these traits. Arrays of stability variances from different subsets showed correlations that ranged from 0.06 to 0.12 for grain yield and from −0.01 to 0.30 for straw yield. Obviously, the stability‐variance parameter was only repeatable to a limited extent for the materials and environments studied. These repeatabilities were discussed with reference to breeding for improved stability.
Pigmentation Differences of Soybean Cultivars with Green Hypocotyl Color when Grown in Continuous Light1
Authors: Payne R. C. , Sundermeyer E. W.
Published: July 2010

Samples of 20 soybean (Glycine max L.) cultivars, classified as having green hypocotyl color, were grown in continuous 34,500 lux light. These cultivars could be placed into either of two groups based upon the presence or absence of a band of bronze pigmentation. The use of growth chamber light could be of value for the differentiation of soybean cultivars and the detection of offtypesin soybean seed lots.
Use of Genetic Male Sterility for Simultaneous Conversion and Improvement of Alien Sorghums1
Authors: Singh Shree P.
Published: July 2010

A breeding method is described for simultaneous conversion and improvement of alien sorghums (Sorghum bicolor (L.) Moench). In addition to recessive height and maturity genes the procedure requires genetic male sterility. This integrated and pragmatic approach for population breeding seeks the development of widely adapted cold tolerant sorghum cultivars, while converting the alien lines to short stature and early maturity types by recurrent backcrossing. However, the procedure can be used, with necessary modifications, for the improvement of other traits in sorghum and also in other crops where suitable systems exist for easy recombination.
Variable Expressivity and Gene Action of Gland‐Determining Alleles in Gossypium hirsutum L.1
Authors: Wilson F. D. , Smith J. N.
Published: July 2010

We studied the variable expressivity of gland‐determining alleles at three loci in stigmas and bolls of cotton (Gossypium hirsutum L.) and their effects on the amounts of flower‐bud (square) gossypol that occur those glands. High levels of square gossypol provide resistance in the plant to certain insect pests. The alleles gl1 and gl1y reduced stigma‐gland density and square gossypol content slightly but rendered bolls glandless, or nearly glandless. The Gl2 allele was more expressive than Gl3 for boll gland density and seed‐gossypol content, but less expressive for stigma‐gland density and square gossypol content. The relative potency of three alleles at the gl3 locus was Gl3'>Gl3ru1>Gl3. Judicious combinations of alleles should maximize gossypol content in the squares without changing it as much in the seeds. The alleles Gl2, Gl3, and Gl3rui repressed the gland‐determining action of the high‐potency Gl3' because F1 means were below the midparental value (MP) when any one of these alleles was present, but above MP when they were absent in combinations carrying Gl3'. All F1 combinations carrying Gl3 had lower amounts of square gossypol than MP. Additive genetic effects were similar and predominant in a halfdiallel set that included four parents and their hybrids carrying all combinations of Gl2, gl2, Gl3, and gl3, and in a diallel set to which had been added a fifth parent and hybrids carrying Gl3'. Nonadditive effects, however, differed for gland density, emphasizing the variable action of these alleles in different parts of the plant. The halfdiallel analysis showed only additive effects for square gossypol content, but the F1. —MP relationship indicated that nonadditive effects were also present. Thus, direct selection for high gossypol content, even though much more efficient than selecting for high gland density, could still present some breeding problems.
Amino Acid and Carbohydrate Composition of Leaves of Tall Fescue Genotypes Differing in Malic Acid Accumulation1
Authors: Boland R. L. , Garner G. B. , Nelson C. J. , Asay K. H.
Published: July 2010

