bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of Resistance to Phytophthora megasperma in Diploid Alfalfa1
Authors: Irwin J. A. G. , Maxwell D. P. , Bingham E. T.
Published: July 2010

Few genetic studies have been made to determine the inheritance of disease resistance in diploid alfalfa (Medicago sativa L.). The objectives of this study were to determine the inheritance of resistance to Phytophthora root rot in Wisconsin cultivated diploid alfalfa (CADL) and in diploid Medicago coerulea Less. (PI 299046).

S1 populations and F1 populations from crosses of resistant and susceptible plants of CADL were generated, and their segregations for disease reaction indicated that resistance was conditioned by two dominant complementary genes, designated Pm1 and Pm2. The observed segregations in S2 F2 testcross families of CADL provided additional evidence to support this model. Segregations for resistance to Phytophthora root rot in S1, F1 and F2 families from intercrosses of two resistant Medicago coerulea plants and two susceptible CADL plants indicated that resistance in M. coerulea was complex, and that epistatic relationships might be of importance.

These studies indicate the potential usefulness of diploid alfalfa as new sources of resistance to Phytophthora root rot.
Inheritance of Resistance to Phytophthora megasperma in Tetraploid Alfalfa1
Authors: Irwin J. A. G. , Maxwell D. P. , Bingham E. T.
Published: July 2010

Phytophthora root rot (PRR) of alfalfa (Medicago sativa L.) is one of the most important diseases of that crop. Previous studies on the inheritance of resistance to PRR in ‘Lahontan’ and ‘Vernal’ clones indicated susceptibility was conditioned by a single incompletely dominant tetrasomic gene, designated Pm. This paper reports studies on the inheritance of resistance to PRR in two different tetraploid breeding lines: North American Plant Breeders (NAPB) No. 0310 and Hunter River P3 (Australian breeding line) which had both shown different responses to recurrent selection than would have been expected if susceptibility was conditioned by a single incompletely dominant gene.

The observed segregations for disease reaction in S1 populations and in F1 populations from crosses of two resistant NAPB 0310 plants and two susceptible plants from ‘Saranac’ and ‘Vernal’ suggested that resistance was conditioned by two incompletely dominant complementary genes, Pm1 and Pm2. An arrangement o[ at least a duplex genotype at one locus (Pm1 or Pm2) and a simplex genotype at the other locus was required before resistance was expressed. S2 and F2 family segregations for disease reaction provided further evidence to support the two locus model. An intercross between a resistant plant from NAPB 0310 and a resistant plant from Hunter River P3 indicated that different genes conditioned disease reaction in these two sources. Susceptibility was incompletely dominant in Hunter River P3.

These studies have identified a new genetic system conditioning resistance to PRR. Due to the high degree of dominance expressed for the resistant reaction in plants from NAPB 0310, this type of resistance could be readily utilized in breeding alfalfa with multiple pest resistance.
Effect of the Number of Parents of Performance of Alfalfa Synthetics1
Authors: Hill R. R. , Elgin J. H.
Published: July 2010

An experiment was conducted to determine the optimum number of parents that can be used in the development of synthetic cultivars of alfalfa, Medicago sativa L. Five populations of experimental synthetics each with 1, 2, 4, 8, or 16 parents were evaluated in small plots for forage yield at two locations in 1978 and 1979 to determine the effects of the number of parents per synthetic on performance. The parents were random selections from Beltsville 2‐An4 alfalfa. The average yield of the synthetics increased and the variance among synthetics decreased as the number of parents per synthetic increased. The number of parents per synthetic had no detectable effect on the magnitudes of the different genotype × environment interaction variances. The greatest expected gain from selection within a large population of experimental synthetic cultivars that trace to one parental population was when the synthetics had more than 4 but less than 16 parents each. Our results indicated that gains from selection within large populations of experimental synthetic cultivars produced with randomly selected parents would not be as great as those from population improvement and progeny test methods currently used in alfalfa breeding.
A New Linkage Relationship in Cotton1
Authors: Lee Joshua A.
Published: July 2010

A chromosome, or a chromosomal segment, transferred from Gossypium davidsonii Kell., an American diploid taxon, to the glandless G. barbadense stock, 15‐4, harbored the gland‐determining allele, G1dav3, and the complementary lethal factor, Ledav. Linkage between the genes was estimated at 25.9 ± 3.0 recombination units.
Hybrids in the Genus Arachis Between Sections Erectoides and Arachis1
Authors: Stalker H. T.
Published: July 2010

The objective of this study was to determine whether diploid members of section Arachis could potentially be used as bridges between section Erectoides Krap. et. Greg. nom. nud. and A. hypogaea. Two diploid (2n = 20) taxa of section Erectoides and their F1 and F2C1 hybrids were evaluated. The female parent, A. rigonii Krap. et Greg. (PI 262142, collection no. GKP 10034), and male parent, A. sp. (PI 262278, collection no. GKP 9841) had perfect bivalent formation, but the F1 did not produce enough flowers to cytologically examine. The F2C1 averaged 2.76 univalents, 18.48 bivalents, 0.04 trivalents, and 0.04 quadrivalents per pollen mother cell and pairing of chromosomes between the two section Erectoides species is believed to be minimal. Hybrids between the F2C1 and the diploid section Arachis species A. stenosperma Greg. et Greg, nom. nud. (PI 338280, collection no. HLK 410) and A. duranensis Krap. et Greg. nom. nud. (PI 219823, collection no. K 7988) were studied. Multivalents were observed at a low frequency. Members of sections Erectoides and Arachis may have a common genome.

