bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental Effects on Turgor Pressure Response in Range Grasses1
Authors: Johnson Douglas A. 
Published: July 2010

The effect of environment on turgor pressure responses was determined over a range of drought stress for the following grass species: Agropyron caninum (L.) Beauv.; A. desertorum [Fisch. ex Link] Schult.; A. intermedium (Host) Beauv.; A. trachycaulum (Link) Malte ex H. F. Lewis; Elymus cinereus Scribn. & Merr.; E. junceus Fisch. Plants of each species were started from seed and exposed to environments characterized by three nightday temperature combinations of 5/10, 10/15, and 15/25C. Water potential components of detached leaf samples were determined throughout a drying cycle with a psychrometric technique.Turgor pressure responses changed as environmental conditions changed. Generally, plants in the low‐temperature environment maintained turgor over a wider range of leaf water potentials than plants did in the two higher temperature environments. Temperature environments also influenced turgor responses to a larger degree in some species than in others. The effect of environments on the leaf water potential where turgor declined to zero ranged from about 4 bars in E. junceus and A. intermedium to more than 8 bars in E. cinereus. When values of leaf water potential where turgor equals zero were used to rank species for drought resistance, rankings changed in different environments. These resuls suggest that the environments in which plant materials are grown should be carefully considered if maintenance of turgor is used to estimate relative drought resistance.
Isozyme Patterns and Differences in Plant Parts and Their Callus Cultures in Common Bean1
Authors: Bassiri A. , Carlson P. S. 
Published: July 2010

Changes that occur in different enzyme systems during the culture of cells or callus have been extensively studied in several plant species. A question exists whether different tissues of the same plant maintain persistent tissuespecific patterns of gene expression during in vitro culture or whether in vitro cultures are characterized by identical patterns of gene expression no matter what their tissue of origin. This question is of importance to crop improvement since many genetic selections in vitro and rapid assays for agronomic traits in vitro require the cellular expression of tissue specific traits.Extracts of primary leaf, epicotyl tip, epicotyl, cotyledon, mesocotyl, and radicle tissues of Phaseolus vulgaris L. and of callus derived from them were subjected to electrophoretic separation and assays of cathodal and anodal peroxidases and malate dehydrogenases and anodal acid phosphatase isozymes. The patterns of most of the isozyme systems were specific at the organ tissue level; however, a great uniformity of isozyme pattern occurred within and between the calli of the same or different origins. Rapidly growing calli derived from different plant parts expressed similar, though not in all cases identical, isozyme patterns.
Effect of Durable‐Press Resin Treatment on Tenacity and Elongation of Fiber from Upland Cotton Strains1
Authors: Lawson Reba , Ramey H. H. , Meredith W. R. 
Published: July 2010

Untreated and mercerized fiber samples from 14 cultivars and breeding strains of Upland cotton (Gossypium hirsutum L.) were evaluated for changes in tenacity when given durable‐press (DP) treatment. The average loss of tenacity after DP treatment of untreated cotton was about 59%, with little variation among cultivars and strains. Mercerization increased fiber tenacity by 50%. The tenacities of premercerized‐resinated samples were 25% lower than mercerized but 12% higher than that of untreated fibers. Strength uniformity, the ratio of the tenacity at 3.2‐mm gauge length (T1) to the tenacity at 0‐gauge (T0), was negatively correlated with the ratio of T1 for premercerized DP‐treated samples to T1 for untreated samples.Results of the study support the use of T1 as a breeding criterion of high fiber quality. Strength uniformity may also be valuable for the selection of breeding strains because it is a measure of the stress points along the length of the cotton fiber.
Effect of Change in Time of Flowering, Induced by Altering Photoperiod or Temperature, on Attributes Related to Yield in Maize1
Authors: Allison J. C. S. , Daynard T. B. 
Published: July 2010

