bluuebunny/crossref_metadata_2025 huggingface dataset:
Simplification of the Heat Treatment Technique to Enhance Pseudo‐Self‐Compatibility in Trifolium pratense L.1
Authors: Kendall W. A.
Published: July 2010

A simplified incubator is described for controlling temperature of red clover (Trifolium pratense L.) flower heads during anthesis in order to promote pseudo‐selfcompatibility. The incubator was used to study the variability of self‐seed yields. The yields were greatest, with excised stems at 20 to 25 C and flower heads at 31 to 38 C with 25 to 50% relative humidity. Illumination during anthesis had no effect on yield. When plants had grown under adequate light intensities there were no differences in seed yields between excised and intact stem treatments. However, seed yields were highest from excised stems when growth was limited by low light conditions. There were no advantages in seed yields from treatments to the lower end of excised stems with extreme heat, cold, or pressure, which killed the cells. Pollen tubes grew through fewer pistils of the self‐ than of the cross‐pollinated florets. The percentage of pistils in which pollen tubes grew into the ovulary that eventually set seed, the correlation of pollen tube growth and seedset, and the percentage of seeds that germinated were all similar for both mating types. These data indicate that the selfincompatibility alleles do not directly influence fertilization, seed development, or seed germination.
In Vivo and In Vitro Relationships in Evaluating Digestibility of Selected Smooth Bromegrass Synthetics1
Authors: Kamstra L. D. , Ross J. G. , Ronning D. C.
Published: July 2010

Reliable laboratory tests to indicate forage quality have a tremendous potential as tools for screening material in a breeding program. Within a 6‐clone diallel cross of smooth bromegrass (Bromus inermis Leyss.) those progenies showing highest and lowest in vitro digestibility were identified and then produced as 2‐clone synthetics and tested in a large scale experiment. The synthetics were more digestible in vivo and in vitro than the cultivar ‘Sac,‘ but no digestibility differences occurred between synthetics. Although the expected difference between the synthetics was not found, the high correlation between the in vivo and in vitro techniques indicates that the in vitro method may be used as a selection tool in breeding. The reason for the lack of correspondence between spaced plant and field results is being investigated.
Bloat Investigations: Determination of Soluble Protein Concentration in Alfalfa1
Authors: Howarth R. E. , McArthur J. M. , Goplen B. P.
Published: July 2010

A rapid, reliable method for the determination of soluble protein concentration in alfalfa was developed for use in studies on the bloat potential of alfalfa (Medicago sativa L.) and in breeding a low bloat‐causing alfalfa cultivar. A two‐step extraction procedure was used to obtain a crude aqueous extract. The colorimetric, biuret method for protein determination was modified by taking absorbance readings at two wavelengths (550 and 708 nm) to correct for interference by colored substances in the alfalfa extract.

By this method the soluble protein concentration in fresh alfalfa was 50 to 70% of crude protein concentration. The correlation (r = 0.36) between soluble and crude protein was low (p > 0.05). The coefficient variation for soluble protein concentration was 10.5% in a population of 289 plants of diverse genetic origin, indicating the possibility of selecting for low soluble protein concentration as a means of developing a low bloatcausing alfalfa cultivar.
Trisomic Analysis of Greenbug Resistance in Barley, Hordeum vulgare L.1
Authors: Gardenhire J. H. , Tuleen N. A. , Stewart K. W.
Published: July 2010

The linkage group of the gene for greenbug (Schizaphis graminum Rondani) resistance in the barley (Hordeum vulgare L.) cultivar ‘Will’ was determined by using primary trisomics and tertiary trisomic homozygous translocations. The gene for greenbug resistance was found to be on linkage group 1 and on the centromere‐bearing segment of chromosome 1 in the Tl‐6a translocation. Previous attempts to locate the gene using standard marker genes were unsuccessful.
Recurrent Selection for Lint Percent within a Cultivar of Cotton (Gossypium hirsutum L.)1
Authors: Meredith William R. , Bridge R. R.
Published: July 2010

We conducted this study to determine if a modified form of recurrent selection for lint percent within a cotton (Gossypium hirsutum L.) cultivar, ‘Deltapine 523,’ could improve lint yield. Three cycles of selection, beginning in 1965, were completed, with selection for lint percent being practiced first on a plant basis and then on a progeny‐row basis. Plant populations of 430, 828, and 800 plants were used to initiate the S1, S2, and S3 populations, respectively. From each population, 16 progenies were ultimately selected on the basis of high lint percent, and 8 crosses were made among them to initiate the next cycle. In each cycle, an equal number of seeds from each of the 16 selections were combined to form the bulk populations tested in 1971. Eight progenies selected in the S3 for higher 2.5% span length were bulked and designated as the S3L. population.

In 1971, Deltapine 523 (S0) and the four selected populations were grown in replicated experiments at four locations. Mean lint precent was 33.8, 35.4, 36.6, 38.0, and 37.1 for the S0, S1, S2, S3, and S3L. populations, respectively. The S2, S3, and S3L populations produced significantly greater lint yield than did S0 and S1. As lint percent was increased by selection, there were concurrent decreases in seed index and 50 and 2.5% span length. Selection for fiber length in the S3 population restored most of the fiber length previously lost. As lint percent was increased by selection, there were simultaneous increases in lint index, seeds per boll, and Micronaire. No consistent trend or change was observed for boll size, number of bolls per plot, fiber strength, and fiber elongation. The primary cause of the increase in lint yield resulting from selection for lint percent was the association of lint percent with increased number of seeds per boll and higher lint index.

