bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Three Cycles of Reciprocal Recurrent Selection on the N and Plant Population Responses of Two Maize Hybrids in Kenya1
Authors: Allan A. Y. , Darrah L. L. 
Published: July 2010

H611(R), a variety cross of two maize (Zea mays L.) populations improved by reciprocal recurrent selection, and H613(R), a topcross hybrid with the same male parent, were evaluated to determine if responses to N or population density had changed through three cycles of selection for yield. The evaluation was done with 40, 140, and 240 kg/ha N and 33,300, 44,400, and 55,500 plants/ha at three sites in western Kenya. Significant progress was made from selection in improving the yield of H611(R), but not H613(R). The rate of improvement of H611(R), 8.5% per cycle, agreed with past estimates. Both hybrids showed a significant (P<0.01) linear response to N and H613(R) had a significant (P<0.05) linear response to population density. The quadratic response of H611(R) to N was significant (P<0.05), that of H613(R) was not.H611(R) showed a significantly (P<0.01) improved response to higher plant populations from cycle 0 to 3. H613(R) was found to respond more efficiently to N fertilizer than the unselected population.
Mode of Pollination and Reproduction of Meadowfoam1
Authors: Devine M. B. , Johnson J. W. 
Published: July 2010

Two plant introductions, P.I. 374793 and P.I. 374800, were selected to study the mode of pollination and reproduction of the potential new oil crop, meadowfoam (Limnanthes alba Benth.). Seven pollination methods were compared in the greenhouse, utilizing the percentage of seed set for evaluation.Pollination methods which assured either self‐ or cross‐pollination were highly effective for seed production. Methods employing undisturbed or emasculated‐isolated treatments resulted in inferior seed set. Self‐pollination and cross‐pollination were equally effective in seed production, indicating that meadowfoam was highly self‐compatible and seed from cross‐pollination could be easily obtained. The use of glycine bags to isolate artificially crossed flowers did not interfere with seed formation or development. Therefore, glycine bags can be used to isolate flowers from foreign pollen and insure controlled cross‐pollination. Observations of calyx pubescence and petal width on F1 progeny from reciprocal crosses revealed that offspring arose as a result of sexual reproduction, Limnanthes.
Alfalfa Weevil Resistance Mechanism Characterized by Larval Convulsions1
Authors: Thompson T. E. , Shade R. E. , Axtell J. D. 
Published: July 2010

While screening 150 alfalfa (Medicago sativa L.) introductions for resistance to the alfalfa weevil [Hypera postica (Gyllenhal)], a new resistance mechanism was discovered in P.I. 247790 from Peru. A portion of the weevil larvae reared on this introduction convulsed, dehydrated, and died before pupation. One clone produced up to 20% convulsing larvae and 40% mortality. Due to the large degree of variability for this trait in P.I. 247790, it should be possible to increase this type of antibiosis through selection.Another resistance mechanism characterized by delayed larval development was also discovered in P.I. 247790. Larvae reared on one clone had a longer development period than those reared on other clones. This mechanism appears to have limited potential in producing resistant cultivars because development is only delayed and insects are not killed.
Genotype ✕ Environment Interactions in Bush Bean Cultivars in Monoculture and Associated with Maize1
Authors: Francis C.A. , Prager M. , Laing D. R. , Flor C. A. 
Published: July 2010

Interactions of genotypes of bush beans (Phaseolus vulgaris L.) with planting system and cropping season were evaluated on the CIAT station at 1,000 m elevation in Colombia. The objective was to determine if selection in monoculture can result in genetic progress for yield in complex multiple cropping systems. Cultivars of bush beans, defined as non‐climbing and including both determinate and indeterminate plant types, were tested in monoculture and associated with maize (Zea mays L.) in three seasons in 1975 and 1976.Significant correlations of bean yields were obtained for these cultivars grown in monoculture and in association with maize. Higher yields and greater absolute differences among cultivars in monoculture favor this system as most efficient for early generation genotype selection and yield testing. Late generation yield evaluation of promising lines may be necessary in more than one system to evaluate adaptation to a wider range of cropping systems.Season ✕ cultivar interactions in either system could complicate selection and rapid elimination of large numbers of progeny in a breeding program. Early generation selection for yield must be practiced with care, and most decisions on promising families delayed until replicated trial data are available from two to three generations in one location or several locations in one season.
Genotype ✕ Environment Interactions in Climbing Bean Cultivars in Monoculture and Associated with Maize1
Authors: Francis C. A. , Prager M. , Laing D. R. 
Published: July 2010

