bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraspecific Competition, Competition with Weeds, and Spacing Response in Rice1
Authors: Kawano K. , Gonzalez H. , Lucena M.
Published: July 2010

Intraspecific‐intergenotypic competition, competition with weeds, and spacing response were studied in 25 rice (Oryza sativa L.) cultivars with different growth habits in Lambayeque, Peru. The actual yield of genetically mixed rice populations was always below the yield of the better component genotype in pure populations. The yield of the mixtures seldom exceeded the average yield of the pure populations of the component genotypes. Thus, yield reduction in one genotype as a result of competition was not compensated by the yield increase in another.

Intraspecific competition, competition with weeds, and spacing response were highly intercorrelated with each other, suggesting that these were controlled largely by the same genetic factors through the same physiological process. Vegetative vigor, large leaf area, a high rate of N absorption in early growth stages, and plant height were the most significant characters related to competitive ability. Tillering itself was not related to either competitive ability or to spacing response. Tall, vigorous genotypes with a long growth duration were adapted to extremely primitive agronomic conditions. The evolution of cultivars has been accompanied by the evolution of cultural methods and the loss of competitive ability.
Inheritance of Tassel Branch Number in Maize1
Authors: Mock J. J. , Schuetz S. H.
Published: July 2010

We studied the inheritance of tassel branch number in maize (Zea mays L.) by analyzing data collected from five generations (P1, P2, F1, F2, and F3) of a cross involving two inbred lines that differed significantly for tassel branch number. Estimates of genetic effects and genetic variance components were obtained from generation mean analyses and expectations for generation variances, respectively. Our data indicated that: 1) tassel branch number was quantitatively inherited (minimum of eight genetic factors involved), 2) high tassel branch number was dominant to low tassel branch number (data from crosses involving other parental inbreds showed the expression of dominance was genotype dependent), 3) no reciprocal effects were detectable, 4) additive gene action was most important, but dominant gene action should be evaluated carefully in future studies, and 5) heritability estimates were high, suggesting selection for tassel branch number should be possible.
Cytology and Breeding Behavior of Brachiaria Ruziziensis Germain Et Evrard1
Authors: Ferguson J. E. , Crowder L. V.
Published: July 2010

The diploid chromosome number of 2n=l8 was recorded in plants from 16 accessions of Brachiaria ruziziensis Germain et Evrard. Meiosis appeared regular and pollen stainability averaged 87%. The female gametophyte was derived from a megaspore and when mature had eight nuclei. Cross‐fertilization occurred at a very high frequency under conditions of natural open‐pollination. Seed set averaged 21 and 0.4% for open‐ and self‐pollination, respectively, suggesting the operation of a self‐incompatibility mechanism. One generation of self‐fertilization reduced seedling germination and survival. Significant inbreeding depression for total dry matter production was found in 4 of 6 S, families.
Solute Loss from Deteriorated Cottonseed: Relationship Between Deterioration, Seed Moisture, and Solute Loss1
Authors: Halloin John M.
Published: July 2010

Loss of electrolytes from cottonseed (Gossypium hirsutum L.) soaked in water was influenced by factors in the processing history of the seeds, such as delinting procedure and post‐delinting washing. Measurements of electrolyte loss were most reproducible if they determined a change during an interval (15 to 45 min) not inclusive of zero time. Cottonseed (G. hirsutum ‘Deltapine 16’) that deteriorated under controlled conditions of 100% relative humidity and 35 to 50 C was reduced in viability and exhibited increased rates of solute leakage and moisture contents. Seeds that deteriorated under conditions in which their moisture contents were held at 20% showed a slight increase in solute loss upon deterioration, but the rates of solute loss were not significantly correlated with viability losses. Experiments with both viable and heat‐killed seeds revealed that the increases in solute loss were proportional to degrees of seed hydration. Solute loss from heat‐killed seeds was greater than that from viable seeds at equivalent moisture contents, indicating that embryo tissue viability influenced solute leakage. However, increased solute losses due to differences in seed moisture were of greater magnitude than those due to changes in seed viability. Rate of electrolyte loss is therefore not a valid measure of cottonseed deterioration.
Identification and Prevalence of White Clover Viruses and the Resistance of Trifolium Species to These Viruses1
Authors: Barnett O. W. , Gibson P. B.
Published: July 2010

White clover, Trifolium repens L., plants from 19 pastures in eight southern states were collected without regard for symptoms. Viruses infecting these plants were detected and identified by the use of differential hosts and serological techniques. Alfalfa mosaic virus (AMV) was found in 7 pastures, clover yellow vein virus (CYVV) in 15, peanut stunt virus (PSV) in 14, and white clover mosaic virus in 5. Clover yellow mosaic virus was not found. Of 636 plants sampled, 237 were infected with one to three viruses. The percentage of virus‐infected plants in a pasture varied from 0 to 86. How concentrated pastures were in the vicinity, how many years the pasture was in perennial clover, and whether the white clover persisted from year to year, as a perennial plant or by annual reseeding, influenced the amount of virus infection. Twenty‐three Trifolium species were mechanically inoculated with six or seven viruses to find resistant germplasm. Although some variation was detected, all plants of most species were infected. Clover yellow mosaic virus infected 10% of the T. ambiguum Bieb. plants inoculated, whereas no plants were infected with the other 6 viruses. A few white clover plants were resistant to mechanical inoculation with each of the three most prevalent viruses, AMV, CYVV, and PSV.
Effect of Blooming Date on Boll Retention and Fiber Properties in Cotton1
Authors: Verhalen Laval M. , Mamaghani Reza , Morrison Walter C. , McNew Ronald W.
Published: July 2010