The genetic variability for lint percent within the S1 and S2 populations was found to be 188 and 83%, respectively, as compared to that of the S0 population. The genetic variability for an unselected trait, boll size, was similar, with the S1 and S2 populations expressing 233 and 186%, respectively, as much variability as that of the S0 population.
Symbiotic Nitrogen Fixation in Soybeans. I. Effect of Photosynthetic Source‐Sink Manipulations1
Authors: Lawn R. J. , Brun William A.
Published: July 2010

Symbiotic nitrogen fixation of two field grown soybean [Glycine max (L.) Merr.] varieties, ‘Chippewa 64’ and ‘Clay,’ was measured at 7 to 10 day intervals starting at flowering, using the acetylene reduction assay. At he end of flowering, treatments were applied which were designed to alter the relationship between the photosynthetic source and sink components in the plants. The treatments were supplemental light, 25% shade, 50% depodding, 60% defoliation, and control.

Total acetylene reduction activity per plant increased in both varieties during the flowering period, reached a maximum near the end of flowering, and then declined markedly during the early podfilling stage. The activity decline was due to a decline in the specific activity of the nodules, and occurred immediately prior to the time when the growth rate of the pods (including seed) exceeded that of the total plant tops in the respective varieties. Treatments designed to enhance he photosynthetic source/sink ratio (supplemental light and depodding) maintained nodule activity well above the control in both varieties. Conversely, treatments designed to reduce the source/sink ratio (shading and defoliation) decreased nodule activity below the level of the control. Treatment effects on total plant protein recovered at maturity closely reflected the treatment effects on total nodule activity. The results of this study are interpreted as evidence that symbiotic nitrogen fixation in these varieties declined during podfilling as the result of inadequate assimilate supply to the nodules.
Symbiotic Nitrogen Fixation in Soybeans. III. Effect of Supplemental Nitrogen and Intervarietal Grafting1
Authors: Lawn R.J. , Brun William A.
Published: July 2010

Two field experiments were conducted to determine the effect of 1) grafting onto root genotypes with different nitrogen fixation rates, and 2) supplemental nitrogen applied at the time of declining nodule activity (end of flowering), on nodulation, seed yield, and protein yield of ‘Chippewa 64’ and ‘Clay’ soybeans (Glycine max (L.) Merr.). The experiments were conducted in situations of low available soil nitrogen to ensure a strong reliance on symbiotic nitrogen fixation. In the first study, seedling shoots of both varieties were grafted onto four roofstocks: ‘Wayne’, ‘Altona’, Chippewa 64 and Clay.

Differences were evident among root genotypes, independent of shoot genotype, for acetylene reduction activity per plant, but not for nodule fresh weight. for Chippewa 64 shoots, seed yield and seed protein content were significantly altered by grafting onto other rootstocks, whereas for Clay shoots only seed protein content was significantly changed from that of the selfgrafted controls. The effects of the root genotypes on seed yield were related in part to the respective differences in ability to support nitrogen fixation.

In the second study, supplemental nitrogen (0, 224, and 448 kg per ha) was applied as ammonium nitrate at the end of flowering to Chippewa 64 and Clay soybeans. The application of nitrogen caused a decline in acetylene reduction activity for both varieties. Seed yield and seed protein content for Clay, and seed protein content and vegetative protein yield for Chippewa 64, were all increased by the application of nitrogen.
Field Measurement of Photosynthesis in a Forage Grass Breeding Program1
Authors: Nelson C. J. , Asay K. H. , Horst G. L. , Hilderbrand E. S.
Published: July 2010

A system for rapid measurement of net carbon exchange (NCE) by leaves of clonal lines of forage grasses growing in the fidd has been developed. Air‐sealed leaf chambers of laminated construction connected to a manifold permit the determination of the average NCE of several leaves measured simultaneously. With 4 replications and more than 10 genotypes, the average NCE from 6 individual leaf measurements per plot was adequate to detect statistical differences of 2.0 mg dm−2 hour−1 between 2 genotypes with 83% power. Two units of six leaf chambers, each operating simultaneously, are monitored by one infrared CO2 analyzer, allowing the average NCE rates of 20 plots/hour to be accurately measured. The system is reliable, rapid, relatively simple, and uses intact leaves for field measurement. The technique is being used to determine genetic variability, heritability, and potential use of NCEin a tall fescue (Festuca arundinacea Schreb.) breeding program.
Recurrent Selection for Seedling Vigor in Birdsfoot Trefoil1
Authors: Twamley B. E.
Published: July 2010

In 1969, a program of recurrent selection for seedling vigor in ‘Leo’ birdsfoot trefoil (Lotus corniculatus L.) was initiated. Seed for all tests was garnered from openpollination nurseries, small‐seeded lines were discarded, and seedling vigor tests were conducted indoors on the remainder. In each cycle the most vigorous seedlings from the most vigorous lines were selected to be the parents of the next cycle. Three cycles were completed. In 1972, nursery material representing cycles 0, 1, 2, and 3 was established and harvested for seed.

Three types of experiments were used to evaluate progress: 1) random seed samples from each cycle were bulked within cycles to provide four treatments, including the check; 2) pedigree test—18 lines from each cycle, randomly chosen from within seed weight classes, were tested; and 3) a series of routine tests were used primarily to identify superior lines. In these routine tests only lines that were at least average in seed size were included.

In the bulk test the percentage improvement in seedling vigor for cycles 1, 2, and 3 over the cydc 0, or Leo population, was 10, 34, and 40%, respectively. For the pedigree test it was 20, 36, and 36%. For four routine tests the average improvement was 30, 47, and 52%. The average improvement in seed size was 36%. Inbreeding and a relaxation of selection pressure were considered responsible for the lack of progress in cycle 3 compared to cycle 2.