Interactions of genotypes of indeterminate, climbing beans (Phaseolus vulgaris L.) with planting system and cropping season were evaluated at the CIAT location in Colombia, 1,000 m elevation and 4° N lat. Since most climbing beans in Latin America are grown in association with maize (Zea mays L.), the objective was to determine whether selection of beans in monoculture would be a valid approach to genetic improvement. Climbing bean cultivars were tested in monoculture and associated with maize in three seasons in 1975 and 1976.Significant correlations for yields were obtained for the cultivars tested in association with maize and in monoculture in two seasons (r=0.90, r=0.81). Bean yields averaged 2,200 kg/ha in monoculture and 680 kg/ha in association over three seasons, with coefficients of variation of 15.2 and 22.5%, respectively. Higher yields, more precise evaluation of differences among cultivars, and significant positive correlations with associated crop yields favor the monocrop system as most efficient for early generation selection and testing of climbing beans.Season ✕ cultivar interactions in both planting systems could complicate selection for broad adaptation and confident early generation selection in a breeding program. This early selection should concentrate on qualitative traits such as disease and insect resistance, seed color, and desired maturity, with decisions on yield potential delayed until replicated trials in more than one season or more than one location provide adequate evaluation of yield.
Nitrate Reductase Assays as a Prediction Test for Crosses and Lines in Spring Wheat1
Authors: Deckard E. L. , Busch R. H. 
Published: July 2010

The in vitro and in vivo nitrate reductase (NR) activity of four high and four low yielding hard red spring wheat (Triticum aestivum L.) parents and the highest and lowest yielding F7 lines from each of 25 crosses were determined under growth chamber and field conditions. Ranking of genotypes was more consistent between the two sampling dates in the field or between growth chamber samples and field samples for the in vitro assay than the in vivo assay. Except for the parental seedling activities, the in vitro and in vivo activities were not significantly correlated.The mid‐parent values for NR activity significantly predicted those crosses that produced a higher frequency of high yielding lines. However, the highest yielding line within a cross could not be differentiated from the lowest yielding line on the basis of NR activity by either assay method. Also, the NR activity (in vitro and in vivo) of the lines from all crosses was not significantly correlated with yield of grain or grain protein. The relationship between in vitro NR activity and yield of grain or grain protein was improved if crosses involving the more diverse genotypes were deleted, but significant relationships generally were not obtained. The grain protein yields and reduced N partitioning data indicated that the NR values obtained in this experiment were not closely related to the genotypic ability to accumulate reduced N under field conditions. The reason for this remains unclear.
Sensitivity of Ion Accumulation by Cucumber Seedlings to Nitrapyrin and to 6‐Chloropicolinic Acid1
Authors: Zawistowska Teresa , Barker A. V. , Glover L. J. 
Published: July 2010

Certain plants, such as cucumber (Cucumis sativus L.), are very susceptible to growth restrictions and aberrations induced by nitrapyrin, a nitrification inhibitor, or by its metabolite, 6‐chloropicolinic acid (PCA). Injuries produced by these materials closely resemble those caused by growth regulator substances, which are known to affect cell membrane permeability and ion uptake. Because ion uptake may be similarly affected by nitrapyrin or PCA, this study was undertaken to investigate the effects of these chemicals on NO3− C1−, K+ and Ca++ absorption by cucumber.Two‐week‐old plants were grown in growth chambers using nutrient solutions with nitrapyrin or PCA added during a treatment period which ranged from 30 to 96 hours. Relative to untreated controls, NO3−, K+, and Ca++ absorptions were restricted 24, 17, and 25%, respectively, by nitrapyrin and 52, 36, and 28% by PCA at 5.0 x 100M. Likewise, relative chloride absorption was doubled by nitrapyrin and more than quadrupled by PCA.It was suggested that nitrapyrin and PCA affect ion uptake by altering membrane permeability in a fashion similar to that proposed for auxin types of compounds.
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.
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.
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).
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.
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.
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.
Growth Type and Yield Comparisons of Forage Species after Seed Multiplication in Germany and in the United States. II. Meadow Fescue, Timothy, and Perennial Ryegrass1
Authors: Simon Uwe , Kastenbauer A. 
Published: July 2010

Seedlots of meadow rescue (Festuca pratensis Huds.), timothy (Phleum pratense L.), and perennial ryegrass (Lolium perennial L.) were increased for two to four consecutive generations at one location in Germany and three locations in the United States. The population structure and forage yields of the original seed and advanced generations were investigated at Weihenstephan, Germany.All meadow rescue progenies were significantly taller and earlier and made better regrowth than the original seed. American lots and the corresponding German populations did not significantly differ in these characters. In timothy, variation of plant characteristics among locations and generations was neglegible. In perennial ryegrass, most progenies were significantly more vigorous in spring, earlier and taller than the original lot. American lots from lower latitudes were taller and earlier. The fourth subsequent generation from the most south. erly location, Shafter, Calif., headed 6 days earlier and grew 11 cm taller than the original lot. Percentage of seedling fluorescence of samples from the United States did not differ from the corresponding German progenies. There was no detrimental effect on dry‐matter forage yield due to seed multiplication in the United States.