Six cultivars of upland cotton (Gossypium hirsutum L.) were studied to determine the influence of blooming date on boll retention and selected fiber properties in experiments conducted over 3 years at a single location. Flowers were tagged at weekly intervals; and after frost, bolls within plots were harvested by tagging dates. Records were kept by dates of blooms tagged/row, tagged bolls set/row, and percent tagged bolls set/row. Fiber properties (2.5% span length, 50% span length, uniformity index, micronaire, and 1/8‐inch gauge stelometer) were also studied to determine their patterns of variation.

In general, blooms tagged increased from the beginning of the flowering season until shortly after mid‐season, then declined to form a fairly symmetrical distribution. Boll set increased rapidly during the first 3 weeks of the season, then gradually decreased. Percentage boll set was highest at the first of each season, then declined fairly continuously. As a consequence, shedding rate increased in a linear fashion as the seasons progressed. In one instance, it appeared that the cotton plant exhibited increased boll retention efficiency when blooms were limited. The 2.5 and 50% span length measurements exhibited similar distributions within each of the 3 years; however, both showed moderately different patterns between years. Their means did decrease fairly steadily, particularly during the latter part of each season. Evidence in 1 year suggested that about a week's delay was required to obtain a response in the longer fibers comparable to that in the shorter ones. Uniformity index was higher at the end of each season than in midseason; and in 2 of ~ years, it was also higher at the first of the season. All cultivars except one displayed lower micronaires at the end of the flowering season than at the beginning. The 1/8‐inch gauge stelometer reading also declined toward the end of the flowering period.

Relative performance among cultivars for each trait and their differential response patterns over the season are discussed in the text.
Carbon Dioxide Enrichment Effects Upon Yield and Yield Components in Wheat1
Authors: Krenzer E. G. , Moss Dale N.
Published: July 2010

Two hard red spring wheat (Triticum aestivum L.) genotypes, the commercial variety ‘Era’ and an experimental genotype ‘8037,’ selected for this work because it had unusually large heads, were grown in normal air and in atmospheres enriched in CO2 to 600 ppm by volume in the field and in growth chambers in two day/night temperature regimes of 25/20 and 13/17 C. The growth period was divided into three stages: a) the vegetative period from germination to floral initiation; b) the floral development stage from floral initiation until anthesis; and c) the grain development stage from anthesis until maturity. Normal or CO2 enriched air was applied during each of these developmental stages in all possible combinations giving eight treatments in each experiment.

Both genotypes showed an increase in grain yield in the field and in the 25/20 C temperature regime in growth chambers when CO2 enrichment was applied during stage b or c or both. No effect of CO2 enrichment on grain yield was observed when the enrichment was applied before stage b in any experiment or at any development stage in the 13/17 C temperature regime. For both genotypes in the field and in the 25/20 temperature regime, CO2 enrichment caused an increase in kernel number/plant when applied during stage b, and in kernel size when applied during stage c. This suggests that kernel number and size are both dependent on the supply of photosynthate. Thus, we conclude that a screening procedure, that is effective in classifying genotypes as to their photosynthetic capacity during either stages b or c, might be useful in identifying desirable parental lines for a yield‐oriented wheat breeding program.
Effect of Honey Bees on Yield of Three Soybean Cultivars1
Authors: Erickson Eric H.
Published: July 2010

The importance of insects in the pollination of soybeans [Glycine max (L.) Merr.] was studied over a year period by comparing the yields from plots caged with honey bees (Apis mellifera L.), plots without bees and without insects (insecticide treatment), and open plots. The pollinating activity of bees resulted in significantly greater yields from ‘Corsoy’ and ‘Hark’ cultivars but not from ‘Chippewa 64.’

The foraging activity of bees on soybeans was dependent on the floral response of each cultivar to the environment. Hark had a high percentage of dissolved solids in the nectar and the highest quantity of nectar/floret.
Evaluation of Freezing Hardiness in Winter Wheat1
Authors: Gullord M. , Olien C. R. , Everson E. H.
Published: July 2010

Freezing hardiness was evaluated for several winter wheat (Triticum aestivum L.) cultivars and eight selections under controlled freezing conditions. High and low intensity freezing was achieved by decreasing the temperature slowly in hardened wheat crowns containing high and low amounts of water respectively. Freezing hardiness was assessed in terms of lower peripheral crown meristem (root) regrowth on a 0 (dead) to 5 (undamaged) scale.

The standard deviation for the freezing test was approximately one meristem rating unit when the number of pots/replication were less than four. Standard deviation increased when the number of pots/replication increased.

Different genotypes were easily differentiated when freezing hardiness was evaluated in terms of meristem rating and each genotype replicated 50 times.

Many tests were required over a wide range of test temperatures to obtain satisfactory LD50 values.

