bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of Some Agronomic Characters in a Cross of Safflower1
Authors: Ehdaie B. , Ghaderi A.
Published: July 2010

Parents, F1, F2, and backcross generations (BC1 and BC2) of a cross of safflower, Carthamus tinctorius L., were planted at two locations in Iran (Safiabad and Ahvaz). Data were collected on yield/plant, heads/plant, seeds/head, seed weight, flowering time, and height. Location effects were either significant or highly significant for all traits except for heads/plant. Generation differences were either significant or highly significant for all traits except for heads/plant and seeds/head. Location ✕ generation interaction was significant only for seed weight. Genetic analysis of the generation means were carried out at each of the two locations for those traits that showed significant differences among generaions. Dominance played a major role in the variation of yield/plant and seeds/head at Safiabad. For the remaining traits at either location, in addition to different degrees of additive and dominance effects, significant interallelic interactions were obtained. The full model analysis for seed weight showed, in addition to highly significant additive and dominance effects, a highly significant additive ✕ location interaction. Dominance ✕ location was not significant for seed weight
Genetic Variability of Leaf Nutrient Concentration in Oil Palm1
Authors: Tan Geok‐Yong , Rajaratnam J. A.
Published: July 2010

The objective of this study was to determine the genetic variation of leaf nutrient concentration of eight elements (N, P, K, Mg, Ca, Mn, B, and Cu) and ash content of oil palm (Elaeis guineensis Jacq.) leaves from 20 single crosses grown in Malaysia. Measurements of general combining ability for both the paternal and maternal lines were significantly different for N, P, and Cu, while only the paternal lines deviated significantly in Mg and ash content. Specific combining ability was significantly different for K, Mg, Ca, and B. High values of narrow sense heritabilities were obtained for N (0.88 and 0.75) and P (0.97 and 0.78) as measured both parental lines, and for Mg (0.85) by parental lines only. Thus, the major portion of the total genetic variances for N, P, and Mg were additive.

Results from phenotypic and genotypic correlations indicated that the concentration of certain nutrients would simultaneously increase or decrease the concentration of other elements in the leaves. Selection for greater N concentration increased the concentration of P and Cu. Increased Ca also increased the concentration of Mg, Mn, and B. However, Mg, Ca, Mn, and B decreased with increasing concentration of K. High positive correlations were found between the concentration of N and P and yield. Further analysis of yield components revealed that N increased yield through weight of bunches, while P influenced yield through the number of bunches produced. Maximum yield could therefore be expected through simultaneous selection for high concentration of N and P in the leaves. The results also suggested that variation attributed to materials with different genetic backgrounds should be taken into consideration in the interpretation of leaf analysis data for fertilizer recommendation.
Maternal Effects on Sugar Content in Soybean Seeds1
Authors: Openshaw S. J. , Hadley H. H.
Published: July 2010

The feasibility of using single‐seed selection to change individual and total sugar content in seeds of soybeans [Glycine max (L.) Merr.] was investigated. In four sets of crosses involving six genotypes, comparisons of F1 seeds with parental selfed seed failed to show a consistent paternal effect. In two crosses, variances of sugar content among F2 seeds were compared to corresponding parental variances, without detecting any significant genetic variation. In the one cross studied on an individual plant basis, the average individual and total sugar content of seeds on F1 plants fell midway between those of seeds produced on the two parents. Comparisons of means of reciprocal F1 plants gave no indication of cytoplasmic effects. Results indicate that selection for sugar content among single seeds would be inferior to selection among individual plants or plant progenies.
Inhibition of Cowpea Seedling Growth by Methionine Analogs1
Authors: Dessauer Dan W. , Hannah L. Curtis
Published: July 2010

The effects of reported methionine analogs on seedling growth of cowpea (Vigna unguiculata L.) were studied. L‐methionine‐DL‐sulfoximine (MS) was the most toxic, followed in order by ethionine, a‐methyl methionine (MM), and norleucine. Application of methionine protected seedlings from the inhibitory effects of ethionine and MM. Simultaneous addition of lysine and threonine in nutrient solution did not inhibit seedling growth, while methionine at 300 ppm was partially inhibitory. Screening of 33,000 M2 seedlings from ethylmethane sulfonate‐treated seeds resulted in the recovery of one plant resistant to ethionine and one resistant to MM. The latter was not viable. Seeds produced from plants grown in nutrient solution plus 200 ppm methionine contained approximately 10% more protein, total methionine, and free methionine in comparison to seeds produced in the absence of exogenous methione.
Empirical Models for the Analysis of Unreplicated Lattice‐Split‐Plot Cultivar Trials1
Authors: Cornelius P. L.
Published: July 2010

“Lattice‐split‐plot“ designs have been devised for the evaluation of a large number, k2. of cultivars, the subplot factor, at several levels of another factor which constitutes the main‐plot factor. Examples of possible mainplot factors are plant density levels or fertilizer treatments. The arrangement of cultivars within a main plot is that of a lattice design, each plot corresponding to a lattice replicate. The experiment may or may not have true replication. If not, a regression model which describes cultivar response to the main‐plot factor is used to make error estimable and adjustment for lattice blocks possible. This paper describes techniques for obtaining an empirical model in the event that the appropriate choice of a parametric model is unknown. These techniques, most of which use a principal components approach, are illustrated for an example of an unreplicated 7 X 7 lattice‐split‐plot experiment in which 49 maize (Zea mays L.) cultivars are evaluated with four plant‐density levels as main plots. Six empirical models were found for which results of analyses agreed closely with results obtained using what is believed to be the appropriate parametric model.
Photosynthate Partitioning in Sugarbeet1
Authors: Snyder F. W. , Carlson G. E.
Published: July 2010