Malic acid has been shown to vary in concentration among tall fescue (Festuca arundinacea Schreb.) genotypes. The purpose of this study was to determine free amino acid and nonstructural carbohydrate composition in genotypes that had high and low levels of malic acid. Serine, glutamic acid, and alanine were the most abundant free amino acids in leaf tissue after 2 weeks of regrowth in a greenhouse. Of the 15 amino acids analyzed, all except proline showed significant differences (p < 0.05) in concentrations among the eight genotypes. Concentration of total free amino acids was highest (1.48% of dry wt.) in genotype 184‐1 which had the lowest malic acid content (0.35% of dry wt.) Genotype V6‐4 was low in free amino acids (0.69% of dry wt.), but highest in malic acid content (1.93% of dry wt.). The other six genotypes were similar to V6‐4 in total free amino acid content (0.63 to 0.97% of dry wt.) even though there was a wide range 0.49 to 1.76% of dry wt.) in malic acid. Concentrations of total nonstructural carbohydrates, and the fructosanplus‐sucrose fraction were positively associated with malic acid content genotypes. Results suggest that free amino acids may substitute for malic acid and fructosan plus sucrose as temporary storage of carbon in some genotypes of tall fescue (e.g. 184‐1). Genotype 184‐1 was most noticeably higher than other genotypes in serine and glutamic acid.
Selection and Characterization of Amino Acid Analog Resistant Plant Cell Cultures1
Authors: Widholm Jack
Published: July 2010

A method is outlined which may be useful for increasing the levels of specific free amino acids in plants.

Carrot (Daucus carota L.) and tobacco (Nicotiana tabacum L.) cell culture lines have been selected which are resistant to growth inhibition caused by tryptophan, phenylalanine, lysine, methionine, and proline analogs. Most of these lines accumulate six to 30 times the normal levels of the corresponding natural free amino acid and these increases apparently cause the resistance to the analog, since exogenous amino acids will reverse the inhibition. At least in the case of lines resistant to 5.methyltryptophan and p‐fluorophenylalanine, the control enzymes in the tryptophan and phenylalanine biosynthetic pathways, respectively, have altered feedback control properties which apparently allow the oversynthesis of the endproduct amino acids. Studies of the enzymes in the lysine, methionine, and proline pathways have not been carried out.

Increases in the free amino acid content can cause very marked increases in the total content of a particular amino acid. Regeneration of plants from such altered lines may give plants with increased levels of certain amino acids. With species where plant regeneration is not possible from established cultures, seedlings can also be screened by growing them in nutrient solution containing inhibitory amino acid analogs. Some evidence suggests that these approaches may be successful in increasing the levels of certain amino acids in plants, but only continued study can provide a definite conclusion.
Inheritance of Tolerance to Hoe 23408 in Corn1
Authors: Geadelmann J. L. , Andersen Robert N.
Published: July 2010

We conducted experiments to determine the inheritance of tolerance in corn (Zea mays L.) to HOE 23408 (methyl‐2‐[4‐(2,4‐dichlorophenoxy) phenoxy]propanoate), an herbicide that has been effective in controlling volunteer corn in soybeans [Glycine max (L.) Merr.]. Three tolerant and three susceptible inbred lines, their 30 singlecross hybrids (Fl's) including reciprocals, and the sibbed Fl's (F2's) were grown in two adjacent experiments planted 4 weeks apart in 1975 near Rosemount, Minn. Each experiment contained three replications of pairedrow plots, and one row of each pair was sprayed over the top with 0.86 kg/ha of HOE 23408 when the corn had six to seven fully‐expanded leaves. Percent control was rated 3 weeks after spraying.

Percent control did not differ significantly between experiments or among reciprocals. Genotype ✕ experiment interaction was significant but accounted for less than 5% of the variation among genotypes and experiments. Gene action for percent control was primarily additive, with 91% of the variation among F1 means accounted for by fitting only general combining ability effects. Analysis of F2 data also indicated a preponderance of additive gene action. Significant heterosis and nonadditive gene action were present, but they were not of major importance. Broad‐sense heritability values (individual F2‐plant basis) averaged 95.3%, and relative frequency distributions of percent control ratings on F2 plants indicated several loci controlled tolerance to HOE 23408. More than half of the F2 plants from tolerant ✕ tolerant and tolerant ✕ susceptible F1's were less than 75% controlled by HOE 23408. Therefore, satisfactory control of volunteer corn in soybeans by foliar application of HOE 23408 depends in part on the pedigree of corn hybrids grown the previous year.
Cultivar ✕ Environment Interactions in Soft Red Winter Wheat Yield Tests1
Authors: Campbell L. G. , Lafever H. N.
Published: July 2010