Significant interaction in freezing hardiness evaluated either as meristem ratings or as percent survival was found between eight winter wheat selections and freezing condition, but not between 14 wheat cultivars and freezing condition.
Carbon‐14 Assimilate Translocation in Nodulated and Nonnodulated Soybeans1
Authors: Russell W. J. , Johnson D. R.
Published: July 2010

Nodulating and nonnodulating soybean [Glyclne max (L.) Merr.] isolines were grown for 30 days in silica sand in the greenhouse with 0, 50, and 100 μg N/g sand to evaluate 14C translocation in plants dependent solely on N fixation or nitrate uptake or both.

No differences were observed between the two geno. type's translocation patterns at the vegetative stage, when they are totally dependent on soil nitrate up to 120 hours after 14CO2 exposure.

Plant leaves, totally dependent on symbiotically fixed N, exported 14% more 14C to the roots and nodules when compared to plants with total inhibition of nodulation. No more than 2% of the total recovered 14C was found in the nodule component at any harvest time.

Plants with partial inhibition of nodulation (grown with 50 μg N/g sand) exhibited relatively intermediate characteristics. The stem component contained significantly less 14C than the other treatments and was accompanied by a decrease in stem dry weight.
Factors Influencing the Susceptibility of Male‐sterile Barley to Ergot1
Authors: Cunfer B. , Mathre D. E. , Hockett E. A.
Published: July 2010

This study was undertaken to determine whether susceptibility of male‐sterile barley (Hordeum vulgare L.) to ergot [Claviceps purpurea (Fr.) Tul.] is influenced by characteristics of the host, fertilization, and inoculum density. A suspension of conidia (106/ml) was atomized into florets in which the lemma and palea had been clipped back to expose the pistil. Most of the 12 lines tested were moderately to highly susceptible with more than 25% of the florets infected.

Inoculation at various times after hand pollination showed that 9 of 12 lines were immune to ergot infection by 5 days and all were immune by 8 days after pollination and fertilization. Some lines became immune much faster than others, with ‘Hoodless Beardless’8 msg1 msg1 developing immunity within 24 to 48 hours after pollination.

Increasing the inoculum density from 104 to 106 conidia/ml increased the incidence of ergot. All five lines tested showed similar reactions to the different inoculum densities.
Inheritance of Pubescence and Its Use in Outcrossing Measurements Between a Crambe Hispanica Type and C. abyssinica Hochst. ex R. E. Fries1
Authors: Beck L. C. , Lessman K. J. , Buker R. J.
Published: July 2010

The inheritance of glabrous vs. pubescent leaf type was studied in a plant introduction designated Crambe hispanica L. (PI 279346). Normally the species has densely pubescent leaves, but observations on a small sample of this introduction revealed one selection which segregated with respect to leaf type and another which produced all glabrous leaves. Further selections were made within each of these progenies. Selected plants were paired randomly with other C. hispanica types and crossed reciprocally to determine inheritance and potential of the trait as a genetic marker. Segregation ratios in 44 F2 families involving 4,004 seedlings indicated that pubescent leaf was controlled by a single recessive gene p.

Glabrous leaf was used as a dominant marker in measuring percent outcrossing between C. abyssinica Hochst. ex R. E. Fries and C. hispanica types. Four normally glabrous C. abyssinica pollinator lines were planted in a circular row design with a pubescent C. hispanica type line planted in concentric rows outside each pollinator row. Row spacings were 50.8, 76.2, and 101.6 cm from the pollinator row with each spacing in a different subunit. To determine wind affects on pollen dispersal, circles were divided into four segments corresponding to northeast, northwest, southwest, and southeast quadrants.

Differences in outcrossing due to pollinators and to row spacings were found. Outcrossing over the various treatment combinations ranged from 0.5 to 7.0% with a mean of 2.7%.
Evaluation of Crimson Clover for Resistance to Leaf Feeding by the Adult Clover Head Weevil1
Authors: Smith C. M. , Pitre H. N. , Knight W. E.
Published: July 2010

Feeding preference of the adult clover head weevil (Hypera meles F.) was determined on 90 inbred lines of crimson clover (Trifolium incarnatum L.). Significant differences were observed among inbred lines in whole plant (seedling) feeding tests in the greenhouse and mature leaf disc tests, but not in seedling stem feeding tests in a growth chamber. Whole plant feeding tests yielded results similar to leaf disc tests but required much less labor. Correlations between leaf disc feeding and leaf pubescence were to variable and too low to be of much value in selection for weevil resistance.
Selection Criteria for Yield and Quality in Big Bluestem Grass1
Authors: Ross J. G. , Thaden R. T. , Tucker W. L.
Published: July 2010

Agronomic characters (e.g., vigor, leafiness, height, seed set, proportions of plant parts, and in vitro dry matter digestion, IVDMD, of plant parts) were studied in a breeding nursery of big bluestem (Andropogon gerardii Vitman), a native warm season grass. Significant differences were found among 23 families for all characters studied except seed weight from five aggregates of racemes and leaf IVDMD. Seedling height was not highly correlated with plant weight at the end of the second and third growing season. Since seed set was not correlated with vigor or leafiness, selection for seed set should not affect forage yield potential.

Lack of significant differences among families for leaf IVDMD indicated that selection for IVDMD would have questionable value, because summer grazing would be the only use for a cultivar from this species. High production of seed should be a realizable objective of a breeding program in this species.
Effectiveness of Early‐generation Yield Selection of Heterogeneous Lines in Soybeans1
Authors: Boerma H. R. , Cooper R. L.
Published: July 2010

F2−derived, heterogenous soybean [Glycine max (L.) Merr.] lines (HL) were selected for high seed yield by the early‐generation yield‐testing procedure (EGT), based on F3, F3−F4, and F3−F4−F5 combined generation means in four soybean crosses. Pure lines (PL) were selected for high seed yield from these same four crosses by the pedigree selection (PS) and single‐seed‐descent (SSD) procedures.