The results indicate that gene transfer from section Erectoides species into the cultivated peanut seems possible by using diploid members of section Arachis as bridge species. Early metaphase I microsporocytes with an unreduced chromosome number were observed in three hybrids. Two fruits were recovered from intersectional colchicine‐treated hybrids, but the seeds were inviable. Future success in restoring fertility may depend on propagating large numbers of colchicine‐treated cuttings.
Breeding Cicer Milkvetch for Improved Forage Yield1
Authors: Townsend C. E.
Published: July 2010

Cicer milkvetch (Astragalus cicer L.), a potentially valuable species, does not yield as well as the more commonly grown forage legumes when harvested for hay. In developing information to improve the hay yield of cicer milkvetch, we conducted two studies. In the first study, 109 polycross progenies from three breeding populations and three reference entries, including the cv. ‘Lutana,’ were evaluated in a spaced‐plant nursery for forage yield in the seedling year and for agronomic traits related to forage production for 2 years. The mean forage yield of the population selected for excellent mature plant vigor was 115% of that of Lutana, while the yields of the two populations selected for improved seedling emergence and average or above‐average mature plant vigor were 102 and 105%, respectively. During both years the tallest and most vigorous plants occurred in the population selected for excellent mature plant vigor.

Plants with excellent mature plant vigor from the previous study were selected for early initiation of spring growth or more rapid recovery after harvest or both. Fifty‐seven polycross progenies derived from these selections and the same three reference entries used in the first study were evaluated in a spaced‐plant nursery for forage yield for 3 years. During the first 2 years the mean forage yield of the polycross progenies was 130% of that of Lutana and the yields of individual progenies ranged from 110 to 160%. In the 3rd year, progeny yields ranged from 81 to 117% of that of Lutana. The improved performance of Lutana relative to the polycross progenies in the 3rd year was attributed, in part, to its better spreading ability. The prospects for improving the hay yield of cicer milkovetch appear promising.
Response of Winter Wheat Cultivars to Barley Yellow Dwarf Virus Infection1
Authors: Carrigan L. L. , Ohm H. W. , Foster J. E. , Patterson F. L.
Published: July 2010

The response of winter wheat cultivars and advanced generation lines (Triticum aestivum L. em Thell.) to barley yellow dwarf virus (BYDV) infection was investigated. In 1976, the yields of 1,200 early seeded cultivars and lines, which were infested with naturally occurring viruliferous Rhopalosiphum padi. L. aphids, were compared with yields of those from a late planting date, which escaped infestation. Yields in the early seeded plots ranged from 63 (for most of the 1,200 lines) to 85% of the yields in late seeded plots.

In 1978 and. 1979, the effect of barley yellow dwarf virus (BYDV) infection on yield and certain yield components was measured for 10 cultivars and lines. Treatments were: a control (non‐infested) and a fall, spring, and fall plus spring infestation with greenhouse‐reared viruliferous aphids. In 1979, the effect of three levels of N fertilization on barley yellow dwarf (BYD) symptom expression was also measured.

BYD significantly reduced the grain yield, number of heads, plant height, kernel weight, kernel number, and above ground plant weight. It did not affect the harvest index or lysine percentage.

In 1978, grain yields were reduced by 58 and 38% when the wheat was infected with BYDV in the fall and spring, respectively. In 1979, yield reductions of 44, 33, and 27% resulted in plots which were infested with viruliferous aphids in the fall plus spring, fall, and spring, respectively. The cultivars and lines differed in response to BYDV with respect to grain yield and number of heads. Of the cultivars and lines tested, Purdue breeding lines P65256A1‐8‐7 and P6376B3‐8‐2 showed the most effective resistance to BYD.
Use of Partially Male‐Sterile Perennial Ryegrass for Hybrid Cultivar Production1
Authors: Ahloowalia B. S.
Published: July 2010

The possibility of breeding ryegrass hybrid varieties based on partial male‐sterility was investigated. Frequency of hybridization between perennial ryegrass, Lolium perenne L., and annual ryegrass, L. multiflorum Lam., was determined by using two partially male‐sterile perennial ryegrass genotypes. Clones of a desynaptic diploid (2n = 14) and a trisomic (2n = 15) perennial ryegrass plant were inter‐pollinated with annual ryegrass plants having the dominant markers fluorescent‐roots and awned‐florets. The progeny of perennial × annual ryegrass showed fluorescent‐roots and all except two plants had awned‐florets, suggesting 100% hybridization on inter‐pollination. In the reciprocal crossings, annual × perennial ryegrass, hybridization frequency approached 100% with the trisomic pollinator, but was only 29% with the perennial desynaptic pollinator. Although most F1 plants were fertile and had good seed set, mortality in F2 and back‐crosses was high. It was concluded that partially male‐sterile genotypes can be used for the production of hybrid ryegrass cultivars.
Long‐Term Subfreezing Storage of Forage Crop Seeds1
Authors: Rincker Clarence M.
Published: July 2010