Flowering date of maize (Zea mays L.) was advanced, by increasing temperature or decreasing photoperiod, in order to study the effect of a decrease in length of vegetative phase on leaf area at flowering, number of female florets, and length of grain‐filling period. Plants of two single‐cross hybrids were grown at temperatures of 20 or 25 C, combined with 10‐ or 15‐hour photoperiods, until ears started developing, and then transferred to a single regime of a 14 hour photoperiod and 23/19 C light/dark temperature.Increased temperature shortened the intervals from sowing to start of ear initiation and from ear initiation to silking. Decreased photoperiod shortened only the first period. Total leaf area per plant decreased as temperature increased, because leaves were smaller, and as photoperiod decreased, because fewer leaves were formed. Change in temperature altered total leaf area and time between sowing and silking by proportionately similar amounts, but change in photoperiod altered leaf area proportionately more than it did time to silking. Number of florets per ear row was little affected by temperature or photoperiod; apparent rate of floret initiation was unaffected by photoperiod but increased with temperature. Some plants died prematurely, evidently because of insufficient assimilate to maintain plant tissues. The black layer, denoting grain maturity, formed sooner in the kernels of these plants than in those of the remaining plants. In the latter, number of days from silking to black layer formation was decreased slightly by an increase in either temperature or photoperiod during the period before ear initiation.
Soybean Hypocotyl Growth Under Field Conditions1
Authors: Knittle K. H. , Burris J. S. 
Published: July 2010

In soybeans (Glycine max (L.) Merr.) an epigeal emerger, the sole seedling organ responsible for elevating the cotyledons and epicotyl to the soil surface is the hypocotyl. Yet, soybean seedling and, in particular, hypocotyl growth under field conditions have not been well studied.We measured hypocotyl length and swelling index (mg fresh weight/cm length) of several cultivars and two seed sizes at several planting dates and depths. Genetic variability was found in these two measurements. Cultivar differences in hypocotyl length generally followed the “long” and “short” hypocotyl classification of cultivars based on hypocotyl growth at 25 C. Hypocotyl swelling‐index differences generally were independent of the “long” and “short” cultivar classification. Hypocotyl length was highly correlated with rapidity of emergence, whereas hypocotyl swelling index was not highly correated with this measurement. Small seed of ‘Amsoy 71’ and ‘Corsoy’ produced seedlings with longer hypocotyls than did large seed, but there was no effect of seed size on hypocotyl length in ‘Wayne’. Small seed of all cultivars produced seedlings with lower values of hypocotyl swelling‐index than did large seed. Depth of planting significantly affected hypocotyl length and swelling index, but the specific soil factors affecting these two measurements were not identified. The consistently larger values of hypocotyl swelling index at deep as compared with shallow plantings, as web as the relatively large values for this measurement in the field as compared with those obtained in the laboratory, suggested that soil resistance is one limiting soil factor.
Photosynthetic Selection of Zea mays L. II. The Relationship Between CO2 Exchange and Dry Matter Accumulation of Canopies of Two Hybrids1
Authors: Vietor D. M. , Musgrave R. B. 
Published: July 2010

Carbon dioxide exchange rate (CER) responses to irradiance level and temperature, and dry matter accumulation of the above‐ground portion of plants, were measured for field‐grown multiplant canopies of the maize (Zea mays L.) hybrids NY821 L1 ✕ C153 L1 and NY821 H6 ✕ C153 L3. A semiclosed and an open arrangement of a field scale gasometric system were used to measure the CER's in daylight and in darkness respectively. The objective of the measurements as to relate canopy CO2 exchange to dry matter accumulation rate of the above ground portion of the field grown canopies of each hybrid during grain filling.Variation of solar irradiance at the top of the canopies and of plant age accounted for more than 90% of the variation of CERs measured in daylight. Variation of air temperature accounted for more than 77% of the variation of the CER's in darkness. The mean CERs in the dark changed less than 23 and 13% at 15 and 30 C, respectively, from the early dough to late dent stage. The CO2 efflux in darkness was attributed largely to maintenance metabolism in vegetative tissues because the small changes or reductions of CERs in darkness were observed while mean cob and kernel dry weights increased 220% from early dough to late dent.Cumulative CO2 exchange from early dough to late dent was computed from regression models of the irradiance and temperature responses for each hybrid, and climatic data. The ratio of above‐ground dry weight change to cumulative CO2 exchange deviated from an expected value of 0.65 for both hybrids: they were 0.77 and 0.59 for L1 ✕ L1 and H6 ✕ L3, respectively.A dry weight loss of from 11.7 to 16% from the vegetative tissues was larger than the substrate requirement for the estimated CO2 efflux that was attributed to maintenance metabolism from early dough to late dent. Part of the weight loss could have resulted from remobilization of stored carbohydrates from the vegetative tissues to the cob and kernels.
Forage Production and Quality of Synthetics Derived from Lolium ✕ Festuca Hybrids1
Authors: Berg Clyde C. , Hill R. R. , Buckner R. C. , Barnes R. F. 
Published: July 2010