Selection of superior‐yielding HL in the F3, F4, and F5 generations decreased the coefficient of genetic variability in each generation of selection. The yield performance of the selected HL in the 1970 uniform preliminary test II also suggested that the HL were uniform among lines in yielding ability and the HL from one cross were equal in yield to the reference varieties.

The results indicated that in one of the four crosses PL selected by the SSD procedure were significantly higher in yield and earlier in maturity than the HL. In the other crosses, no significant yield differences existed between PL and HL, although the PL were usually earlier in maturity than the HL. These results suggested that pure lines from a cross will be equal to or higher in yield than F2−derived heterogeneous lines.
Combining Ability Analysis of Anatomical Components of the Dry Fruit in Chili Pepper1
Authors: Omar Marin V. , Lippert L. F.
Published: July 2010

Percentages and combining abilities for five fruit components in dry chili peppers (Capsicum annuum L.) were analyzed in a diallel cross involving nine parental entries. Endocarp comprised approximately 52% of the total dry fruit, seed 25%, exocarp 12%, placenta 6%, and stem 5%. Increases in endocarp percentage were generally associated with decreases in seed content. Variability in fruit components among F1 hybrids were predominantly attributable to general combining ability (GCA), suggesting additive gene action. Neither mean heterosis in hybrids nor mean squares for specific combining ability (SCA) were significant for any of the fruit components. GCA effects and GCA variances of parents for endocarp and seed components compared favorably with parental performance. Procedures for improving endocarp percentage and reducing seed and exocarp percentages are discussed. Parental lines are evaluated for incorporation into base population development for recurrent selection breeding programs. Information from this study is integrated with previously reported information on yield and fruit quality characteristics from the same diallel study.
Inheritance of Stalk Quality Characteristics in Maize1
Authors: Arnold J. M. , Josephson L. M.
Published: July 2010

The inheritance of percentage senescent stalks, crushing strength, and rind thickness, was studied in six maize (Zea mays L.) crosses by the generation mean analysis method. Heritability estimates also were obtained for crushing strength and rind thickness. Additive genetic effects were more important than non additive effects for the three characters. Heritability estimates ranged from 0.28 to 0.53 for crushing strength and from 0.33 to 0.62 for rind thickness for the six crosses. Results indicate that a selection procedure that takes advantage of additive genetic effects and variance would be effective in improving these characters.
General and Specific Combining Ability for Several Agronomic Traits in Diallel Cross Progenies of Cicer Milkvetch1
Authors: Townsend C. E.
Published: July 2010

Cicer milkvetch (Astragalus cicer L.) was evaluated in a six‐parent diallel for vigor score, height, and date of flowering for 2 years and for spread and seed weight for 1 year. F1 progenies, their reciprocals, and parental clones were grown under irrigation. Significant differences occurred among crosses and among parental clones for all characters each year. The variance for these traits was partitioned into general combining ability, specific combining ability, and reciprocal effects. General combining ability was significant for all characters, except vigor score in the seedling year. Specific combining ability was significant for vigor score both years, height in the seedling year, and date of flowering in the second year. Reciprocal effects were significant for vigor score both years, date of flowering both years, and height in the second year. Because most of the genetic variance for all characters except 1971 vigor was caused by the additive component, recurrent selection should be an effective method for improving cicer milkvetch.
Ripening of Sugarcane: Effects of Sunlight, Temperature, and Rainfall1
Authors: Legendre B. L.
Published: July 2010

The effects of incident sunlight, temperature, and rainfall on ripening of sugarcane (Saccharum spp.) were studied with five interspecific hybrids selected for subtropical conditions. Ripening was associated with both incident sunlight and temperature, but not with rainfall. Partial correlations reinforced the independence of ripening on incident sunlight, but showed that the associations of ripening with temperature were spurious. Partial correlation also showed an interacting effect of incident sunlight and temperature on ripening that varied with the cultivar. There was a significant difference between cultivars in the associations between ripening and sampling dates.
Frequency, Size, and Distribution of Stomata in Triticale Leaves
Authors: Sapra V. T. , Hughes J. L. , Sharma G. C.
Published: July 2010

Base, middle, and tip part of the abaxial surface of flag and two succeeding lower leaves of 13 cultivars of triticale (× Triticosecale), wheat (Triticum aestivum L.), and rye (Secale cereale L.) with varying ploidy level were studied for stomatal frequency and size (guard cell length). Significant differences existed among cultivars within species, among leaves within cultivars, and among positions within leaves for both frequency and size. Hexaploid triticale ‘Rosner’ had significantly greater number of stomata/unit area than ‘Blueboy’ (wheat) while ‘Snoopy’ (rye) had significantly less. Stomatal frequency and size were negatively correlated (r = −0.80, significant at the 1% level).