Partitioning of photosynthate to various parts of a crop has a marked influence on economic yield. We used the sugarbeet (Beta vulgaris L.) to investigate quantitatively the effect of this partitioning on growth. Plants were grown for 21 days in the growth chamber. Partitioning was measured indirectly by using the Taproot‐ Leaf Weight Ratio (TLWR), where TLWR = Taproot fresh weight + Leaf lamina fresh weight. Our objectives were to study the pattern of variability of TLWR within and among sugarbeet breeding lines and hybrids, the effect of selection on TLWR, and the detectability of differences in TLWR at various stages of vegetative development.

In selection studies, seedlings with the lowest and highest TLWR 21 days from emergence were selected for polycross seed production. Progenies of two cycles of selection were tested. Ontogeny of TLWR was followed for 21 days from emergence.

Populations differed significantly in mean TLWR. Within unselected populations, TLWR of individual seedlings varied more than twofold among some of the 24 breeding lines and hybrids examined. In the first cycle of selection in line EL 40, mean TLWR of the high‐ TLWR parents was 83% greater than that of the low, and progenies from the high TWLR selections differed from the low by 38%. In the second cycle, the parents differed by 118% and the progenies by 60%. The responses observed in the two cycles of selection indicate that TLWR is genetically controlled.

During the 21 days from emergence, the TLWR was high at 3 days, the first measurement, decreased more than fivefold to a minimum near 15 days, and then increased gradually thereafter. TLWR is not correlated with taproot weight and only slightly correlated with leaf lamina weight at 21 days.
A Comparison of Early Generation (F3) Yield Testing and Pedigree Selection Methods in Triticale1
Authors: Salmon D. F. , Larter E. N. , Gustafson J. P.
Published: July 2010

During the summer of 1974, four F3 populations of hexaploid triticale (X Triticosecale Wittmack) were evaluated for yield in an F3 yield nursery and concurrently in a head‐row nursery. Ten high‐yielding, 10 lowyielding, and 10 randomly sampled lines along with 10 lines selected visually for yield in the head row nursery were retained for further evaluation. Lines from each of the four selection groups in each population were bulked and compared in a 10‐replicate yield trial at Obregon, Mexico, during the winter of 1975‐76. The analyses indicated that no significant differences existed between bulks produced from high‐yielding lines selected by the early generation yield trial and the head row nursery. Both yield trial and head row bulks were superior in yield to the bulk of randomly sampled lines at all locations. The present results indicate that pedigree selection and early generation yield testing procedures are equally efficient methods for yield selection in triticale.
Epicuticular Wax Ultrastructure Among Lines of Eragrostis lehmanniana Nees Developed for Seedling Drouth Tolerance1
Authors: Hull Herbert M. , Wright L. Neal , Bleckmann Charles A.
Published: July 2010

Leaf surface ultrastructure was studied on seven lines of Lehmann lovegrass, Eragrostis lehmanniana Nees. These were selected from 36 experimental lines that had previously exhibited a wide range of seedling drouth tolerance. They included four of the most drouth‐tolerant lines and three that were drouth susceptible. Electron microscopy revealed that leaves of all lines were covered with a basic type of epicuticular wax structure, consisting of small crystalline bodies in combination with various types of ribbons and tubes. Presence of the large wax plates were unique on leaf surfaces of drouth‐tolerant lines. The plates were never found on the drouth susceptible lines. Investigation by transmission electron microscopy suggested that the plates were situated horizontally on top of the smaller aggregates, but subsequent examination by scanning electron microscopy revealed that they were oriented vertically to the leaf surface. The wax morphology could serve as a valuable characteristic for selection of germplasm for seedling drouth tolerance and associated responses among Eragrostis sp. and other arid grassland species.
Delaying Flowering of Grain Sorghum Lines for Hybrid Seed Production1
Authors: Trybom J. C. , Vanderlip R. L. , Moore W. A.
Published: July 2010

A problem facing producers of hybrid grain sorghum, Sorghum bicolor (L.) Moench, seed is using lines that have different flowering times. This study compared flaming, clipping, and applying a contact herbicide as methods to delay flowering. Two pollinator and two male‐sterile lines were treated at the three‐leaf stage, five‐leaf stage, or both. Generally, flaming and clipping produced similar delays; applying a contact herbicide produced significantly less delay. Flaming or clipping at the three‐leaf stage or five‐leaf stage produced 3 to 8 days delay at Manhattan and 2 to 6 days delay at Hutchinson, Kansas. Treating the plants twice resulted in the greatest delay using all three methods at both locations.
Gene Effects on Kernel Moisture and Sugars of Near‐Isogenic Lines of Sweet Corn1
Authors: Soberalske R. M. , Andrew R. H.
Published: July 2010