Uniform Eastern Soft Winter Wheat Nursery data from nine locations and 3 years were used as a basis for examining cultivar selection and testing procedures in the northern soft red winter wheat (Triticum aestivum L. em Thell) region. Variance components for cultivars ✕ locations, cultivars ✕ years, and cultivars ✕ locations ✕ years indicated that the interaction of cultivars with environments was of considerable importance in determining relative yields. Progress in the development of high yielding adapted cultivars was apparent in comparisons of some of the new cultivars and experimental lines with ‘Trumbull’, a 1908 release. Newer cultivars tended to be more productive, more responsive to changes in environment, and more predictable in specific environments.

Lafayette, Ind., appeared to be a better site for selection of widely adapted cultivars than Wooster, Ohio, with the other locations between these extremes. The results indicated that some selection for specific adaptation occurred in most breeding programs and that the site of early generation selection had a major role in determining the range of adaptation. Methods of numerical taxonomy were used to group locations and examine location similarities. The results indicated that cultivars should be tested more than 1 year; however, testing more than 3 years appeared to be of little value especially as the number of locations was increased.
Fertile Sterility Maintainer Mutants in Cytoplasmic Male Sterile Pearl Millet1
Authors: Burton Glenn W.
Published: July 2010

One hundred seven natural male‐fertile mutants occurring in the A1 and A2 cytoplasms of cytoplasmic male sterile (cms) pearl millet, Pennisetum americanum (L.) K. Schum., were studied. Three, or perhaps four, of these arose as nuclear mutations of tile recessive r cms maintainer gene to the dominant R male fertility restorer gene. The remaining 103 appeared to be cytoplasmic mutations that changed cms A cytoplasm to the N cytoplasm that makes B lines male‐fertile cms maintainers. The B lines resulting from such mutation appear to be stable and identical to normal B lines in appearance and performance. The frequency of these male‐fertile mutants, in terms of plants affected, ranged from 1 : 431 to 1 : 737 male‐fertile mutants : cms plants. In terms of florets or seeds affected, the ratio would approximate 1 : 1,500 to 1 : 2,500. Tilt 239 A2, increased a number of generations without roguing, contained one male‐fertile mutant for every 48 plants. Roguing or limited generation increase from breeder cms seed will be required to prevent the deterioration of cms lines due to natural mutation.
Corn Hybrid Mixtures in a Southern Environment1
Authors: Thompson D. L.
Published: July 2010

Three corn (Zea mays L.) mixtures with relatively large maturity differences between their two component hybrids were tested to provide mixture information in a southern environment. Tests were small‐plot trials at one location for 3 years for yield, ears/plant, ear weight, ear height, grain moisture, and erect plants. Five ratios were tested for each mixture: 1:0; 3:1; 1:1; 1:3; and 0.1. Regression responses were predominantly linear and indicate that mixture performances could be predicted from the performance of component hybrids in pure stands. Overcompensation was not detected. Mixtures are not practically appropriate at present but if circumstances were to develop indicating their use, only minimal verfication testing should be necessary.
Selection for Seedling Cold Tolerance in Safflower with Modified Controlled Environment Chambers1
Authors: Zimmerman L. H. , Buck B. B.
Published: July 2010

