bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon and Nitrogen Reserve Remobilization Following Defoliation: Nitrogen and Elevated CO2 Effects
Authors: Skinner R. Howard , Morgan Jack A. , Hanson Jon D. 
Published: July 2010

ABSTRACTEarly regrowth following defoliation of forage species often depends on remobilization of nitrogen and non‐structural carbohydrate (TNC) reserves stored in roots and crowns. The degree to which TNC and N remobilization contribute to regrowth can depend on internal concentrations and on external CO2 and N supplies. We studied the effect of CO2 and N supply on reserve remobilization during the first 20 d following defoliation of 9‐wk‐old alfalfa (Medicago sativa L.), western wheatgrass [Pascopyrum smithii (Rydb) A. Love], and blue grama [Bouteloua gracilis (H.B.K.) Lag ex Steud]. plants. Reserve remobilization was studied in controlled‐environment chambers set at either ambient (350 μmol mol−1) or elevated (700 μmol mol−1) CO2 Plants were fertilized twice weekly with Hoaglands solution containing either 0 mg L−1 (low N) or 400 mg L−1 N (high N). Elevated CO2 increased the total amount and percent of available TNC that was remobilized in alfalfa, and the amount of remobilized TNC in western wheatgrass, but reduced TNC remobilization in blue grama. Nitrogen fertilization had little effect on TNC remobilization at ambient CO2, but increased remobilization in alfalfa and reduced remobilization in the two grasses under elevated CO2 Alfalfa remobilized a greater percentage of its root and crown N reserves than either grass species. Nitrogen remobilization was highest under high N and ambient CO2 conditions for all species. Nitrogen deficiency and elevated CO2 reduced N remobilization and the contribution of remobilized N to shoot regrowth.
A Diagnosis of Yield‐Limiting Factors on Probe Genotypes for Characterizing Environments in Winter Wheat Trials
Authors: Brancourt‐Hulmel Maryse , Lecomte Christophe , Meynard Jean‐Marc 
Published: July 2010

ABSTRACTGenotype × environment interaction is fully analyzed when genotypes and environments are well characterized. Probe genotypes were studied in a simplified crop diagnosis to show how variates of yield components can strengthen characterization of environments by usual indicators of yield‐limiting factors. The objective of this study was to determine the main limiting factors of yield and to analyze their effects in wheat (Triticum aestivum L.) trials. Fixed genotypes (Talent, Soissons, Camp‐Rémy, and Arminda) were studied as probe genotypes at five experimental stations of the Institut National de la Recherche Agronomique (I.N.R.A.) (Rennes, Mons, La Miniére, Dijon, and Ondes) during 1991 and 1992. Two important variates, the reduction of kernel number and the reduction of thousand kernel weight, were analyzed to characterize the environments during the formation of yield. The former described the time‐period until flowering and the latter the grain‐filling period. In addition, factors that limit yield were determined through indicators such as water deficits, the ratio between nitrogen absorbed and kernel number, radiation, temperature, development of diseases (powdery mildew, strike rust, leaf rust, leaf and glume blotch), and lodging. Our study resulted in providing critical values for grain yield, kernel number, and thousand kernel weight for the four probe genotypes. Then reductions of yield components could be determined and analyzed. They provide useful information for characterizing environments subjected to numerous yield‐limiting factors. Our study also revealed that the biological variates (essentially susceptibility to powdery mildew and to lodging) affected yield more than the climatic variates.
Agronomic Performance of Root Chicory, Jerusalem Artichoke, and Sugarbeet in Stress and Nonstress Environments
Authors: Schittenhelm Siegfried 
Published: July 2010