Numerous genes affect carbohydrate composition of the endosperm of corn (Zea mays L.). The objective of this study was to measure the effect of 10 gene combinations on level, rate of change, and interrelationships of kernel moisture and sugars during the first 4 weeks after pollination as influenced by the modifier complexes of seven adapted sweet corn inbreds. Four genes influencing endosperm carbohydrates, dull (du), sugary‐2 (su2), waxy (wx), and shrunken‐2 (sh2), and one double combination (du wx), each in association with the sugary‐1 alleles (Su1 and su1), were incorporated into adapted sweet corn inbreds to give seven near‐isogenic series. Determinations were made of moisture, reducing sugars, sucrose, and total sugars at four successive harvests. The sh2 gene, and to a lesser extent the du wx combination, show promise for improved kernel moisture and total sugars and for reduced rates of loss of these components as compared to sweet corn presently in use (su1) for processing. In view of the marked differences in the expression of these genes in the inbreds studied here it is desirable to incorporate them into a broad range of germplasm in a search for modifiers that will further improve and utilize their potential in hybrid combinations.
Selection of Safflower for Tolerance to Temperature and Humidity Stress During Flowering1
Authors: Zimmerman L. H.
Published: July 2010

Safflower (Carthamus tinctorius L.) was exposed to temperature and humidity stress in the greenhouse and parameters were developed to evaluate response to this stress in segregating populations. The rank for seed yield of the cultivars (‘N4051’, ‘Pacific 1’, ‘Rio’, and ‘Gila’,) exposed to temperature and humidity stress in the greenhouse was similar to that obtained in a previous study using controlled environment chambers. A fertility index (FI) measuring number of seed per unit of head area of the primary head was closely associated (r = 0.90) with actual fertility, number of aborted ovaries, and seed number. FI was a rapid method of evaluating response to humidity and temperature stress in populations segregating for head size and seed number per head.

In a cross between Pacific 1 (tolerant to humiditytemperature stress) and Rio (much less tolerant), FI of the F1 was not significantly different from the midparent. In mean generation analysis using an additive dominance model, the observed FI means for the P1, P2, F1, F2, B1, and B2 generations were highly significantly different from the expected generation means, suggesting mostly epistatic gene action. There was response to divergent selection for FI in the F2 generation; the means of the F3 bulks for low and high FI selection were significantly different (0.005 > P > 0.001).
Inheritance of Protein and Yield of Grain and Stover in Maize1
Authors: Pollmer W. G. , Eberhard D. , Klein D.
Published: July 2010

Ten flint and nine dent inbred lines of maize (Zea mays L.) comprised the parental material. Four flint and four dent lines were selected for high protein percentage in the grain and good general combining ability (GCA) for agronomic traits, whereas the remaining 11 lines were selected for good GCA for agronomic traits only. The resulting 90 flint ✕ dent hybrid combinations were evaluated at two locations. Data were recorded on percent protein and protein yield of grain and stover, grain and stover yield, percent dry matter in the ear, and 1,000‐kernel weight. In the materials under study, mean squares due to GCA and specific combining ability (SCA) were significant for all traits. Genotype ✕ environment interactions involving both GCA and SCA were generally significant. Percent protein in the grain showed the highest GCA/SCA ratios, indicating that additive gene action relative to non‐additive gene action was more important in its inheritance than for the other traits. Lowest GCA/SCA ratios were observed for grain yield and protein percentage in the stover. As a result of simultaneous selection for high protein percentage in the grain and GCA for agronomic traits, the inbred line that revealed the highest positive GCA effect for protein percentage in the grain was also a significantly good general combiner for grain yield. No association was observed between percent protein in the grain and grain yield.
Recurrent Selection for Changing Gene Frequency of Germination Rate in Blue Panicgrass1
Authors: Wright L. Neal
Published: July 2010

Genotypes of blue panicgrass, Panicum antidotale Retz, with extreme rates of germination were isolated through succeeding cycles by recurrent phenotypic selection with restricted intercrossing by random mating. The number of days required to germinate 50% of the seed was used to estimate rate of germination. Daily germination data were used to determine germination rate estimates by the Regression Index (RI) method. Genetic variability was evident in each cycle of selection. The frequency of desired genotypes for rate of germination increased through the sixth cycle. The estimated number of days required to germinate 50% of seed of the sample in the sixth cycle was 5.5 days (range 0.4 to 8.3) for the fast rate of germ. ination and 13.8 days (range 8.0 to 32.3) for the slow rate of germination. Results indicate that phenotypic recurrent selection can effectively shift the frequency of genes affecting germination rate in blue panicgrass.
Pod Development Period in Cowpeas: Varietal Differences as Related to Seed Characters and Environmental Effects1
Authors: Wien H. C. , Ackah E. E.
Published: July 2010

Yield production in grain legumes is governed by the length of the reproductive period which in turn depends on the time from anthesis to maturity of individual pods (pod development period). To determine genetical and environmental effects on pod development period (PDP) in cowpea (Vigna unguiculata L. Walp.), individual flowers were tagged at anthesis and the time to pod maturity noted in several experiments. In two field experiments, PDP of 91 and 65 cowpea lines, respectively, varied from 17 to 24 days, and was positively correlated with seed weight. Long PDP was also associated with rough seed‐coat texture. Dry matter accumulation by individual pods of three cultivars differing in PDP determined in a pot experiment showed differing durations of pod and seed growth. Altering temperature of individual pods by covering with black or white cloth sleeves demonstrated the temperature dependence of PDP.
Natural Selection in a Bulked Hybrid Population of Upland Cotton1
Authors: Quisenberry J. E. , Roark Bruce , Bilbro J. D. , Ray L. L.
Published: July 2010