‘6TA 204’ had the lowest number and largest stomata size of 6x triticales. With increasing ploidy level within a species, the number of stomata/unit area decreased and stomata size increased.
Associations Among Traits in Progenies from Avena sativa L. ✕ A. sterilis L. Crosses1
Authors: Lyrene P. M. , Shands H. L.
Published: July 2010

The relationships between groat protein percentage and several other agronomic traits were studied in F2 and F3 progenies of six Arena sativa ✕ A. sterilis crosses. Groat protein percentage was negatively correlated with groat plumpness, groat percentage, and grain yield. High groat protein was associated with several undesirable spikelet characteristics inherited from A. sterilis, including spikelet shattering, lemma awns and pubescence, and brown lemma color. The association between shattering spikelets and high groat protein percentage was especially pronounced. F2 plants with shattering spikelets averaged 3.0% higher in groat protein than those with nonshattering spikelets. The comparable difference for F3 lines was 3.8%.

Development of useful cultivars from A. sativa ✕ A. sterilis progenies will require selection for groat plumpness, high grain yields, A. sativa spikelet type, and several other agronomic traits in addition to high groat protein percentage. The unfavorable associations noted, undoubtedly will reduce the rate of progress in increasing protein percentage.
Effect of Helminthosporium maydis, Race T, Pathotoxin on Growth and Ribonuclease Levels of Corn Roots1
Authors: Wilson C. M. , Apel G. A.
Published: July 2010

The growth of corn (Zea mays L.) roots with Texas male‐sterile cytoplasm is inhibited by. a pathotoxin produced by race T of Helminthosporium maydis Nisik. and Miyake. Application of toxin solutions to the primary root tip for only 20 rain was enough to inhibit root growth. This inhibition formed the basis for a rapid semi‐quantitative toxin assay requiring only small volumes of toxin solution. Also, the geotropic response of roots was affected by the toxin.

Changes in ribonuclease (RNase) activity of toxintreated roots were studied to determine whether or not the known corn RNase could be specifically implicated in the processes leading to inhibition of growth. The RNase activity of inhibited root tips was greatly increased over that of untreated controls, but only when growth was drastically reduced. The increase in RNase was concluded to be a secondary reaction occurring after the toxin had damaged the growing regions of the root. Tests for the specific nucleases in corn roots did not detect appreciable differences in the relative amounts of the different enzymes; all increased together. RNase increased in the terminal 15 mm of the tip; the increase could be detected within 6 hours after a brief treatment of the tip with pathotoxin.
Origin, Cytology, and Reproductive Characteristics of Haploids in Pearl Millet1
Authors: Powell Jerrel B. , Hanna Wayne W. , Burton Glenn W.
Published: July 2010

Pearl millet [Pennisetum americanum (L.) K. Schum.] is an important introduced forage species in the U.S. Thirteen haploid plants with seven chromosomes in somatic cells were studied. Two plants resulted from a twinembryo caryopsis, whereas the others were discovered in field plantings. The rate of spontaneous haploid occurrence was 1 per 10,000 plants in the inbred ‘Tift 23A.’ Seed set on individual haploid plants ranged from 502 to none. No haploids were recovered from progeny of seeds harvested from haploid plants. Spontaneous chromosome doubling occurred in several plants. The doubled sectors in the inflorescences were characterized by good exsertion and good dehiscence of anthers. Haploids were conspicuous because of their small inflorescence diameters, narrow leaves, and poor exsertion and dehiscence of anthers. Meiotic chromosomes of haploids were mostly univalents, but occasional pairing of two or more chromosomes was observed at metaphase I.
Effect of Chilling Duration on Germination of Cottonseed1
Authors: Cole D. F. , Christiansen M. N.
Published: July 2010

Seed of genetic selection M‐8 (Gossypiura hirsutum L.) and ‘Pima S‐4’ (G. barbademe L.) were subjected to various levels of chilling (0, 1, 2, 4, 8, 16, and 32 days at 5 C in water) after the seed were preconditioned by inbibition for 6 hours at 30 C in water. Seed for evaluation of chilling injury were germinated over a temperature range of 15 to 30 C on a thermogradient plate and in rolled towels at 30 C. Percent emergence and stand survival were determined for both cultivars.

Higher percent germination over the same range of temperatures on the thermogradient plate was obtained with M‐8 than with Pima S‐4. Seed chilled for 16 and 32 days was very low in viability and germinated over a narrower range of temperatures than seed chilled for shorter periods. Preconditioning increased germination of both selections and improved emergence of M‐8. Seed of Pima S.4 inbibed water at a faster rate than M‐8. Selections differed in their responses to different durations of chilling.
Response of Beans to Shading1
Authors: Crookston R. K. , Treharne K. J. , Ludford P. , Ozbun J. L.
Published: July 2010

Two dry bean (Phaseolus vulgaris L.) cultivars were grown in controlled‐environment chambers under standard light [390 μ Einsteins m‐2 sec‐1 (400 to 700 nm) = approx. 22,000 lux] and shaded light [55 μ Einsteins m‐2 sec‐1 (400 to 700 nm) = approx. 3,200 lux] intensities. Experimental observations included measurement of gas exchange and photosynthetic and respiratory enzyme activity along with examination of plant morphology, leaf anatomy, and chloroplast ultrastructure.