Possible uses of seedling vigor tests to provide information on breeding methods are discussed.
Dry Matter Contribution by Cotyledons of Lima Beans and Other Epigeal Legumes1
Authors: Machado A. D. , Williams W. A. , Tucker C. L.
Published: July 2010

Lima beans (Phaseolus lunatus L.) were compared with four other species of epigeal legumes for the effectiveness of their cotyledons in carbon assimilation. Measurements of growth of seedling organs following shading of the cotyledons permitted the species to be divided into three groups: 1) species in which the cotyledons have negligible photosynthetic activity — lima beans, mung beans (P. aureus Roxb.), and kidney beans (P. vulgaris L.); 2) a species in which the cotyledons have a slight significance as photosynthetic organs — soybean (Glycine max (L.) Merrill); and 3) a species in which the cotyledons are important as photosynthetic organs — subclover (Trifolium subterraneum L.)
Genetics and Breeding of 42‐Chromosome Triticale. I. Evidence for Substitutional Polyploidy in Secondary Triticale Populations1
Authors: Gustafson J. Perry , Qualset C. O.
Published: July 2010

F2 plants from two hybrid populations of 42‐chromosome triticale (X Triticosecale Wittmack) were crossed to Triticum aestivum L. em. Thell. cv. ‘INIA 66’ and to diploid rye (Secale cereale L. cv. ‘Merced’). The numbers of univalent chromosomes in the crosses to INIA 66 or paired chromosomes in the crosses to Merced were determined to estimate the number of rye chromosomes in the F2 triticale plants. The results indicated that 3 to 6 rye chromosome pairs were present and thus support the hypothesis that D genome chromosomes are present hi some 42‐chromosome triticales. Such triticales can have various combinations of D and R chromosomes in addition to the A and B genomes of, Triticum, and hybrids among these triticales are essentially interspecific crosses with resultant sterility in the F1 and subsequent generations.
Inheritance of Hilar Layer Coloring in White Corn (Zea mays L.)1
Authors: Zuber M. S. , Wolf M. J. , Hilderbrand E. S. , Cull Irene
Published: July 2010

The inheritance of hilar layer coloring (also known as black layer) in maize (Zea mays L.) was studied using 4 white endosperm inbred line parents, their 6 possible F1 and F2 generation single crosses, and 12 first generation backcrosses and their reciprocals. The results showed that the inheritance of hilar layer coloring is complex in this set of material, but it should be possible to develop corn strains with less hilar layer coloring. However, because hilar coloring may be due to condensed phenolic compounds that may inhibit the passage of certain pathogenic fungi into the kernel, reducing the level of pigmentation might lower resistance to kernel‐rotting fungi. Further studies are needed to determine if hilar layer pigmentation inhibits kernel‐rotting fungi.
Seed Transmission of Maize Dwarf Mosaic and Wheat Streak Mosaic Viruses in Maize and Response of Inbred Lines1
Authors: Hill J. H. , Martinson C. A. , Russell W. A.
Published: July 2010

Wheat streak mosaic and maize dwarf mosaic viruses were isolated from a number of maize (Zea mays L.) plants in seed production fields in Iowa. A low percentage of seed transmission (0.1% for wheat streak mosaic virus and 0.2% for maize dwarf mosaic virus in one line) of the two viruses was found. Results from mechanical inoculation of several maize inbred lines showed that both viruses could be recovered from some symptomless plants. The Ht gene does not impart susceptibility to wheat streak mosaic virus.
Gl28—A New Allele for Pigment Glands in Cotton1
Authors: Barrow J. R. , Davis D. D.
Published: July 2010

A new gland phenotype was observed in cotton (Cossypium hirsutum L.) segregating for Gl2 and Gl3. A genetic analysis was conducted to determine the inheritance of this character. It was found that the gene responsible was allelic to Gl2. The new allele was designated Gl28. Gl28 in the homozygous condition (Gl28Gl28 gl3gl3) imparts reduced gland density in the cotyledons, as compared to Gl2 or Gl3, with apparent normal gland distribution in the stems and petioles.
Ozone Damage to Wheat Varieties at Anthesis1
Authors: Shannon J. G. , Mulchi C. L.
Published: July 2010

Two wheat (Triticum aestivum L.) cultivars, ‘Arthur 71’ and ‘Blueboy,’ were exposed to 0.2 ppm ozone at anthesis for 4 hours/day for a week in a growth chamber. Yields were reduced by about 30 and 23% for Arthur '71 and Blueboy, respectively. However, the reduction for Blueboy was not statistically significant. Reductions in seed per plant and seed per head were not significantly different in the ozone treatment as compared to the controls.