Subfreezing storage of seed is a comparatively new technique; therefore, few reports are available on longterm effects, particularly on retention of viability by forage crop seed lots produced under different environments. This study was based on 291 seed lots from seven forage crop species produced at three locations (Prosser, Wash., Shafter and Tehachapi, Calif.) during 1957‐1960. All seed lots were stored in a refrigerator at 5 C from year of harvest until placed in a freezer in told‐1960 for long‐term storage at ‐15 C and 60% relative humidity. All seed lots were tested for germination in the year of production and in 1971 and 1978 to determine germinability of each lot in those years. Original high seed quality was more important than location of seed production for retention of germinability although crop species did differ in germinability retention among the three production locations. Most notable was orchardgrass (Dactylis glomerata L.) seed produced at Shafter, which lost 22.5% in mean germinability in 19 years compared to 6.5% for seed grown at Prosser. Combined results for the three locations showed that birdsfoot trefoil (Lotus corniculatus L.), white clover (Trifolium repens L.), and alfalfa (Medicago sativa L.) seed retained germinability best, followed by timothy (Phleum pratense L.) and orchardgrass. Red clover (Trifolium pratense L.) and bromegrass (Bromus inermis Leyss.) suffered the greatest loss in germinability. The bromegrass seed, which had good original mean germination (90%), retained germination reasonably well until 1971 (12 years) but lost 11.8% in mean germination during the 7 additional years of storage. The original mean germination of the red clover seed lots was only 74.7% which undoubtedly contributed to the I 1% loss in germinability the first 12 years of storage. With the exception of bromegrass seed, germinability of forage crop seed can be maintained for up to 20 years if the seed was of high germination before subfreezing storage.
High Intensity Selection for Percent Oil in Corn1
Authors: Miller R. L. , Dudley J. W. , Alexander D. E.
Published: July 2010

Seven cycles of high‐intensity within half‐sib family selection for percent oil in the ‘Reid Yellow Dent’ corn (Zea mays L.) cultivar resulted in an increase in oil from 4.0 to 9.1%, while kernel weight and ear height were reduced slightly and grain moisture at harvest increased. No significant changes in yield, silking date, or plant height were found. Realized heritability for percent oil was 43%.

Estimates of genetic variance for percent oil and 100‐kernel‐weight were obtained in 1977 and 1978, for Cycles 0 and 5. All estimates of additive genetic variance (ó2A) were greater than zero; however, change in ó2A occurred between cycles. Estimates of dominance genetic variance did not differ from zero.

A comparison of the predicted gains from within half‐sib family selection, mass selection, and combined selection among and within half‐sib families revealed that maximum gain is expected when a higher selection intensity is used within half‐sib families than among half‐sib families.
A New Concept in Assessing Cotton Pollen Germinability1
Authors: Barrow Jerry R.
Published: July 2010

Contrary to current concepts of pollen germination and tube growth, intact pollen tube‐like structures up to 4,000 µm in length were forcefully ejected, instantly, from pollen grains of cotton, Gossypium barbadense L. and G. hirsutum L., suspended in a hanging droplet, indicating a unique mechanism for pollen tube formation. Tubes disintegrated instantly after “germination” unless the germinating medium was supplemented with certain calcium, manganese, zinc, chlorine, or magnesium salts. The optimal combination was Ca[NO3]2 and MnSO4, each at 0.14 g, in 100 ml of distilled water. As sucrose concentration increased, the tubes became shorter and smaller in diameter and were ejected at a slower rate. The frequency of germination was unaffected until the sucrose concentration reached 1.7 M.

Germination dropped to about 50% in concentrations from 1.7 to 2.0 M. Cotton pollen did not germinate until after anthesis. From 30 min to 8 hours after anthesis, germination exceeded 98%. It dropped to 30% after 24 hours and to 1% in 32 hours. Cotton pollen viability was sensitive to temperature, in that full viability was observed in the range of 32 to 40 C with no germination above 42 C. This technique is a simple and effective method for inducing more than 98% germination in both G. hirsutum and G. barbadense and accurately measures cotton pollen viability.
Retention of Resistance by Mutants of ‘Floratam’ St. Augustinegrass to the Southern Chinch Bug and St. Augustine Decline1
Authors: Reinert James A. , Toler R. W. , Bruton B. D. , Busey P.
Published: July 2010

St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze, a widely used turfgrass in the southern coastal states, has two major limiting pests, southern chinch bug, Blissus insularis Barbar, and St. Augustine decline strain of Panicum mosaic virus. Gamma‐rayderived mutants of ‘Floratam,’ a very coarse cultivar which is resistant to both pests, were evaluated for stability of resistance and turf characteristics. All mutants retained resistance to PMV‐SAD and all except #14 caused higher antibiosis to the confined bugs than the susceptible ‘Florida Common’ St. Augustinegrass (22%). Mutant #6 produced 76% mortality of the confined southern chinch bugs at 7 days which was significantly greater than the mortality produced by four of the other mutants. However, none of the mutants was significantly more resistant than Floratam (65% mortality). Egg deposition was significantly less on Floratam and all mutants (from 4 to 13 eggs/stolon) than on the Florida Common (average of 23 eggs/stolon). One of the mutants had a faster rate of establishment and all mutants had shorter internodes than Floratam, all were immune to PMV‐SAD, and only one had lost its southern chinch bug resistance.
Genetic Variation for Acetylene Reduction Rate and Other Characters in Alfalfa
Authors: Tan Geok‐Yong
Published: July 2010