Shading reduced leaf number, area, and thickness. Photosynthesis/unit area of shaded leaves was decreased by an average of 38%. Transpiration was not significantly affected. Increased intracellular resistance of the shaded leaves was more important in reducing CO2 uptake than was the increase in stomatal resistance. The increase in mesophyll resistance was reflected both in the biochemical reactions of the leaf (activity of all measured enzymes being reduced by 70%) and in the ultrastructure of the leaf chloroplasts (reduced quantities of starch in spite of extensive grana).
Wind Barriers Most Beneficial at Intermediate Stress1
Authors: Skidmore E. L. , Hagen L. J. , Teare I. D.
Published: July 2010

A slat‐fence wind barrier, installed midfield and oriented east‐west, was used to investigate leaf‐water potential and stomatal resistance of winter wheat (Triticum aestivum L.) as influenced by barrier‐induced microclimate in a semiarid macroclimate. Leaf‐water potential, stomatal resistance, and micrometeorological parameters indicated that shelter affected neither leaf‐water potential nor stomatal resistance when stress was low. At intermediate stress, leaf‐water potential was significantly higher in the sheltered area than in open field. Under high stress, leaf‐water potentials of plants hi the two areas did not differ significantly; however, stomatal resistance was higher in the open field than in the sheltered area.
Partial Reversal of Temperature‐dependent Inhibition of Soybean Hypocotyl Elongation by Cotyledon Excision1
Authors: Burris J. S. , Knittle K. H.
Published: July 2010

The effect of removal of cotyledonary tissue on the subsequent hypocotyl elongation at 25 C of four soybean (Glycine max L. Merr.) cultivars was studied. Following a 24‐hour imbibltion period, cotyledonary tissue was removed from seed of “short” hypocotyl ‘Amsoy’ and ‘Beeson’ and “long” hypocotyl ‘Corsoy’ and ‘Hawkeye.’ Seed were then grown on paper towels for 7 days at 25 or 31 C. Inhibition of Amsoy and Beeson hypocotyl elongation at 25 C was reduced by this technique. Hypocotyl dry weight decreased, but hypocotyl length increased with increasing percentage removal of cotyledons. Removal of 50% gave the greatest reversal of the inhibition; at 75% removal, limited food reserves apparently decreased hypocotyl length. Hawkeye and Corsoy hypocotyl length did not increase with increasing cotyledon removal. Resuits suggested that inhibition of Amsoy and Beeson hypocotyl elongation at 25 C may be due to an inhibitory substance, or its precursor, located in the cotyledons.
Inter‐row Competitive Effects among Four Cotton Cultivars1
Authors: Moran‐Val Cesar A. , Miller P. A.
Published: July 2010

Inter‐row competition among cotton (Gossypium hisutum L.) genotypes may cause major biases in the estimation of cultivar performance. The objective of the present study was to evaluate the nature and importance of such effects among four cotton cultivars and relate the results to field evaluation techniques.

Four cultivars, representing the extremes of vegetative growth habit among the strains currently being tested in North Carolina, were grown. Inter‐row competition was measured using each cultivar as a test cultivar subjected to all possible pair wise combinations of the same four entries as competitors. Thus, there were 10 competitor combinations for each test cnltivar, for a total of 40 treatments. A randomized block design of six replicates was grown at each of three locations in North Carolina. Six traits were measured including seed cotton yield, lint yield, lint percent, boll weight, plant height, and plant width.

The four cultivars differed significantly in competitive ability. Although effects on all traits were noted, fiber and seed cotton were the only traits which were modified sufficiently to be of major concern in an evaluation program. Both additive (average) and specific inter‐row competitive effects were observed for yield. Mean squares for average effects were consistently larger than those for specific effects. Averaged over the three locations, biases expected from the use of nonbordered single‐row plots ranged up to 13.2% for lint yield. Competition effects of this magnitude suggest the need to use bordered plots for measuring yield, at least in advanced trials.
Performance of Anthracnose‐resistant Alfalfa Strains1
Authors: Devine T. E. , McMurtrey J. E.
Published: July 2010

Seven alfalfa (Medicago sativa L.) strains, bred in the laboratory for resistance to anthracnose caused by Colletotrichum trifolii Bain, were evaluated for resistance and performance in field tests. The breeding procedure used was designed to maintain the original genetic background, while gene frequencies for resistance to specific diseases were increased. The original susceptible populations and then resistant derivatives were used as bioindicators to assay the contribution of anthracnose resistance to performance. All strains bred for resistance were highly resistant under a naturally occurring anthracnose epiphytotic in the field. Following development of the epiphytotic, anthracnose resistance greatly increased forage yield, competitiveness against weed encroachment, and stand persistence. A fixed quadrant procedure was devised to measure alfalfa stand persistence. Susceptibility to bacterial wilt [incited by Corynebacterium insidiosum (McCull.) H. L. Jens.] vitiated the effect of anthracnose resistance.
Protein Concentration and Amino Acid Composition of Avena sterilis L. Groats1
Authors: Briggle L. W. , Smith R. T. , Pomeranz Y. , Robbins G. S.
Published: July 2010