The unpredictable occurrence of cold stress in the southwestern U. S. makes selection in the field for seedling cold tolerance in safflower (Carthamus sp.) a sporadic effort. Use of a conventional cold chamber has not been practical for us because temperatures within it differed by as much as 3 C among positions only 30 cm apart, and they changed among subsequent tests. Installation of a turntable made it possible to subject seedlings growing in pots placed within the same radius (circle) to a similar cold stress. We were then able to differentiate known genotypes for degree of seedling cold tolerance with as few as 10 plants of each. This degree of precision, along with controlled hardening temperatures for as little as 1 week before the cold stress, gave considerable flexibility in selection for seedling cold tolerance. In a fourway cross in which one parent was a cold tolerant selection out of the wild species, Carthamus flavescens Spreng, it was possible to program a cold stress (_16 C for hours) in which none of the most cold tolerant domestic parent, about 50% of the wild parent, and 0.5% of the seedlings in the segregating population survived. With controlled hardening temperatures and programmed cold stresses, time involved in breeding and genetic studies of seedling cold tolerance in safflower need be limited only to the time required for growing the filial generations.
Photosynthesis and Cold Hardening in Zoysia and Bermudagrass1
Authors: Rogers R. A. , Dunn J. H. , Nelson C. J.
Published: July 2010

Objectives of this research were to evaluate ultrastructural and physiological factors associated with cold‐hardening in the field of three bermudagrass (Cynodon dactylon L.) and three zoysia (Zoysia spp.) cultivars. Cold tests of rhizome tissue in December showed that zoysia cultivars survived colder temperatures than bermudagrass cultivars which agrees with most field observations. Midwest zoysia and Midway bermudagrass were the most low temperature tolerant of their respective genera.

During October, ultrastructural changes occurred which indicated differences between hardy and non‐hardy cultivars. For example, bermudagrass chloroplasts took on a globular shape compared with an elongated shape in late summer. Chloroplasts of zoysia cultivars usually showed no alteration in shape in October.

During November in 1973 and 1974, plots of both zoysia and bermudagrass appeared to be only 10 to 12% green, but green tissue of zoysia was four to eight times more photosynthetically active than that of bermudagrass. Amylolytic enzyme activity was also higher in zoysia at that time. Grana lamellae of chloroplasts of green zoysia tissue were mostly still intact in November, but were usually damaged in bermudagrass. The higher photosynthetic rate observed in zoysia compared to bermudagrass during the cold hardening period would be an advantage since carbohydrate could be conserved or used to prepare the plant cells for winter when little or no growth was occurring.
Effect of Cyclic Selection for High and Low Crushing Strength on Rind, Pith, and Whole Stalk Composition in Corn1
Authors: Undersander D. J. , Bauman L. F. , Lechtenberg V. L. , Zuber M. S.
Published: July 2010

Two synthetic corn (Zea mays L.) populations were selected for high and low crushing strength through five cycles of recurrent selection. Stalk sections from the second internode above the ground were collected from the fifth cycle plants. The stalk sections were separated into pith and rind components and analyzed for lignin and cellulose. In one synthetic (MoSQA) the lignin percentages in the stalk sections were 16.6 and 19.2 for low and high crushing strength selections, respectively. Lignin percentages were 15.9 and 17.6, respectively, for the low and high crushing strength selections in the second synthetic (MoSQB). However, stalk lignin percentages for the high and low selections in each population were not significantly different from stalk lignin percentages in the original unselected populations. Lignin percentage of the pith was not affected by selection for crushing strength. In MoSQA the lignin percentage of the rind increased with increased crushing strength. Lignin percentage of the rind in MoSQB did not change. However, the proportion of rind in the stalk changed from 75.8 to 82.1% due to selection for low and high crushing strength.

The changes in stalk composition were small relative to the large differences in crushing strength and lodging percentage between the high and low selections. This suggests that crushing strength and lodging resistance can be increased considerably without greatly affecting the composition, and presumably, the digestibility of corn stover.
Interrelationships Among Yield Stability and Yield Components in Early Maize1
Authors: Cross H. Z.
Published: July 2010

A very early and an early set of made (Zea mays L.) hybrids were grown in nine and 11 environments, respectively, to evaluate the relationships between yield stability, as estimated by regression analysis, and various agronomic traits. Results indicated that general stability, as estimated by the regression coefficient, was associated with yield, kernel depth, and number of kernel rows per ear. Specific stability, estimated by the mean squares of deviations from regression, was associated with ears per plant. Within the later maturing diallel set, hybrids with more ears per plant had lower deviation mean squares, while the opposite was found within the earlier diallel set.