A bulked hybrid population of upland cotton (Gossypium hirsutum L.) was grown without artificial selection for 10 generations in a nonirrigated, semiarid nursery at Lubbock, Texas. In 1972 and 1976, seeds from all generations were grown in replicated tests to estimate the effects of natural selection on several traits in the population and to compare the responses of seed trait to the more vauable traits of lint yield and fiber quality. Traits measured were seeds/m, seeds/boll, seed size, lint yield, fiber length, strength, and micronaire. Data were evauated by anaysis of variance and regression techniques. Seeds/m, lint yield, and coarseness of the fiber increased while seed size and fiber strength decreased over the 10 generations. Significant differences were not detected for seeds/boll or fiber length. Bulk population breeding appeared to be a useful method for improving climatic adaptation of upland cotton in environments where moisture is limiting.
Factors Associated with Differential Response of Two Oat Cultivars to Zinc and Copper Stress1
Authors: Brown J. C. , McDaniel M. E.
Published: July 2010

Oat (Avena byzantina C. Koch) cultivars ‘TAM 0‐312’ (Fe‐inefficient and Ca‐efficient) and ‘Coker 227’ (Feefficient) were subjected to Zn and Cu stresses to determine consequent effects on Fe and Ca nutrition in the two cultivars. To induce Zn and Cn stress, the plants were grown in low‐Zn Taunton and Shano soils, and in low‐Cu limed Bladen soil. Under zinc stress, Coker 227 used Fe more efficiently than TAM 0‐312. TAM 0‐312 tops contained 3600 µg/g (dry wt) more Ca than comparable Coker 227 tops and this higher Ca seemed to enhance both Fe‐ and Zn‐deficiency symptoms in TAM 0‐312. Top leaves of Cu‐stressed TAM 0‐312 contained 4300 µg/g (dry wt) more P than comparable Coker 227 leaves. This Cu‐deficiency stress induced accumulation of phosphate seemed to inactivate Ca in TAM 0‐312, causing ‘withertip’ to develop. Coker 227 did not develop ‘withertip’ symptoms. Ca‐efficiency did not alleviate Cu‐inefficiency in TAM 0‐312.
Neutralizes and Pesticides and their Sequence of Application to Acid‐delinted Cottonseed: Effects on Germination, Stand, and Verticillium Wilt of Cotton1
Authors: Minton Earl B.
Published: July 2010

Neutralizing acid residues on cottonseed after HCl delinting contributed to seedling emergence and survival in field plantings and emergence in greenhouse plantings, but not necessarily to survival in the greenhouse where seedling diseases were severe or to germination in the laboratory. Similar results were obtained with an experimental neutralizer (EN) and the standard neutralizer (NH3) used alone or in combination with fungicides and the insecticide, disulfoton. The percentage of plants with foliar symptoms of Verticillium wilt was reduced by the neutralizers and pesticides. Decrease in wilt symptoms was related to increased plant populations. Percentage germination, emergence and survival of seedlings and Verticillium wilt were similar when EN and pesticides were applied simultaneously or sequentially. Use of EN can eliminate ammonia and ammonium chloride pollutants currently associated with acid delinting of cottonseed.
Variation in Seed Quality Characteristics of Tropically Grown Soybeans1
Authors: Paschal E. H. , Ellis M. A.
Published: July 2010

Twenty‐four soybean [Glycine max (L.) Merr.] collections were grown in two different seasons in Puerto Rico to determine the extent of variation in the incidence of seed infection by fungi and its effect on seed viability under tropcal conditions. Plants were harvested at maturity and 2 and 4 weeks after maturity to provide seed samples that were used to determine the incidence of total fungi, incidence of Phomopsis sp., sand emergence, and field emergence. Yield and other agronomic characters were determined from the plants that were harvested at maturity. The 2‐week harvest delay reduced sand emergence and field emergence 7 and 14%, respectively. The 4‐week harvest delay reduced sand emergence and field emergence 12 and 37% respectively. The incidence of fungi increased from 9% in the seed examined at maturity to 21% in the seed from the 2‐week delayed harvest and 45% in the seed from the 4‐week delayed harvest. The incidence of Phomopsis sp. exhibited a similar trend. Substantial genetic varation was encountered for the seed quality characters measured. Field emergence percentage was negatively correlated with the incidence of total fungi, the incidence of Phomopsis sp., seed size, and seed quality score. Many of the strains with superior seed qualty were from Southeast Asia where environmental conditions are not conducive to production of high quality seed.
Differential Responses of Guinea Grass Populations to Drought Stress1
Authors: Klar A. E. , Usberti J. A. , Henderson D. W.
Published: July 2010

