bluuebunny/crossref_metadata_2025 huggingface dataset:
An Efficient method for Transferring Genetic Male Sterility to Soybean Lines1
Authors: Carter T. E. , Burton J. W. , Young M. F.
Published: July 2010

An efficient method is outlined for transferring genetic male sterility to desirable genotypes of soybean [Glycine max (L.) Merr.]. The method requires no identification of male‐sterile plants at flowering and no manual cross‐pollination. Backcrnsses are accomplished through insect vectors in natural crossing blocks. Lines segregating for sterility, but homozygous recessive for a genetic marker, are surrounded by a recurrent parent with the gene dominant to the marker. The marker is used to identify progeny from the recurrent parent by male‐sterile crosses. Self ed seed from those crosses are used to form a crossing block (along with the recurrent parent) in which segregating plants displaying the dominant marker are removed before fruit set. Thus, any male‐sterile plant in the crossing block will be recessive for the genetic marker. Crosses of the recurrent parent to male‐sterile plants can again be identified by the dominant genetic marker. Contamination is minimized by bordering the crossing block with plants recessive for the genetic marker. Appropriate population sizes and linkage effects are described.
Seedling Vigor of three Lotus Species1
Authors: Beuselinck P. R. , McGraw R. L.
Published: July 2010

Birdsfoot trefoil (Lotus corniculatus L.) is characterized as having low seedling vigor. Seedling vigor, estimated by seedling shoot, root, or total dry weight at 2, 4, and 6 weeks after seeding, was determined for 11 cultivars of birdsfoot trefoil, as well as 27 plant introductions of birdsfoot trefoil, 18 of L. tenuis L., and 17 of L. pedunculatus L. Our objective was to identify germplasm sources having high seedling vigor for use in intra‐ and inter specific improvement of birdsfoot trefoil. Seedlings were grown in vermiculite in a greenhouse during April and May. Differences (P ≤ 0.01) among species and among entries within species were observed for average shoot, root, and total seedling dry weights in each 2‐week period. The L. corniculatus introductions and cultivars generally had the highest dry weight at all dates. Average dry weights of L. pedunculatus were consistently lower than the other species and the cultivars. Seedling dry weight was positively correlated (P ≤ 0.05) with 100‐seed weight but the coefficients varied among species with highest values observed for L. tenuis and the cultivars. Of the 10 entries with highest shoot, root, and total seedling dry weights at 2 weeks after seeding, only L. corniculatus introductions 194228 and 226796, L. tenuis introduction 302921, and ‘Maitland’ and ‘LA synthetic’ remained among the 10 highest at 6 weeks. Broad‐sense heritability estimates for average total seedling dry weight ranged from 0.56 to 0.96 at 6 weeks, indicating a large portion of the variation observed was from genetic differences. There appears to be sufficient intraspecies variation to make genetic progress by selection. However, interspecific crosses, especially with L. tenuis, may be a feasible alternative to improve seedling vigor of birdsfoot trefoil.
Genotypic Variation in Epicuticular Wax of Rice1
Authors: O'Toole J. C. , Cruz R. T.
Published: July 2010

Improvement of rice (Oryza sativa L.) cultivars for drought‐prone regions involves assessment of genotypic variation within specific adaptive mechanisms. This note describes the variation in amount of epicuticular wax (EW) among 30 rice cultivars from varying hydrological origins. Leaf wax extracts were analyzed by gas liquid chromatography (GLC) for quantitative and qualitative differences. A five‐fold difference in total EW per unit leaf area was found among cultivars. Total amount of EW and the amount in GLC peak 3 were positively correlated with cultivars originating at higher elevations. Results suggest the relative amount of an unknown wax constituent (GLC peak 3) is associated with adaptation of rice cultivars to hydrologically drier habitats.
Bacterial Tan Spot, A New Foliar Disease of Soybeans1
Authors: Dunleavy J. M.
Published: July 2010

A new soybean [Glycine max (L.) Merr.] disease that causes large tan necrotic spots on soybean leaves was first observed in Iowa in 1975. Necrotic areas usually fell to the ground during high winds, giving a ragged appearance to leaves. The disease was confined to leaves and was never observed on stems or pods; wilting did not occur. The causal bacterium was gram positive, motile, formed a medium‐yellow endopigment, grew well at 37 C, hydrolyzed esculin, did not produce urease, and was pathogenic to soybeans and beans (Phaseolus vulgaris L.). The bacterium was identified as Corynebacterium flaccumfaciens (Hedges) Dowson, and the name bacterial tan spot was proposed for this disease (which had been observed in 16 counties in Iowa through 1981). One isolate of C. flaccumfaciens from soybeans, two isolates from beans, and one isolate each of C. flaccumfaciens subsp. aurantiacum Schuster and Christiansen and C. flaccumfaciens subsp violaceum Schuster, Vidaver, and Mandel from beans were used to inoculate leaves of soybeans and beans. All isolates caused a leaf spot and wilt of beans, but only the soybean isolate caused a leafspot on soybeans. Of 20 northern‐grown soybean cultivars tested, three were resistant to the disease, seven were slightly susceptible, three were susceptible, and seven were very susceptible. Of 20 southern‐grown cultivars, eight were resistant, and 12 were slightly susceptible.
Application of GOSSYM to Genetic Feasibility Studies. I. Analyses of Fruit Abscission and Yield in Okra‐Leaf Cottons1
Authors: Landivar J. A. , Baker D. N. , Jenkins J. N.
Published: July 2010

