bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetics of Vegetative Stand Establishment Characters in Reed Canarygrass Clones1
Authors: Casler M. D. , Hovin A. W.
Published: July 2010

The objectives of this study were to evaluate characters related to vegetative stand establishment of reed canarygrass (Phalaris arundinarea L.), their heritabilities, interrelationships, and responses with plant age. Characters were evaluated for 22 clones and 12 full‐sib families grown in the field and included plant height, plant maturity, axillary shoot length, and node diameter. Vegetative stand establishment characters evaluated in the greenhouse included percentage of rooted nodes (RN%) and number of adventitious roots produced per node (R/N). In the field, chopped culms were covered with soil to determine number of plants produced per culm, number of plants produced per fresh weight of culms (P/W), percentage of nodes establishing plants, and number of tillers per plant (T/P). Axillary shoot length (SL) was measured on plants grown in four environments and all other characters were measured on plants grown in two environments.

Narrow‐sense heritabilities of R/N, RN%, P/W, and T/P were estimated by midparent‐progeny regressions and ranged from 0.36 to 0.78. Broad‐sense heritability estimates ranged from 0.53 to 0.79 based on clones and 0.65 to 0.79 based on full‐sib families.

Comparisons among previously established clonal classes of vegetative stand establishment capacity were significant for R/N. Mean R/N was significantly higher for clones classified as high compared to clones classified as intermediate and was lower for eiones classified as low compared to all other clones. Mean R/N and RN% were highly correlated (r = 0.85; P < 0.01), but variation among clonal classes for RN% was nonsignificant. Mean R/N and RN% were significantly greater in a 4‐year‐old stand compared to a 1‐year‐old stand. Basal nodes had higher mean R/N than did apical nodes. Vegetative propagation of reed canarygrass should, if possible, be done with initial growth forage from the lower portion of the canopy of stands at least 3 years old. Genotypes with improved establishment capacity can be identified by their root and shoot production potential in the greenhouse.
Capitate Hairs on Cotton Leaves and Bracts1
Authors: Kosmidou‐Dimitropoulou K. , Berlin J. D. , Morey P. R.
Published: July 2010

Significant differences in the capitate hair density of different cotton, Gossypium hirsutum L and G. arboreum L., stocks were revealed by quantitative analysis of scanning electron micrographs of leaf and involucral bract epidermal surface;. The density of capitate hairs on eight greenhouse‐grown stocks ranged from 2.1 to 8.7 and from 4.7 to 31.6 per mm2 on the adaxial and abaxial leaf surfaces, respectively. The capitate hair density on bracts of seven greenhouse‐grown stocks ranged from 0.9 to 45 and from 3.4 to 8.6 per mm2 on the adaxial and abaxial surfaces, respectively. There were significant differences among stocks in capitate hair density on both leaves and bracts. Capitate hairs were present on leaves of plants with the H2, Sm1s1Sm2, ne1ne2, or gl2gl3 mutant genes. There were no significant differences in capitate hair density on leaves of the same stock collected two years apart or on bracts collected from the same plant at anthesis or at 30 and 60 days postanthesis.
Comparison of Artificial and Natural Selection in American Pima Cotton under Different Environments1
Authors: Feaster C. V. , Young E. F. , Turcotte E. L.
Published: July 2010

The effectiveness of artificial vs. natural selection for improving lint yield and other traits in American Pima cotton (Gossypium barbadense L.) when grown in predictable environments was evaluated at low and high elevations. A cross was made between ‘Pima S‐3,’ adapted to the less fertile soils at high elevations, and ‘Pima S‐4,’ adapted to low elevations and to the more fertile soils at high elevations. F2 through F8 populations from this cross were grown at one low‐elevation and two high‐elevation locations. These populations were subjected to natural selection by bulking all plants to form the next generation, or to artificial selection by bulking only selected plants to form the next generation. Phenotypic differences for lint yield, plant height, and fruiting height among plants within the succeeding generations were greatest at Phoenix, next greatest at Safford, and least at El Paso. Therefore, selection of genotypicaliy productive plants was most effective at Phoenix, somewhat less effective at Safford, and the least effective at El Paso.

Artificial‐ vs. natural‐selection cycles 0 (F2), 3, and 6 from each of the three locations were evaluated at all locations. The populations developed by artificial selection at a given location tended to yield more than naturally selected populations at that location, with the greatest advantage at Phoenix, next greatest at Safford, and no advantage at El Paso. Likewise, among locations, natural selection had the most influence on yield potential at Phoenix. In some years, the artificially selected populations from one location tended to yield well at the other locations, but no population yielded well at all‐three locations in both years. Selection for improvement of traits such as lint yield in the environment where the selected population will be utilized was effective. However, if the Pima improvement program were confined to one location, Phoenix appears to be the best of the three locations. At Phoenix, the magnified expression of productivity, and fruiting‐ and plant‐height differences would permit the selection of genotypes that would be productive at each elevation of the American Pima Belt.
Effect of Genotype and Tuber Size on Eye Number and Blind Seedpieces in Potato1
Authors: Reeves Alvin F. , Hunter James H.
Published: July 2010

Samples of 60 to 200 tubers from each of 10 potato cultivars (Solanum tuberosum, L.) and six different unnamed clones from the Maine Potato Breeding Program were hand‐sized and the number of eyes per tuber ascertained. Eye number showed significant positive correlation with tuber size. Each of three size categories differed significantly from the other two in mean eye number. Although several clones and cultivars differed significantly in mean eye number, the relationship of eye number to tuber size was similar for all clones and cultivars tested.