Cultivars did not always respond in the same way to ozone for the characteristics studied. Ozone only slightly reduced kernel weight in Blueboy as compared to a significant, 17.4% reduction for Arthur '71; however, seed set was significantly reduced by 22.1% in Blueboy compared to 8.3% for Arthur '71. Since the ozone levels used in this experiment are often attained in fields near urban areas, the responses to ozone for wheat yield and yield components for the varieties studied should be comparable to actual field conditions.
Inheritance of Floral Characteristics Influencing Outcrossing in Rice
Authors: Virmani S. S. , Athwal D. S.
Published: July 2010

The genetics of three floral characters influencing outcrossing in rice (Oryza sativa L.) was studied in a cross between Accession 100183 of wild rice (Oryza sativa f. spontanea) and the cultivar ‘IR8.’ A high percentage of exserted stigma, short anther, and short stigma were partially dominant. Both additive and nonadditive effects were important in the inheritance of these floral traits. The prevalance of a duplicate type of epistasis in their inheritance indicated that these traits may be improved through recurrent selection in biparental progenies which would allow recombination and concentration of genes with additive effects. The percentage of exserted stigma was positively correlated with stigma length. Both traits were correlated positively with anther length.
Genetics of Resistance in Maize to First‐ and Second‐Brood European Corn Borer1
Authors: Jennings C. W. , Russell W. A. , Guthrie W. D.
Published: July 2010

One 10‐inbred‐line diallel of maize (Zea mays L.) was evaluated for 2 years for resistance to second‐brood European corn borer [Ostrinia nubilalis (Hübner)], and a second 10‐line diallel was evaluated for 1 year for resistance to first and second broods. First‐brood evaluations were based on leaf‐feeding ratings in the pretassel stage, and second‐brood evaluations were based on plant‐cavity counts in mature plants. Variations attributed to general combining ability and general combining ability ✕ years were highly significant in the first diallel, but none of the F‐tests for specific combining ability were significant. Different levels of borer infestation in the 2 years probably affected the estimates of genetic effects. In the second diallel, variations attributed to general combining ability and specific combining ability were highly significant for both first‐ and second‐brood data. Also, heterosis was highly significant, with resistance being partially dominant. Inbred B52 contributed the most resistance to second brood, and CI31A and B49 contributed the most resistance to first brood. There are differences in the genes of the maize plant that condition resistance to first and second broods, but some genes may contribute resistance to both broods.
Method of Determining Genome Locations of Single Genes in Wheat1
Authors: Merkle O. G. , Gough F. J. , Green J. A.
Published: July 2010

Wheat (Triticum aestivum L.) seedling reactions to stem rust (Puccinia graminis Pets. f. sp. tritici Erlks. and E. Henn.) were determined for F2 populations from selfed pentaploids from crosses between a susceptible tetraploid (AABB) and two resistant hexaploid lines (AABBDD). One of the hexaploid lines had Sr6 located on chromosome 2D and the other line had Srl6 located on chromosome 2B. A good fit to 3:1 ratio occurred when the resistance gene was located on chromosome 2B. The F2 segregation differed from the single gene Mendelian ratio when the resistance gene was located on chromosome 2D. The test demonstrated the feasibility of assigning resistance genes to the proper genome in single‐gene hexaplold lines by crossing to appropriate tetraploid tester lines and testing the F2 populations.
Genetic Effects for Mean Yield and for Yield Responses to Environments in Three‐Way and Single‐Cross Hybrids of Grain Sorghum1
Authors: Patanothai Aran , Atkins R. E.
Published: July 2010

Grain yields of three‐way and single‐cross hybrids of sorghum (Sorghum bicolor L. Moench) were obtained from experiments grown in nine environments in Iowa during 1969 through 1971. The purpose of the study was to obtain, estimates of the relative impact of various types of geneuc effects on mean grain yield and on stability of yield over environments. Analyses of the data indicated that differences among the entries for mean yield were ascribable to both additive and dominant gene effects. Variations among parameters that describe stability of yield over environments could be attributed largely to additive gene action. Significant epistatic effects were not indicated for the expression of either mean yield or stability of yield.

A second objective of the study was to compare observed and predicted values for grain yield and yield stability of the three‐way crosses. Relative effectiveness of five prediction methods generally was in accord with significance of the genetic effects included in the prediction equation. The method analagous to Jenkins's Method B (J. Amer. Soc. Agron. 26:199–204, 1926) for predicting the yield of a double cross seemed preferable to the other methods because of its simplicity and its suitability for use with any set of crosses.
Days from Pollination to Seed Maturity in Crownvetch1
Authors: Al‐Tikrity Wail , Clarke W. W. , McKee G. W. , Risius M. L. , Peiffer R. A.
Published: July 2010

Flowers of crownvetch, Coronilla varia L., were hand pollinated in the field at approximately weekly intervals during the growing seasons of 1969 and 1970 to ascertain the time required from pollination to seed maturity. Averaged over both years, the mean time from pollination to fully mature seed was 50 days but ranged from 46 to 59 days, depending upon the date of pollination and the field. Mature seeds are plump with either dull brown or reddish‐brown seedcoats. In 1969, none of the flowers pollinated after July 22 produced seeds that matured before commercial harvest in late September and early October, while in 1970, none of the flowers pollinated after August 16 produced mature seeds. The mean number of seeds per pod was 6.7. Mature seeds collected in 1971 from seedpods resulting from flowers pollinated during July had a total germination of 96% of which 92% were hard seeds. Seeds from flowers pollinated in mid‐August had a total germination of 82% of which only 11% were hard. These studies suggest that to increase seed yield and seed quality, crownvetch seed fields pollinated by honeybees should be managed so that flowers are pollinated as early as possible during the growing season.
Effect of an Alien Cytoplasm and Fertility Restoring Factor on Growth, Agronomic Characters, and Chemical Constituents in a Male‐Sterile Variety of Flue‐Cured Tobacco1
Authors: Hosfield George L. , Wernsman Earl A.
Published: July 2010

Experiments conducted with cytoplasmic male‐sterile lines of flue‐cured tobacco (Nicotiana tabacum L.) have shown that male‐sterile inducing cytoplasms can adversely affect plant growth rate and agronomic characters.