The cotton (Gossypium hirsutum L.) model GOSSYM was used to demonstrate how a computerized crop simulation model can be used in a breeding or in an agronomic research program to predict the performance of cottons such as okra leaf when grown under various environmental conditions. The GOSSYM computer simulations indicated that the higher fruit load produced in okra‐leaf compared to normal‐leaf cottons results from the carbohydrate (not used in leaf material) being used in the initiation of more fruiting sites. Then, as the fruit load increases late in the fruiting period, larger carbohydrate stresses develop in the okra‐leaf type than in the normal‐leaf crop. The plant simulated by GOSSYM balances those shortages of materials by aborting fruit. The abortion of fruit is higher in okra‐leaf than in normal‐leaf cotton because it develops a higher fruit load. GOSSYM predicted that the percent fruit retention in okra‐leaf cottons was not correlated with N‐application rate; however, as the application rate increased, the number of fruiting positions produced also increased. Increasing carbohydrate supply by increasing the photosynthetic rate by 50% improved percent fruit retention at all rates of N. Okra‐leaf cottons perform inconsistently under field conditions apparently because the plants fall to produce and maintain sufficient leaf area index (LAI) to intercept enough solar radiation and provide the photosynthate required to meet the fruit growth requirements under adverse growing conditions. Under favorable growing conditions, both normal and okra‐leaf types produced a dense canopy; however, the LAI was larger in the normal‐leaf type. The more efficient distribution of carbohydrates into the fruits by the okra‐leaf type resulted in higher yield. Under adverse conditions, the LAI was lower in both genotypes. However, it remained higher in the normal than in the okra‐leaf type, which thereby intercepted more solar radiation and resulted in higher yield. Okra leaf appears superior for yield under optimum conditions, normal leaf under adverse conditions. An intermediate leaf type such as sub okra may be valuable in increasing the stability of cottons to adverse environmental conditions.
Effects of Gibberellic Acid on the CO2 Exchange Rates of Bermudagrass and St. Augustinegrass when Exposed to Chilling Temperatures1
Authors: Karnok K. J. , Beard J. B.
Published: July 2010

This study was conducted to determine if a relationship exists between chilling injury and carbon dioxide exchange rate (CER) of two warm‐season turfgrasses, and also to see how the relationship is influenced by exogenously applied gibberellic acid (GA3). The CER ‘Ormond’ (chill tolerant) and ‘Pee Dee’ (chill sensitlve) bermudagrass [Cynodon dactylon (L.) Pers] and ‘Floratam’ (chill tolerant) and ‘Texas Common’ (chill sensitive) St. Augustlnegrass [Stenotaphrum secundatum (Walt.) Kuntze] were monitored continuously for 14 days chilling temperatures (day/nlght, 7/5 C, respectively). Ormond, Pee Dee, Texas Common, and Floratam showed reductions of 54, 68, 79, and 84% respectively, in daytime CER during the initial chilling photoperiod. Both bermudagrass cultivars showed a significant increase and Floratam a significant decrease in daytime CER 10 hours after GA3 application. Texas Common did not respond. After 2 weeks of chilling stress, Ormond exhibited a significantly higher percentage of the prechill daytime carbon dioxide exchange rate (PCER) than Pee Dee, Texas Common, and Floratam. Ormond and Pee Dee treated with GA3 had significantly higher daytime PCER than nontreated Ormond and Pee Dee, as well as treated and nontreated Texas Common and Floratam. All treatments showed a rapid and continual reducton in nighttime CER with increased chilling exposure.
Irrigation of Soybean Genotypes During Reproductive Ontogeny. I. Agronomic Responses1
Authors: Korte L. L. , Williams J. H. , Specht J. E. , Sorensen R. C.
Published: July 2010

Successful irrigation management for soybeans [Glycine max (L.) Merr.] requires a knowledge of the effect of irrigations applied during specific stages of reproductive ontogeny. Eight soybean cultivars, varying in stem growth habit and maturity, were subjected to a factorial set of eight irrigation treatments involving either no irrigation or one irrigation applied at three reproductive stages: R1 to R2 flowering (F), R3 to R5 pod elongation (P), or R5 to R6 seed enlargement (S). The experiment was conducted for 3 years on a Sharpsburg silty clay loam (Typic Argiudoll). An F irrigation had little effect on ultimate seed yield (+20 kg/ha) and for some cultivars actually depressed yield below that of the nonirrigated check. A P irrigation consistently increased seed yield (+379 kg/ha), irrespective of cultivar or year. An S irrigation also enhanced seed yield (+ 384 kg/ha), but the degree of enhancement was inconsistent across years, being influenced by the amount of natural rainfall occurring during the seed enlargement stage. Although a dual F‐P irrigation treatment enhanced seed yield above that for both the nonirrigated check and single F irrigation treatment, the seed yield increase was significantly smaller (+166 kg/ha) than that achieved with a single P irrigation treatment. Soybean maturity was delayed 2 to 6 days with irrigation but the delay was greatest when irrigation was applied late in reproductive ontogeny. This senescence delay lengthened the seed‐fill period and was responsible in part for the seed yield enhancement effected by irrigation. Increases in soybean plant height and lodging were greatest with an F irrigation, intermediate with a P irrigation, and minimal with an S irrigation. Although irrigation effects on seed quality were variable depending on the cnltivar, there was an overall tendency for a P irrigation to improve and an S irrigation to worsen seed quality. An F irrigation had no effect on seed quality. Of the eight cultlvars evaluated, the determinate ‘Elf’ was the most yield responsive to irrigation and was relatively resistant to changes induced by irrigation in plant height, lodging, and seed quality. Based on these data, optimal yield enhancement in irrigated soybean culture can be achieved with the use of short‐stature or lodging‐resistant cultivars irrigated during pod elongation (R3 to R4) and seed enlargement (R5 to R6).
A New Gene for Resistance to Bacterial Blight in Rice1
Authors: Singh R. J. , Khush G. S. , Mew T. W.
Published: July 2010