A study of drought stress was carried out on three guinea grass (Panicum maximum Jacq.) populations having three different levels of genetic variability; the most variable reproduces sexually. Three preconditioning treatments were used. In the wet treatment, plants were watered daily; in the medium, when soil water potential (ψs) reached about —1.0 bar (18 drying cycles); and in the dry when ψs reached about — 15 bars (eight drying cycles). For all three populations, drought‐preconditioned plants had significantly lower leaf water potentials (ψL) and relative water contents (RWC) than daily‐watered plants when turgor pressure reached zero during a drying cycle. Additionally, ψL values for stomatal closure (threshold ψL) were lower for the dry and medium treatments than for the wet one. Adaptability to drought was measured in terms of stomatal closure and forage production under stress conditions. Populations with intermediate to high levels of genetic variability performed best in relation to drought adaptability and forage production. Threshold leaf water potential appeared to be useful in selecting new germplasms for drought resistance. The variable populations might therefore allow improvement of forage production by breeding under water stess conditions.
Effects of Alien Cytoplasms on Agronomic and Bread‐Making Traits of Two Spring Wheat Cultivars1
Authors: Busch R. H. , Maan S. S.
Published: July 2010

The genomes of ‘Chris’ and ‘Selkirk’, two hard red spring wheat (Triticum aestivum L.) cultivars, were substituted into the cytoplasms of Triticum macha L., T. dicoceoides Korn, Aegilops squarrosa L., Ae. cylindrica Host., Ae. ventricosa Tausch, and Ae. juvenalis Thell Eig by repeated backcrossing to produce ailoplasmic lines. T. mocha, T. dicoccoides and Ae. squarrosa cytoplasms generally did not greatly affect the agronomic or breadmaking quality traits studied. Ae. cylindrica, Ae. ventricosa, and Ae. juvenalis cytoplasms reduced yields although the plants appeared relatively normal. Ae juvenalis cytoplasm differed from Ae. squarrosa, Ae. cylindrica, and Ae. ventricosa cytoplasms by causing larger yield reductions. The hypothesis that Ae. squarrosa contributed the cytoplasm as well as the D‐genome to Ae. cylindrica and Ae. ventricosa but not to Ae. juvenalis appears to be supported by these results. T. mocha, T. docoecoides, and Ae. squarrosa cytoplasms may be useful sources of cytoplasmic variability for broadening the genetic diversity of wheat.
A Simulated Selection Experiment in Sugarcane1
Authors: Lyrene P. M.
Published: July 2010

Two objectives of the experiment were: 1) to estimate the probability that the best clones in the test would be retained in selection at various intensities for stalk diameter, stalk length, stalk number per plant, and Brix in single‐stool sugarcane (Saccharum L.) cultivar tests; and 2) to see if subpopulations obtained by selection were superior to the unselected population. Twenty randomly selected sugarcane seedlings from the Florida cultivar development program were clonally propagated by single‐bud cuttings and transplanted to an 18‐block field test with a single plant of each clone per block. The following were later determined for each plant: stalk diameter, stalk length, stalk number per plant, and Brix. Within each block, the 20 plants were ranked for each of the four traits. The ranks were than used to simulate selection within each block at the 5, 10, 15, … 100% levels for each trait. In addition, means for each clone over all blocks were obtained and ranked. In selection at the 5% level (selection of the one best plant per block) the plant of the clone with the best overall mean was retained in 50%, 31%, 28%, and 36% of the blocks for stalk number, Brix, stalk length, and stalk diameter, respectively. For each trait, stringent selection yielded subpopulations averaging better than the unselected population. As we would expect because of environmental variation, some clones that averaged good over all blocks did poorly in one or more individual blocks. It was less common for clones with poor averages over all blocks to excel in an individual block. It was concluded that the population improvement possible with single‐plant sugarcane selection warrants increased use of single‐plant tests.
Symbiotic N2(C2H2) Fixation by Bean1
Authors: Westermann D. T. , Kolar J. J.
Published: July 2010

The response of bean (Phaseolus vulgaris L.) to N fertilization under field conditions indicates different Rhizobia‐cultivar relationships or symbiotic N2‐fixation limitations due to the cultivars. We have used the acetylene reduction method to determine the relative seasonal N2(C2H2) fixation of several field‐grown bean cultivars. The relative nitrogenase activity was estimated from 8‐ ✕ 15‐cm soil cores taken around the main root of a decapitated plant. Activities rapidly increased from the three‐node vegetative (V3) to early pod‐filling (R3‐R4) growth stages, thereafter decreasing to zero at physiological maturity (R9). Accumulated daily activity totals showed a five‐ to sixfold difference in seasonal N2(C2H2) fixation between cultivars, which was significantly related to the average nodule weight and to the plant dry weight near physiological maturity. However, cultivars with similar plant dry weights had a two‐ to threefold difference in relative N2(C2H2) fixation. Seed yields and total‐N uptakes were also positively related. These observations indicate that it may be possible to increase both the symbiotic N2 fixation and seed yields through plant breeding.
Comparison of Cyanogenesis in Four Sources of White Clover Plants1
Authors: Knight W. E. , Gibson P. B. , Cope W. A. , Miller J. D. , Barnett O. W.
Published: July 2010

Four sources of the cyanogenesis‐conditioning genes Ac and Li were developed, two from intermediate types and two from ladino types of white clover (Trifolium repens L.). Field plantings of both phenotypes from the four sources were grown at Clemson, S.C.; Blacksburg, Va.; Raleigh, N.C.; and Mississippi State, Miss, to compare the performance of plants that evolve hydrocyanic acid (HCN) and plants that do not evolve HCN.

Genetic sources differed in almost all characters studied at all four locations. This was expected since each source represented a different genetic base. At Clemson and Raleigh no association was found between HCN‐release phenotype and plant performance. However, slug (Limax spp.) damage was higher in acyanogentic than in cyanogenetic plants at Blacksburg, and insect and disease damage was higher in acyanogenetic than in cyanogenetic plants from one source at Mississippi State.