The objective of this study was to determine the general (GCA) and specific (SCA) combining abilities of alfalfa (Medicago sativa L.) for rate of acetylene reduction, plant dry weight, N content (%), total plant N and nodule score. The parental clones were selected from the commercial cultivars ‘Beaver,’ ‘Roamer,’ ‘Saranac,’ and ‘Rambler.’ Five strains of Rhizobium meliloti Dang., including four single strains and one commercial inoculant ‘Balsac’ were used. The most effective strain of Rhizobium was NRG61, while RM110 was the poorest. Diallel analysis of the six‐parent half diallel cross revealed that mean squares of both GCA and SCA were highly significant for all characters except the SCA mean square for nodule score. The highly significant interactions of GCA and SCA with Rhizobium strains suggested differential expressions of gene effects for alfalfa genotypes with different strains of Rhizobium. The GCA variance components were higher than SCA for total plant dry weight, total plant N and nodule score. This suggested that the major portion of the total genetic variation was additive. Recurrent selection for these characters should be possible. However, the additive and non‐additive gene effects were equally important for acetylene reduction rate with Rhizobium strains NRG43, NRG61, and NRG118. Reciprocal recurrent selection method might be necessary to improve this character with these single Rhizobium strains. Combining ability analysis for each of the parental clones indicated that Clone 4 had consistently high and positive GCA effects over all Rhizobium treatments. Clone 2 was on the other extreme with negative GCA effects in all cases. None of the other parental clones produced consistently positive GCA effects across all the Rhizobium strains.
Stability and Relative Importance of General and Specific Combining Ability for Forage Yield in Orchardgrass1
Authors: McClain E. F.
Published: July 2010

The objectives of this research were to evaluate the relative importance of general (GCA) and specific combining ability (SCA) for forage yield in orchardgrass (Dactylis glomerata L.) and determine if more nearly consistent results could be obtained by separating GCA and SCA into components associated with annually recurring changes and changes related to age of stand. For this purpose, seeded plots of hybrids from six diallel crosses involving 11 parental clones were harvested 28 times during a 5‐year period (4th year excluded).

GCA was significant for most harvests, seasons, and years, and for total 4‐year production. SCA was significant for spring and annual production of the first 2 years. Interactions of GCA with seasons and of SCA with years were significant. Interseasonal correlation coefficients based on total 4‐year production for spring vs. summer, spring vs. fall, and summer vs. fall, respectively, were 0.25, 0.45, and 0.58 for GCA effects, and 0.64, 0.19, and 0.63 for SCA effects. Interannual correlation coefficients based on annual yields in consecutive years (excluding 1967) starting with 1964–1965 were − 0.16, 0.45, 0.65 for GCA effects and 0.42, 0.38, and − 0.18 for SCA effects.

The data suggested an annual recurrence of relative seasonal magnitudes of GCA and SCA with interannual stability increasing for GCA and decreasing for SCA as the stand aged. Most effective selection for forage production based on GCA probably would be on a seasonal basis in the 3rd year after seeding. Selection based on SCA appears questionable, although it might be successful for initial spring production.
Inheritance of Husk Leaves in Maize1
Authors: Cantrell R. G. , Geadelmann J. L.
Published: July 2010

Leaves that extend from the modified leaf sheaths or husks enclosing the ear of maize (Zea mays L.) are referred to as husk leaves. Husk leaves may add significantly to the photosynthetic area of the husk and compensate for leaf area lost during mechanical detasseling of hybrid seed corn production fields. The inbred parents, F1's and F2's from an eight‐parent diallel, were examined to determine the breeding behavior of husk leaves in Corn Belt dent maize. Four inbreds with high husk leaf area and four with no husk leaves were used in the diallel Husk leaf area was measured with a leaf area meter and visual ratings for husk leaf area were given to individual plants.

Differences in mean husk leaf area of F1's and F2's between two locations suggested that environmental effects, especially plant population, may be important. Midparent heterosis for husk leaf area averged 254% at St. Paul and 169% at Rosemount, Minn., for the high ✕ high F1's; but few of the high ✕ low and none of the low ✕ low F1's displayed significant heterosis which suggested that epistasis may have been involved. Husk leaf expression of inbreds per se and general combining ability effects both satisfactorily predicted the husk leaf area of the hybrids. Broad‐sense heritability value of husk leaf area on an individual F2 plant basis averaged 49% at St. Paul and 69% at Rosemount. Relative frequency distributions of visual husk leaf ratings on F2 plants indicated that alleles favoring low husk leaf area appeared to be at least partially dominant to alleles favoring high husk leaf area and that several loci controlled the trait. Husk leaf area of the materials we studied should be regarded as a quantitative trait that could be modified by standard maize breeding procedures.
Evaluation of Alfalfa and Rhizobium meliloti for Compatibility in Nodulation and Nodule Effectiveness1
Authors: Hardarson G. , Heichel G. H. , Vance C. P. , Barnes D. K.
Published: July 2010

The purpose of this investigation was to develop a procedure for testing strains of Rhizobium meliloti and cultivars of alfalfa (Medicago sativa L.) for symbiotic compatibility. Antiblotic‐resistant mutants were developed from four strains of R. meliloti that differed for plant dry matter yield, days to initial nodulation and nodule numbers when inoculated onto one cultivar of alfalfa. The mutant strains were not significantly different from their corresponding parental strains in either days to initial nodulation or host dry matter production on N‐free medium. The preference of alfalfa for different strains of Rhizobium was not altered by 0 to 300 ppm N and 33 to 300 ppm potassium phosphate.