The mode of inheritance and allelic relationships of the genes for resistance to bacterial blight caused by Xanthomonas campestris pv oryzae (Ishiyama 1922) Dye 1978 in 58 rice (Oryza saliva L.) cultivars were studied in the field. The analysis of F1 and F2 populations from the crosses of resistant cultivars and susceptible ‘TN1’ revealed that single dominant genes conditioned resistance in each of 48 cultivars whereas single recessive genes conveyed resistance in 10 remaining cultivars. The allele tests indicated that the 48 cultivars have the Xa 4 gene for resistance. The recessive genes for resistance in eight cultivars are allelic to xa 5. However, the recessive genes for resistance in ‘Khao Lay Nhay’ and ‘Sateng’ are allelic to each other but are nonallelic to and segregate independently of Xa 3, Xa 4, xa 5, Xa 7, and xa 8. This new recessive gene is linked with Xa 6 with a crossover value of 5.9%. Thus cultivars Khao Lay Nhay and Sateng have a new gene for resistance, which was designated xa 9.
Direct Microscopic Observations of Stomata in the Field—Quick and Easy
Authors: Woolley Joseph T.
Published: July 2010

Field determination of stomatal status has previously depended upon surface replication techniques or on porometers. The former are inconvenient and often damage the leaf, while the latter are difficult to calibrate and often cannot be used on wet leaves. Adaptation of a commercially‐available field microscope now allows rapid, non‐destructive field observation and photography of stomata on wet or dry leaves.
Crown Depth in Eastern Soft White Winter Wheats1
Authors: Hunt L. A. , McKersie B. D. , Tanner D. G.
Published: July 2010

Seventeen cultivars of winter wheat (Triticum aestivum L.) were tested for depth of crown development under two temperature regimes. Significant effects of both cultivar and temperature were noted, but no genotype by temperature interaction was observed. Cultivars of similar origin exhibited widely different crown depths, and some cultivars of high winterhardiness had shallow crowns. It was concluded that the variation available for crown depth either has not been fully exploited, or the advantages of deep crown placement for survival under some stress situations are offset by disadvantages for survival under other conditions.
Inheritance of Resistance in Maize to Kabatiella zeae1
Authors: Reifschneider F. J. B. , Arny D. C.
Published: July 2010

Inheritance of resistance to Kabatiella zeae Narita & Y. Hiratsuka in maize (Zea mays L.) was studied in four crosses involving two resistant (R) and three susceptible (S) inbred lines, as follows. WF9(S) ✕ C123(R), W64A (S) ✕ Oh43 (R), Oh43(R) ✕) C123(R), and W64A (S) ✕ W117 (S). The inbreds, F1's, F2's, and backcrosses of F1's both inbred parents of each cross were evaluated by artificial inoculation in the field. The segregation observed suggested that resistance is partially dominant and qualitatively inherited. Estimates of minimum number of genes involved in the inheritance of reaction in the S ✕ R crosses gave values close to two. Broad‐sense heritability estimates for the S ✕ R crosses were approximately 75%. The reactions of the two resistant inbreds and behavior of various generations in crosses involving them indicate that C123 contains modifiers not present in Oh43.
Field Use of Screen‐Caged Thermocouple Psychrometers in Sample Chambers1
Authors: Walker Sue , Oosterhuis Derrick M. , Savage Michael J.
Published: July 2010

These investigations attempt to answer questions still remaining concerning the use of thermocouple psychrometers for measurement of leaf water potential when laboratory facilities are located some distance from the field. Our results show that with the necessary precautions, field use of thermocouple psychrometers provides a practical and useful method for measurement of plant water potential components. Wheat [Triticum aestivum (L.) em. Thell.] leaf samples taken in the field were sealed in sample chambers containing screencaged thermocouple psychrometers, and transported 30 km to the laboratory. Thermal equilibrium was attained in 4 min, and vapor pressure equilibrium in 4 h, after placement of the sample chambers in a constant temperature waterbath. Osmotic potential measurements could be delayed for up to 24 h as the equilibrium value remained constant after 4 h in the waterbath. Equilibration times were the same for different wheat species and cultivars tested and were unaffected by tissue water content. The temperature of the sample chamber during transit from the field to a laboratory did not affect the vapor pressure equilibration time or the water potential measured. Water potentials were however affected if transit time exceeded 2 h. Significant water loss (233 kPa in 15 s) was found to occur immediately after leaf excision before the leaf sample was sealed in the chamber. Procedures which take account of all these affects enable reliable measurements of leaf water potential components to be obtained when laboratory facilities are located some distance from the field. Leaf water potential values compared favorably with those in the literature and gave a near linear (1:1) relationship with measurements made using a Scholander pressure chamber. The osmotic potential at incipient plasmolysis as measured by the pressure‐volume method compared favorably with the osmotic potential as measured with psychrometers.
The Solar Tracking Pattern in a Closed Alfalfa Canopy1
Authors: Travis R. L. , Reed R.
Published: July 2010