Nine experimental four‐parent synthetics from derivatives of Lolium ✕ Festuca hybrids and five cultivars of tall rescue (Festuca arundinacea Schreb.) were evaluated for spring growth, maturity, dry matter yield, in vitro dry matter disappearance (IVDMD), and other characters. Three synthetics were from parents that had been selected for yield and vigor in a topcross progeny test; four were from parents that were palatable in an animal acceptance trial; two were from parents that were unpalatable in an animal acceptance trial. Our objectives were to determine the effects of parental selection methods on performance of the synthetics and to compare the performance of the synthetics with that of tall rescue cultivars.Synthetics from topcross‐selected parents had greater vigor and forage yields and matured earlier than those from palatable or unpalatable parents. IVDMD of the synthetics from topcross‐selected parents was not significantly different from the average IVDMD of synthetics from palatable and unpalatable parents. The synthetics from palatable parents had significantly greater IVDMD means than those from unl~alatable parentsThe synthetics were less vigorous, matured earlier, had less first‐harvest, third‐harvest, and total season yield, and had a lower IVDMD mean than the tall rescue cultivars. Average second‐harvest yield of the synthetics significantly exceeded that of the tall rescue cultivars. Variability among the synthetics suggested that breeding could correct most of these deficiencies.
Direct and Indirect Recurrent Selection for Protein in Soybeans1
Authors: Miller J. E. , Fehr W. R. 
Published: July 2010

Our objectives were to evaluate the effectiveness of population improvement by recurrent selection for protein percentage in soybean [Glycine max (L.) Merr.] seed by direct selection for high protein and indirect selection based on low oil, and to investigate methods of preventing change in maturity of populations during recurrent selection. A population was developed by crossing 12 high protein lines with 12 high yielding lines and intermating their progeny three times. A random sample of 100 S1 lines from the cycle 0 population was evaluated in two replications at two locations in Iowa in 1975. The 10 lines with highest protein and 10 with the lowest oil were used to develop two cycle 1 populations. Performance of 100 S1 lines from each population was evaluated in two replications at two locations in Iowa in 1976.Protein increased from 43.1% in the cycle 0 population to 44.6% in the high protein and 43.9% in the low oil populations. Direct selection caused a significant decrease in both oil and carbohydrate, and indirect selection significantly reduced oil but did not change carbohydrate percentage. Selection for low oil cannot be considered an efficient method for protein improvement when cost and time for protein analysis are not limiting factors.Maturity was 5.3 days later in the high protein population and 9.3 days later in the low oil population than in the cycle 0 population. The change in maturity was unacceptable, and three selection methods were evaluated, with and without restrictions on inbreeding, for avoiding similar shifts in the selection of lines for development of cycle 2 populations. Maturity class selection, linear regression adjustment, and a selection index were all successful in selecting lines with an average maturity similar to the cycle 1 populations. Restrictions on amount of inbreeding generally reduced expected gain from selection for seed composition.
Allocation of Resources in Selection for Resistance to Alfalfa Blotch Leafminer in Alfalfa1
Authors: Hill R. R. , Byers R. A. 
Published: July 2010