Larger samples of the six unnamed clones were sized and cut by machine. The percentage of blind seedpieces (pieces with no eyes) was then determined for the three tuber size categories. In general, larger tubers produced more blind seedpieces. Clones with low eye numbers produced four times as many blind seedpieces in all size categories as clones with high eye numbers.
Influence of Semidwarfism and Genetic Background on Stand Establishment of Wheat1
Authors: Allan R. E.
Published: July 2010

The objective of this study was to determine the influence of genetic backgrounds and semidwarf plant height genes (Rht1 and Rht2) on wheat (Triticum aestivum L.) stand establishment. Final stands (FS) and emergence rate indexes (ERI) were measured in 2 test years for eight populations, each including 15 isolines of two‐gene scmidwarf, one‐gene semidwarf, and normal heights. In 62 of 64 comparisons, the FS and ERI values of two‐gene semidwarfs were significantly lower than those of their one‐gene semidwarf or normal counterparts. One‐gone semidwarfs usually had lower FS and ERI values than their normal counterparts and these differences were significant for 23 of 32 comparisons.

Two‐gene and one‐gene semidwarfs and normal isolines of the eight populations averaged 38.9, 51.9 and 61.0 seedlings per plot (FS), respectively; the average ERI values of these three height classes for all populations were 89.7, 161.2, and 228.2, respectively. However, highly significant differences for both FS and ERI occurred among the eight populations during both test years. Variations due to height classes, test years, populations, and their interactions were also significant.

Results indicate that the Rht1 and Rht2 genes for semi‐dwarfism either reduce stand establishment capabilities or are genetically related to genes which do. The extent to which semldwarfism influences FS and ERI was appreciably altered by different genetic backgrounds. The backgrounds of the ‘Omar’ and ‘Golden’ cultivars minimized adverse effects of semidwarfism on FS and ERI, whereas the backgrounds of ‘Brevor,’ ‘Burt,’ ‘Itana,’ and ‘Marled’ cultivars had especially adverse or erratic effects on both stand establishment traits.
Inheritance of β‐Amylase Nulls in Soybean Seed1
Authors: Hildebrand D. F. , Hymowitz T.
Published: July 2010

The soybean [Glycine max (L.) Men.] cultivar ‘Altona’ lacks β‐amylase activity (AM null 1) and the Sp1b seed protein electrophoretic band. Altona also has a genotype with β‐amylase activity and the Sp1b band (Rf 0.42). The cultivar ‘Chestnut’ lacks detectable β‐amylase activity (AM null 2), but it produces the Sp1a seed protein electrophoretic band (Rf 0.36). Seed from reciprocal crosses of Altona (AM null 1) and ‘Amsoy 71’ (Sp1a), the cross Altona (Sp1b) ✕ Altona (AM null 1), the cross Altona (AM null 1) ✕ ‘Corsoy’ (Sp1b), reciprocal crosses of Chestnut (AM null 2) and Altona (Sp1b), reciprocal crosses of Chestnut (AM null 2) and Amsoy 71 (Sp1a), and the cross Chestnut (AM null 2) ✕ Altona (AM null 1) were analyzed to determine the inheritance of AM nulls 1 and 2 relative to Sp1a and Sp1b.

The F2 and F3 data establish that AM null 1 is recessive to the codominant alleles Sp1a and Sp1b for both β‐amylase activity and the seed protein band. AM null 2 is recessive to Sp1a and Sp1b for β‐amylase activity but codominant to Sp1b for the seed protein band. The symbols sp1 are proposed for the AM null 1 allele and Sp1an for the AM null 2 allele.
Performance of Paired Nectaried and Nectariless F3 Cotton Hybrids1
Authors: Meredith William R.
Published: July 2010

Amino acids and sugars are removed from cotton, Gossypium hirsutum L., nectaries in large amounts by various insects. Nectariless [2(ne1ne2)] cottons conceivably could utilize this photosynthate to increase yield or fiber quality. The possibility of identifying superior nectariless populations motivated this study. The objectives were to: 1) evaluate a method of detecting nectariless populations that contained favorable interactions of yield and fiber quality with nectariless genes and 2) determine the magnitude and frequency of occurrence of these favorable interactions.

Nectaried (Ne) and nectariless (ne) hybrid populations were derived from crosses of DES 24‐8ne with 19 diverse strains (S) at Stoneville, Mississippi. In 1976, 8 pairs and in 1977, 11 pairs of Ne and ne F3 hybrids were each grown in six replications at two Stoneville locations. Averaged over both years, nectaried plants had 1.8% larger seeds and 1.6 and 0.9% longer fiber (50 and 2.5% span length, respectively) than nectariless plants. In 1977, boll size in nectaried plants was 1.5% larger than in nectariless ones. No other significant differences or trends were detected. These results reinforced previous studies indicating no strong deleterious association between nectariless and yield and fiber properties. No significant Ne vs. ne ✕ S interactions were detected for lint yield, but small significant interactions were detected for lint percentage in 1977 and 2.5% span length in both years. Breeders should therefore not expect any large increases in yield due to the ability of nectariless plants to utilize the nectar photosynthate for agronomic purposes. However, the detection of favorable small interactions for lint percentage and fiber length suggested small advances in germplasm development.
High Temperature Stress and Pollen Viability of Maize1
Authors: Herrero Maria Pilar , Johnson R. R.
Published: July 2010