The average cosine of the solar incidence angle for all leaflets within a closed alfalfa canopy [leaf area index (LAI) = 4 to 5] was relatively high during the morning hours, decreased to a minimum level during the early afternoon, and increased again during late afternoon hours. High values for cosine of the solar incidence angle indicate the leaflets were exposed near normal to the sun's rays. This resulted from diaheliotropic leaflet movements. The lower, midday values were associated with leaf cupping movements. Leaf cupping began about 3 h after the beginning of the midday decline in xylem water potential but the recovery from cupping, as evidenced by the return of diaheliotropic movements, occurred in the absence of the recovery of xylem water potential. An evaluation of tracking ability revealed an increasing average cosine of incidence angle with increasing leaflet age resulting in a canopy architecture which would enhance light interception by the lower strata. Light flux density measurements indicated that most leaflets in the upper canopy were exposed to sufficient photosynthetic photon flux density (PPFD) to saturate nearly saturate the photosynthetic process. However, PPFD available to leaflets in the lower canopy ranged from 45% required for saturation of photosynthesis for the average nontracking leaflet to about 85% for leaflets with a cosine of incidence of 1.0. Since most leaflets in the lower strata maintained relatively high cosine of incidence angle values, the results suggest that the observed tracking gradient (increasing ability with leaflet age) may provide the alfalfa plant with a mechanism for maintaining photosynthetic productivity in lower leaves. The data are discussed in terms of the potential carbon gain benefit to the alfalfa plant resulting from the tracking gradient within the canopy.
Differences in Endosperm Proteins Between Yellow Berry and Normal Triticales
Authors: Bietz Jerold A. , Sharma Govind C.
Published: July 2010

Endosperm proteins involved in the expression of the yellow berry (YB) phenomena in triticale (X Triticosecale Wittmack) were investigated. The protein fractions isolated from single kernels of normal and YB triticales were characterized by electrophoresis combined with densitometry and by high‐performance gel filtration chromatography. Electrophoresis of gliadins revealed significant qualitative differences between YB and normal types; in addition, multiple biotypes were apparent in some lines. Reduced glutenin subunits of normal and YB triticales had very similar molecular weight distributions, but subtle differences in amino acid composition and sequence were revealed by different detection methods. Results indicated that normal triticales contain more residue protein (unreduced high molecular weight glutenin) than YB kernels. Consequently, numerous subtle quantitative and qualitative differences in amounts of various protein types seem to influence interactions of proteins with each other and with starch. These interactions may lead to the differences in endosperm vitreosity and hardness between normal and YB kernels.
Effect of a Second Cycle of Anther Culture on Flue‐Cured Lines of Tobacco1
Authors: Brown J. S. , Wernsman E.A. , Schnell R. J.
Published: July 2010

Doubled haploid (DH, 2n = 48) lines were produced via anther culture from two long‐term inbred flue‐cured tobacco (Nicotiana tabacum L.) cultivars. Anther culture was then performed on the first cycle DH lines, generating arrays of second cycle DH lines. Chromosome doubling was accomplished either with colchicine treatments or via leaf midvein culture. Source cultivars and first and second cycle doubled haploids (DHS) were tested in agronomic performance trials in 1980 and 1981. Each cycle of anther culture resulted in a reduction in vigor approximately equal in magnitude when compared to selfed progenies of their respective anther source. Cured leaf yields were reduced an average of 17% per cycle of androgenesis. Anther culture was also associated with the creation of significant genetic variability among lines arising from a single homozygous source, regardless of cycle number. These results cannot be explained in classical genetic terms by the existence of residual heterozygosity in the original source cultivar. Results of the second cycle of anther culture and chromosome doubling of the haploid confirm the capacity of the system to induce genetic changes in flue‐cured tobacco.
Differential Survival of Genes in a Composite Cross of Sorghum1
Authors: Keim K. R. , Rosenow D. T. , Miller F. R. , Quisenberry J. E.
Published: July 2010

A composite‐cross population, grown to the F7 generation under nonirrigated field conditions at Lubbock, Tex., was evaluated for the effect of natural selection on the expression of six simply inherited plant and grain traits in sorghum, Sorghum bicolor (L.) Moench. Results indicated that endosperm type was not affected by natural selection. Genes producing awns, red pericarp color, and presence of a seed testa were at a selective advantage. The linked traits of midrib juiciness and plant color indicated that midrib color was not subject to natural selection, but tan plants were at a selective disadvantage. Data presented indicate which of the traits studied are advantageous in a semi‐arid environment.
Histological Differences in Moisture‐Stressed and Nonstressed Kleingrass Forage1
Authors: Pitman W. D. , Holt E. C. , Conrad B. E. , Bashaw E. C.
Published: July 2010