Sixteen plants from each of 54 polycross families of alfalfa (Medicago sativa L.) were evaluated for reaction to the alfalfa blotch leafminer (Agromyza frontella Ron‐dani). Reaction to the insect was measured as the number of mined leaflets in a 30‐leaflet sample taken from each plant on first harvest and later‐season forage in 1976 and 1977. Estimates of variance components were used to calculate heritability of resistance and estimated gain from mass, half‐sib family, and modified ear‐to‐row selection. Predicted gains were compared to determine optimum allocation of number of replications and selection pressures to apply within and among families.Variability among families was significant, but the heritability estimate was low (4.18%). Predicted gains with modified ear‐to‐row selection were greater than with mass selection only if the number of replications was large and the selection intensity within families was moderate. Half‐sib family selection always had smaller predicted gains than the most effective modified ear‐torow procedure. Mass selection had greater predicted gains when the number of replications was low and selection intensity within families was very low or very high. The predicted efficiency of mass selection increased relative to that of the other methods when the overall selection intensity decreased. The modified ear‐to‐row procedure with high selection intensity was recommended for increasing resistance to the leafminer alfalfa.
Recurrent Selection in Soybeans. I. Seed Yield1
Authors: Kenworthy W. J. , Brim C. A. 
Published: July 2010

Three selection criteria were compared after three cycles of a recurrent selection procedure in soybeans (Glycine max (L.) Merr.). The criteria were seed yield per se, efficiency expressed as the ratio seed weight]straw weight, and an index in which the ranks of the components seed yield and efficiency were weighted equally. Selection was based on S1 progeny performance in a replicated nine‐hill plot grown at one location. Composites of S3 seeds from selected St progenies from each cycle within the three selection criteria were evaluated in four environments with 12 replications per environment to compare the effectiveness of each selection criterion for yield response. Only selection for seed yield per se was effective in significantly increasing the yield of the base population. An average yield increase of 134 ± 30 kg/ha/cyde of selection was observed for seed yield per se and 38 ± 55 kg/ha/cycle for the index. Yield decreased an average of 2 ± 47 kg/ha/cycle for selection based on efficiency.Selection for seed yield per se had no significant effect on the unselected traits of seed size, percent oil, and percent protein. The favorable yield response observed in this recurrent selection program suggests that this breeding scheme may be used to develop populations of greater diversity and productivity.
Regression Analysis of Genotype‐Environment Interaction in Smooth Bromegrass1
Authors: Tan Wai‐Koon , Tan Geok‐Yong , Walton P. D. 
Published: July 2010

Twenty‐one single crosses and seven selected parental clones of smooth bromegrass (Bromus inermis Leyss.) were grown in replicated trials at four locations in Alberta (Lethbridge, Edmonton, Kinsella, and Beaverlodge). Lethbridge and Edmonton were higher yielding environments than either kinsella or Beaverlodge. Plants at Beaverlodge had the highest yield per unit area and tiller dry weight.The analyses of variance revealed that genotypes interacted significantly with environments for all characters. The genotype ✕ environment interaction source was further partitioned into the heterogeneity among regression and the residual. Environments were assessed in two ways: (i) the mean expression of all genotypes and (ii) the average performance of the seven parental genotypes. When environments were measured by the mean of all genotypes, a significant part of the interaction was ascribed to the heterogeneity among regression lines for all characters. The residual components were also significant in most cases indicating the presence of some unpredictable variation. The test of the heterogeneity of regressions against residuals revealed that the linear model would retain considerable predictive value for characters such as tiller density, yield per area, and fall yield since most of the interactions were accounted for by the heterogeneity of regressions.When environment was assessed independently by the mean of the seven parents of the single crosses, the proportion of the interaction attributed to heterogeneity of regression differed considerably from that assessed dependently by overall genotypes. Height was the only character which failed to fit the linear model. Despite the differences obtained from the test of significance for heterogeneity of regressions, the rankings of the genotypes on the basis of their linear regression coefficients were similar. The results showed that the conclusions drawn from regression data were unaffected by the choice of measure of environment and that predictability of genotypes varied with characters measured.
Tolerance of Glabrous and Pubescent Cottons to Tarnished Plant Bug1
Authors: Meredith W. R. , Schuster M. F. 
Published: July 2010