Correlations among general combining ability (GCA) effects for various traits were computed to evaluate their associations within each of the two populations. Correlations among GCA effects were in general agreement with the phenotypic correlations. Generally, inbreds with high GCA effects for kernel depth and kernel rows per ear had high GCA effects for yield. Correlations between GCA effects for kernel depth and kernel rows per ear were 0.62 and 0.64 for the late and early maturing diallels, respectively.

The absence of environmental interactions with GCA or specific combining ability (SCA) effects for kernel depth indicated selection for this trait may be important for development of high yielding hybrids from these inbreds or populations derived from these inbreds. The failure to detect SCA effects or interaction with environment for ears per plant indicates a selection scheme such as mass selection should be effective in changing this trait within derived populations, but the results indicate prolificacy may be undesirable within the earlier hybrids.
Cytology and Morphology of Maize‐Tripsacum Introgression1
Authors: Stalker H. T. , Harlan J. R. , de Wet J. M. J.
Published: July 2010

Intergeneric hybrid derivatives of a cross between Zea mays L. and tetraploid Tripsacum dactyloides (L.) L. (2n =72) were compared cytologically and morphologically with a maize genetic stock. The objective of this study was to detect genetic transfers from Tripsacum into the maize genome that might have occurred in the backcross generations. Seven backcrosses to maize were required to eliminate either all the Tripsacum (Tr) chromosomes or all but one pair of the Tr chromosomes. Thirty‐three morphological characters were used to differentiate three groups of plants: (a) lines carrying one pair of Tr chromosomes plus 20 maize chromosomes; (b) lines of fully recovered maize with 20 chromosomes; and (c) a maize genetic stock control. The 22‐chromosome plants clustered as a sharply distinct but variable group. The characters by which they differed most from 20‐chromosome maize were: reduced cob length; increased number of nodes bearing ear shoots and number of ears at a node; increased cupule depth and size; decreased pubescence of the cupule; increased male spikelet pedicel length; increased frequency of tassel‐tipped ears; reduced diameter of the cob pith; and increased caryopsis abortion. These characters show obvious genetic influence from Tr chromosomes as well as Zea characters not present in the original maize parent. The 20‐chromosome recovered maize lines were generally intermediate between the tripsacoid group and standard maize in morphology. The F values for between‐group comparisons were highly significant, and the study verified genetic exchange between the two genomes.
Effect of Soybean Male‐Sterile Gene ms1 on Organization and Function of the Female Gametophyte1
Authors: Cutter G. L. , Bingham E. T.
Published: July 2010

The female gametophyte of genetic male‐sterile soybeans [Glycine max (L.) Merr.] (ms1 ms1) was examined histologically to gain insight into the association of the ms1 gene with polyembryony, haploidy, and polyploidy. Embryo sacs on the day of flowering appeared normal in only 28% of 225 male‐sterile ovules examined. The most common abnormality was supernumerary nuclei in the regions of the secondary nucleus and egg apparatus. It was concluded that these nuclei could arise by proliferation of nuclei during embryo sac development. Presence of supernumerary nuclei and their restitution products provides an explanation for polyembryony, haploids, and polyploids found among male‐sterile progeny. Ovules without an embryo sac occurred at a frequency of 11 and 12% in male‐sterile and normal fertile plants, respectively. Only one‐fourth of the embryo sacs of male‐sterile plants examined at 3 to 4 days post‐pollination contained an embryo, which agreed with the 29% normal embryo sacs observed before pollination. This also provides an explanation for the single‐seeded pods and the reduced seed set associated with the male‐sterile ms1 ms1 plants.
Direct and Correlated Responses to Selection for Specific Leaf Weight in Reed Canarygrass1
Authors: Topark‐Ngarm Anake , Carlson I. T. , Pearce R. B.
Published: July 2010