Leaf sections from 15‐day old kleingrass (Panicum coloratum L.) plants grown under moisture stress, optimal moisture conditions, and an intermediate moisture level were examined by light microscopy. The proportion of cell volume of parenchyma bundle sheath cells occupied by the protoplast and vacuole was markedly less for plants grown at the lower moisture levels than for plants at the highest moisture level. Increased sclerenchyma tissue development and increased thickness of the metaxylem cell walls were noted with reductions in moisture. Selective staining also revealed increases in lignification with moisture stress. These histological observations indicate that an increased proportion of cell wall components and increased lignification of kleingrass plants grown under moisture stress could account for at least some of the reduced digestibility reported previously with moisture‐stressed kleingrass forage.
N2 Fixation (C2H2) and Ureide Content of Soybeans: Ureides as an Index of Fixation1
Authors: Patterson T. G. , LaRue T. A.
Published: July 2010

The ureide contents of soybeans [Glycine max (L.) Merr.] were measured to determine if ureide concentration is a useful indicator of N2 fixation. Acetylene reduction activity (ARA) excised roots and the concentrations of ureides in stem segments were measured in field grown soybeans at weekly intervals. Ureides occurred in every soybean cultivar tested. Their concentration in the shoot varied over the growing season. The concentration droppeduring early vegetative growth, then rose and fell during reproductive growth. The plant age when maximum ureide concentration occurred was similar in three seasons. Within maturity groups there was little difference in ureide concentration. Stem nitrate levels decreased continuously over the season and were negatively correlated with ARA and ureides. A relative abundance of ureides was calculated as the fraction of ureide‐N in the ureide‐N + NO3‐N pool. The relative abundance correlated well with ARA, and gave a correction for the effect of soil nitrate on ureide concentration. Ureide concentration and ARA, measured at the same time, were significantly correlated. Dinitrogen fixation over the season was estimated by integrating ARA. The concentration of ureides in the young stem at the R3 stage showed the highest significant correlation with integrated seasonal ARA. The single ureide sampling was not as closely correlated with the estimated seasonal fixation as a single ARA determination at the R2 or R3 stage.
Sulfur Fertilization and Rumen Microbial Degradation of Cell Walls in Digitaria pentzii (Stent)1
Authors: Akin Danny E. , Hogan J. P.
Published: July 2010

Sulfur fertilization of deficient Digitaria forages can increase voluntary intake and digestibility over unfertilized forages, and often the response is greater than that obtained with sulfur supplementation. Our objectives were to analyze D. pentzii grown with (+S) or without (−S) sulfur fertilization for anatomical changes related to digestibility and to determine the degradation of specific cell walls in each of these forages. Blades and stems were examined microscopically and percentages of tissue types in cross‐sectional areas calculated. Cell wall digestion was evaluated by gravimetric analysis and by scanning and transmission electron microscopy. Our results indicated no differences in plant anatomy related to digestibility between the +S and −S forages. Digestibility studies using rumen microbial populations from sheep fed an alfalfa‐oats (60:40) diet showed no differences dry matter digestibility or in the degradation of specific tissues. The degradation of the digestible leaf tissues, mesophyll and epidermis, was faster and more extensive with microbes from sheep fed +S D. pentzii than from those fed unfertilized forage. Further, sporangia‐like structures that selectively attacked the sclerenchyma and the breakdown of sclerenchyma cells in association with pleomorphic microbial structures occurred within animals fed +S but not −S forage. The parenchyma bundle sheath, cuticle, and lignified vascular tissue were not degraded with any of the microbial inocula or with pure cultures of Ruminococcus flavefaciens FD‐1. Results indicated that sulfur‐fertilization did not affect plant anatomy but enhanced the fiber‐digesting capability of the rumen population. Additional research is necessary to delineate microbial differences and their relationship to fiber degradation.
Alfalfa Seed Germination in Antiobiotic Agar Containing NaCl1
Authors: Carlson J. R. , Ditterline R. L. , Martin J. M. , Sands D. C. , Lund R. E.
Published: July 2010

The development of cultivars with the ability to germinate under high salt stress would be useful in the reclamation of saline soils. One of the major problems has been the development of uniform, repeatable methods for selecting for the ability to germinate under salt stress conditions. Our objectives were to determine if agar could be successfully used as a saline medium to rapidly screen large numbers of alfalfa (Medicago sativa L.) seeds for ability to germinate under salt stress, and if progress through selection could be made for this trait. Seeds from 15 different alfalfa cultivars were germinated on agar containing varying concentrations of NaCl. Significant differences among the cultivars were observed for ability to germinate under salt stress. Selection within ‘Ladak 65’ at 1.75% NaCl in the agar medium resulted in a 3.75 fold increase in germination at that salt concentration. Selection within Ladak 65 using NaCl on blotters did not improve germination on saline agar.
A comparison of Selection Methods for Reduced Shattering in Wild Rice1
Authors: Everett L. A. , Stucker R. E.
Published: July 2010