High temperatures during maize (Zea mays L.) pollinatiou are known to result in poor kernel set, but little is known of the direct effects of temperature on pollen germination. The purpose of this research was to determine how in vitru pollen germination of different maize genotypes is affected by high temperature stress during anthesis. Tassels from field‐grown plants were excised at beginning anthesis, placed in water and transferred to growth chambers maintained at daytime temperatures of 27, 32, and 38 C. Nighttime temperatures were maintained 6 C cooler. In vitro germination was measured after 24 and 48 hours in the growth chamber as well as on pollen collected directly in the field. Genotypes differed in their response to temperature. In some genotypes pollen germination steadily decreased as temperature increased. Others either germinated equally well at 27 and 32 C or germinated better at 32 than at 27 C. All genotypes had a lower germination at 38 C than at 32 or 27 C, and several genotypes exhibited no germination after 48 hours at 38 C. After 24 hours in the 38 C chamber, six inbreds widely used in the 1970's germinated significantly better as a group than inbreds widely used in the 1950's and 1930's. Growth environment affected the absolute in vitro germination percentage, but in general genotypes retained similar relative responses to increasing temperature. Results from this study suggest that prolonged exposure to temperatures above 32 C can reduce pollen germination of many genotypes to levels near zero.
A Search for Condensed Tannins in Annual and Perennial Species of Medicago, Trigonella, and Onobrychis1
Authors: Goplen B. P. , Howarth R. E. , Sarkar S. K. , Lesins K.
Published: July 2010

Bloat of ruminant animals feeding on fresh, green alfalfa (Medicago sativa L.) is caused by high levels of soluble plant proteins which act as foaming agents. It is postulated that bloat‐safe cultivars may be bred by introducing condensed tannins (flavolans) which would act as protein precipitants to preclude foam formation and consequent bloat. Using the vanillin‐HCl spot test, large populations of alfalfa were screened for tannins. These included several accessions, cultivars, and breeding populations. Extensive screening of 2n M. falcata L. and 4n M. sativa treated with the chemical mutagens ethyl methanesulfonate or ethyleneimine failed to reveal any mutations for tannins. Screening of 33 species (a total of 86 accessions) of annual Medicago was negative. Similarly, screening of 28 species (a total of 92 accessions) of perennial Medicago was also negative. Examination of 30 species (46 accessions) of the closely related Trigonella genus did not reveal any tannin‐containing plants. On the other hand, testing of 123 accessions of 10 species of Sainfoin (Onobrychis) showed that all plants examined within this bloat‐safe genus contained high levels of tannins.

Several of the common pasture legumes, including both bloat‐causing and bloat‐safe types, were examined for tannins in leaf tissue, flower (petal) tissue and seeds. All of these legumes except alfalfa and cicer milkvetch (Astragalus cicer I.,) contained tannins in petal tissue. All of the legumes, including alfalfa, contained tannins in seedcoat tissue except that of a homozygous recessive, white‐seeded strain of alfalfa.

The implications of breeding for tannins to provide a bloat‐safe alfalfa are discussed.
Development of Root‐branching in Three Alfalfa Cultivars1
Authors: McIntosh M. S. , Miller D. A.
Published: July 2010

A study of rooting habit of three winter‐hardy alfalfa, Medicago sativa L., cultivars was conducted at the Univ. of Illinois Agronomy South Farm. The objectives were to study the rooting habit of three high‐yieldlng, winterhardy alfalfa cultivars during their first growing season in order to determine if any differences in root branching exist among the cultivars and to estimate phenotypic correlations between the branching‐root habit and other agronomic characters. ‘Saranac,’ ‘Victorian’ and ‘Iroquois’ alfalfa plants were sampled eight times during the first growing season. Root and top growth of the alfalfas were measured and rooting habit was evaluated on a scale where l=tap‐rooted and 5=branching‐rooted.

The majority of the plants in all three cultivars were predominantly tap‐rooted, although there was a considerable amount of variation for rooting habit within cultlvars. Nine percent of the plants were classified as branching‐rooted by the last harvest. The mean root branching scores, which fluctuated during the growing season, ranged from 1.9 to 2.5. The branching.root habit in all three cultivars was positively correlated with top (r=0.27 to 0.53, significant at the 0.01 level) and root (r=0.36 to 0.57, significant at the 0.01 level) dry weights. The results indicated that these cultivars could be used as germplasm sources in developing high‐yielding, branching‐rooted alfalfa.
Effectiveness of Single Plant Selection During Successive Generations of Inbreeding in Soybeans1
Authors: Wilcox J. R. , Schapaugh W. T.
Published: July 2010

Phenotypically superior plants were selected in the F2 through the F4 generations in 12 soybean [Glycine max (L.) Merr.] crosses, three among superior soybean cultivars and nine between those cultivars and plant introductions. Seed from the selected plants within each cross was composited to form the bulk for the succeeding generation of selection. The objective was to determine how effective single plant selection would be in the heterogeneous bulk populations.

