bluuebunny/crossref_metadata_2025 huggingface dataset:
Boll Weevil Resistance, Agronomic Characteristics, and Fiber Quality in Progenies of a Cotton Cultivar Crossed with 20 Primitive Stocks1
Authors: McCarty Jack C. , Jenkins Johnie N. , Parrott W. L.
Published: July 2010

Primitive race stocks of cotton (Gossypium hirsutum L.), were crossed and backcrossed twice to the recurrent cultivar ‘Deltapine 16.’ These progenies were evaluated for boll weevil (Anthonomus grandis Boheman), oviposition suppression in 1973, 1974 or both, and for agronomic characteristics and fiber quality in 1973. Lines were grown in replicated field tests, and oviposition was measured weekly during the fruiting period under boll weevil infestations. T‐25B‐58 (BC2F3), T‐80 (BC2F2), and T‐209 (BC2F2) had significantly less oviposition than the control, Deltapine 16 in 1973. Resistance is in diverse genetic stocks of cotton, which might be of economic importance. The agronomic characteristics and fiber properties of the progenies have rapidly approached those of commercial cultivars. Since no character associated with the primitive race stock adversely affected agronomic quality, these lines might be useful in the development of boll weevil‐resistance cottons if satisfactory yields could be obtained.
Gaseous Exchange of Simmondsia chinensis (Jojoba) Measured with a Double Isotope Porometer and Related to Water Stress, Salt Stress, and Nitrogen Deficiency1
Authors: Adams J. A. , Johnson H. B. , Bingham F. T. , Yermanos D. M.
Published: July 2010

Gaseous exchange of Simmondsia chinensis [(Link) Schneider] (a desert shrub which may provide a substitute for sperm whale oil) was studied by exposing leaves simultaneously to radioisotopes of water (3HHO) and CO2 (14CO2) to determine conductances to water vapor and total conductances to CO2 assimilation, respectively. Fixation rates of CO2 and mesophyll conductances to CO2 were calculated. Leaf conductance to water vapor and CO2 fixation rates decreased markedly only at very low values of soil‐water and leaf‐xylem pressure potentials and recovered to maximum values after having been subjected to soil water potentials below ‐‐40 bars, indicating the extreme drought tolerance of S. chinensis. The ratios of increased as water stress became more intense, suggesting that transpiration was reduced relatively more than photosynthesis, which could have considerable value under drought stress. Plants under intense water stress generally had little or no reduction in mesophyll conductance to CO2.

There was no significant decrease in conductance to water vapor, CO2 fixation rate, or mesophyll conductance to CO2 with increasing salinity down to root medium osmotic potentials as low as —9 bars. This is consistent with the reported high salt tolerance of S. chinensis. Nitrogen‐deficient plants had significant reductions in CO2 fixation rate and mesophyll conductance to CO2 but not in conductance to water vapor.
Defoliation Effects on Root Weights and Total Nonstructural Carbohydrates of Blue Grama and Western Wheatgrass1
Authors: Buwai M. , Trlica M. J.
Published: July 2010

Several studies have indicated that clipping or grazing reduces root weights, whereas other studies have indicated little or no change in root weights after defoliation. Root production and carbohydrate reserve stores are important in maintaining forage production after defoliation. Therefore, the effects of intensive defoliations on root weights and carbohydrate reserves of blue grama [Boutelotta gracilis (H.B.K.) Lag.] and western wheatgrass (Agropyron smithii Rydb.) were studied on a shortgrass prairie range. Small differences in root weights among undefoliated and heavily defoliated blue grama and western wheatgrass plants were found. However, undefoliated western wheatgrass plants had significantly more carbohydrate reserves than did the defoliated plants. Resistance of blue grama to grazing may be related to its ability to maintain a vigorous root system and carbohydrate reserve levels after defoliation.
Interrelationships Between the Pale‐Yellow Character and Other Traits in Flue‐Cured Tobacco1
Authors: Chaplin James F.
Published: July 2010

The interrelationship between the pale‐yellow character and certain agronomic and chemical traits was studied in isogenic lines derived from five cultivars of flue‐cured tobacco (Nicotiana tabacum L.). Isogenic lines with the pale‐yellow character were compared with their green recurring parent and a green sister selection in each family. The pale‐yellow gene had little or no effect on days to flower or total alkaloid content. Slightly reduced leaf number and yield were associated with pale‐yellow lines in some families. A decrease in starch and sugar and an increase in alpha amino nitrogen were associated with the pale‐yellow character. The grade index of pale‐yellow lines was equal to or better than that of the recurrent parent or green sister selections.
Effect of Rhizosphere pO2 on Nitrogen Fixation by Excised and Intact Nodulated Soybean Roots1
Authors: Criswell J. G. , Havelka U. D. , Quebedeaux B. , Hardy R. W. F.
Published: July 2010