Current wild rice (Zizania palustris L.) cultivars are considered to be recessive for a two‐complementary‐gene system in which complete seed shattering is dominant. The strength of seed retention in these nonshattering cultivars is not adequate to prevent substantial field losses. To test for the existence of quantitative genetic variability above that conditioned by the two‐gene qualitative system and to compare selection systems, two forms of selection were conducted in the cultivar Netum. The selection criterion was strength of individual seed retention on plant main‐stems at maturity as measured with a hand‐held spring operated meter. Two cycles of mass selection in the greenhouse and one cycle of half‐sib family selection in the field, both at a 10% selection intensity, produced two populations which were compared to each other and to Netum at Grand Rapids and Excelsior, Minn. Progress from selection for tensile strength was 49.6% for two cycles of mass selection and 15.9% for one cycle of half‐sib family selection. Realized heritability estimates for seed retention were 0.58 and 0.55 at the two test locations. Selection for tensile strength had no effect on flowering or maturity date.
Predicting Crude Protein, In Vitro True Digestibility, and Leaf Proportion in Alfalfa Herbage1
Authors: Onstad David W. , Fick Gary W.
Published: July 2010

Simple equations to predict alfalfa (Medicago sativa L.) herbage quality are needed for economic analysis of management alternatives. In this study, regression analysis was used to formulate and test prediction equations for leaf proportion (LP), for crude protein (CP), and in vitro true digestibility (IVTD) levels of leaf and stem fractions of standing herbage with canopy age, heat sums with a 5°C base temperature, and daylength sums as independent variables. All data were for pure alfalfa samples collected in central New York State between 1972 and 1980 from established stands with canopies ranging in age from 7 to 66 days. Separate equations were needed to predict LP in first growth and regrowth, but a corresponding distinction was not necessary for leaf and stem CP and IVTD. Heat‐sum‐based equations gave good fits (R2 from 0.75 to 0.97) for all predicted variables. In few cases, equations with both heat and daylength sums fit equally as well. Canopy age adequately predicted only leaf CP and IVTD. Equation form varied from simple linear to polynomial and logarithmic. Thirteen equations were selected for testing by regressing independent field observations on model predictions of those observations. The r2 values in these tests for the various herbage components were as follows: LP in regrowth, 0.81 to 0.87; leaf CP, 0.55 to 0.59; leaf IVTD, 0.44 to 0.46; stem CP, 0.72 to 0.76; and stem IVTD, 0.89 to 0.92. In general, predicting standing alfalfa herbage quality from heat summation is a promising approach.
Simultaneous Evaluation of Grain Sorghum A‐Lines and Random‐Mating Populations with Topcrosses1
Authors: Hookstra G. H. , Ross W. M. , Mumm R. F.
Published: July 2010

Grain sorghum [Sorghum bicolor (L.) Moench] topcrosses from 19 A‐lines crossed to six random‐mating populations were evaluated for general combining ability (GCA) and specific combining ability (SCA) effects. Topcrosses were produced by interplanting short rows of the A‐lines within each population in an isolation block. Six replications of a split‐plot experimental design with populations as main plots and A‐lines as subplots were grown at Mead, Nebr., in 1979 and 1980. Data were recorded on seven traits. Significant differences were detected among A‐lines and among populations for grain yield, plant height, days to flowering, tillering, and percent oil and among A‐lines for 100‐seed weight and percent protein. No genotype ✕ year yield interaction was significant for either parental group. Significant A‐line ✕ population interactions existed for yield, height, and flowering although individual analyses by population often ranked the A‐lines similarly. There were no significant A‐line ✕ population ✕ year interactions. Based on GCA effects, A‐line N37 and population RP1R were superior parents for producing high yielding topcrosses. The SCA yield effects were significant in only eight topcrosses. N37 ✕ RP1R had the highest yield, but its SCA effect was nonsignificant. Topcrosses appear to be suitable for preliminary evaluation of grain sorghum germplasm. They identify superior A‐lines and identify populations in which to initiate inbreeding to develop R‐lines.
Effect of Seedborne Fusarium moniliforme and Irrigation Scheduling on Colonization of Root and Stalk Tissue, Stalk Rot Incidence, and Grain Yields1
Authors: El‐Meleigi M. A. , Claflin L. E. , Raney R. J.
Published: July 2010

Eighty percent of the 486 000 ha of corn production in Kansas is irrigated and Fusarium stalk and root rots (primarily incited by Fusarium moniliforme Sheld.) is the most damaging diseases of irrigated corn with estimated annual statewide losses ranging from 5 to 10%. The purpose of this study was to investigate the effects of seedborne, airborne, and soilborne F. moniliforme inoculum and irrigation scheduling on F. moniliforme colonized root and crown tissue, grain yields and stalk rot incidence. Parameters included four levels (0, 12.5, 25, and 50%) of F. moniliforme infested seed lots and four irrigation schedules: 1) non‐irrigated; 2) irrigating when the available soil moisture was 50% depleted as determined by a neutron probe; 3) 50% depleted as determined by a computer model; and 4) 35% depletion until tasseling, then 65% until harvest as determined by a computer model. Colonization of the root and crown tissue by F. moniliforme increased nearly three‐fold during the growing season as the fungus was detected in 23.1% of the corn plants in May and 62.5% in August. Fungal colonization of plant tissue could not be correlated to infested seed lots or irrigation schedules. Stalk rot incidence and grain production were not significantly influenced by the various levels of infested seed lots. Yields were increased nearly 85% with a concomitant decrease (59.8%) stalk rot incidence in the irrigated plots. The highest levels of soilborne inoculum (210 propagules/g of soil) and airborne inoculum (0.3 propagule/L of air) were found near the end of the growing season.
Characteristics of the Stigma of Chickpea1
Authors: Turano Margaret Jorgensen , Baird Lisa Morrison , Webster Barbara D.
Published: July 2010