Visual selection for superior plants from the heterogeneous populations had no effect on seed yield. selected F4 bulks matured later than the unselected F2 populations in 7 of the 12 crosses and were taller than unselected F2 populations in 9 of the 12 crosses. Selected F4 bulks from crosses among the three cultivars lodged more than their F2 progenitors; however, only three F4 bulks from crosses between cultivars and plant introductions lodged more than the unselected F2 populations. The data indicated that even though tall, late maturing plants in these bulk populations appeared to be phenotypically superior, they were not superior in yield to the unselected bulks.
Artifact Autogamy in Sunflower1
Authors: Robinson R. G.
Published: July 2010

Prior to the development of autogamous cultivars, cross‐pollination was required for high yields of sunflower (Helianthus annuus L.). This research was undertaken to identify highly autogamous cultivars and to compare cloth and mesh bags in measuring autogamy for yield, achene weight, and achene oil percentage. Sixty‐two cultivars in 1978 and 75 in 1979 were planted at Rosemount, Minn. Cloth or mesh bags were placed over 10 different sunflower heads in each cultivar plot to exclude Hymenoptera insects. Autogamy percentages were calculated from the achene yield/ha of the bagged heads times 100 divided by the achene yield/ha of the exposed heads. Weights/100 fertile: achenes and achene oil percentages from bagged and exposed heads were determined for each cultivar. ‘Peredovik’ and ‘Sputnik’ nonhybrid cultivars were low in autogamy both years whereas 28% of the hybrids in 1978 and 36% of the hybrids in 1979 were 100% autogamous for yield. Achenes from heads under bags were heavier than those from exposed heads, even in hybrids of 100% autogamy. Consequently, these hybrids had artifact autogamy and compensated for their partial autogamy by increasing weight/fertile achene. The increase in achene weights from bagging was accompanied by a decreaiie in achene oil percentages. This research indicates that hybrids with artifact autogamy may require insect pollinators for maximum oil concentrations. Either true or artifact autogamy is effective in maintaining achene yields/ha in the absence of insect pollinators. Mesh bags were less harmful to sunflower than cloth bags and consequently, preferable for determining artifact autogamy.
Inheritance of Reaction to the Reniform Nematode in Soybean1
Authors: Williams C. , Gilman D. F. , Fontenot D. S. , Birchfield W.
Published: July 2010

Inheritance of reaction to reniform nematode (Rotylenchulus reniformis Linford and Oliveira), a pest of soybean [Glycine max (L.) Merr.] in many areas of the southeastern U.S.A., was studied in the cross ‘Forrest’(resistant) ✕ ‘Ransom’ (susceptible). Parental, F1,F2, and F3, populations were screened in soil infested with 2,000 to 4,200 reniform nematode larvae per 500cc of soil. Segregation ratios indicated that reniform nematode resistance was recessive and controlled by alleles at one locus. Intermediate infection classes in the F2 not shared by F1 and parental types probably resulted from environmental effects or one or more minor genes. The symbols Rrn and rfn are proposed for the major gene pair.
Duration of Grain Filling and Kernel Weight of Wheat as Affected by Temparature1
Authors: Wiegand C. L. , Cuellar J. A.
Published: July 2010

Once kernels are set, cereal grain yields are proportional to kernel weight. Thus environmental effects on kernel size merit better understanding as a source of yield variability.

Plant phenology was observed, environmental conditions were monitored, and kernel weights were determined for wheat during two seasons at 26°N. Lat. These observations provided data sets for relating mean daily temperature during grain filling (from the beginning of flowering to mealy ripeness of the kernels) to kernel weight and to duration of grain filling.

The data indicate a 3.1 day shortening of grain filling per degree C increase in mean daily air temperature during grain filling which compares with 2.8 days C‐1 for seven studies reported in the literature. Kernel weight in this study decreased 2.8 mg kernel ‐1 C‐1 compared with 1.5 mg for each degree C increase in temperature for seven studies in the literature.

We concluded that temperature is pacing plant senescence and that shortening the duration of grain filling is its common manifestation in commercial winter and spring wheats. Temperature, when in excess of about 15 C, apparently explains the dependence of 1,000 kernel weight on grain filling duration.

The findings imply that genetic variability in plant senescence and grain filling rates need to be searched for and exploited to help stabilize the kernel size component of yield.
Variation Among Alfalfa Cultivars for Indices of Nitrogen Fixation1
Authors: Hoffman David , Melton Bill
Published: July 2010

Alfalfa (Medicago sativa L.) cultivars with increased nitrogen fixation potential would be beneficial. The desirability of existing cultivars as genetics source material for a breeding program to accomplish this objective has not been reported.

Ten alfalfa cultivars contrasting in fall dormancy, date of release, and germplasm origin were evaluated as 10‐week‐old seedlings for indices of N2‐fixation under nil‐nitrate sand culture in a lathehouse during the summer months. Largest variability for indices at N2‐fixation was among plants within cultivars and not among cultivars. The results indicated that all of the cultivars evaluated would be equally desirable as source material to improve N2‐fixation potential in alfalfa. No effects were noted which could be attributed to fall dormancy, age of the cultivar, or germplasm source.
Estimating Genetic Variance in Sugarcane Using a Factorial Cross Design1
Authors: Hogarth D. M. , Wu K. K. , Heinz D. J.
Published: July 2010

Progeny from seven factorials of crosses were studied to examine the quantitative genetics of a breeding population of clones used in the Hawaiian sugarcane (Saccharum spp. L.) breeding program and the applicability of quantitative genetic theory to sugarcane. Nonadditive genetic effects were equally important to additive genetic effects, which suggests that increased yields could result from utilizing both polycrosses and crosses where both parents are known. There was relatively little genetic variability for sugar content as measured by refractometer solids compared to the genetic variability for yield of cane as measured by volume. Thus, the greatest progress in breeding and selection is more likely to come from increasing the yield of cane rather than from increasing sugar content.