Protein concentration and amino acid composition were determined in groats from 68 collections of Avena sterilis L. The data were compared with groat protein concentration and amino acid composition in 289 common oat (Avena sativa L.) cultivars, in 68 of the 289 cultivars having the smallest seeds, and finally with 68 of the 289 cultivars having largest seeds. A. sterilis collections contained from 22.1 to 31.4% protein (mean of 25.9%) compared to 12.4 to 24.4% (mean of 17.1%) for all 289, 14.4 to 22.3% (mean of 17.6%) for 68 small seeded, and 12.4 to 24.4% (mean of 17.5%) for 68 large seeded cultivars. There were significant differences in protein concentration and amino acid composition in groats of the two species. A. sterilis contains more protein and amino acids: histidine, arginine, threonine, proline, valine, isoleucine and leucine, but less, lysine, alanine, and glutamic and aspartic acid.
Heritability of Stomatal Density and Distribution on Leaves of Grain Sorghum1
Authors: Liang George H. , Dayton A. D. , Chu C. C. , Casady A. J.
Published: July 2010

Stomatal density was recorded on every leaf of plants sampled from six varieties of grain sorghum, Sorghum bicolor (L.) Moench, and their 15 F1 hybrids. The plants were grown in the field at two locations in Kansas. Stomatal density on abaxial leaf surfaces was highest at the basal portion of the leaves. Heterosis was not observed when stomatal densities of parents and hybrids were compared. Among the 15 uppermost leaves, the second leaf from top had the highest density, and leaf no. 15 had the lowest. Stomatal density was higher on abaxial surfaces than on adaxial sides. Heritability estimate for stomatal density was high. That high befitability and little heterosis were observed for stomatal density supports the general principle that traits showing little or no heterosis tend to have high heritabillties. Total stomatal number per plant was higher in hybrids than in parents; the difference was attributable to more leaf‐blade area. Stomata on abaxial surfaces were longerthan those on adaxial surfaces; hybrids tended to have longer stomata than did parents. Grain yield per unit leaf area and per 106 stomates showed a similar trend: the performance of progeny resembled that of their parents. However, neither leaf area nor total stomatal number was significantly correlated with grain yield. Stomatal density was negatively correlated with grain yield and with stomatal length; total stomatal number was positively correlated with total leaf blade area.
Cephalosporium Stripe of Winter Wheat: Procedures for Determining Host Response1
Authors: Mathre D. E. , Johnston R. H.
Published: July 2010

Techniques were evaluated for determining the response of winter wheat (Triticum aestwum L.) to infection by Cephalosporium gramineum Nisikado and Ikata. The objective was to develop a system that would allow large scale field screening for resistance to this pathogen. Use of a root inoculation technique indicated that cultivars differed in the severity of symptoms that developed but the technique was laborious and difficult to use. An oat kernel inoculum, added with the seed at the tune of planting, produced high levels of infection and closely approximated a natural inoculum situation. Early fall seeding accompanied by the use of 10 to 20g of oat inoculum per 3.6 m of row maximized disease development. Thirty entries were evaluated for their response to this disease using the oat kernel technique. A few entries, including 'Trader,' PI 178383, and PI 347737, appeared to have a low degree of susceptibility. Counts of white heads were positively correlated with degree of yield reduction.

The oat kernel technique should be of use to plant breeders and plant pathologists interested in a screening program to develop resistant and/or tolerant cultivars.
Intergenotypic Competition Between Tall and Dwarf Wheats. II. In Hybrid Bulks1
Authors: Khalifa M. A. , Qualset C. O.
Published: July 2010

Intergenotypic competition was studied in populations developed from a hybrid of two wheats (Triticum aestivum L. em. Thell.), ‘D6301’ (short‐statured) and ‘Ramona 50’ (standard‐height). The F2 through F6 generations were grown in the field in two replicate subpopulations without artificial selection. Heights of individual plants, taken from the F3, F4, F5, and F6 bulk populations, were studied in the same environment. Mean height increased and frequency of short‐statured plants decreased markedly from F3 to F6. Height of 62 random lines isolated from each of the F2, F4, and F6 generations showed a decrease in phenotypic variance from F2 to F6. Grain yields of the F2, F4, and F6 bulk populations and the means of 62 random lines (in F3, F5, and F7) indicated a significant increase from the F4 to F6 and from the F5 to F7 generations. At F7 the yield of the bulk population equalled the yield of the lower‐yielding parent, Ramona 50. Variance in yield among lines increased from F3 to F7, but extremely short genotypes did not appear in the F7. Extremely tall genotypes yielded less than those of intermediate height. Thus, in the bulk population directional and stabilizing selection affected both yield and plant height. Some lines in the F7 had higher yields than either parent. Thus, in spite of natural selection against the agronomically desirable short plants, the bulk populations were useful as source materials in selection for increased grain yield.
Selection of T‐Cytoplasm Maize Callus Cultures Resistant to Helminthosporium maydis Race T Pathotoxin1
Authors: Gengenbach B. G. , Green C. E.
Published: July 2010

Texas male‐sterile cytoplasm (cms‐T) maize (Zea mays L.) is susceptible to Helminthosporium maydis (Nisikado and Miyake) rate T and its pathotoxin; whereas nonsterile (N) cytoplasm maize is resistant. Callus cultures of cms‐T and N versions of A619 maize were established to study the effect of the toxin on maize callus and to select for toxin‐resistant cms‐T callus. Toxin in the culture medium inhibited cms‐T growth, while N grew normally. The percent inhibition of cms‐T callus growth depended on the toxin concentration. Complete inhibition was obtainable.