Frost damage and rabbit (Sylvilagus floridanus) feeding were greater in taller, more rapidly growing plants and were not associated with HCN‐release phenotype. The taller plants may have been more palatable and succulent due to more rapid growth; therefore, they might be preferred by rabbits and be more susceptible to frost damage.

Our results suggest that further studies, longer, and with larger populations are needed to justify a decision to breed either for plants that evolve HCN or for those that do not.
A Modified Transplanter For Establishing Space‐Planted Nurseries1
Authors: Engelke M. C. , Naivar J , Davis J. , Smith R. R.
Published: July 2010

Mechanical transplanters reduce labor requirements while providing uniform planting depth, consistent water supply to, and uniform soil compaction around each transplant. However, commercially available machines are not designed to plant in a grid pattern that would permit cross cultivation. Therefore, we adapted the check planting system to a commercially available transplanter. Using this modified mechanical transplanter, we could establish nurseries in a uniform grid pattern, permitting cross cultivation for mechanical weed control and nursery maintenance. This system reduces the hours of hand cultivation by about 60% and expedites establishment of the nurseries.
Effects of Natural Selection and the Relationship of Leaf Traits with Yield in Hard Red Spring Wheat Crosses1
Authors: Cregan P. B. , Busch R. H.
Published: July 2010

The F2 through F4 bulks of five crosses between adapted hard red spring wheats (Triticum aestivum L.) were grown in solid‐seeded competitive conditions for 3 years in two contrasting environments. One environment (East) was characterized by conditions which imposed relatively infrequent moisture stress and the other (West) in which moisture stress was common. The five East derived bulks (East Bulks), the five West derived bulks (West Bulks), and 25 Foderived lines from each bulk (East and West Lines) were evaluated for yield and other characteristics for 2 years at East and West sites to detect possible differential natural selection. The mean yield of the West Bulks was significantly greater than yield of the East Bulks at the West test site, while East and West Bulks yielded similarly at the East site. No differences, however, were detected between the mean yields of East and West Lines over crosses at either site. Short term natural selection failed to aid in the extraction of more adapted lines. In two crosses segregating for photoperiod reaction, the West Lines had a significantly greater proportion of insensitive genotypes than expected. Evidently natural selection favored insensitive types in the more droughty West environment. Stomatal frequency, stomatal diffusion resistance, and other leaf characteristics were measured in the East environment to determine if any leaf trait measured in the East was indicative of yield in the more droughty West conditions. No consistent relationships were noted between the yield of lines in the West and any leaf characteristics or combination of characteristics in the East.
Genetic Male‐Sterility in Red Clover1
Authors: Taylor N. L. , Kitbamroong C. , Anderson M. K.
Published: July 2010

The inheritance of a male‐sterile condition in red clover (Trifolium pratense L.) was determined. Appropriate crosses were made onto a male‐sterile clone, 740, and onto clone 66 which possessed a previously identified malesterile gene (ms1). Segregations for male‐fertility and male‐sterility were observed in the following generations: F1, generation, F1 and F2 testcrossed to respective parent clones and F1's, F2 generation from sib‐mated F1's and sib‐mated F2's. All ratios observed indicated a second single recessive gene was responsible for male‐sterility in clone 740. This locus was apparently independent from in ms1, of clone 66 and also from the incompatibility factors (S‐alleles). Accordingly, this locus was designated ms2 to distinguish it from ms1. The two loci (ms1 and ms2) interacted in the sib‐mated F2 generation to give a duplicate recessive epistatic type of gene action as indicated by a 9:7 ratio.
Effect of Inoculation with Azospirillum and Azotobacter on Tuff‐type Bermuda Genotypes1
Authors: Baltensperger A. A. , Schank S. C. , Smith Rex L. , Littell R. C. , Bouton J. H. , Dudeck A. E.
Published: July 2010

Eight selected bermudagrass (Cynodon dactylon L. Pers.) genotypes were inoculated with a mixed culture of the N2‐fixing bacteria, Azospirillum and Azotobacter, to determine plant growth response to inoculation under greenhouse conditions. Top, crown, and root growth and N content were measured. At low N fertility, top growth was increased 17% as a result of inoculation. Inoculation also resulted in increased total N accumulation in the top growth. Crown and root growth was not increased by inoculation and total dry weight of all plant parts was not significantly increased. The high fertility treatments gave significantly higher clipping yields, as expected, but no significant differences were observed between the inoculation treatments. No leaf color differences were observed as a result of inoculation. Bermudagrass genotypes were not significantly different in response to inoculation treatments.
Germination Stimulation of Kentucky Bluegrass Seed Permeated with Plant‐Growth Regulators Dissolved in Acetone1
Authors: Phaneendranath Bangalore R. , Funk C. Reed
Published: July 2010

Freshly harvested Kentucky bluegrass (Poa pratensis L.) seed generally fail to germinate rapidly. Such seed germinate poorly under warm temperatures. The objective of this study was to permeate seeds with vartous plant‐growth regulators and determine their effects on speed and total germination under favorable and unfavorable conditions. Freshly harvested ‘Merion’ and ‘H.1’ Kentucky bluegrass seed were used in this study. Samples of seed were soaked for 1 hour in acetone containing gibberllic acid (0.5 mM), kinetin (0.1 mM), ethephon (500 ppm), abscisic acid (0.04 mM), or fusicoccin (25 ppm) alone, or in various combinations. Seeds were vacuum‐dried after treatment.