Breeding advancements in the chickpea, Cicer arietinum L. have been hampered by limited success in cross‐pollination attempts. This study was undertaken to examine the characteristics of the stigma microscopically and histochemically to determine the period of maximum receptivity. The high degree of self‐pollination in the chickpea is attributed to the fact that flowers are autogamous and that only certain papillate cells of the stigma are specialized to receive pollen when it is shed prior to full flower bloom. During the white bud stage, such specialized cells produce a localized secretion which reacts positively to an esterase test. This test detects stigmatic surface proteins which are believed to be functionally important in the retention and hydration of pollen grains and, possibly indicates the site of the stigma‐pollen compatibility reaction. These observations suggest that the low success rate of artificial hybridizations in chick‐pea may be related to the timing of stigma receptivity and to the limited number of cells on the stigmatic surface which appear to be receptive to pollen. Functional specialization of stigmatic cells has not been reported in other legumes, and may be unique among crop plants.
Effects of Temperature and Photoperiod on Stolon Characteristics, Dry Matter Partitioning, and Nonstructural Carbohydrate Concentration of Two White Clover Ecotypes1
Authors: Boller Beat C. , Nösberger J.
Published: July 2010

Carbohydrate reserves are necessary for survival of perennial plants, but excess accumulation at the expense of harvestable new growth may interfere with the agronomic goal of maximizing herbage yields. The objective of this research was to examine the response of reserve carbohydrate storage and dry matter partitioning in white clover (Trifolium repens L.) to low temperature and short photoperiod. Spaced plants of two altitudinal ecotypes were grown in growth chambers at day/night temperatures and photoperiods of 18°/13°C, 16 h; 10°/7°C, 16 h; and 10°/7°C, 12 h. Plants grown under the lower temperature regime showed an increase in stolon diameter (+33% on average) and thus established a greater stolon volume (+53%) unit leaf area. Shortening the photoperiod resulted in a marked decrease in length of stolon internodes (−54%) and leaf size (−29%), but favored stolon branching (+ 23%). Low temperature depressed net assimilation rate (NAR) to a lesser extent (−38%) than rate of leaf appearance (−52%). Increased photosynthate availability under low temperature was expressed in higher total nonstructural carbohydrate (TNC) content of the leaves (+ 63%), and enabled a greater accumulation of TNC in stolons and roots (+48%). A shorter photoperiod caused a marked decrease TNC content of the leaves (−78%), but only slightly depressed reserve accumulation in stolons and roots (−14%). The alpine ecotype allocated a higher proportion of dry matter to the stolons (+ 35%) than did the valley type, which showed higher root weight proportions (+23%). It is concluded that ecotype and environment influence photosynthate partitioning by affecting plant morphology, by changing the ratio of photosynthate supply to demand, and by controlling carbohydrate use. Low temperature, short photoperiod, and alpine origin favor carbohydrate reserve storage, and thus improve prerequisites for winter survival in white clover.
Effect of Genotype, Flowering Date, and Environment on Oil Content and Oil Quality of Wild Sunflower Seed1
Authors: Seiler Gerald J.
Published: July 2010

The effects of environmental conditions during sunflower (Helianthus annuus L.) seed development and maturation on the final oil content of seed and composition of the oil have been studied extensively in commercial sunflower, but very little is known about the wild sunflower (H. annuus L.). Neither is there much known about the sequential changes that occur in seed and oil during seed development and maturation. A better understanding of these changes could lead to a greater utilization of wild sunflower in breeding programs. The objective of this study was to determine the influence of genotype, flowering date, and environment on oil content and oil quality of maturing wild sunflower. Thirty‐eight populations of wild annual sunflower indigenous to areas from 29° to 46° N Lat and 81° to 122° W Long were planted in a randomized field plot design on 12 May 1980. Five heads per population per week were sibbed or interpollinated, and seeds were collected 28 days later for determination of oil content, fatty acid composition of oil, seed weight, and test weight. Flowering date and genotypes (populations) significantly affected all dependent variables. Oil content averaged over all populations increased from the first to last sampling. This is opposite the trend found in commercial hybrids. Oleic and linoleic acid concentrations of the oil decreased and increased, respectively, for later flowering dates. Oleic and linoleic acids began at lower and higher levels, respectively, in the wild sunflower compared to the commercial hybrid but all were about the same concentration at the last samplings. Based on multiple regressions, daylength and Julian day significantly influenced oil content. Linoleic acid was significantly influenced by Julian day, total solar radiation, and maximum temperature; whereas, oleic acid was influenced only by the latter two factors. Oil content and linoleic acid concentration differed significantly in seeds of the original population vs. the seeds grown at a single location. Sibbed and open‐pollinated seeds did not differ in total oil content when grown at a single location, but linoleic acid did. Oleic acid concentrations of sibbed and open‐pollinated seeds of populations grown at a single location did not differ significantly from the seeds of the original populations.
Cytology and Leafspot Resistance of Section Arachis Amphidiploids and their Hybrids with Arachis Hypogaea1
Authors: Gardner M. E. B. , Stalker H. T.
Published: July 2010