The estimates of additive genetic variance, σ2A1 and σ2A2, were obtained, respectively, from the regression of progeny means on mid‐parent means and the progeny analysis; the estimates of total genetic variance, σ2G! and σ2G2 were obtained, respectively, from the analysis of parental clones and the progenies. The ratios of σ2A1/σ2A2 and σ2G1/σ2G2, however, were generally less than one, which suggests that the assumptions underlying quantitative inheritance analysis were violated. This is probably because the clones in the breeding population were highly selected for yield potential.
Indirect Selection for Resistance to the Fusarium Wilt‐Root‐Knot Nematode Complex in Cotton1
Authors: Kappelman A. J. , Bird L. S.
Published: July 2010

The reaction to fusarium wilt [Fusarium oxysporum Schlect. f. vasinfectum (Atk.) Synd. & Hans.] and rootknotnematode (Meloidogyne spp.) of nine families and cultivars of cotton (Gossypium hirsutum L.) that were developed using the multi‐adversity resistance (MAR) selection program, was compared with that of susceptible ‘Rowden’ and resistant ‘McNair 511.’ These materials were field tested at Tallassee, Ala., in 1974, 1975, and 1976 growing seasons. Use of the MAR technique increased the resistance of strain composites for four new families by recombination of strains within families. The mean wilt resistance over 3 years of all nine of the final strains or composites of strains representing families developed by this indirect MAR selection technique was greater than that in Rowden, while resistance in seven of these strains was equal to that of McNair 511. Two older MAR cultivars, ‘Tamcot SP 21’ and ‘Tamcot SP 37,’ developed during the early phases of the MAR program, were less susceptible than Rowden but only Tamcot SP 21 was as resistant as McNair 511. Three new MAR cultivars, ‘Tamcot SP 21S,’ ‘Tamcot SP 37H,’ and ‘Tamcot CAMD‐E; released from the composite cultivars tested during 1974, 1975, and 1976, and evaluated in 1978 had resistance equal to that of McNair 511 and were significantly less susceptible than Rowden. The high degree and rapid development of resistance in these composites achieved through indirect selection indicates that use of the MAR breeding technique can contribute significantly to the development of fusarium wilt resistance in cotton.
Cytogenetic Analysis of Interspecific Hybrids Between Common Bean and Scarlet Runner Bean1
Authors: Cheng S. S. , Bassett M. J. , Quesenberry K. H.
Published: July 2010

Meiotic analyses in F1 hybrids between three lines of common bean, Phaseolus vulgaris L., and two lines of Scarlet runner bean, P. coccineus L., were conducted to study the degree of similarity between the two genomes. The quantitative data indicated that meiosis in the three F1 hybrids studied was abnormal. At least two pairs of chromosomes were differentiated by inversions. Data on bridge and laggard frequencies taken from anaphase I and II pollen mother cells (PMCs) were interpreted to mean that cross‐over within these inverted segments was responsible for 20 to 40% of the 58 to 79% pollen abortion observed in the interspecific hybrids. The identical frequency of PMCs with bridgelaggards in anaphase I and II indicated that the inversions were located at the end of the differentiated chromosomes.
Alfalfa Water Potential Measurement: A Comparison of the Pressure Chamber and Leaf Dew‐point Hygrometers1
Authors: Brown P. W. , Tanner C. B.
Published: July 2010

Unambiguous measurements of plant water potential are necessary for the study of crop response to water deficits. Our purpose is to describe procedures for field measurement of alfalfa (Medicago sativa L.) water potential using the pressure chamber and a commercial in situ leaf dew‐point hygrometer. Valid pressure chamber measurements require protection against transpiration following sample excision, immediate measurement, and low chamber pressurization rates so that false endpoints can be circumvented. Valid hygrometer measurements require scrupulous hygrometer hygiene, hygrometer placement to avoid shading of the exposed leaflets on the measured leaf and insulating hygrometers against rapid temperature changes. When compared on the same plant, the pressure chamber and hygrometer measured similar water potentials. When sampling comparisons were made on different plants, the water potential measured with the hygrometer was always greater than that measured with the pressure chamber. The good agreement between methods on the same plant was due to the pressure chamber measuring the ψ of the leaf to which the hygrometer was attached. The higher ψ measured by the hygrometer when different plants were sampled was caused by the hygrometer covering one leaflet of the alfalfa leaf and decreasing leaf transpiration. Use of the hygrometer to determine the ψ of a fully‐exposed leaf can result in overestimates of more than 2 bars. Using either method to determine small ψ differences between field‐grown alfalfa plants at a given time may be impossible due to the large between‐plant variability.
Effect of Preparation and Storage Environment on Lifespan of Shelled Peanut Seed1
Authors: Norden A. J.
Published: July 2010