In both laboratory and greenhouse studies, permeation of gibberellic acid alone, or in combination with kinetin and/or ethephon dissolved in acetone, generally increased the speed and/or total germination. At a sub‐optimal temperature, none of the treatments was effective in improving germination. At supra‐optimal temperature, germination of the control was almost completely inhibited. Kinetin and ethephon by themselves or in combination did not improve the germination. Gibberellic acid, on the other hand, by itself or in combination with kinetin and/or ethephon, improved germination significantly.
Vegetative and Grain‐Filling Periods of Growth in Barley1
Authors: Rasmusson D. C. , McLean I. , Tew T. L.
Published: July 2010

Nine barley (Hordeum vulgare L.) cultivars and five populations obtained from intercrosses among them were used to study duration of the vegetative and grain‐filling periods. Identifying and characterizing the variation that may exist is an essential first step in determining if higher grain yield gains can be obtained by optimizing the duration of the vegetative and grain‐filling periods.

Nine cultivars representing three distinct types spent 25, 33, or 39% of their growth cycle in grain filling when grown in field environments. The nine cultivars maintained about the same ranking in five field environments; however, the ranking was different in the growth chamber, and the proportion of time in grain filling was greater than that in the field. Estimates of heritability (parent‐progeny and variance component methods) were high for duration of the vegetative period. Estimates were low for the grain filling period when based on a single plot (parent‐progeny method), but relatively high when based on means of replicated plots (variance component method). Correlations between the two growth periods and between them and days to maturity suggest that selection aimed at optimizing duration of the two growth periods and days to maturity would be hindered, but not precluded by the associations. However, we recommend that more information be obtained about the relationship between effective grain filling and duration of the growth periods before substantial breeding work is done.
Response of Pearl Millet Inbreds and Hybrids to Inoculation with Azospirillum brasilense1
Authors: Bouton J. H. , Smith Rex L. , Schank S. C. , Burton G. W. , Tyler M. E. , Littell R. C. , Gallaher R. N. , Quesenberry K. H.
Published: July 2010

Plant yield and acetylene reduction were measured on six hybrids and 15 inbreds (including the hybrid parents) of pearl millet, Pennisetum americanum (L.) K. Shum., after field inoculation with Azospirillum brasilense, Sp 13t (reclassified from Spirillum lipoferum Beijerinck). During the first year of testing, inoculation responses were investigated among all plant genotypes by measuring plant dry weight, % N, total N, and acetylene reduction activity. A smaller population of genotypes were tested a second year for repeatability of inoculum response. The first year, one hybrid, Tift 23DA ✕ Tift 186 (‘Gahi 3’), gave significantly higher plant dry weight and total N in response to inoculation. Inoculated Gahi 3 produced 31.7% more dry weight and 37.4% more total plant N when compared to autoclaved inoculum controls. No inbred was found to respond. Acetylene reduction values were low among all genotypes (range 0.54 nmole/[g dry root ✕ hour] and did not support yield effects or confirm inoculum treatments. Inoculation responses were found to be repeatable for all genotypes tested during the second year (positive or negative) but not of a statistically significant magnitude. Of the genotypes tested both years, a combined analysis of the 2‐year yields revealed significant dry weight increases after inoculation of 19.2 and 14.0% with Gahi 3 and the inbred, Bil 3B, respectively. Again, acetylene reduction values did not explain any data. A N balance study was conducted in greenhouse containers on inoculated Gahi 3 plants in an attempt to repeat the yield differences observed in the field and to monitor inputs of N into the soil‐plant system. No significant yield increase of N into the soil‐plant system was found due to inoculation. Sampling error possibly negated an accurate measurement of all N.
Estimation of Outcrossing Rates: Some Alternative Procedures1
Authors: Jain S. K.
Published: July 2010

Several alternative methods of estimating natural outcrossing rates are reviewed in order to emphasize their genetic and statistical features. The methods range from the standard procedure of counting outcrosses in the progeny of recessive genotypes grown mixed with the dominants to the estimation of genetic structure of natural populations and measures of inbreeding depression. Examples are cited from our recent work in wild oats (Avena fatua L. and A. barbata Pott ex Link), barley (Hordeum vulgare L.), and meadowfoam (Limnanthes alba Hartw.), and from several recent publications in crop science literature. Formulae giving correct estimators for the various methods are included as a handy reference. Use of the variety of procedures frequently available within the context of ongoing plant breeding research will enrich the interface between population genetics and plant breeding.
Hop Yield Stimulation by Triploid Males Under Field Conditions1
Authors: Haunold Alfred , Nickerson Gail B.
Published: July 2010

Triploid male hops (Humulus lupulus L.) have the potential for yield stimulation of diploid female cultivars without excessive production of unwanted seeds, as shown from earlier hand‐pollination experiments during the 1972 and 1973 growing seasons. However, confirmation of these data from commercial field testing of triploid pollinators was still needed before specific pollinators could be recommended to growers.