Substantial progress was made by one cycle of selection for high and low specific leaf weight (SLW) in the broadbased germplasm source NCRC1 of reed canarygrass (Phalaris arundinacea L.). In a space‐planted test, populations derived from 48 high and 48 low selections from 1,016 plants of NCRC1 averaged respectively 11% higher and 10% lower in SLW than NCRCI. Average estimates of realized heritability were 0.59 for high and 0.55 for low SLW, indicating a relatively large additive component of genetic variance for this trait. Changes in SLW were accompanied by changes in other leaf characteristics and agronomic components of forage yield. Compared with NCRCI, the high SLW population averaged 11% greater in leaf thickness (LT), 9% higher in COx‐exchange rate (CER), 21% higher in dry weight per tiller, 24% lower in tiller number, and 2% higher in dry matter yield per plant. In contrast, the low SLW population avesaged 7% less, 7 and 8% lower, 16% higher, and 2% lower than NCRCI in those traits, respectively. The low SLW population had the smallest phenotypic variance among plants within plots for all traits except tiller number and weight, with differences among populations being significant in five of 12 instances. Specific leaf weight was positively correlated with LT and CER within populations.
Spatial Orientation of Wheat Leaves1
Authors: Ledent J. F. , Moss Dale N.
Published: July 2010

A model is presented for characterizing and summarizing leaf spatial orientation in wheat (Triticum aestivum L. em Thell) canopies. The model assumes a random azimuth we found to be valid for wheat. The inputs to the model are based on measurements of the angle to the horizontal of the basal and distal segments of each leaf midrib and a visual classification of the leaf into twist categories based on the number of twists along the leaf. Each leaf is considered to be made up of small, sequential, planar segments, and the relative distribution of area along the length of the midrib must be determined on a few leaves to fit the model to a particular genotype. With these relatively few and simple measurements to “calibrate” each genotype and two measurements of angle on each leaf, the spatial orientation of the entire leaf surface can be determined.

The spatial orientation can be expressed in various ways. The customary cumulative angle distribution for all the leaf tissue can be obtained from the model. Other statistics have proven useful in our studies. The mean basal angle, MBA, (the mean for all leaves of the angle between the plane of the base of the midrib and the horizon) is useful for following changes in time of the angular display of individual leaves or of leaves at a particular insertion level. The planar equivalent angle, PEA, (the angle equivalent to that which all leaves would have if they were rigid planes and set at an angle which would give the same horizontal projection as that found in the canopy) is useful to express the leaf angle of a canopy as a single number.

In addition to the measurements listed above, the relative distribution of area among leaf insertion levels and the leaf area index are required to utilize the orientation model in photosynthetic simulation.

The orientation of leaves of the wheat cultivar ‘Era’ and an upright‐leaved mutant of Era were compared in controlled environments and in field plantings. Canopies became increasingly more planophile with time because leaves drooped as they aged. Leaf drooping was characterized by a change in the angle of the base of the leaf blade with the leaf sheath.
Basis of Heterosis in the Differentiating Sorghum Panicle1
Authors: Blum A.
Published: July 2010

Heterosis in grain sorghum (Sorghum bicolor L. (Moench)) yield has been previously traced to heterosis in the number of grains per basal branch in the panicle. A comparative quantitative morphogenetical study of the differentiating panicle was performed to explore the origin of this heterotic effect. Field grown plants of RS 610 hybrid and its two parental lines (B‐Combine Kafir 60 and Tx 7078) were dissected and studied microscopically.

Heterosis (advantage of the hybrid over both parental lines) was identified in faster formation of primary and secondary panicle branches; faster panicle growth rate and larger primary basal branch primordia. The hybrid did not differ from the parental lines in the number of branch whorls per panicle, growth rate of basal primary branches, and the length of time period between spikelet and floret initiation.