The competitive ability for nodulation of effective and ineffective strains of R. meliloti was investigated using ‘Saranac’ and MnNC 4, an experimental population of alfalfa. Antibiotic‐resistant mutants were used to verify the relative proportions of effective and ineffective nodules on each plant. A significant positive correlation was observed between the percentage of nodules produced by the effective strains and the dry matter production of plants grown at zero N. Acetylene reduction assays indicated that differences in competitive ability of the effective strains against the ineffective strains measured by the antibiotic‐resistant mutant technique and seedling growth were associated with nitrogenase activity.

A procedure of inoculating alfalfa plants with a mixture of effective and ineffective strains at zero N and measuring shoot dry weight might be used to identify strains of Rhizobium of high competitive ability and plants with increased preference for effective strains of Rhizobium. This approach should expedite attempts to select Rhizobium‐alfalfa combinations with enhanced N2‐fixation capacity.
Genotype‐Environment Interactions for Forage Yield of Reed Canarygrass Clones1
Authors: Barker R. E. , Hovin A. W. , Carlson I. T. , Drolsom P. N. , Sleper D. A. , Ross J. G. , Casler M. D.
Published: July 2010

Limited information is available on genotype‐environment (GE) interactions of dry matter yields in reed canarygrass (Phalaris arundinacea L.). We measured forage yield on 60 clones of reed canarygrass for 3 years in Minnesota, Iowa, Wisconsin, and North Dakota, 2 years in Missouri, and 1 year in South Dakota. Objectives were to determine the magnitude of GE interactions for forage yield testing, to characterize testing environments, to determine an efficient allocation of testing sites, and to ascertain effectiveness of stability parameters in selecting clones for breeding programs. Significant genetic differences were found for harvest 1, regrowth, and season total dry matter yields. Genotype ✕ location and genotype ✕ location ✕ year variances were significant, whereas genotype ✕ year interactions were not. Location and genotype ✕ location effects were inconsistent among years. Year ✕ location interactions were very large in relation to all other sources of variation. Correlations of clonal mean total dry matter yields among locations and resultant cluster analyses indicated that la. and Mo. should represent the minimum number of yield testing sites. Iowa had a high value as a testing site whereas Mo. was intermediate. North Dakota and/or S. Dak. could be added if additional information is desired on broader adaptability and to identify superior genotypes for these locations. Consistent conclusions regarding clonal performance could not be drawn from the stability parameters b, r2, and sy.x. Mean yields per se appeared to be the most useful in determining genetic yield potential.
Primary Trisomics of Ryegrass: Their Isolation and Identification1
Authors: Ahloowalia B. S.
Published: July 2010

Trlsomics (2n + 1 = 15) of perennial ryegrass (Lolium perenne L.) were obtained either by crossing clones of a near‐triploid (2n = 3x + 1 = 22) with diploid plant or open‐pollination with diploid and tetraploid plants. Trisomics occurred with a frequency of 22% on crossing with the diploid and 8% on open‐pollination. Of the trisomics isolated, 16 were primary and one a tertiary trisomic. Trisomes were identified as nucleolar (tri 2, 3, and 4) or non‐nucleolar (tri 1, 5, 6, and 7) from the association of trivalents with the nucleolus at diakinesis, and later identified from the relative size of univalents at diakinesis, mean meiotic association at metaphase I, and pollen fertility. Trisome identity in a few cases was confirmed from somatic karyotypes. The trisomics could be divided into seven groups, probably representing all the seven primary trisomes. The relatively larger trisomes, i.e., tri 1 to 4, showed a higher trivalent frequency than the smaller trisomes, tri 5 to 7, which formed mostly univalents. The trisomic for chromosome 1 was completely male‐sterile. Pollen fertility of tri 2 to 6 ranged from 4 to 80%. In general, trisomics had narrower leaves, shorter spikes, and were less vigorous during winter than their disomic sibs. The trisomic for chromosome 1, however, was highly vigorous and had dark green, wide leaves. The tertiary trisomic involved one nucleolar chromosome, was desynaptic and male‐sterile.
Isolation Requirements for Foundation Alfalfa Seed Fields1
Authors: Brown D. E. , Kehr W. R. , Manglitz G. R.
Published: July 2010

Two alfalfa (Medicago sativa L.) cultivars in commercial production were used to study isolation distance for foundation seed production using insect resistance traits as genetic markers. Twenty‐one seed samples were obtained for comparison with foundation and certified seed lots. Spotted alfalfa aphid [Therioaphis maculata (Buckton)] resistance values indicated adequate isolation at 0.4 km (1,320 feet) and no shift in resistance from breeder seed to the foundation seed generation. Resistance to pea aphid [Acyrthosiphon pisum (Harris)] could not be used to measure cross‐fertilization between cultivars because the range of resistance overlapped between cultivars.
Spring and Winter Genetic Male‐Sterile Barley Stocks1
Authors: Hockett E. A. , Reid D. A.
Published: July 2010

Genetic male‐sterile stocks of 176 spring and 147 winter barleys (Hordeum vulgare L.) are available for distribution. Stocks are in both two‐ and six‐rowed backgrounds and vary widely in heading date, plant morphology, and area of origin. A new permanent system of assigning genetic symbols to mutant genetic stocks is described. Three letters designate the character; a number, the locus; and one or more letters, the mutational event. These stocks are used for developing hybrid barley in routine breeding programs, development of recurrent selection populations, interspecific crossing, and in studies on the physiology of flowering and microspore formation.
Analysis of Quantitative Traits in PP9 Random Mating Sorghum Population1
Authors: Bittinger Tom S. , Cantrell R. P. , Axtell J. D. , Nyquist W. E.
Published: July 2010

Genetic variability was investigated in a diverse, random‐mating population of sorghum [Sorghum bicolor (L.) Moench]. A Design I mating system was used where 50 random pollen parents each were crossed to a different set of three random seed parents. The 150 resulting progenies were evaluated in a randomized complete‐block design over 2 years at the Purdue Agronomy Farm.