The N2‐fixing legume nodule has an O2 requirement for ATP production to support nitrogenase (ECI.7.99.2) activity, however, the internal partial pressure of O2 (pO2) in the nodule must be maintained at low level because of the O2 sensitivity of nitrogenase. Effects on N2 fixation of short‐term exposures of the rhizosphere to altered external pO2's using both excised nodulated soybean [Glycine max (L.) Merr.] roots and intact plants were investigated utilizing acetylene (C2‐H2) reduction. Exposures of 30 min to supra‐ambient pO2's of 0.26 to 0.41 atm stimulated N2[C2H2] fixation by excised roots, but not intact plants while short exposures to a sub‐ambient pO2 of 0.05 atm reduced N2[C2H2] fixation by excised roots more than by intact plants. Short exposures of 30 rain to a supra‐optimum pO2 of 0.65 to 0.90 atm reduced N2[C2H2] fixation in both excised roots and intact plants, and in contrast to exposure to other O2 concentrations, there was only partial recovery of N2[C2H2] fixation by the intact plants and a further decline by the excised roots on reincubation in ambient O2. With excised roots, altered pO2 effects were age‐dependent with a decline in the optimum pO2 from 0.41 to 0.26 atm and intensification of the detrimental effects of high pO2. It is concluded that; 1) the excised root is more sensitive to altered pO2 than intact plants, 2) measurements of the effects of stress, such as altered pO2, on N2 fixation should be made on intact plants, and 3) ambient pO2 is not limiting for N2 fixation but short‐term exposures to sub‐ambient pO2 will limit N2 fixation.
Evaluating and Selecting Alfalfa for Reaction to Crown Rot1
Authors: Wilcoxson R. D. , Barnes D. K. , Frosheiser F. I. , Smith D. M.
Published: July 2010

Crown rot is a major problem of alfalfa, but cultivars have not been evaluated for resistance. In this study 32 alfalfa (Medicago saliva L.) cultivars in 3‐ and 4‐year‐old broadcast plots at four locations in Minnesota were observed for degree of crown rot. Also, more than 100 cultivars were evaluated for crown rot after 3 years in a spaced‐plant test. Plants with little or no crown rot were selected and intercrossed, and their progenies were evaluated for crown rot severity. All cultivars were injured by crown rot, only small differences were observed among cultivars. In both broadcast and spaced‐plant tests, the winter‐hardy cultivars generally had less crown rot than the moderately hardy cultivars. ‘Teton’, ‘Ramsey’, and ‘Victoria’ (winter‐hardy cultivars), and ‘Pat 30’ and ‘WL 303’ (moderately hardy cultivars), had the least crown rot. The frequency of disease‐free plants was less than 0.2% of the plants evaluated. Intercrossing plants with the least rot produced progenies with significantly lower crown rot scores than the parental cultivars. The pathogenic fungi most commonly isolated from near the necrotic plant tissue were: Phoma medicaginis Malbr. and Roum., Fusarium solani (Mart.) Appel and Wr., and Rhizoctonia solani, Kuehn.
Selection of Superior Cultivars of Oats by Using Regression Coefficients1
Authors: Eagles H. A. , Hinz P. N. , Frey K. J.
Published: July 2010

Regression on environmental mean was investigated for measuring production stability of grain and straw yields of 80 lines of oats (Avena sativa L.) tested in 24 field environments. Mean squares for heterogeneity among regressions suggested that the regression parameter was not heritable for grain yield, but may be heritable for straw yield. The regression lines for straw yield tended to converge at an environmental yield level below that normally used for oat production. Therefore, selection with use of mean yields alone would save cultivars that are superior at all yield levels. This situation was attributed to a high correlation between regression coefficients and mean yields.

Analyses were conducted on direct and cube‐root scales of measurement. The cube‐root scale was chosen to reduce the heterogeneity of error mean squares obtained from the 24 individual environments, but also was found to reduce the significance of the mean squares for heterogeneity among regressions. The effect of a transformation of the data on heterogeneity and usefulness of regression coefficients is discussed.
Morphology, Cytology, and Fertility of F1 and Induced‐amphiploid Hybrids of Elymus canadensis — Agropyron subsecundum1
Authors: Dewey Douglas R.
Published: July 2010

Octoploid (2n=56) amphiploids of Elymus canadensis L. × Agropyron subsecundum (Link.) Hitchc. were obtained by treating sterile tetraploid (2n=28) F1 hybrids with colchicine. Chromosome doubling initially restored fertility but drastically reduced vegetative vigor. Dry matter yields of the amphiploids in the C2 to C5 generations were about 50% of those of the Fl's. The range in chromosome number changed from 2n=54 to 58 in the C1 to 2n=27 to 59 in the C5 generation, while the population means decreased from 2n=55.9 to 2n=53.8. Meiotic irregularities tended to increase in each succeeding amphiploid generation. Fertility declined from 2.36 seeds per spikelet in the Co generation to 0.78, 0.58, 0.50, 0.37, and 0.22 in the C1 to C5 generations, respectively. Amphiploid sterility was attributed to heterogenetic pairing between the closely related E. canadensis and A. subsecundum chromosomes. Chances of synthesizing a fertile, cytologically stable octoploid species from E. canadensis × A. subsecundum amphiploids, or from amphiploids with a similar genome constitution, are remote.
Relationship of Seed Shape and Cotyledon Color to Percent Protein of Peas1
Authors: Shia G. , Slinkard A. E.
Published: July 2010

Three crosses were made between high protein, wrinkleseeded, green cotyledon pea (Pisum sativum L.) lines and low protein, smooth‐seeded, yellow cotyledon pea lines. Comparisons of yellow vs. green cotyledon F3 lines and paired comparisons of yellow vs. green cotyledon seeds from within segregating F3 lines were made to determine the relationship of yellow vs. green cotyledon color to percent protein and other seed characters. Analogous comparisons were made to determine the relationship of cotyledon shape, smooth vs. wrinkled to percent protein. The yellow cotyledon pea seed did not differ from the green cotyledon pea seed in percent protein, whereas the wrinkle‐seeded peas averaged about 3% higher protein than the smooth‐seeded peas. The wrinkle‐seeded peas also exhibited a reduction in seed weight, percent starch and seed yield as compared to the genetically comparable smooth‐seeded peas. However, the weight of protein per seed was similar for both smooth‐ and wrinkleseeded lines.
Cytological and Fertility Characteristics of Some Hybrid Bermudagrass Cultivars1
Authors: Hanna W. W. , Burton G. W.
Published: July 2010