Heterosis in the number of grains per basal primary branch was traced to two major factors: (1) a larger reproductive apex that allowed development of larger basal branch primordia, and (2) a 4‐day time‐lapse between termination of the acropetal formation of branches and the onset of the basipetal formation of spikelets. This time‐lapse was utilized in the hybrid for the increase in basal branch size prior to spikelet initiation.
Alien Chromosome Addition in Wheat1
Authors: Schulz‐Schaeffer Jurgen , McNeal F. H.
Published: July 2010

Alien chromosome addition in the tetraploid wheat Triticum turgidum L. var. durum (AABB) is proposed. An Agrotricum with the constitution AABBII is anticipated. The I genome could consist of any group of seven chromosomes from Agropyron intermedium (Host) Beauv. The amphiploid derivative parent was an F10 strain with an average chromosome number of 2n = 49 (range 25 to 66) resulting from chromosome elimination. Eleven first‐nuclear‐restoration backcross plants (RB1) to the amphiploid of Triticum turgidum L. var. durum (2n = 28) ✕ A. intermedium (Host) Beauv. (2n = 42) have been established. The 11 RB1 plants had a mean chromosome number per cell of 2n = 37.8, with a range of 25 to 50. The mean frequency of bivalent pairing per cell was 10.4 with a range of 0 to 21. The mean univalent number per cell was 17.0, ranging from 2 to 45. The RB1 plants generally had morphological characteristics intermediate between the amphiploid and durum parents, pollen fertility of the RB1's averaged 8.1%, with a range of 0.3 to 35.6%. Further backcrossing of the RB1 material with the durum parent is planned. Selection among RB2 plants for high pollen fertility and a high stable number of univalents will be followed by RB2 ✕ RB1 intercrossing and finally selfing for the elimination of undesirable Agropyron univalents. A final product with 2n = 42 and genome formula AABBII is anticipated from this program.
Inbreeding Depression in Maize by Selfing and Full‐sibbing1
Authors: Good R.L. , Hallauer Arnel R.
Published: July 2010

Three series of unselected lines from ‘Iowa Stiff Stalk Synthetic’ (BSSSCO) were developed by three methods inbreeding: selfing, ful‐sibbing, and full‐sibbing followed by selfing. Data were collected for 12 traits in nine environments to determine: 1) the rate of inbreeding depression by selfing, full‐sibbing, and full‐sibbing and selfing; 2) the differences among means of lines developed by the three methods of inbreeding at comparable levels of homozygosity; and 3) the phenotypic correlation between the traits with the change in homozygosity by inbreeding.

Rates of inbreeding depression were significantly different among the three methods of inbreeding for plant height, cob diameter, yield, kernel weight, stand, and barrenness. In most instances the differences were small. Predicted yields by the linear regression model for F = 1.0 were 23.2, 24.6, and 23.9 q/ha for the selfed, full‐sib, and full‐sib and selfed series of lines, respectively, whereas with F = 0, yield was 69.7 q/ha. Rate of inbreeding depression for yield by selfing was b1 = ‐‐46.53 q/ha and by full‐sibbing, bL = ‐‐45.11 q/ha. At comparable levels of homozygosity, means of the lines developed by selfing and full‐sibbing were not significantly different except for yield at 99% homozygosity. All correlations of traits with percentageo f homozygosityw ere very high. Linear regression of yield on percentage of homozygosity for 22 levels of homozygosity is BSSSCO accounted for 99.1% of the total variation.
Distribution of Sugars in the Soybean Embryo1
Authors: Openshaw Stephen J. , Hymowitz T. , Hadley H. H.
Published: July 2010

In order to investigate the possibility of using single seed selection to change sugar content in soybean (Glycine max (L.) Merr.) seed, the distribution of sugars in the soybean embryo was studied. Seeds of soybean cultivars ‘Jogun’ and ‘Hokkaido’ were sliced into three equal parts with the slices being made parallel to the root: shoot axis. The slices were then analyzed for sugar content by gas‐liquid chromatography of trimethylsilyl derivatives. Sucrose content was highest in Position I, represented by the slice containing the root:shoot axis, and lowest in Position III. Stachyose was lowest in Position II and approximately equal in Positions I and III. Raffinose content was invariant for all positions. A significant cultivar ✕ position interaction for sucrose content indicates that selection for differences in this character based on analyses of only parts of a cotyledon might be unreliable.
New Races of Common Bunt Useful to Determine Resistance of Wheat to Dwarf Bunt1
Authors: Metzger R. J. , Hoffmann J. A.
Published: July 2010