The characters evaluated were flowering, height, lodging, panicle weight, seed weight, panicle length, and grain yield.

Analysis of variance was performed for each trait, and genetic variances were partitioned into additive and dominance components. Additive genetic variance was greater than dominance variance for all traits except yield. The ratio of dominance variance to additive variance was 1.24 for yield and from 0.18 to 0.66 for height, lodging, panicle weight, and seed weight.

Yield showed highly significant positive phenotypic and genetic correlations with flowering and panicle weight. Other significant positive correlations included height with flowering, height with lodging, panicle weight with flowering, and panicle weight with lodging.

Expected genetic gains and heritabilities were calculated for various selection procedures. The effects of major height and maturity genes on variation for yield were discussed.
Performance of Isogenic Soybean Lines in Monoculture and Relay Intercropping Environments1
Authors: McBroom R. L. , Hadley H. H. , Brown C. M.
Published: July 2010

Sets of near‐isogenic lines of soybeans [Glycine max (L.) Merr.], differing in single characteristics, have been tested in monoculture environments but not in relay intercropping environments. These environments seemed different enough to warrant testing several near isogenic lines differing by the genes dt1, Dt2, Lf1, ln, or e3 to determine if any of these genes confer a yield advantage in relay intercropping.

Near isogenic lines in ‘Harosoy’ and ‘Clark’ genetic backgrokunds were grown in monoculture and in relay intercropping systems at Urbana, Ill. in 1978 and 1979 and at DeKalb, Ill. in 1979. In relay intercropping plots, soybeans were planted between rows of small grains 1 to 2 months before small grain harvest. The soybeans germinated and established stands, then the small grains were harvested as they matured.

There was no consistent yield advantage for any of the plant traits when isogenic lines were grown either in relay intercropping or in monoculture systems. The dt1 allele reduced yield in both cropping systems. The ln and Lf1 alleles reduced yields in some environments. The Dt2 and e3 alleles had consistently neutral effects on yield in both cropping systems.
Floral Induction and Forage Yield and Quality of Sparse‐Flowering Orchardgrass Synthetics1
Authors: Berg Clyde C. , Wood G. M. , Hovin A. W. , Rincker C. M.
Published: July 2010

The purpose of this research was to ascertain the genetic control of reproductive tiller production in orchardgrass (Dactylis glomerata L.) and to determine whether sparse panicle production affects.forage yield and quality. We postulated that sparse‐flowering synthetic would retain forage quality longer than normal cultivars as reproductive tillers mature in late spring and early summer. In the greenhouse, up to 12 weeks of cool, short days were required before some orchardgrass plants would flower under long‐day conditions. The response of progeny from three crosses to floral induction treatments suggested that a complex interaction of genetic and environmental factors controls the onset and rate of reproductive tiller production. Reciprocal differences were not observed. Syn 2 generation of synthetics, that produced relatively few flowering tillers when grown in the northeastern USA, flowered and produced satisfactory seed yields at Prosser, Wash.

In the field under a hay management cutting system, the most sparse‐flowering synthetic had slightly lower first harvest forage yield in June. than the check cultivars, possibly because dry matter was produced rapidly by the flowering culms of the cultivars. The absence of significant differences among entries for in vitro dry matter disappearance or lignin concentration suggests that the synthetics and cultivars were similar in forage quality. Thus, the experimental strains exhibited no apparent improvement in forage production or quality.
Influence of Chlorophyll Content on Smoke Constituents in Burley and Flue‐cured Tobacco1
Authors: Legg Paul D. , Chaplin James F.
Published: July 2010

Cultivars of burley and flue‐cured tobacco (Nicotiana tabacum L.) differ in chlorophyll content of growing plants and in many chemical components. The present research was undertaken to determine the genetic diversity between burley and flue‐cured tobacco for smoke components and the influence of chlorophyll level on the components. A backcrossing program was used to obtain near isogenic lines for all genetic factors except alleles at the two loci controlling chlorophyll level. Comparisons among standard cultivars indicated that burley cultivars were generally higher in tar/puff and nicotine/cigarette puff and lower in number of puffs/cigarette than flue‐cured cultivars. The chlorophyll content influenced the level of nine of the 10 cigarette characteristics and accounted for the difference between burley and flue‐cured cultivars for number of puffs/cigarette. Diversity between the two classes of cultivars for tar/puff and nicotine/puff was not totally due to chlorophyll differences. Interclass crosses might be useful in breeding improved cultivars for these components.
Sugar Beets Homozygous for Nematode Resistance and Transmission of Resistance to their Progenies1
Authors: Yu M. H.
Published: July 2010

Heterozygous, cyst nematode (Heterodera schachtii Schm.)‐resistant, self‐compatible sugar beet (Beta vulgaris L.) plants were self‐pollinated in the greenhouse; self‐incompatible plants were interpollinated; and nematode‐susceptable plants derived from resistant parents were sib‐crossed in isolation chambers. Among the 184 S2 and F3 families from resistant parents, five were 100% nematode‐resistant. These were the first homozygous resistant families to be reported. The results indicated that 2.7% of the resistant S1 and F2 plants and only 1.1% of all plants, resistant and susceptible, were homozygous for nematode resistance. The remainder of the resistant S1 plants produced approximately 41.8% resistant progeny. Plants from these true‐breeding families transmitted resistance to 98.4% of their progeny in the following generation. The remaining 1.6% were moderately resistant. Two supposedly S2 progeny plants from a resistant homozygote transmitted resistance to less than 50% of their self‐pollinated progeny. These plants probably resulted from outcrosses.