Preservation of gene resources and the maintenance of breeder seed is an integral part of cultivar improvement programs. Unfortunately, seed of the cultivated peanut, Arachis hypogaea L., generally die within 2 years of storage under ambient conditions, yet an optimal preparation and storage environment for maintaining viability of peanut seed has not been established. Studies were initiated in 1966 with 1965 crop seed to annually examine the effects of four storage temperatures, three moisture contents of the seed at the time of storage, and a fumigant (paradichlorobenzene) on the germination of seed of five genotypes representing three market types of peanuts. The results indicate that shelled peanut seed, which contain no more than 6% moisture, can be stored for at least 10 years without an appreciable loss in germination when held in sealed containers at temperatures slightly above freezing (2 to 5 C) without paradichlorobenzene. The mean loss in germination was 3, 6, and 10% for Virginia, Spanish, and Valencia type seed, respectively. Storage at a controlled temperature of 17 to 20 C kept the seed from deteriorating appreciably for a 4‐year period, after which time seed viability rapidly diminished. Seed which had a high moisture content (8 to 11% when stored) had a shorter lifespan, while lower moisture content (2 to 6%) improved longevity. Paradichlorobenzene had an adverse effect on longevity of seed, especially when stored in sealed containers at storage temperatures sufficiently low to retard sublimation. The viability of Spanish seed decreased at a slightly faster rate than Virginia or Valencia seed under these storage conditions.
Improved Lamb Performance Associated with Breeding for Alkaloid Reduction in Reed Canarygrass1
Authors: Marten G. C. , Jordan R. M. , Hovin A. W.
Published: July 2010

We earlier documented that indole alkaloid concentration of vegetatively propagated reed canarygrass (Phalaris arundinacea L.) clones was inversely associated with average daily gains of lambs and steers. Our objectives were to determine whether alkaloid concentration and type in two commercially available cultivars (‘Rise’ and ‘Vantage’) and in a low‐alkaloid, tryptamine‐carboline‐free strain (MN‐76) were associated with performance and health of grazing lambs. These seed sources of reed canarygrass were each planted in three pastures (0.27‐ha/pasture) in a randomized complete block design.

Lambs that grazed MN‐76 gained from 51 to 95% more per day than did those that grazed Rise and from 14 to 87% more than did those that grazed Vantage during a 2‐year period. Rise contained a mean of 0.28 to 0.32% dry wt of a mixture of gramine and tryptamines‐carbolines, Vantage contained 0.20 to 0.33% gramine, and MN‐76 contained 0.09 to 0.12% gramine. The three grasses did not differ in most other quality components, but MN‐76 had up to 8% less cell walls and up to 9% more crude protein during the 2 years, as well as up to 28% more Ca during Year 1. The correlation between total indole alkaloid concentration of the grasses and lamb average daily gain was −0.97 in Year 1 and −0.66 in Year 2. Incidence of diarrhea among lambs was 4 to 26 times greater when they grazed Rise compared to Vantage or MN‐76.

We conclude that the indole alkaloid concentration threshold in reed canarygrass at or above which lambs will show reduced gain is about 0.20% dry wt, that diarrhea in grazing lambs specifically caused by consumption of reed canarygrass is very likely due to tryptamine‐carboline alkaloids, and that MN‐76 is a biologically significant grass breeding advance.
Greenhouse Selection for Drought Resistance in Rice1
Authors: O'Toole J. C. , Maguling M. A.
Published: July 2010

The protocol used in greenhouse drought resistance screening of rice, including monitoring of soil and plant water status, is described. Monitoring of dawn leaf water potential and subsequent visual scoring for drought resistance of 2,074 entries suggests that ability to maintain relatively high leaf water potential is strongly influencing selection by current visual scoring techniques. Cultivars receiving desirable scores are mainly dryland adapted rices from West Africa, Brazil, and some South and Southeast Asian hill rices.
Digenic Inheritance for the Flop Trait in Peanuts1
Authors: Branch W. D. , Hammons Ray O.
Published: July 2010

The flop phenotype in peanuts (Arachis hypogaea L.) is characterized by large revolute leaflets, coarse stems, and reduced fruit yield. F2 segregation data supported a 15:1 digenic inheritance model, with the flop phenotype governed by duplicate recessive alleles. There were no differences for reciprocal infraspecific cross populations. Gene symbols, fl1fl1fl2fl2 were proposed for the flop genotype.
Genetic Variances and Selection Responses in an Advanced Generation of a Hybrid of Widely Divergent Populations of Maize1
Authors: Moll R. H. , Smith O. S.
Published: July 2010

A resonable approach to the utilization of exotic germplasm of maize (Zea mays L.) is through the development and improvement of composites of exotic and locally adapted maize populations. The effectiveness of conventional recurrent selection procedures relative to the large genetic variances anticipated has not been adequately investigated. A series of experiments was undertaken in a composite of two widely divergent populations, one of which is locally adapted. Experiments were designed to (1) carry out five cycles of full‐sib family selection and S1 progeny selection for yield, (2) evaluate the responses to the two selection methods, (3) characterize genetic variances for yield the composite population before and after selection, and (4) compare expected responses based on variance estimates with responses observed.

Full‐sib family selection was conducted in duplicate, and the selection responses obtained were in close agreement. The rate of response over five selection cycles was slightly greater than those reported for locally adapted populations. Response to S1 progeny selection was approximately 50% greater than responses to fullsib family selection.

Predictions of selection responses computed from estimates of genetic variances were too high when compared with realized responses. Selection resulted in a reduction of genetic variance by about one‐third.