Lint yields of glabrous cottons (Gossypium hirsutum L.) are frequently lower than those of pubescent cottons. Since glabrous cottons might be more sensitive to tarnished plant bugs [Lygus lineolaris (Palisot de Beauvois)] than are pubescent cottons, we investigated the association between plant bugs and reproductive development of glabrous and pubescent cottons. Greenhouse evaluations were conducted in 1975 and 1977 with two plant bug nymphs per five plants. In the first test, reduction of flower buds by the plant bugs was 74% for four glabrous cottons, but was only 15% for two pubescent cottons. Similarly, in the second test, these reductions were 78 and 33% for five glabrous and two pubescent cottons, respectively.We also needed to develop a method for detecting tolerance that was not associated with pubescence. Thirty hybrids were produced by crossing the cultivar ‘Carolina Queen’ and its glabrous (Sm2Sm2) isoline to 15 tester parents. Each tester parent and its two hybrids were grown in the field in two bisect regimes. In one, plant bug infestations were minimized with early‐season use of insecticides, while in the other infestations were encouraged by growing mustard (Brassica juncea L. Czern. & Coss.) nearby. Yields were decreased by the plant bug enhancement; yields of glabrous hybrids were reduced by 239 kg/ha while those of pubescent hybrids were reduced by only 163 kg/ha. Tolerance to plant bugs was observed in eight of the parental lutes, but only hi two of the Sm2sm2 hybrids. One of these hybrids, with ‘Timok 811’ as a parent, was itself hirsute; the other had a high terpenoid nectariless strain, HG‐BR‐8N, as a parent.These data demonstrate that glabrous cottons are more sensitive to plant bugs than are pubescent cottons. They also indicate that possibly detection of germplasm tolerance to plant bugs can be facilitated through field evaluations of Sm2sm2 hybrids.
Frost‐Hardiness in Relation to Leaf Anatomy and Natural Distribution of Several Solanum Species1
Authors: Palta J. P. , Li P. H. 
Published: July 2010

The objective of this study was to determine anatomical and morphological differences related to the frost‐hardiness of tuber bearing Solanum species. Observations were made on about 2‐month‐old plants of 24 species including seven cultivars of potato (Solarium tuberosum L.). These species vary in frost‐hardiness from −2.5 to −5.5 C.No consistent relationship was found between various gross morphological characteristics of the plants and frosthardiness. However, hardy species (frost killing temperature −4.0 C or colder) usually had short and highly branched stems with smaller and thicker leaves.Among the various anatomical parameters studied, the number and thickness of palisade parenchyma layers and the stomatal index on the upper leaf surface were closely related to frost.hardiness. All hardy species had two palisade layers and all except three non‐hardy accessions (frost killing temperature ‐3.5 C or warmer) had one palisade layer. On the average, hardy species had a three times greater stomatal index (26.7%) than non‐hardy species. (8.8%), on the upper, surface of. the leaf, which. is probably due to two palisade layers m hardy species. The palisade parenchyma occupied a larger portion of the leaf cross section in hardy species (62.8%) compared to non‐hardy species (51.2%). No significant differences in cell size and intercellular space were detected between these two types of species. Ploidy was not related to leaf anatomy or frost‐ hardiness. Among the hybrid plants examined, hardy hybrids had two palisade parenchyma layers.The natural distribution patterns of many wild growing hardy and non‐hardy Solanum species were analyzed. A difference in the geographical distribution of hardy and non‐hardy wild species was found. The hardy species (except S. commersonii Dunal ex Poir.) are found in the high Andes of southern Peru, in central and southern Bolivia, northern Chile, and northwestern Argenina. Non‐hardy wild species are primarily distributed in Mexico, Guatemala, Venezuela, Colombia, Ecuador, and northern and central coastal Peru. A close relationship was found between the altitude of origin of a species or collection and its frost‐hardiness.It appears that anatomical features of hardy species are the results of their adaptation to environmental stress (primarily low temperature and in some cases together with water stress) under natural selection.