These findings suggested that resistant homozygotes as seed parents gave full transmission of nematode resistance. Resistant heterozygotes derived from testcrosses to these homozygotes acquired little enhancement in rate of transmission of resistance. Nematode resistance is probably conditioned primarily by complementary genes. In parental line breeding and development after the F1 generation, it would be necessary to use progeny testing to identify true‐breeding individuals. However, nematode‐resistant commercial hybrids could be developed when only one of the parental components is homozygous resistant.
Changes in the Cellular Structure of the Cotton Peduncle Related to Water Transport and Boll Opening1
Authors: Reid Robert K. , Pinckard J. A.
Published: July 2010

Cell number per row and radial width of cells, walls, and cell lumina were measured in rows of cells containing vessels, tracheids, and parenchyma cells in cross sections of 7‐ and 42‐day‐old cotton (Gossypium hirsutum L.) peduncles to ascertain changes reducing water entry into the boll. Three positions in both ages of peduncle: (A) close to the stem, (B) midway between the boll and the stem, and (C) near the boll, were compared to relate anatomical and morphological characters of the peduncle to decreased water supply to older cotton bolls. In the 42‐day‐old peduncle close to the boll no rows containing only vessels were seen. Vessel rows were seen at this level of the 7‐day‐old peduncle, indicating that some cells of the vascular cambium after day 7 ceased producing rows of cells containing only vessels and shifted to tracheid production. Tracheid rather than vessel production would presumably reduce water transporting capacity in older peduncles due to the smaller lumen in tracheids. Overall, there was more vascular cross‐sectional area for water conduction in 42‐day‐old peduncles than in 7‐day‐old ones.
Heritability Estimates for Height, Color, Erectness, Leafiness, and Vigor in Indiangrass1
Authors: Vogel K. P. , Gorz H. J. , Haskins F. A.
Published: July 2010

The purpose of this study was to determine heritability estimates for plant height, leaf color, erectness, leafiness, and vigor and the correlation of these traits with one another and with forage yield, forage in vitro dry matter digestibility (IVDMD), and forage crude protein content for two indiangrass [Sorghastrum nutans (L.) Nash] populations taken from the cultivars ‘Holt’ and ‘Oto’ both of which have broad genetic bases. Narrow sense heritability estimates were obtained by using parent‐progeny regression and by using variance components from the analyses of variance of half‐sib families. Broad sense heritability estimates were obtained using variance components from the analyses of variance of replicated parental clones. Narrow sense heritability estimates averaged over all methods and both populations were 0.75, 0.59, 0.48, 0.36, and 0.50 for plant height, leaf color, erectness, leafiness, and vigor, respectively. Simple correlations of plant height, leafiness, and vigor with forage yield range from 0.24 to 0.58, and all were significant at the 0.01 level. Correlations of color and erectness with yield were very low or nonsignificant. Absolute values of correlation coefficients of IVDMD and protein content with the five traits evaluated were in general very low. These results indicate that vigor or leafiness scores or plant height may be useful in selecting for yield in indiangrass, but leaf color or erectness would have littlevalue in selecting for yield. None of the five traits would be very useful in selecting for IVDMD or protein.
Growth and Composition of Kernels Developing on Excised Oat Panicles in Liquid Culture1
Authors: Lesar Lucia E. , Peterson David M.
Published: July 2010

Excised oat (Avena sativa L., cv. ‘Froker’) panicles were cultured in defined media for 12 days, beginning 8 days after heading, to determine effects of supplied culture nutrients on growth, development, and composition of the grain. The sterile media contained 55.6 mM sucrose, mineral salts, vitamins, and various sources and levels of N. Dry weight increases of the groats were near normal when the N source was mixed amino acids, glutamine, or NH4NO3. The N concentration of the groats was increased to 3.85, 4.30, and 5.08% with mixed amino acids, glutamine, and NH4 NO3, respectively, after 12 days in culture, as compared to a N concentration of about 2.96% for groats on intact plants. Electrophoresis and amino acid analysis of total groat protein revealed no marked differences between cultured and intact plants. The percentage of N in the bran fraction was increased by mixed amino acids medium, and that of the.endosperm by glutamine medium. There was no increase in nitrate in groats of the cultured panicles. Levels of soluble α‐amino N were increased slightly by the glutamine medium. It was concluded that the panicle culture technique is valid for study of the effects of supplied nutrients on grain composition. Groat N is responsive to the level of media N, and glutamine or NH4NO3 adequate as a N source.
Use of R‐nj Aleurone Color to Improve Grain Yields of Early Maize1
Authors: Cross H. Z.
Published: July 2010

Effectiveness of a mass selection technique utilizing variable R‐nj aleurone color expression to select for a correlated yield response in maize (Zea mays L.) was evaluated in 10 North Dakota environments. Two cycles of mass selection for high and low color expression for ears pollinated with a common source of R‐nj pollen were compared with randomly selected check populations. Selection for high R‐nj color expression increased observed yields 0.3 q/ha/cycle and reduced ear moisture at harvest 1.6%/cycle. True gains were estimated to be 2.8 q/ha for yield and − 1.2% for ear moisture. Yield increase was due to an increase in kernels/row. Shelling percentage also was increased.