Improvement of the cultivated peanut, Arachis hypogaea L., by utilizing the germplasm resources found in related members of the genus is complicated by differences in genomic relationships and ploidy levels. To circumvent sterility in interspecific hybrids due to ploidy differences, amphidiploids representing 23 hybrid combinations of six section Arachis nom. nud. species were produced. Most amphidiploids had regular meiosis and produced stainable pollen, but produced few, if any, seeds. Four of five attempted hybrids between A. hypogaea cv. NC 6 and early leafspot (Cercospora arachidicola Hori) resistant amphidiploids were successful. All 59 plants produced were vigorous and flowered profusely, but only two genotypes produced seed, and in a very limited number. The diploid species, F1 hybrids, amphidiploids, and NC 6 ✕ amphidiploid hybrids were resistant to early leafspot in field evaluations. After self‐pollination, F2 progenies of the NC 6 ✕ amphidiploid hybrids segregated for growth habit and fertility. Several plants of the hybrid NC 6 ✕ 4x(A. stenosperma Greg. et Greg. nom. nud. ✕ A. chacoense Krap. et Greg. nom. nud.) produced numerous seeds, and initial sterility barriers which restricted utilization of germplasm within Arachis have been overcome for some species.
Nitrogen Response of Panicum Species Differing in CO2 Fixation Pathways. II. CO2 Exchange Characteristics1
Authors: Brown R. H. , Wilson J. R.
Published: July 2010

The C4 cycle of CO2 fixation may allow for more efficient use of N in CO2 assimilation and dry matter production than the C3 cycle. The association of high N use efficiency with C4 photosynthesis was tested on six Panicum species which differ in CO2 fixation pathway. Panicum maximum (C4), P. prionitis (C4), P. hylaeicum (C3), P. laxum (C3), P. milioides (C3/C4), and P. schenckii (C3/C4) were grown at day/night temperatures of 35/30 and 24/ 19°C and gas exchange measurements were made at 35, 30, and 24°C. Plants were grown in complete nutrient solutions and then N was withdrawn and measurements of carbon dioxide exchange rates (CER) and transpiration were made just before and during the N depleted from the highest levels attained for all the C3 and C3/C4 species. For P. maximum and P. prionitis the CER response was curvilinear with optimum leaf N levels of about 30 to 35 g kg−1, except for P. maximum grown at 24/19°C in which an optimum was not reached. The C4 species, P. maximum, exhibited the highest average CER/N value of 24 mmol CO2 kg−1N s−1 for plants grown at either 24/19 or 30/35°C. For all other species CER/N was lower than for P. maximum, and CER/ N was lower in plants grown at 24/19 than at 35/30°C. The lower CER/N at 24/19°C was associated with higher specific leaf weights. The C4 species, P. prionitis, had the lowest CER/N values of 4.0 and 5.5 mmol CO2 kg−1N s−1 for plants grown at 24/ 19 and 35/30°C, respectively; due perhaps to its very thick leaves with specific leaf weights three to five times higher than the other species. Deficiency of N decreased both leaf conductance and mesophyll conductance in all species, but for plants grown at 35/30°C reduction of mesophyll conductance was much greater than leaf conductance. It is concluded that N use efficiency is not necessarily higher in C4 than in C3 species and that the advantage apparently conferred by the C4 metabolism may be negated by morphological or other leaf characteristics.
Aflatoxin Occurrence and Levels in Preharvest Corn Kernels with Varied Endosperm Characteristics Grown at Diverse Locations1
Authors: Lillehoj E. B. , Zuber M. S. , Darrah L. L. , Kwolek W. F. , Findley W. R. , Horner E. S. , Scott G. E. , Manwiller A. , Sauer D. B. , Thompson D. , Warren H. , West D. R. , Widstrom N. W.
Published: July 2010

Natural aflatoxin contamination of developing corn (Zea mays L.) kernels was studied in one synthetic and 19 hybrids that varied in endosperm and other characteristics. The genotypes were grown at nine diverse locations in the USA in 1980 and 1981. The highest mean aflatoxin level (1846 ng g−1) was detected in kernels of Mo17 ✕ B73. Elevated toxin accumulations were also observed in a waxy hybrid. A normal endosperm hybrid (SC54)✕ SC76) and a synthetic (MoSQA(H)C6) had the est mean toxin levels. From 90 to 100% of the samples from the South and 2 to 25% of the Corn Belt samples were aflatoxin positive. Elevated toxin concentrations (>100 ng g−l) were associated with a high toxin incidence. However, some locations provided numerous, contaminated samples with relatively low levels of aflatoxin. Elevated aflatoxin levels were also associated with increased insect damage.
Combine Harvest and Data Acquisition by One Person1
Authors: Konzak C. F. , Davis M. A. , Wilson M. R.
Published: July 2010

To allow one person to harvest plots and to collect data, a pneumatic grain transport system available for a plot research combine was relocated within easy reach. Components for holding sample bags, an electronic balance, and a portable electronic data terminal were constructed. New procedures permit efficient plot harvest and data acquisition. The time required for combine cleanout between plots is used to bag samples, collect data, tie, and transfer sample bags to a carrier bin conveniently attached to the combine. Small observation windows in the base of the grain collector allow the operator to see grain that enters late, thereby preventing mechanical mixtures. The system saves time and labor and facilitates data summarization and plot selection in the field.