Twelve triploid male hop genotypes were field‐tested or cone yield stimulation in a commercial seedless‐hop production area. Cone yields of a 6.8 ha field of ‘Brewer's Gold,’ a diploid cultivar, pollinated by triploid males averaged 30% higher than those of an untreated 12 ha control field nearby. The α‐acid content in the cones from the two fields did not differ significantly. However, production of α‐acid, which is the desired product, was substantially higher for the field pollinated by triploid males due to higher cone yields. Seed‐set due to triploid males averaged 4% compared to the 2% background seed‐set of the control. Females in the immediate vicinity of triploid pollinators showed substantial cone‐size and weight stimulation. There were significant differences in seed production of Brewer's Gold plants fertilized by different triploid pollinators, reflecting variation in synchronization of flowering with Brewer's Gold, as well as differences in amount of pollen production among males. Seeds from the triploid‐pollination treatment averaged about half the weight of seeds from the control yard. In another experiment, seeds from hand‐pollination of diploids with triploid males contained about 25% fewer lipids and 14% less crude protein than those from pollination by diploid males involving the same female test plant.

Commercial use of triploid pollinators in seedless‐hop production areas would probably result in a seed content of 2 to 3% and a cone‐yield increase of 15 to 25%, accompanied by a corresponding increase in α‐acid production per ha. Eight triploid males were identified as suitable Brewer's Gold pollinators under Oregon conditions.
Regression Equations for Rate of Soybean Hypocotyl Elongation by Using Field Data1
Authors: Knittle K. H. , Burris J. S. , Erbach D. C.
Published: July 2010

To identify limiting factors for soybean (Glycine max (L.) Merr.) hypocotyl elongation rate under field conditions, regression equations were obtained from data collected entirely in the field for cultivar ‘Wayne’. Seedling samples were excavated, and hypocotyl lengths were measured periodically from early seedling growth until 50% emergence. Soil factors measured were temperature, moisture percentage, and resistance. A soil cone penetrometer for measuring soil resistance was developed. Soil moisture percentage and temperature were used as independent variables in a predictive equation for hypocotyl elongation rate during seed germination and initial stages of hypocotyl elongation. Subsequent (> 1 cm) hypocotyl elongation was predicted with soil resistance, temperature and hypocotyl length as independent variables. The identification of soil resistance as a significant factor affecting hypocotyl growth under field conditions explained differences between the equations developed in this study and those obtained previously in a minimal resistance medium.
Regeneration of Plantlets from Callus Cultures of Indiangrass1
Authors: Chen C. H. , Lo P. F. , Ross J. G.
Published: July 2010

Plantlets were regenerated through organogenesis from the callus cultures of 10 agronomically superior genotypes of Indiangrass (Sorghastrum nutans L Nash). Callus was first initiated from segments of young inflorescences explanted on RM medium supplemented with hormonal combinations of 5 or 10 mg 2,4‐D and 0 or 0.2 mg kinetin/liter. Plantlets were then induced from the calluses by subculturing on RM medium with kinetin omitted and 2,4‐D reduced below 1 mg/liter. Of the media tested, callus grew best on RM medium supplemented with 5 mg 2,4‐D and 0.2 mg kinetin/liter. Differential responses to the morphogenetic induction medium were noted among the 10 genotypes tested.
Effects of Microwave Heating on Thioglucosidase Activity in Intact Seeds of Crambe1
Authors: Lessman K. J. , Kirleis A. W.
Published: July 2010

Depodded (silicles removed) and podded seeds of ‘Meyer’ crambe (Crambe abyssinica Hochst.) were subjected to microwave (2450 MHz) heating in a Litton 500 or 850 commercial oven for periods varying from 70 to 270 sec to explore the feasibility of using microwave heating as a means of thioglucosidase inactivation. Individual seeds and samples of ground seeds, from microwave treatments, were assayed for free glucose, a product of enzymatic hydrolysis of the glucosinolate present in the seeds of the Cruciferae. Microwave heating was most effective for thioglucosidase inactivation in the Litton 850 and when seed samples were not stationary during exposure. The efficiency of microwave heating on enzyme inactivation in the Litton 850 ranged from 94 to 100% on a single seed basis. The fatty acid composition of the extracted oil and amino acid profile of the defatted crambe meal protein were not altered by microwave heating.
Evaluation of Factorial Partial Diallel Crosses1
Authors: Dhillon B. S. , Singh Joginder
Published: July 2010

Factorial partial diallel crosses with s = 12 and 7 (s is the number of crosses per parent) and n = 20 (n the number of parents) were sampled from a diallel cross of 190 F1 hybrids, reciprocals bulked, in maize (Zea mays L.), that was evaluated in four environments, represented by two years at two locations. Randomized block designs with four replications were used. Data were recorded on grain yield, plant height, ear height, days to 75% silking, grain moisture at harvest, ear length, ear diameter, and number of kernel rows. In comparison to the full dlallel, partial diallel crosses showed an increased standard error of general combining ability effects, and some inconsistencies in variance estimates which were more frequent at the lower level of s (s = 7) and for the characters with lower heritability (grain yield and ear length). These fluctuations were, in general, more common for those sources of variation that accounted for relatively smaller magnitudes of variability. The results obtained from the partial diallel analyses were, however, on the whole, reliable, and it is proposed that the study of the characters with low heritability such as grain yield should be supplemented by the traits which have, in general, high heritability, and that the experiments be repeated over environments.