Chromosomal behavior, embryo sac development, and seed set were studied in ‘Coastal’, ‘Coastcross‐l’, ‘Midland’, and ‘Suwannee’ bermudagrass, Cynodon dactyion L. Pets. (2n = 36). This information will be useful to plant breeders using these hybrids as parents for further improvement and it will give an indication of the potential contamination problem that may be expected from seed produced on the cultivars. Univalents or quadrivalents at metaphase I were observed in each cultivar. Triva. lents were observed only in Midland and Coastcross‐1. The mean number of bivalents per microsporocyte were 14.0, 16.6, 16.2, and 17.5 for Coastcross‐1, Coastal, Midland, and Suwannee, respectively. High male and female sterility was observed only in Coastcross‐1. Pollen stainability ranged from 2% for Coastcross.l to 88% for Suwannee. The range in size of Suwannee pollen was one‐half that of either of the other three bermudagrasses. Selfed seed set ranged from none on Coastcross‐1 to 11% on Coastal. Cross‐pollinated seed set was as high as 27% on Coastal.
Performance of Diallel Crosses and Second Generation Synthetics of Alfalfa Derived from Partly Inbred Parents. II. Earlines and Mortality1
Authors: Rotili P.
Published: July 2010

In an alfalfa (Medicago sativa L.) breeding study conducted under conditions of high competition between plants, combining ability for earliness and mortality was evaluated from diallel crosses among selected parents, which had been partly inbred by selfing. The performance of first and second generation synthetics was also studied. For both earliness and mortality (percentage of blooming or dead plants, respectively), general combining ability (GCA) was considerably larger than specific combining ability (SCA) for all generations of parental inbreeding (S0, S1, S2, S3, and S4). GCA and SCA increased with the level of inbreeding. Significant correlations were noted between earliness and yield, between mortality and yield and between earliness and persistence. At each level of parental inbreeding the single crosses with the greatest forage yield were also the earliest and the most persistent. Syn 2 generation synthetics had the same response pattern.
Variation of Chloroplast‐associated Processes with Divergent Selections from Zea mays L.1
Authors: Hanson W. D.
Published: July 2010

Associations among chloroplast characteristics were investigated using divergent selections from Zea mays L.; narrow (NL) vs. wide (WL) leaves, two replicates low (LP) vs. high (HP) stalk volume (sixth leaf stage) and golden (g) vs. normal (G) isopopulations. Leaf width selections differed in chlorophyll contents but had similar in vitro rates of ferricyanide reduction and noncyclic photophosphorylation, chloroplast protein levels and rates of net CO2 fixed per mg chlorophyll for three light intensities. The LP selections had inefficient photosynthetic systems relative to HP, while Golden had at least as efficient photosynthetic system as Normal. In contrast, LP selections had 13% and Golden 23% higher ferricyanide reduction and noncyclic photophosphorylation rates than HP and Normal, respectively. Information from in vitro measures was contradictory to that from other sources. Genetically controlled differences for chloroplast protein relative to chlorophyll level were found. Total chloroplast protein (TCP) and a fraction removed by NaOH (CPF) were both highly correlated with ferricyanide reduction rates. While TCP and CPF levels reflected seasonal effects, differences between genotypes for protein levels remained relatively consistent. TCP measure was proposed for population genetic studies to establish whether photochemical properties of chloroplasts have value as selection criteria.
Physical and Chemical kernel Characteristics of Normal and Opaque‐2 Endosperm Maize Hybrids1
Authors: Arnold J. M. , Bauman L. F. , Makonnen Dejene
Published: July 2010

Six normal endosperm maize (Zea mays L.) hybrids and their opaque‐2 counterparts were compared for kernel weight, volume, density, and number on six dates at 7‐day intervals beginning 28 days after pollination. Whole kernel concentration and content of P, K, Mg, Fe, Zn, protein, and oil were also determined. At 56 days after pollination, kernel weight, volume, and density of the opaque‐2 hybrids were 16.7, 6.9, and 10.2% less, respectively, than for the normal hybrids. Kernel weight was only slightly greater for the normal kernels at 28 and 35 days after pollination, but the difference between the endosperm types increased after the 35‐day harvest. Kernel volume was similar at 28, 35, 42, and 49 days but greater for the normal endosperm kernels at 56 and 63 days. Density of the normal endosperm kernels was higher at all harvest dates with the difference between endosperm types being similar at all dates. At 56 days after pollination, the opaque‐2 kernels were significantly greater in P, K, Mg, Fe, Zn, and oil concentration. When amounts of kernel constituents were expressed on a unit weight per 200 kernels basis, the normal kernels were higher than or similar to opaque‐2 kernels for all constituents except K, which was higher in the opaque‐2 kernels. The opaque‐2 kernels were higher in concentrations of all elements at all harvest dates and were higher in content of K per 200 kernels at all harvest dates.
Heritability Estimates, Genetic Correlations, and Predicted Gains from S1 Progeny Tests in Three Grain Sorghum Random‐mating Populations1
Authors: Eckebil J. P. , Ross W. M. , Gardner C. O. , Maranville J. W.
Published: July 2010