In view of the mean yield of the original composite and the rates of gain with selection, the implications with regard to utilization of semi‐exotic composites in practical breeding programs are encouraging.
Inter‐population Improvement Procedures for Alfalfa1
Authors: Rowe D. E. , Hill R. R.
Published: July 2010

We compared methods of improving a synthetic cultivar with parentage that traced to two different populations. Theoretical equations that expressed changes in the mean of a twd‐population synthetic were developed for three methods of selection: (1) selection within each population followed by combination of the selected individuals into a synthetic (CS); (2) selection based on top‐crossing each population to a common tester and combining the selected individuals (TX); and (3) reciprocal recurrent selection (RRS) in which each population served as the tester parent for the other. Theoretical responses were compared for additive, dominant, duplex dominant, and overdominant genetic models in a two‐allele, single locus autotetraploid population. Two pairs of alfalfa (Medicago sativa L.) populations were compared experimentally to test the effectiveness of polycross and topcross selection for resistance to Colletotrichum trifolii Bain, an index of resistance to C. trifolii and regrowth after cutting, and an index of these two traits plus resistance to Leptosphaerulina briosiana (Poll.) Graham and Luttrell.

Each of the selection methods had the same theoretical response with the additive genetic model. The efficiency of TX relative to CS and RRS varied with gene frequency combinations for all nonadditive genetic models. With complete dominance a tester parent existed for which TX selection would be at least as effective as CS or RRS, although differences were small for some gene frequency combinations. Response with TX selection was greater with complete dominance when the tester parent was inferior to the base population. Generalizations could not be made about relative effectiveness of the methods for the duplex dominance model. Negative responses to selection for a trait with overdominance could occur at some gene frequency combinations with CS and TX selection, but response was never negative with RRS.

Experimentally, topeross selection was more effective than polycross selection for resistance to C. trifolii when the tester parent had less resistance than the base population, and topeross selection was less effective when the tester parent was more resistant. Comparisons could not be made for the two‐character index selection, but good agreement with theoretical expectations was observed with the three‐character index.
Epicuticular Fatty Acid, Fatty Alcohol, and Alkane Contents of Bloom and Bloomless Sorghum ‘Redbine 60’ Leaves1
Authors: Wilkinson R. E. , Cummins D. G.
Published: July 2010

Bloom and bloomless sorghum, Sorghum bicolor (L.) Moench, ‘Redbine 60’ are near isogenic lines differing in the presence or absence of a white, powdery‐appearing epicuticular leaf wax which influences plant water relations and animal utilization and whose genetic control and morphological characteristics have been published. Chemical evaluations of bloom and bloomless leaf epicuticular waxes are absent. Waxes were extracted with chloroform, esterified, separated into classes via thin‐layer chromatography, and quantitated via gas‐liquid chromatography utilizing polar and non‐polar columns and relative response curves from pure standard compounds. In leaves of equal density, leaves of the bloomless near‐isogenic line had epicuticular fatty acid, fatty alcohol, and alkane contents that were 73, 118, and 1%, respectively, of those constituents on bloom leaves. There was a 57% reduction on the bloomless leaf of total fatty acids + fatty alcohols + alkanes compared to the bloom leaf. Fatty alcohols longer than C20 were absent from the epicuticular wax of the bloom line. Alkane contents longer than C32 were essentially absent from the bloomless line while the most prevalent alkanes present on the bloom line were C35‐C37.
Use of Small‐seeded Soybean Parents for the Improvement of Large‐seeded Cultivars1
Authors: Bravo J. A. , Fehr W. R. , Rodriguez de Cianzio S.
Published: July 2010

We studied the segregation for seed size in two‐ and three‐way crosses of soybeans [Glycine max (L.) Merr.] involving adapted small‐ and large‐seeded parents. Three lines with small seeds (15.3 to 19.8 g/100 seeds) were crossed to one of two large‐seeded cultivars (25.6 to 28.2 g/100 seeds), and the F1, was crossed to a third parent with intermediate seed size (22.1 to 23.0 g/100 seeds). Seed size of 60 F2‐derived lines in F3 from three two‐way and three three‐way crosses were evaluated with the eight parents in two environments.

The observed population mean was closely predicted by either the arithmetic or geometric mean of the parents. The mean seed size of a three‐way compared with its two‐way cross was directly related to seed size of the third parent. Only four of the 360 F2‐derived lines evaluated had a mean seed size within the confidence interval of the smallest or largest parent in the cross. Our results indicated that, utilization of small‐seeded cultivars for improvement of large‐seeded types will require special care in population development to obtain the desired frequency of large‐seeded segregates.
Yield Stability of Determinate and Indeterminate Soybeans Adapted to the Northern United States1
Authors: Beaver J. S. , Johnson R. R.
Published: July 2010