Low R‐nj color selections had a similar trend toward higher yields, but specific yield instability estimated by deviations from regression was increased as compared to random selection. The low color expression populations had greater ability to respond to high yield environments than the high color expression populations.

Direct evidence on the effects of color selection on duration and rate of grain fill was not obtained, therefore, the hypothesis that selection for high R‐nj color expression parallels increased grain‐fill rate and/or duration could not be tested. This selection method appears promising for maize improvement and should be subjected to more research to determine why yield differences were associated with aleurone color expressions.
Nitrogen Fixation in the Rhizosphere of Cultivated and Wild Rice Strains1
Authors: Sano Y. , Fujii T. , Iyama S. , Hirota Y. , Komagata K.
Published: July 2010

A modified assay system using the acetylene reduction technique was devised in order to measure large numbers of plants easily, to look into variations among genotypes for N2 fixation in the rhizosphere of paddy rice (Oryza sativa L.), this assay system showed that the activity could be detected immedidately after incubation and the amount of ethylene produced increased linearly with time. It was considered that rice roots were essential for the activity of heterotrophic bacteria contributing N2 fixation in paddy rice. The highest activity was found at flowering stage though large diurnal fluctuation was observed. The differences in nitrogenase activity among rice species and strains were highly significant. In comparisons between cultivated and wild rice strains, cultivated strains generally showed higher activities than wild relatives. These results suggested that the association between rice plants and N2‐fixing bacteria was controlled by the genotypes of the plants, and the association might have been enhanced in the course of domestication.
Allelopathy in a Grass‐Legume Association: I. Effects of Hemarthria altissima (Poir.) Stapf. and Hubb. Root Residues on the Growth of Desmodium intortum (Mill.) Urb. and Hemarthria altissima in a Tropical Soil.1
Authors: Young C. C. , Bartholomew D. P.
Published: July 2010

In Hawaii, Desmodium intortum (Mill.) Urb. ‘Greenleaf’ could not be established in a pasture of the tetraploid Hemarthria altissima (Poir.) Stapf. and Hubb. ‘Bigalta,’ while good survival of ‘Greenleaf’ seedlings was obtained in a sward of the diploid H. altissima ‘Greenalta.’ To help characterize the association further, Greenleaf seeds were planted alone and in mixtures with cuttings of Bigalta or Greenalta in pots with soil containing root residues of Greenleaf and the two grasses. The effects of these residues on the growth and mineral nutrient content of the three species were measured.

Growth of Greenleaf was very poor in soil containing root residue of Bigalta. Plant fresh weights were only about one‐fourth of those obtained in the presence of Greenleaf and Greenalta residues. Levels of N, K, Mg, and Ca in the tops of Greenleaf were unaffected by residue source. However, the level of P in Greenleaf tops grown in Bigalta residue was 0.15% on a dry weight basis compared to 0.20% or greater for plants grown in the other two residues. The inhibition of Greenleaf growth in soil in which Bigalta had been grown previously was likely due to allelopathic substances in the Bigalta root residues rather than to competition for environmental factors.
Moisture Migration into Soybean Pods1
Authors: Yaklich R. W. , Cregan P. B.
Published: July 2010

An evaluation of moisture absorption by soybean [Glycine max (L.) Merr.] pods was conducted in 1978 and 1979. Forty‐six cultivars representing Maturity Groups II through VI were grown to harvest maturity in the field. Representative plants from each cultivar were taken to the laboratory and intact pods were removed from each plant. In each year, two sets of 20 pods from each cultivar were submerged in water for 0, 1, 6, and 24 hours to allow moisture uptake by the pod and seed.

Pods and seeds from cultivars in Maturity Groups II through IV absorbed significantly more moisture than those from Maturity Groups V and VI. Pods of ‘Williams’ and ‘Celest’ absorbed the least amount of moisture in Maturity Groups III and V, with both having absorbed approximately 78.0 g H2O/100 g dry wt at 24 hours. Water uptake in these two cultivars were significantly different from the cultivars that absorbed the most water within their respective maturity groups. Seed of ‘Perry’ and ‘Ware’ absorbed the least moisture of the 16 cultivars in Maturity Group IV.
Induced Translocations in Safflower1
Authors: Singh R. B. , Pillai R. S. N. , Kumar H.
Published: July 2010

Sixty‐two translations were isolated in the M1 generation of gamma‐irradiated plus sodium‐azide treated populations of safflower (Carthamus tinctorus L.). Most of the simple translocations were induced at 30 and 45 kR, whereas the high dose (60 kR) produced complex interchanges which failed to produce seed. Sodium azide alone induced no chromosomal interchanges. The pollen sterility of the interchange heterozygotes ranged from 1 to 99.6% with an average of 53.76%; 10 of the translocation heterozygotes showed pollen sterility comparable to the standard normal. The interchange heterozygotes at metaphase I had characteristic chain and ring multivalents, mostly quadrivalents. Chain configurations were in excess of the rings in most of the translocations. Alternate orientation of the quadrivalents was most common.