Means, variances, heritabilities, genetic correlations, and predicted responses were obtained for grain yield, other agronomicharacters, and grain protein by testing 200 S1 families from each of three random‐mating populations of Sorghum bicolor (L.) Moench. Means of the three populations differed significantly for all characters except kernel weight. The NP3R population, composed of adapted material, was higher yielding than NP5R, which contained exotic germplasm; however, NP5R had twice as much genetic variability for yield and most other characters. NP7BR, a narrow population, yielded the same as NP5R but had the lowest variability for plant height and days to bloom. The grain yield of NP7BR was decreased and its grain protein increased because of poorly pollinated antherless (al al) male‐sterile plants. Variances for yield‐related characters in NP7BR also were biased. Genotype × year interaction variances were low in all populations compared to genetic variances except threshing percentage in NP5R. Broad‐sense heritability estimates for bloom date, plant height, yield, and kernel weight were high in all populations. Heads per plant had the lowest heritability, especially in NP3R and NP7BR.

Genetic correlations usually had the highest values in NP5R and the lowest in NP7BR. Grain yield per unit area generally was best correlated with grain yield per head, plant height, and threshing percentage. Days to bloom and grain protein percentage were negatively correlated with yield and had low values, except for NP5R.

Predicted gains in yield from selecting the highest 20% of the families in each population were 16.3, 10.2, and 8.7 q/ha per cycle for NP5R, NP3R, and NP7BR, respectively. The smallest predicted gains were for tillers per plant and grain protein percentage. Both NP3R and NP5R appear suitable for recurrent selection studies.
Growth Analysis of a Sorghum Hybrid and its Parents1
Authors: Gibson P. T. , Schertz K. F.
Published: July 2010

Growth rate, leaf area index, net assimilation rate, and distribution of dry matter among aboveground plant parts were determined for sorghum [Sorghum bicolor (L.) Moench] hybrid ‘RS 610’ and its parents throughout the growing season in a replicated field experiment. Dry weight and leaf area were measured twice weekly before flowering and weekly thereafter. The hybrid developed faster than its parents. It had greater leaf area than its parents until 1 week prior to flowering, and less leaf area than its parents thereafter. The hybrid had greater total dry weight than its parents throughout the growing season. The crop growth rate (CGR) of the hybrid was greater than that of either parent from emergence to panicle initiation, while net assimilation rate and relative growth rate did not differ among genotypes at this period. RS 10 outyielded its parents in grain, and had more kernels per panicle than the female parent, but did not differ from the male parent in this characteristic. The yield superiority of RS 610 was attributed mainly to the combination of the high CGR of the female parent during grain filling with the effective conversion of dry matter to grain of the male parent. More rapid seedling growth and a longer grain filling period were also advantages of the hybrid over its parents.
Resistance of selected Soybean Genotypes and Segregating Populations to Cabbage Looper Feeding1
Authors: Luedders V. D. , Dickerson W. A.
Published: July 2010

Soybean [Glycine max L. (Merr.)] introductions PI 171451, PI 227687, and PI 229358; commercial cultivars ‘Amsoy 71’ and ‘Beeson’; and F3 and F4 generations of four resistant‐susceptible crosses were field tested for resistance to leaf feeding by second‐instar cabbage looper larvae (Trichoplusia ni Hubner). The three plant introductions were highly significantly more resistant than the two commercial cultivars. The parental range in feeding scores was recovered in the F4 generation even though the number of progenies was small. Heritabilities were estimated by correlation of F3 with F4 feeding scores and ranged from 6 to 44%. The possible linkage of maturity genes with genes for resistance to cabbage looper feeding in the plant introductions (maturity adapted to the Southern U.S.) did not appear to be a factor in transferring resistance to cultivars adapted in more northern latitudes.
Evaluation of Early Generation Soybeans for Resistance to Soybean Looper1
Authors: Kilen T. C. , Hatchett J. H. , Hartwig E. E.
Published: July 2010

The soybean [Glycine max (L.) Merr.] cultivar ‘Davis’, × P.I. 229358, and F1 and F2 generations from the cross Davis Χ P‐I‐ 229358 were grown in a greenhouse and rated visually for leaf‐feeding damage by soybean looper [Pseudoflusia includens (Walker)]. Parents and 365 F3 lines were then rated for leaf‐feeding damage by soybean looper in a field cage. The rating on F2 plants in the greenhouse was significantly correlated (r = 0.52) to the rating of their F3 lines in the field cage. The average rating of F3 lines changed 0.6 unit for each unit change in the rating of F2 plants (b = 0.61). Data from parents and F1 plants suggested no dominance for resistance to feeding by soybean looper. The F2 distribution was skewed in the direction of the susceptible parent. The study indicated that large numbers of F2 plants segregating for reaction to leaf‐feeding by soybean looper may be effectively evaluated in the greenhouse.
Growth Analysis of Isoline‐Recurrent Parent Grain Yield Differences in Oats1
Authors: Brinkman M. A. , Frey K. J.
Published: July 2010

Growth analysis studies were made on sets of four early and four midseason isolines of oats (Avena sativa L.) that had significant grain‐yield deviations from their recurrent parent in each series. These yield deviations occurred when yield genes, tightly linked to crown rust resistance genes, were transferred from unadapted Avena germplasm into the recurrent parent backgrounds through backcrossing. The higher yielding C.I. 8079‐ and C.I. 7171‐derived isolines had increased growth trait means in each series. Generally, these increases were significant in the early series but not in the midseason series, which also had smaller grain yield increases. C.I. 9170, the early C.I. 8079‐derived isoline, had a significantly higher leaf area duration (LAD), leaf area ratio (), growth rate (), and relative growth rate () than the early recurrent parent. The midseason C.I. 8079‐derived isoline, C.I. 9183, had increases for these traits, but none was significant. Leaf growth increases in the early and midseason C.I. 7171‐derived isolines, C.I. 9178 and C.I. 9188, were very small and presumably did not contribute to the grain yield advantages of these isolines. The low‐yielding C.I. 7232‐derived isolines X550I and C.I. 9192, had significantly lower LAD's, and their 's and 's were reduced, but not significantly.