In the present study isogenic lines of a cytoplasmic male sterile and two fertility‐restored male steriles (N. suavveolens Leh. cytoplasm) were compared with normal fertile tobacco to determine the effect of fertility restoration on growth rate, agronomic performance, and chemical characteristics. The two fertility‐restored tobacco lines possessed N. suaveolens cytoplasm and were homozygous and heterozygous, respectively, for a chromosomal segment from N. suaveolens marked by a factor for fertility restoration.

The N. suaveolens cytoplasm exerted a retarding effect on growth rate, causing plants to be taller, to mature later, and to produce more leaves. Nevertheless, the effect of the cytoplasm per se did not cause yield or quality reductions in cured leaf.

Genetic activity associated with the N. suaveolens chromosomal segments in the fertility‐restored lines overcame some of the suppressing effects of the cytoplasm on growth rate, yet their final productivity was inferior to the male sterile and normal fertile control. A dosage effect of the introgressed chromosomal segment was evident since the fertility‐restored heterozygote deviated less from the control than the homozygote.

Differences among treatments for chemical constituents in cured leaf were minimal, although all entries with N. suaveolens cytoplasm had lower quantities of reducing sugars and the fertility‐restored lines exhibited a twofold increase in nornicotine over the control.
Rapid Procedure for Estimating Cyclic Hydroxamate (DIMBOA) Concentration in Maize1
Authors: Long B. J. , Dunn G. M. , Routley D. G.
Published: July 2010

A rapid procedure was developed for estimating the concentration of a cyclic hydroxamic acid 2,4‐dihydroxy‐ 7‐methoxy‐l,4‐benzoxazin‐3‐one (DIMBOA) for potential use in a maize (Zea mays L.) breeding program. Samples (0.2 to 0.5 g stem tissue) were collected from seedlings at 36 cm to 41 cm extended leaf height. The rapid procedure, essentially a simplification of the colorimetric procedure of Hamilton, was significantly correlated with the latter (r = +0.82) based on the analysis of 13 inbred lines of maize.
Breeding Root‐Knot‐Resistant Gossypium hirsutum L. Using a Resistant Wild G. barbadense L.1
Authors: Shepherd Raymond L.
Published: July 2010

Three screening techniques for resistance to the rootknot nematode (Meloidogyne incognita acrita Chitwood & Oteifa 1952) were compared. These were agar, infested soil, and disinfected larvae. The latter was the most effective in differentiating between resistant and susceptible entries.

Using the disinfected larval technique, 173 BC3F5 families were screened for resistance. These were from Gossypium hirsutum L. ✕ a wild, root‐knot‐resistant G. barbadense L., followed by three backcrosses to G. hirsutum. In the order of backcrossing, backcross parents were Z106 (a doubled haploid), var. ‘Empire,’ and var. ‘Auburn 56.’ The first two backcross parents were highly susceptible, and the last was moderately resistant to M. incognita acrita. Pedigree‐selection, recurrent‐selection, and progeny‐testing procedures were followed. Three lines (S3, S22, S28), intermediate in resistance between Auburn 56 and G. barbadense, were developed. These lines represented signficant progress in breeding G. hirsutum with a higher level of resistance to M. incognita acrita than presently grown varieties.
Genotypic Responses in Sorghum to Drought Stress. II. Leaf Tissue Water Relations1
Authors: Blum A.
Published: July 2010

The sigmoid relationship between leaf water saturation deficit (WSD) and leaf water potential, as a measure of dehydration avoidance, was investigated in 10 sorghum (Sorghum bicolor L. Moench.) genotypes grown in the field in 1971 and 1972. The leaf water potential at which an exponential increase in WSD commenced appeared to vary among genotypes, ranging from about −10 to −12 bars in Feterita and RS‐610 to −16 bars in Hegari. When genotypes were ranked according to mean increase in WSD per unit decrease in leaf water potential, the greatest dehydration avoidance was observed in Hegari and the Kafirs, and the least in RS‐610 hybrid and Feterita.
Influence of Drought on Tillering and Internode Number and Length in Alfalfa1
Authors: Perry L. J. , Larson K. L.
Published: July 2010

‘Vernal’ and ‘Sonora’ alfalfa (Medicago sativa L.) plants were grown from seed in the greenhouse under two soil water levels, 49 and 100% field capacity as defined. Vegetation of the primary growth was harvested at the vegetative, 5 to 10% bloom, and seed pod stages. Top growth was again harvested when the regrowth was at 5 to 10% bloom. ‘Travois’ and ‘Lahontan’ were included in a subsequent experiment and were harvested only at the 5 to 10% bloom stage of the primary and recovery growth.

Stem number per plant, number of internodes per stem, and individual internode length of the primary stem were greatly reduced by water deficits (49% field capacity) for all cultivars at each harvest. The cold‐hardy cultivars, Travois and Vernal, had significantly more internodes per stem under both soil water levels than the nonhardy cultivars, Lahontan and Sonora. Length of the internode between the unifoliolate and first trifoliolate leaves on the primary stem of Travois and Vernal under both soil water levels was significantly less than that of Lahontan and Sonora. The pattern of morphological differences among hardy and nonhardy cultivars was the same with or without drought stress.
Characterization of the Bean Pod as a Photosynthetic Organ1
Authors: Crookston R. K. , O'Toole J. , Ozbun J. L.
Published: July 2010