ABSTRACTIntroduction of the fructan crops root chicory (Cichorium intybus L.; RC) and Jerusalem artichoke (Helianthus tuberosus L.; JA) into agricultural production systems is desirable to diversify crop rotation. Field experiments were conducted to compare the agronomic performance of RC and JA with sugar beet (Beta vulgaris L.; SB). One set of cultivars during 1995, 1996, and 1997 and an additional set in 1997 were grown on a sandy loam soil (Haplic Luvisol) at Braunschweig, Germany. Crops were cultivated with and without supplemental irrigation, complete and no weed control (1995 and 1996), and N fertilization rates of 0, 60, and 120 kg ha−1 Severe water stress caused significant but similar storage organ yield losses in all crops, whereas mild water stress mainly affected JA yields. Averaged across years and N levels, storage organ yield losses through weed competition under irrigation amounted to 70, 47, and 8% in SB, RC, and JA, respectively. Averaged across years, in the absence of water and weed stress, SB, RC, and JA at their respective optimal N levels gave root and tuber dry matter yields of 14.8, 15.0, and 11.5 Mg ha−1, and sugar yields of 11.5, 11.2, and 8.1 Mg ha−1, respectively. Maximal SB and JA yields generally were achieved at the highest N rate, while RC peak yields were attained at 60 kg N ha−1 With the same amount of N taken up, RC in 1995 and SB in 1996 and 1997 produced the highest sugar yields.
Protein Degradation and Fermentation Characteristics of Red Clover and Alfalfa Silage Harvested with Varying Levels of Total Nonstructural Carbohydrates
Authors: Owens V. N. , Albrecht K. A. , Muck R. E. , Duke S. H. 
Published: July 2010

ABSTRACTExtensive degradation of protein during fermentation of high‐protein crops reduces efficiency of dietary N utilization in ruminants. Evidence suggests that enhanced levels of fermentable carbohydrates can reduce proteolysis. Our objective was to evaluate whether delaying daily cutting time, to allow total nonstructural carbohydrates (TNC) to accumulate, would inhibit protein degradation by way of greater acid production in the silo. Red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) were harvested at 0600, 1000, 1400, and 1800 h in 1993, 1994, and 1995 and wilted to a dry matter (DM) content of 350 g kg−1 before ensiling. The level of TNC in fresh forage of both species increased throughout the day. Starch accounted for most of the daily change in TNC in fresh alfalfa, whereas in red clover, quantitative increases in sugar and starch impacted TNC similarly. Level of TNC at initiation of ensiling did not consistently affect protein degradation during fermentation as confirmed by generally insignificant correlation coefficients. The extent of proteolysis in the silo was consistently greater in alfalfa than red clover. Silage pH typically decreased and starch increased as cutting time was delayed from 0600 to 1800 h. While the extent of proteolysis was largely unaffected by inherent increases in TNC, lower silage pH and higher starch concentrations indicate that silage from the afternoon cuttings may be better preserved and higher in quality.
Dimensions of Diversity in Modern Spring Bread Wheat in Developing Countries from 1965
Authors: Smale M. , Reynolds M. P. , Warburton M. , Skovmand B. , Trethowan R. , Singh R. P. , Ortiz‐Monasterio I. , Crossa J. 
Published: July 2010

ABSTRACTDiverse and varied crop genetic resources are necessary (though not sufficient) for adequate food production in a rapidly changing world. Since the scientific community first raised public concern several decades ago, modern cultivars have been viewed as the cause of declining diversity in the world's crop genetic resources. This paper tests the hypothesis of increasing genetic uniformity in modern spring bread wheat (Triticum aestivum L.) cultivars from 1965, a year which marks the release of some of the first modern semidwarf cultivars carrying Rht1 and Rht2 genes in the developing world. Results from previously published studies are summarized. Preliminary molecular analyses, and new analyses of cultivar numbers, areas, ages, and genealogies are presented. An estimated 77% of the spring bread wheat area in the developing world today is sown to CIMMYT‐related wheats, but this does not imply that they are genetically uniform. The hypothesis of increasing genetic uniformity is tested by assessing changes in the diversity of leading progenitors over three decades, in terms of several dimensions of diversity. Latent dimensions include genetic distance and genealogies. Apparent dimensions include performance with respect to yield potential, maintenance and stability across management (input use), and growing environments. The data are not consistent with the view that the genetic diversity of modern semidwarf wheat grown in the developing world has decreased over time. Moreover, since national programs in developing countries cross CIMMYT lines with their own materials before releasing them, the genetic diversity in their cultivars is at least as great as that present among CIMMYT lines.
Combining Cytoplasmic Male Sterility and Xenia Increases Grain Yield of Maize Hybrids
Authors: Weingartner Urs , Kaeser Olivier , Long Muhua , Stamp Peter 
Published: July 2010