Although isoline‐recurrent parent growth trait differences were not always significant, the trends for these traits in the C.I. 8079‐ and C.I. 7232‐derived isolines, when compared to the recurrent parents, indicated that yield differences within these sets of closely related lines have morpho‐physiological causes that can be explained by growth analysis. LAD, , and were growth traits associated with grain yield differences in these isoline‐recurrent parent comparisons. However, C.I. 7171‐derived isolines had higher grain yields but similar LAD's when compared to their recurrent parents.
Effects of Plant Density and Nitrogen Fertility on Purity Components of Sugarbeet1
Authors: Smith G. A. , Martin S. S.
Published: July 2010

The influence of plant density and nitrogen fertility level on purity, sucrose content, and eight other chemical components affecting purity were examined in a 2‐year field study of three sugarbeet (Beta vulgaris L.) cultivars. There were significant differences among cultivars for all analyzed characters in one or both years. Between the two N levels, raw juice concentrations of ash, total N, amino N, nitrate, betaine, sodium, and potassium were greater, and chloride, sucrose, and purity lesser under regular N than low (residual) N, though the differences were not always statistically significant. Impurities generally decreased with increasing plant density, and differences among the four densities were significant for most components in both years. These differences were largely but not solely due to differing amounts of N per plant. Of the three main effects analyzed, plant density and cultivar were followed by soil N level with respect to effect on the ten variables measured, and very few first or second or second order interactions were detected.
Genetic Diversity of Weedy Rye Populations in California1
Authors: Jain S. K.
Published: July 2010

Eight populations of weedy rye, Secale spp., from the Cascade range counties in northern California were scored for characters describing the wild and cultivated gene complexes. The relative frequencies of individuals with non fragile rachis, short awn, blue aleurone, and bronze lemma represent the postulated gene flow by introgression from cultivars into the original Secale montanum Guss. × S. cereale L. hybrids giving rise to the present genetic diversity and geographical patterns of variation in weedy rye. Although characters representing the wild and cultivated forms are not associated into distinct gene complexes, the weedy rye populations have a varied mixture of them. This confirms an earlier report on the origin of weedy rye and suggests continuing genetic shifts in weedy rye toward the cultivated forms.
Plant Population Effects on the Seed Yield Components of Beans1
Authors: Westermann D. T. , Crothers S. E.
Published: July 2010

Knowledge of the effect of plant populations on the seed yield components of beans (Phaseolus vulgaris L.) is needed to design management systems utilizing the genetic potential of different cultivars and to aid in the development of higher seed‐yielding cultivars. The objectives of this study were to evaluate (a) the effect different plant populations (area/plant) on the seed yield components as related to seed yield/plant, and (b) the relative differences between determinate (‘Canyon’, and ‘Blue Lakes 274’) and indeterminate (‘UI‐II4’, and ‘Big Bend’) bean cultivars. Seed yield/plant and the seed yield components were measured on plant populations from 107,600 to 968,700 plants/ha (100 to 930 cm2/plant) grown in a systematic design. Data were evaluated by path coefficient analysis based on correlations calculated from logarithmically transformed data. Pods/plants increased linearly as area/plant increased (decreasing plant population) for all cultivars studied, and had the largest effect on seed yield/plant. Seeds/pod and g/seed also increased as area/plant increased for the indeterminate cultivars, but remained relatively constant for the determinate cultivars. As a result, the seed yield/area is relatively constant over a wide range of plant populations for the indeterminate cultivars, but decreases at the smaller plant populations for the determinate cultivars. It also indicates that the determinate cultivar is subject to less competitive stress than the indeterminate one at the higher plant populations. The greatest potential for seed yield increases in high plant populations is with determinate cultivars.
Heterosis and Variation of Yield Components in F1 Hybrids Between Group Tuberosum and Group Andigena Potatoes1
Authors: Tarn T. R. , Tai G. C. C.
Published: July 2010

Five clones of Solanum tuberosum L. Group Tuberosum (T) and five long‐day adapted clones of Group Andigena (A) were crossed to produce four populations (TT, AA, TA and AT) in such a way that there was selling in the intra‐Group crosses. The populations were grown for 2 years as spaced plants in a randomized, complete‐block design and compared for plant vigor, maturity, tuber number, mean tuber weight, and total yield to evaluate the potential of the inter‐Group hybrid (TA and AT) populations in broadening the genetic base of potato cultivar development. In four comparisons, the TA and AT populations outyielded the TT population by 8.6 to 32.9%. Also, the TA and AT populations generally had larger variance estimates for total yield. It is concluded from the analysis of population means for tuber number, mean tuber weight, and total yield that in the TA and AT populations the heterosis for total yield results largely from the multiplicative interaction of the two yield components. The TA and AT populations showed no consistent reciprocal differences. The TA and AT populations showed greater stability than the TT population. These results have important implications for potato breeding.
Variation in Some Plant and Seed Oil Characteristics of Meadowfoam
Authors: Pierce R. O. , Jain S. K.
Published: July 2010