Stability of performance of determinate and indeterminate soybean [Glycine max (L). Merr.]genotypes was compared using regression on environmental means. Seed yields from portions of the 1976 to 1978 USDA Uniform Group III Soybean Test and seed yields from eight Illinois environments were analyzed in four separate joint regression analyses. Regression explained a significant portion, but not all, of the genotype × environment interaction. The Group III indeterminate cultivars in this study possessed desirable stability characteristics, having average or greater than average mean seed yields, average seed yield response to environments of varying levels of productivity, and minimum deviations from regression. Mean seed yields of some determinate genotypes were as great as the best performing indeterminate cultivars. The determinate genotypes also showed an average seed yield response to environments of varying levels of productivity. However, deviations from regression for most determinate genotypes were significant, indicating that the determinate growth habit might possess a less predictable performance when grown in the northern soybean growing region. Repeatability estimates of values of the regression coefficients and the deviations from regression across joint regression analyses were significant, suggesting that the selection of soybean genotypes with more stable performances might be possible.
Genetics of Isozyme Variants in Barley II. 6‐Phosphogluconate Dehydrogenase, Glutamate Oxalate Transaminase, and Acid Phosphatase1
Authors: Kahler A. L. , Heath‐Pagliuso S. , Allard R. W.
Published: July 2010

Progeny arrays derived by self‐pollinating barley (Hordeum vulgare L.) plants which differed in isozyme phenotype were assayed for enzyme systems 6‐Phosphogluconate dehydrogenase (6‐PGDH), Glutamate oxalate transaminase (GOT), and Acid phosphatase (ACPH) by starch‐gel electrophoresis. The results of inheritance studies of three enzyme loci (6‐Pgdh 1, Got 1, and AcPh 1) show that progeny arrays segregate as expected for single loci with codominant alleles. Linkage tests among the three loci and with four additional esterase loci (Est 1, Est 2, Est 3, and Est 4) showed that the four loci, Est 4, 6‐Pgdh 1, Got 1, and AcPh 1 are inherited independently of each other and they are also inherited independently of the Est 2‐Est 1‐Est 3 linkage group on chromosome 3. It is concluded that the three enzyme loci 6‐Pgdh 1, Got 1, and AcPh 1 provide additional useful genetic markers for population studies in the barley species.
Tissue Culture of Plants from a Chimeral Mutation of Tobacco1
Authors: Kasperbauer M. J. , Sutton T. G. , Andersen R. A. , Gupton C. L.
Published: July 2010

Somatic mutations may contain genetic characteristics usable in plant improvement. Meristem tissue was cultured to obtain healthy plants from a chimeral mutation of a tobacco (Nicotiana tabacum L.) plant that was infected with tobacco vein mottling virus. Parts of some of the leaves originating from a narrow mutated strip on one side of the stalk exhibited a ruffled characteristic. The other leaves on the plant were smooth. Thin layers of cells from the meristematic domes of apical and axillary buds were excised from an axillary shoot (sucker) that originated at the edge of the mutated strip. The explants were cultured on a shoot regeneration medium. The regenerated plants included two that had ruffled and 59 that had smooth leaves. Regenerated plants of both leaf types had the normal somatic chromosome number, did not exhibit virus symptoms, were self‐fertile, and produced abundant seed. Selfed progeny of the regenerated ruffled‐leaf plants included some with smooth and some with ruffled leaves; whereas, all progeny of the regenerated smooth‐leaved plants had smooth leaves. Selfed progeny of doubled haploids cultured from a ruffled‐leaf haploid plant had ruffled leaves, and selfed progeny of doubled haploids cultured from a smooth‐leaved haploid plant had smooth leaves. Recovery of somatic mutants using tissue culture offers a means of obtaining plants with potentially useful mutated characteristics.
Selection of Peas for Photosynthetic CO2 Exchange Rate under Field Conditions1
Authors: Mahon J. D. , Hobbs S. L. A.
Published: July 2010

The variability and heritability of photosynthetic CO2 exchange rate (CER) in peas (Pisum sativum L.) were examined. Twenty‐five genotypes were measured in the field during 1976 and 1977, and genotype mean CER differed significantly ranging between 12.1 and 19.5 mg CO2 dm−2 hour−2 (1976) and between 18.9 and 35.5 mg CO2 dm−2 hour−1 (1977). Three genotypes with high (‘Trapper’ ‘Alaska,’ PI356998) and three with low (JM9, PI269812, PI180700) CER were selected and retested in the field and in a controlled environment. Despite a significant genotype ✕ environment interaction, these high and low groups were consistently separable in the field. Under more equable environmental conditions in the growth cabinet however, CER differences were not apparent. Diallel crosses were made within the high and low groups and, although parental genotypes selected for high CER did not differ from each other, the F4 lines showed significant segregation, and ft lines reselected for high CER and retested in the F4 and F5 generations, had higher values than the parents. F4 progeny from high CER crosses showed some evidence of reciprocal effects, but F1 and F2 progeny from a high ✕ low CER cross gave no indication of non‐additivity. Heritability of CER estimated by several methods averaged 0.7. The results demonstrate the theoretical feasibility of using CER as a selection criterion, the practical limitations of methodology, and the likelihood of genotype ✕ environment interactions in a broad range of environments.
Inheritance of Tolerance to High Manganese Supply in Soybeans1
Authors: Heenan D. P. , Campbell L. C. , Carter O. G.
Published: July 2010

Soybean [Glycine max (L.) Merr.] cultivars show differential tolerance to high manganese (Mn) supply levels as evidenced by severity of symptoms and reductions in yield. Crosses of the tolerant cv. ‘Lee’ with a susceptible cv. ‘Bragg’ gave F1 plants with only moderate Mn toxicity symptoms and the F2 generation showed a continuous distribution in symptoms that was skewed towards tolerance. The F6 progeny from a cross of ‘Amredo’ (tolerant) and Bragg (susceptible) had a bimodal distribution. Tolerance to high Mn levels is an inherited character.