The photosynthetic characteristics of the pod of Phaseolus vulgaris L. cv. ‘Redkote’ were determined by measurements of CO2 exchange, enzyme activities, and anatomical observations. Per unit area, the pod incorporated only 5 to 9% as much atmospheric CO2 as its subtending leaf. It appeared to be recycling substantial amounts of internally‐released CO2 however, and its total CO2‐fixing capacity was estimated to be 26% that of the leaf. Enzyme activity measurements showed that the pod had 40% as much ribulose diphosphate carboxylase and glycolate oxidase activity and over 700% as much malate dehydrogenase activity per unit area as the leaf. Cells in the outer half of the pod wall had numerous chloroplasts which increased in frequency and starch content with proximity to vascular tissue. There were no plastids in the inner half of the pod wall. The pod surface contained 25% as many stomata per unit area as the lower surface of the leaf. Some of the pod stomata appeared to be partially or completely obstructed.
Breeding for Resistance in Maize to First and Second Broods of the European Corn Borer1
Authors: Russell W. A. , Guthrie W. D. , Grindeland R. L.
Published: July 2010

Resistance to first and second broods of the European corn borer [Ostrinia nubilalis (Hübner)] in maize (Zea mays L.) is not conditioned by the same genes. Our purpose was to determine if we could combine the two kinds of resistance into one genotype by a simple inbreeding and selection technique. Starting with 200 F3 lines from B52 ✕ Oh43, we obtained 1 F6 inbred line slightly better than Oh43 for first‐brood resistance and equal to B52 for second‐brood resistance. Because several loci are involved, a backcross program may not be successful in transferring all resistance genes to other lines. A sampling of a synthetic variety, ‘BS9,’ developed by combining 10 inbred lines that among them contributed first‐ and second‐brood resistance, showed a correlation near zero for evaluations to the 2 kinds of resistance. A recurrent selection program based on S1 line evaluation is recommended to increase gene frequencies to both broods in a population which can then be used as a source for resistant lines.
Effect of Water Stress and Temperature on Leaf Size and on Size and Number of Epidermal Cells in Grain Sorghum1
Authors: McCree K. J. , Davis S. D.
Published: July 2010

Experiments were designed to assess the relative importance of rates of cell division and cell enlargement in determining the final sizes of sorghum [Sorghum bicolor (L.) Moench, cv. ‘Oro’] leaves grown under varying degrees of water stress. Well‐watered sorghum plants were grown under atmospheric conditions which simulated natural daily cycles of air temperature and dewpoint in warm, moist conditions (experiment 1) and hot, dry conditions (experiment 2). In experiment 3, the plants were subjected to hot, dry conditions and five cycles of soil water deficit. Both the rate of increase of leaf area and the final leaf area declined progressively from experiment 1 to experiment 3. Between experiments 1 and 2, the average area per epidermal cell in leaf 11 decreased by about half as much as the leaf area. The area per cell did not decrease at all between experiments 2 and 3, despite a large decrease in leaf area. There was a progressive decline in the number of epidermal cells per leaf from experiment 1 to experiment 3. The proportion of stomatal cells changed only slightly. It was evident that the rate of cell division was at least as important as the rate of cell expansion in determining the final leaf area (assuming that epidermal cells are reasonably representative of all the cells in a leaf).
Relationship of Protein Percent with other Phenotypic Characters in Interspecific Oat Crosses1
Authors: Spilde LeRoy A. , Albrechtsen R. S. , Rumbaugh M. D.
Published: July 2010

Protein percentage and its relationship with 15 other agronomic characteristics were studied in F5 generation progenies of F4 plants from crosses between Avena sterilis L. Var. Maxima Perez Lara and five A. sativa L. cultivars in an attempt to determine the relationships among factors involved in the improvement of oat quality. Mean percent protein of the progenies was intermediate between their parents. Transgressive segregation was present for both percent protein and yield in four crosses. The possibility of simultaneous improvement of these characteristics is suggested.

Simple correlation coefficients indicated percent protein was positively associated (P<.01) with characters typical of A. sterilis. Regression analysis indicated yield had the most influence on percent protein of the characters studied.
Fully Automatic Subirrigation System for Glasshouse and Growth Chamber Use1
Authors: Stanwood P. C. , Phillips J. C. , Chilcote D. O.
Published: July 2010

A fully automatic subirrigation system is described for use in the glasshouse or environmental control chambers. Versatility in watering schedules, rooting mediums, and potting containers is provided. A number of crop species have been successfully grown using this system.
Effect of the Brittle‐1 Sugary‐1 Double Mutant Combination on Carbohydrate and Postharvest Quality of Sweet Corn1
Authors: Tsai C. Y. , Glover D. V.
Published: July 2010

Whole kernels of the double mutant combinations of brittle‐1 sugary‐1 of maize (Zea mays L.) contain about 40 and 200% of the water‐soluble polysaccharides and sucrose, respectively, of the sugary‐1 mutant alone. More important, the double mutant preserves 90% of the sucrose even up to 4 days postharvest at room temperature. These features of the double mutant may offer a desirable new high quality sweet corn with the added potential for improving post‐harvest quality.
Significance of First Leaf Type to Growth of the Sainfoin Seedling1
Authors: Cooper Clee S.
Published: July 2010

The incidence of unifoliolate and trifoliolate first leaves and the importance of first leaf type to photosynthesis and growth of sainfoin (Onobrychis viciaefolia Scop.) seedlings were studied. Sainfoin accessions had a higher proportion of unfoliolate than trifoliolate first leaves. The percentage of trifoliolate first leaves varied among 30 sainfoin accessions from 1 to 50%. Frequency of fist leaf types was not related to seed size, but leaf area within a type increased significantly with seed size. Trifoliolate first leaves had more area than unifoliolate leaves. Seedlings with trifoliolate first leaves had higher rates of net carbon enchange (NCE) and grew more rapidly during the early seedling growth period. However, forage yields of seedlings with unifoliolate or trifoliolate first leaves were similar when seedling‐were grown to 8 weeks of age in the greenhouse or to maturity in the field.
Influence of Sorghum Seed Weight on the Performance of the Resulting Crop1
Authors: Suh Hyoung W. , Casady A. J. , Vanderlip R. L.
Published: July 2010

Crops grown in 1971 and 1972 from sorghum [Sorghum bicolor (L.) Moench] seed of two different weights were compared to determine the influence of seed weight on the resulting crop. The lighter seed weighed about 86% as much as the heavier seed. Genetic differences were essentially eliminated and quality differences minimized between the two seed weights.