Meadowfoam (Limnanthes spp.), like jojoba (Simmondsia chinensis), promises to be a new agronomic substitute for sperm whale oil. Original bulk seed materials of four Limnanthes species from 35 collection sites were studied for interpopulational variation in fatty acid composition, oil content, and seed weight. Analyses of variance indicated significant interpopulational differences in the relative content of 22:1 and 22:2 fatty acids for the three species L. alba, L. floccosa, and L. douglasii. Differences among species for oil content, fatty acid composition, and seed weight were statistically as large as the estimates of interpopulation variances. A pilot study of heritability and interpopulational variation was carried out, using material from five collections, for oil content, component fatty acids, number of seeds per flower, flower number, branch number, plant height, and seed weight. Parentprogeny regression coefficients, calculated for the first four of these characters, indicated low heritability; likewise, the estimates of genetic component between vs. within families varied depending on the character and population involved. Correlations between several growth and reproductive characters suggested that yield components such as flower number, branching, and seed set per flower could be simultaneously improved by selection in the progeny of interpopulation hybrids.
Rumen Microbial Degradation of Starch‐Containing Bundle Sheath Cells in Warm‐Season Grasses1
Authors: Akin Danny E. , Burdick Donald
Published: July 2010

Leaf sections of the warm‐season grasses ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.), ‘Pensacola’ bahiagrass (Paspalum notatum Flugge), and ‘Pangola’ digitgrass (Digitaria decumbens Stent.) were evaluated for the ease of rumen microbial degradation of cells with high nutrient contents using electron microscopy. Observations of IKI‐stained sections viewed by light microscopy confirmed those of others in that most starch was found in the chloroplasts of parenchyma bundle sheath cells while little or no starch was seen in mesophyll chloroplasts. Parenchyma sheath cells were less rapidly degraded than mesophyll cells in all species. Observations from transmission electron microscopy revealed that in these warm season grasses starch was undegraded until the thick, laminated wall of the parenchyma sheath was degraded or disrupted by rumen bacteria; starch grains were then degraded. These results indicated that the large amount of potential nutrients in the parenchyma bundle sheath of these warm‐season forages may not be readily available because of slow degradation of the sheath cell wall by rumen bacteria.
Photosynthetic Selection of Zea mays L. I. Plant Age and Leaf Position Effects and a Relationship Between Leaf and Canopy Rates1
Authors: Vietor D. M. , Ariyanayagam R. P. , Musgrave R. B.
Published: July 2010

Leaf apparent photosynthetic (Pn) rates of inbred, hybrid, and open pollinated plants were studied in association with a continuing program of photosynthetic selection and improvement of Zea mays L. Of major interest was the influence of plant age and leaf position on Pn rates and on results of Pn selection. Apparent photosynthetic rates of multiplant canopies (Pc) of hybrid strain combinations of NY821 and C153 were also measured to determine if variation of Pn rates was indicative of variation of Pc rates.

ANOVA revealed highly significant variation of Pn rates among pretassel, silk, and dough stages of inbred and open pollinated plants and among stages ranging from silk to late dent for hybrids. Pn rates generally declined as plants aged, but a small increase from dough to early dent was observed for two maize hybrids.

Variation of Pn rates among lower, middle, and upper leaf positions was highly significant for three hybrids, but was rarely significant for the inbred and open pollinated plants. Pn rates of the three hybrids were substantially higher at upper positions from blister through early dent. A significant statistical interaction of age and position effects on the hybrid Pn rates alluded to a more marked age effected decline of Pn at upper positions.

A simple comparison of mean Pn rates indicated that Pn response to plant aging and leaf position differed among maize genotypes. The differential response was potentially detrimental to Pn selection efforts.

The similarity of trends of mean Pn and Pc rates and a highly significant regression relationship between Pn and Pc rates over time and between two hybrids provided evidence that variation of Pn rates was indicative of variation of Pc rates.
Assay of p‐Hydroxybenzaldehyde as a Measure of Hydrocyanic Acid Potential in Sorghums1
Authors: Gorz H. J. , Haag W. L. , Specht J. E. , Haskins F. A.
Published: July 2010

A method of assessing the hydrocyanic acid potential (HCN‐p) of sudangrass [Sorghum sudanense (Piper) Stapf] and sorghum [S. bicolor (L.) Moench] seedlings is described. This procedure is based on the determination of p‐hydroxybenzaldehyde (p‐HB), which is released upon hydrolysis of dhurrin, the cyanogen normally present in plants of Sorghum species. Extraction and hydrolysis of dhurrin are accomplished by autoclaving young leaf tissue in water. The content of p‐HB in the aqueous extract is then determined by spectrophotometric assay in alkaline solution at 330 nm. Uniform samples for the comparison of widely divergent genotypes are obtained by using the first leaf of young, chamber‐grown, green seedlings. Relative ranks of a wide variety of sorghum germplasm assayed for HCN content by this technique are in good agreement with those obtained by other methods. The procedure shows promise of providing a rapid and precise tool for conducting genetic and breeding studies with sorghums.
Genetic and Environmental Effects on the Grain Protein Content in Wheat1
Authors: Miezan Kouame , Heyne E. G. , Finney K. F.
Published: July 2010