Selection of toxin‐resistant A619(cms‐T) callus began with cultures grown on sublethal toxin concentrations. The fastest growing callus or callus sectors were subeultured for additional selection. After four subculture cycles (160 days on toxin), 14 callus clones were selected for growth analysis in the absence and presence of toxin concentrations lethal to unselected A619(cms‐T) callus. Growth rates at these toxin concentrations were 53 to 111% of the growth without toxin. This high degree of toxin resistance remained stable for 127 days growth in the absence of toxin.

The in vitro effects of toxin on NADH oxidation, oxidative phosphorylation, malate‐driven 2,6‐dichlorophenol indophenol reduction, and swelling of mitochondria isolated from unselected A619(N) and A619(cms‐T) callus and from resistant A619(cms‐T) callus were determined. These four activity parameters of mitochondria from susceptible A619(cms‐T) callus were significantly affected by toxin added to the reaction medium. Mitochondria isolated from A619(N) and resistant A619(cms‐T) callus were not affected by toxin addition. This association of mitochondrial insensitivity to the toxin with resistance at the callus level may help clarify the role of mitochondria in resistance to this disease.
Relations of Photosynthetic Rates and Leaf and Canopy Characters to Sugarcane Yield1
Authors: Irvine James E.
Published: July 2010

Simple correlations showed photosynthetic rates at low air velocities to be closely associated with leaf width, porosity, and specific leaf weight, and less closely associated with stomatal number, plant fresh weight, and, probably spuriously, leaf thickness. Photosynthetic rates/unit of leaf area did not increase with increasing yield, and selection of cultivars for these or for leaf characters related to high photosynthetic rates would be of little practical value to the sugarcane (Saccharum sp.) breeder. Photosynthetic rates/unit of land area are more likely to be related to yield. Leaf‐area index was positively associated with tonnage in two field tests. Leaf arrangement was associated with higher sugar/metric ton in one test, but not in a second. Selection by breeders for higher leaf‐area indices and for optimum leaf arrangement is recommended.
Photosynthetic Characteristics of Panicum milioides, a Species with Reduced Photorespiration1
Authors: Brown R. H. , Brown W. V.
Published: July 2010

A species (Panicum milioides Nees ex. Trin.), has been found which apparently has a reduced rate of photorespiration compared to other C3 plants. It was found in preliminary studies that the response of net photosynthesis (Pn) to O2 concentration was less for this species than for other C3 plants. Therefore, this work was conducted to characterize for five accessions of P. milioides the CO2 exchange related to photorespiration. Panicum maximum Jacq. (C4), P. laevifolium Htack. (C4), and tall fescue (Festuca arundinacea Schreb. (C3) were included for comparison. Leaf cross‐sections of P. milioides were examined for characteristics known to be related to photosynthetic carbon pathways. 13C/12C ratios were determined on P. milioides tissue.

P. milioides photorespired less than tall fescue and more than P. maximum as determined by the three criteria: Pn response to O2, CO2 evolution in the light, and CO2 compensation concentration. The change in Pn for each 1% increase in O2 was from −0.36 to −0.48 mg CO2 dm−2 h−1 for five accessions of P. milioides compared to −0.10, −0.13, and −0.61 mg dm−2 h−1 for P. maximum, P. laevifolium, and tall fescue, respectively. P. milioides evolved an average of 0.85 mg CO2 dm−2 h−1 in the light at 20% O2 compared to 0.02 mg dm−2 h−1 for P. maximum and 2.96 mg dm−2 h−1 for tall fescue. CO2 compensation concentrations determined by a Mylar bag technique were 0.4, 15.8, and 54 ppm for P. maximum, P. milioides, and tall fescue, respectively. Determination of CO2 compensation from Pn response to CO2 gave a similar trend, although actual concentrations were different. P. milioides tissue had δ 13C values of about −25 ‰, characteristic of C3 species. A leaf anatomical study showed that P. milioides had enlarged parenchyma sheath cells with centripetally located chloroplasts and mesophyll cells arranged in a radial manner around the parenchyma sheath. The parenchyma sheath cell walls appeared to be thicker than those of most C3 species. It is concluded that while P. milioides exhibits mostly C3 characteristics, its reduced photorespiration rate and some C4‐like anatomical characteristics indicate a degree of intermediacy between C3 and C4.
Rapid Method for Estimating Leaf Area Per Plant in Maize1
Authors: Pearce R. B. , Mock J. J. , Bailey T. B.
Published: July 2010

We grew four maize (Zea mays L.) genotypes, representing a wide range of leaf area/plant, at two plant densities in 1973 to develop a simple, rapid, and nondestructive method for estimating average leaf area/ plant. Immediately after pollen‐shed, we measured lengths and maximum widths of all leaves on all plants in each plot and subsequently calculated individual leaf areas.

Individual leaf areas were summed to give total leaf area/plant. Correlations of individual leaf areas with total plant leaf area revealed that leaf #8 (from the top of the plant) was the most highly correlated (r = 0.95). Therefore, the regression of total plant leaf area on area of leaf #8 was computed and the resulting b‐value (9.39 ± 0.04) used as the leaf area factor for estimating average leaf area/plant.

Results indicated average leaf area/plant for normal maize plants can be estimated by measuring length and maximum width of leaf #8 on several competitive plants/ plot, calculating area of leaf jS, and multiplying that leaf area by 9.39. Genotype means can often be obtained across replications by measuring only one plant/plot. This method is rapid, nondestructive, and should allow estimation of leaf area of more genotypes and/or experimental treatments/experiment than is currently feasible with conventional techniques.