Characteristics of the crops studied were emergence percentage; seedling weight; days to 50y0 bloom; leaf blade width, length, and area; culm diameter; plant height; number of nodes; test weight; kernel weight; kernels per panicle; panicles per plant; and grain yield. Except for a difference of 0.03 cm in culm diameter in 1971 and a difference of 0.6% in emergence in 1972, the crops from the two seed weights did not differ significantly for the characteristics studied.
Correlation of Mitochondrial Activities and Plant Vigor with Genotypic Backgrounds in Maize and Soybeans
Authors: Hanson W. D. , Moreland D. E. , Shriner C. R.
Published: July 2010

Characteristics of mitochondria isolated from genotypes differing in plant vigor were evaluated with divergent selections from a population of Zea mays (L.) and selections within a broad‐base population of random homozygous lines in Giycine max (L.) Merr. These selections differed markedly in plant growth by the sixth leaf (or trifoliolate leaf) stage of growth. Cytoplasmic backgrounds were controlled so that variability under nuclear gene control was investigated primarily. Significant variability among mitochondria isolated from soybean genotypes was found for adenosine diphosphate‐oxygen (ADP/O) ratios with malate. However, selection groups in both maize and soybean had similar ADP/O ratios. Mitochondria from vigorous selections had higher respiratory control ratios (RC) with malate and lower succinate to malate ratios (S/M) for ADP‐activated (state‐3) respiration than the nonvigorous selections in both maize and soybean material. No mitochondrial complementation between diverse soybean genotypes was found when realate, succinate, and nicotinamide adenine dinucleotide (NADH) were used as substrates. With α‐ketoglutarate as substrate, no complementation for efficiency of phosphorylation was found between two pairs of soybean lines representing the extreme contrasts available. A highly significant reduction in state‐3 oxidation rates occurred when the mitochondria were mixed; however, no differences in mitochondrial activities were found between vigorous and nonvigorous genotypes, a difference required if the complementation effect reflected a genotypic potential. Mitochondrial complementation effects did not appear to reflect productivity in soybeans.
Influence of Herbicides on Root Rot in Processing Peas1
Authors: Harvey R. G. , Hagedorn D. J. , DeLoughery R. L.
Published: July 2010

The interaction between eight herbicides and the susceptibility of processing peas (Pisum sativum L.) to common root rot was studied under field, greenhouse, and laboratory conditions. In the field, methyl bromide fumigant was applied in a split‐plot design in order to provide pathogen‐free reference treatments. None of the following herbicides increased susceptibility to common root rot: atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], cyanazine {2‐[4‐chloro‐6‐(ethylamino)‐ s‐triazin‐2‐yl]amino‐2‐methylpropionitrile}, dalapon (2, 2‐ dichloropropionic acid), dinoseb (2‐sec butyl‐4, 6‐dinitrophenol), EPTC (S‐ethyl dipropylthiocarbamate), MCPB {4‐[(4‐chloro‐o‐toly)oxy]butyric acid}, propachlor (2‐ chloro‐N‐isopropylacetanilide). However, trifluralin (α, α,α‐trifuoro‐2, 6‐dinitro‐N,N‐dipropyl‐p‐toluidine) appeared to reduce the disease injury.

When peas were planted in pathogen infested soil in 1973, trifluralin at 0.56 kg/ha followed by 5.6 kg/ha of propachlor increased shelled pea yields 29% above that of controls. Higher trifluralin rates did not improve yields, but did reduce root rot symptoms. Methyl bromide fumigation increased pea stands, but reduced yield of shelled peas. In the greenhouse trifluralin at rates of 1.12 kg/ha or more, resulted in nearly complete prevention of root rot in peas. The 0.56 kg/ha rate provided partial control. In culture, trifluralin at 10 mg or more per liter of medium, reduced mycelial growth and zoospore production of Aphanomyces euteiches, but had no effect on the fungus at rates similar to those used in the field applications.
Effects of Daylength and Temperature on Soybean Development1
Authors: Major D. J. , Johnson D. R. , Tanner J. W. , Anderson I. C.
Published: July 2010

Dates of emergence, flowering, beginning pod fill, termination of flowering, and physiological maturity were recorded for two soybean [Glycine max (L.) Merr.] cultivars from each of the maturity groups I to V. The cultivars were planted in five dates at three Missouri locations in 1971–73; at weekly intervals from April to August at Columbia, Mo., in 1972 and 1973; and at weekly intervals from May to July at Ames, Iowa and Elora, Ont. in 1973. An iterative regression analysis (IRA) technique was used to develop mathematical equations relating the rate of development to daylength and temperature. The IRA equations predicted development more accurately than calendar days or “growing degree days” at all of the locations studied.