The effects of environmental and genetic factors on grain protein content of wheat (Triticum aestivum L. em Thell.) were tested in two 2‐year experiments, the first at two locations, and the second at 10 locations. Five selections from the cross ‘Kaw’/‘Atlas 50’ and seven from Kaw/ ‘Atlas 66’ were studied. The 12 selections were genetically higher in grain protein than the control, Kaw. Nitrogen applied at blooming time increased protein content in all environments. A significant location‐genotype interaction occurred because some locations had greater increases than others. Nitrogen applied at blooming did not affect ripening, yield, or test weight. Statistical analyses confirmed the strong influence of environment on grain protein content of wheat. However, some of the high protein genotypes yielded consistently higher and had more protein than the control in all environments.
Relation Between Inbred and Hybrid Traits in Maize1
Authors: e Gama Elto E. G. , Hallauer Arnel R.
Published: July 2010

We conducted correlation studies between plant and ear traits of inbred lines and single‐cross hybrids of maize (Zea mays L.) developed from Iowa Stiff Stalk Synthetic. We included 160 S7 lines and 320 single‐cross hybrids produced among the lines by use of the cross‐classification mating design. The 160 S7 lines were partitioned into 20 sets of eight lines to produce the 320 single‐cross hybrids (16 hybrids per set). Objectives of our study were to determine the relation between plant and ear traits of the inbred lines and their single‐cross hybrids and to determine the relation of plant and ear traits of the inbred lines with yield of the single‐cross hybrids. Two procedures were used: (1) correlations of inbred lines themselves with means of hybrids that had one inbred line in common and (2) correlations of the means of two inbred lines with their specific hybrids. Simple and multiple correlations were computed for each set of eight inbred lines and 16 single‐cross hybrids and combined across the 20 sets.

Simple correlations of plant and ear traits of inbred lines and single‐cross hybrids were small in all instances for both procedures when combined across sets. The coefficient of determination (r2) was less than 0.16 in all instances. Correlations for individual sets for all traits ranged from significantly (P ≤ 0.01) negative to significantly positive. Sampling error was high among individual sets, indicating that small sample sizes can give misleading associations of traits. Multiple correlations of plant and ear traits of inbred lines with yield of singlecross hybrids were only 0.23 (Procedure 1) and 0.21 (Procedure 2). Our results showed that plant and ear traits of inbred lines were not good indicators of their performance in single‐cross hybrids. Correlations of yield of inbred lines with yields of single‐cross hybrids were 0.09 and 0.11. It seems that yield testing of inbred lines in single‐cross hybrids is the only procedure for determining the potential usefulness of an inbred line in single‐cross hybrids. Visual selection of morphological traits in inbred lines will not insure development of higher yielding single‐cross yields.
Crop Improvement in Sugarcane: Studies Using in vitro Methods1
Authors: Nickell Louis G.
Published: July 2010

Present advances in plant cell and tissue culture have increased the use of the many approaches afforded by these techniques for practical exploitation in agriculture. Now that the earlier problems of demonstrating totipotency, obtaining suspension cultures of cells and protoplasts, and inducing haploid clones from pollen and anthers have been solved (at least for some plants), the techniques of microbial genetics are being applied to higher plant systems. The stage is now set for the induction, detection, and identification of desirable mutants for the study of biosynthetic pathways and for increasing desirable agronomic characteristics such as disease resistance.
Stomatal Responses to Water Stress and Light in Plants Grown in Controlled Environments and in the Field1
Authors: Davies W. J.
Published: July 2010

Experiments were performed to investigate the water relations of plants grown in controlled environments and in the field. Cotton (Gossypium hirsutum cv. ‘McNair 511’) and soybeans (Glycine max cv. ‘Ransom’), were grown from seed in pots in a phytotron growth chamber, an air‐conditioned greenhouse, and in a field plot. All plants were well‐watered but minimum midday water potentials were lower in field‐grown plants than in chamber‐ or greenhouse‐grown plants, and lower in cotton than in soybean. Predawn‐ (in the field and greenhouse) and “before lights on‐” (in the chamber) water potential (ψ) levels were consistently lower in cotton than in soybean. In both soybean and cotton, adaxial stomata were more sensitive than abaxial stomata to decreasing leaf water potential. Stomatal sensitivity to decreasing leaf water potential and leaf water content (RWC) was related follows: Chamber‐grown plants> greenhouse‐grown> plants> field‐grown plants. There were differences in the ψ/RWC relationships of the two species and in soybeaus, the ψ/RWC relationship differed between chamber‐ and field‐grown plants. Adaxial stomata of both species were considerably more sensitive to low light intensity than were abaxial stomata. In soybeans, both abaxial and adaxial stomata of chamber‐grown plants were more sensitive to low light intensity than were respective abaxial and adaxial stomata of greenhouse‐ or field‐grown plants. In cotton, stomata of chamber‐ and greenhousegrown plants behaved similarly and were considerably more sensitive to low light intensity than were stomata of field‐grown plants. The effect of plant growth conditions may not be uniform for all species. Considerable care should be exercised in making comparisons among species or varieties grown in the field or in different types of controlled environments.
Seed Setting Efficiency in Eight Cultivars of Upland Cotton1
Authors: Turner John H. , Stewart J. McD. , Hoskinson P. E. , Ramey H. H.
Published: July 2010

Seed setting efficiency was determined for six cultivars of Upland cotton (Gossypium hirsutum L.) in 1974 and eight cultivars in 1975 at Jackson, Tenn. The number of ovules per ovary was determined by examining blooms at weekly periods. Simultaneously tagged blooms provided identifiable bolls from each bloom period to determine the number of seeds per boll. Seed setting efficiency (S.S.E.) was calculated from: (seeds/boll ÷ ovules/ovary) in percent

Cultivars differed in ovules/ovary, seeds/boll, and S.S.E. both years. The influence of bloom periods, although significant for ovules/ovary both years, was less than cultivar influence. S.S.E. was also influenced by bloom period in 1974, with lower efficiency at the late bloom period. Cultivar ✕ period interactions were detected for ovules/ovary and seeds/boll in 1974 and for ovules/ovary in 1975.