Two new races of the common bunt fungus, Tilletia caries (DC.) Tul., were obtained from inoculations with teliospore mixtures. One race, T‐29, was virulent on wheat, Triticum aestivum L., cultivars carrying combinations of bunt resistance genes Bt1,2,7,9 and 10. The other race, T‐30, was virulent on cultivars carrying combinations of Bt 1,2,4,6,7,9 and 10. Using these new races in combination with other races of the common bunt fungi, breeders can identify wheat selections resistant to most races of the dwarf bunt fungus, T. controversa Kühn, known to be present in the northwestern U.S.
Some Influences of Hardseededness on Soybean Seed Quality1
Authors: Potts H. C. , Duangpatra J. , Hairston W. G. , Delouche J. C.
Published: July 2010

The effects of the impermeable seed coat characteristic in soybeans (Glycine max (L.) Merr.) on the seed's sponse to field environment, artificial drying, and storage potential were evaluated. Comparisons were made be. tween seed of ‘Dare’ and those of an experimental hardseeded line, D67‐5677‐1 which is similar to Dare in growth type and maturity. Hardseededness was beneficial in maintaining the viability of seed remaining in the field for up to 9 weeks after seed moisture initially declined to 20%. Resistance to moisture reabsorption by seed on unharvested plants of the hardseeded line was clearly superior to that of Dare, indicating a possible solution to seed viability problems encountered in areas where mature seed are exposed to extended periods of warm, humid weather. Drying hand harvested seed had no effect on viability but increased the number of hard seed. Seed from the hardseeded line displayed a substantially greater storage potential than those of the normal, Dare.
Variability, Combining Ability, and Interrelationships of Anther Length, Anther Extrusion, Glume Tenacity, and Shattering in Spring Wheat1
Authors: Atashi‐Rang G. , Lucken K. A.
Published: July 2010

Thirty spring wheat (Triticum aestivum L., T. aestivum with T. timopheevi Zhuk. cytoplasm, and T. turgidum L. var. durum) cultivars and lines, both normal (B‐line) and restorer (R.line) genotypes, were grown at Fargo, N.Dak. in 1968 to assess variability and intercharacter associations for four floral traits: anther length, anther extrusion, glume tenacity, and shattering. In a second experiment the following year, 36 B‐line/R‐line (B/R) hybrids and their six B‐line and six R‐line parents were grown to further evaluate variability and intercharacter associations and to obtain estimates of the relative magnitude of general and specific combining ability effects for anther length, anther extrusion, and glume tenacity.

Substantial variation among genotypes was found for each of the four traits in both experiments. Significant differences for both general and specific combining ability effects of parents were obtained for anther length, anther extrusion, and glume tenacity. The general combining ability to specific combining ability variance component ratio was approximately 5:1 for anther length, 1:1 for anther extrusion, and 8:1 for glume tenacity. Narrowsense heritabilities on a per spike basis were 0.61, 0.19, and 0.54 for the three respective traits. Correlations between F1's and each parent or mid‐parent were relatively high for anther length and glume tenacity but low or nonsignificant for anther extrusion. Selection to alter anther length and glume tenacity should be effective in this group of wheats. Selection in stress environments was suggested as a possible means of improving and stabilizing anther extrusion.

All intercharacter associations were nonsignificant except for a low positive correlation between anther extrusion and shattering, and a low negative correlation between glume tenacity and shattering, both in the second experiment. Thus, adverse associations with glume tenacity or shattering should not seriously impede progress in improving anther length and anther extrusion.