The IRA equations were also used to assess the relative effects of daylength and temperature on soybean development. Cooler temperatures and longer daylengths encountered at northern latitudes were additive in their delaying effects on flowering. The effects of cool spring temperatures on flowering predominated in the early part of the season whereas daylength predominated in plantings after June 1. Hastening effects of short days on maturity were greater than delaying effects of cool autumn temperatures. The most obvious difference among genotypes was found for sensitivity to daylength in the flowering period; later maturing cultivars were more sensitive than early cultivars.
Resistance to Cereal Leaf Beetle in Wheat: Density and Length of Leaf‐surface Pubescence in Four Wheat Lines1
Authors: Webster J. A. , Smith D. H. , Rathke E. , Cress C. E.
Published: July 2010

Measurements of leaf hair length and quantity of leaf hairs were made from seedlings of four wheat (Triticum aestivum L. em. Thell.) cultivars to develop bench marks for certain genotypes and to determine the effect of leaf size on hair density. Length was measured from photographs of cleared leaf material; density was determined directly from cleared material with the aid of a compound microscope. The superior resistance of Cl 9321 to oviposition of Oulema melanopus (L.), compared with that of ‘Selkirk,’ occurred because of the greater hair density of Cl 9321. The hair length of Selkirk was probably the main factor responsible for the greater resistance of this cultivar compared with that of ‘Chris.’ The importance of choosing leaves of similar growth stages for pubescence studies was demonstrated.
Leaf Area and Carbohydrate Reserves in Regrowth of Tall Fescue1
Authors: de Booysen P. V. , Nelson C. J.
Published: July 2010

Four combinations of low and high levels of watersoluble carbohydrate (WSC) reserves (LC, HC) and residual leaf area (LL, HL) were evaluated in terms of vegetative regrowth in a controlled environment at 20 C. HL contributed more than did HC to relative growth rate and to total plant size at the end of a 20‐day regrowth period. Rate of increase in leaf area was similar for plants with HL or HC or both. LC/LL plants did not rapidly replenish WSC, and produced leaf area at a slower rate. In LL plants, irrespective of WSC content, leaf area was produced initially at the expense of stored carbohydrate energy. Leaf growth was the dominant sink throughout the 20‐day period in LC/LL; whereas by day 15, HC/LL had reached the photosynthetic entity, the point at which the relative rate of increase in leaf area was the same as for total plant weight. In HL, again irrespective of WSC level, leaf growth was dominant initially, but by day 5 the photosynthetic entity had been reached. New tiller formation was lowest in the LC/LL treatment and was increased by HC, and especially by HL. After 20 days, weight of WSC in the stubble plus roots was highest in the HC/HL treatment, followed by LC/HL, HC/LL, and LC/LL, respectively. It is apparent that both residual leaf area and reserve carbohydrates contribute energy to regrowth of grasses, and that severity of defoliation affects the dependence of regrowth on stored energy.
Aflatoxin Production in Aspergillus flavus Inoculated Ears of Corn Grown at Diverse Locations
Authors: Lillehoj E. B. , Kwolek W. F. , Vandegraft E. E. , Zuber M. S. , Calvert O. H. , Widstrom N. , Futrell M. C. , Bockholt A. J.
Published: July 2010

Normal and opaque‐2 endosperm counterparts of two Zea mays L. hybrids were grown during 1973 at locations in Illinois, Missouri, Georgia, and Texas; 20 days after silking test ears were inoculated with Aspergillus flavus Link ex Fr. spores. Other ears were mechanically damaged or untreated. Sample ears were harvested 15, 30, 45, and 70 days after treatment. After shelling the corn was ground, examined for bright‐greenish yellow (BGY) fluorescence, and assayed for aflatoxin. The number of aflatoxin‐positives in 128 inoculated ears/plot increased generally from North to South: Illinois, 28; Missouri, 86; Texas, 111; and Georgia, 117. The mean levels of aflatoxin B1 in toxin‐contaminated ears showed a similar geographical pattern: Illinois, 2.4 ppb; Missouri, 22.5 ppb; Texas, 114.5 ppb; and Georgia, 133.9 ppb.

Almost all the toxin production occurred during the initial 30 days after inoculation. Fewer toxin‐contaminated ears were found in the doublecross hybrid than in the single cross, but no significant difference in aflatoxin incidence was observed between endosperm types (normal vs. opaque). Sixty of 512 damaged uninoenlated ears and 21 of 512 untreated control ears contained aflatoxin; 80% of the aflatoxin‐positives associated with physically damaged or control ears were observed in corn from the Georgia location.
Comparison of Early Generation Yield Testing and a Single Seed Descent Procedure in Wheat Breeding
Authors: Knott D. R. , Kumar J.
Published: July 2010

Two breeding procedures were compared in two spring wheat (Triticum aestivum L. em. Thell.) crosses. Both procedures were started from the same selected F2 plants in each cross. In one procedure, a single seed was taken from each F2 plant to produce the F3 generation, the process was repeated for the F4. The F5 lines were then produced from the seed of individual F4 plants (single seed descent method, SSD). In the second procedure, the F3 lines were yield‐tested and a pedigree method followed in the F3 and F4 (YT method). Each F4 line was bulked to provide seed for a yield test in the F5. The F6 SSD lines and F5 YT lines were then compared in yield tests.

The mean yield of the YT lines was significantly higher in both crosses, mainly because there were fewer, very low yielding YT lines. The correlations between the F3 and F5 yields of the YT lines were significant in both crosses, but were not particularly large (0.29 and 0.14). The yield of the F5 YT lines, derived from the highest yielding 20% of the F3 lines, was compared with the highest‐yielding 20% of the Fo SSD lines. In each cross, the SSD lines were at least as good as the YT lines. Although selection based on F3 yields would have had some effect, it is doubtful that it was worth the labor involved. The SSD procedure appears to have considerable merit