The combined analysis with six of the cultivars show that cultivars influenced ovules/ovary and seeds/boll far more than years or period of bloom. Year ✕ cultivar and year ✕ period interactions obscured the main effects upon seed setting efficiency.
Inheritance of a Second Trypsin Inhibitor Variant in Seed Protein of Soybeans1
Authors: Orf J. H. , Hymowitz T.
Published: July 2010

Soybean [Glycine max (L.) Merrill] seeds from selfed heterozygous F2 plants of the cross ‘Harosoy’ ✕ P‐I. 246367 and F2 seeds from reciprocal crosses of T245 and P.I. 246367 were analyzed for electrophoretic banding patterns of SBTI‐A2 (Kunitz inhibitor). Harosoy seed has the SBTI‐A2 band at Rf 0.79 (Ti1), T245 at Rf 0.75 (Ti2) and P.I. 246367 at Rf 0.83. Seeds having two bands produced plants in which seeds segregated in a 1:2:1 ratio whether in the F2, F3, or F4 generation. All seed with only one band bred true in the next generation. These data along with data previously reported establishes that three forms of the SBTI‐A2 designated as Ti1, Ti2, and Ti3 are electrophoretically distinguishable from one another by their different Rf values of 0.79, 0.75, and 0.83, respectively. The forms are controlled by a codominant multiple allelic system at a single locus
Root and Shoot Development from Sugarcane Callus Tissue1
Authors: Nadar H. M. , Heinz D. J.
Published: July 2010

Growth of shoots differentiated from sugarcane (Saccharum sp.) callus was enhanced by 5 mg naphthalene acetic acid (NAA)/I in the absence of coconut water, while 0.2 mg 2,4‐dichlorophenoxyacetic acid (2,4‐D)/1 stunted their growth. In the presence of NAA, a crown developed at the base of the shoot on which new shoots and roots developed, grew, and formed a clump of plantlets.

Root growth could also be induced by trimming the leaves or by incubation at 15C for 4 to 6 weeks. Leaf trimming resulted in more vigorous root growth than cold treatment, although clonal differences were observed.

Results indicate that a medium which stimulates differentiation does not necessarily stimulate shoot growth, and the hormonal requirements for shoot differentiation differ from requirements for root induction in sugarcane callus.
Preliminary Study of Pachytene Morphology in a Homozygous Line of Sugarbeet1
Authors: Yu M. H.
Published: July 2010

The morphology of the pachytene chromosomes of a homozygous Beta vulgaris L. line 6600 (2n = 18) was analysed. Observations were made on squash preparations of alcoholic hydrochloric acid‐carmine stained microsporocytes. Interpretation of the sugarbeet pachytene chromosomes was difficult because they failed to spread; nonetheless, the bivalents were distinguishable by the patterns of chromomere distribution. The physical lengths of the nine chromosomes were measured and found to range from 12.4 to 33.7 microns, with a total length of 214.3 microns. Based on the probable centromere positions observed, the complement consisted of three chromosomes with median centromeres and six with submedian. The pattern of chromomere distribution of this species was nonproximal. Information on the pachytene morphology will facilitate cytogenetic analysis of structural variation in the chromosome complement.
Analysis of Genotypic Similarity in Terms of Mean Yield and Stability of Environmental Response in a Set of Maize Hybrids1
Authors: Johnson G. R.
Published: July 2010

An analysis providing full information on hybrid similarity and stability of response to environments is developed and applied to a study of 49 maize (Zea mays L.) hybrids grown at 18 locations. The model provides weighted estimates of hybrid means, coefficients of the regression of each hybrid on an environmental index, and coefficients of the regression of each hybrid on a set of orthogonal residual vectors that are the characteristic vectors of R̂R̂‵ where R̂ is the m ✕ n matrix of estimated deviations from the weighted regressions on the environmental index of n hybrids grown in m environments.

Genotypic similarity was defined as euclidian distance between genotypes in the space whose coordinate axes were the 18 locations. In the analysis, the original data were orthogonally transformed into a space whose coordinate axes were the mean vector, environmental index vector, and the characteristic vectors of R̂R̂‵. By means of the transformation, genotypic similarity, mean differences, relative stability, and comparative stability could all be expressed in terms of a model of the regression of genotypic performance on linear comparisons among environments.

A cluster analysis arranged the hybrids into groups that were differentiable in terms of means and stability. Differences among means was the greatest source of variation among clusters. Variation in stability was due primarily to response to the environmental index and the first characteristic vector of R̂R̂'.
Clonal Propagation of Big Bluestem by Tissue Culture1
Authors: Chen C. H. , Stenberg N. E. , Ross J. G.
Published: July 2010

Callus of big bluestem (Andropogon gerardii Vitman) was induced from 5 to 10 mm segments of young inflorescences cultured on Linsmaier and Skoog (RM) solid medium supplemented with 5 mg of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 0.2 mg kinetin/liter in the dark at 25 C. The callus condition was maintained by subculturing on RM medium supplemented with 5 mg of 2,4‐D/liter. Differentiation of numerous plants from callus occurred on the same basal medium with the 2,4‐D concentration reduced below 2 mg/liter. The plants developed normally if grown under light on RM medium free of hormones. At the two‐leaf stage, the plantlets were transplanted into vermiculite and subsequently to the field or into greenhouse pots with a survival rate as high as 85%.