ABSTRACTMale sterility is documented in many plant species. When a plant is male‐sterile, an open pollination by a genetically diverse pollinator is possible. This study investigates the combined effects of nonrestored cytoplasmic male sterility (CMS) and xenia (cross‐pollination) on the grain yield of seven European flint × dent single‐cross maize (Zea mays L.) hybrids. Open pollinated field experiments were conducted in six environments in Switzerland in 1998 and 1999; the design was a split‐plot. The effect of CMS on grain yield was statistically significant (P < 0.05). Three CMS hybrids in nonrestored T‐cytoplasm, pollinated by their male‐fertile isogenic counterparts, had a higher grain yield (+7.4%) than their male‐fertile isogenic counterparts. The higher grain yield was due to a greater number of kernels per square meter (KN). The average increase in grain yield due to xenia was 2.6%. The effects of pollinator hybrids on grain yield, kernel weight (KW), and KN were statistically significant (P < 0.001), whereas the pollinator × environment and pollinator × CMS hybrid interactions were not significant. Thus, the general pollinator ability (GPA) of the pollinator hybrids differed significantly and consistently. Averaged across the six environments, the three CMS hybrids, pollinated by five nonisogenic hybrids, outyielded their male‐fertile, isogenically pollinated counterparts by 2.1, 9.3, and 15.8%, respectively. The best combination of a CMS hybrid and a nonisogenic pollinator hybrid increased grain yield by 21.4% compared with the male‐fertile isogenic counterpart of the CMS hybrid. Therefore, the plus‐hybrid system (CMS hybrids grown in mixtures with male‐fertile nonisogenic pollinator hybrids) combines the grain yield advantages brought about by CMS and xenia.
Winter Survival in Switchgrass Populations Bred for High IVDMD
Authors: Vogel K. P. , Hopkins A. A. , Moore K. J. , Johnson K. D. , Carlson I. T. 
Published: July 2010

ABSTRACTIn vitro dry matter digestibility (IVDMD) was improved by three cycles (C) of recurrent selection in a switchgrass (Panicum virgatum L.) population but significant winter kill occurred in the Cycle 4 (C4) mass selection nursery. Stand density losses in strains differing in IVDMD also were noted in pastures intensively grazed for 3 yr. Two studies were conducted to evaluate the effect of genetic changes in IVDMD on plant survival of switchgrass. Seed was harvested from the original high IVDMD C3 parent clones to produce half‐sib family seedlings that were planted into a replicated half‐sib progeny evaluation nursery in 1991 at Mead, NE. This nursery was harvested in 1993 and 1995 for biomass yield after plants had headed, forage was analyzed for IVDMD, and plant survival was determined. There were significant differences among the families for biomass yield, IVDMD, and plant survival. Among the half‐sib families, the correlations of 1993 and 1995 IVDMD with 1995 survival were not significant nor were the correlations between 1993 and 1995 yields and 1995 stands. In the C3 high IVDMD populations, some families had decreased winter survival but other families had high IVDMD and good survival. Randomly selected plants from pasture trials (PC or pasture clones) of ‘Trailblazer’ and ‘Pathfinder’ were polycrossed and the resulting bulk populations were evaluated with parent populations in replicated sward trials at three locations along with the High IVDMD C3 population and its derived winter survival (WS) population produced by harvesting bulk seed from surviving plants in the C4 selection nursery. Differences among populations for stand were not detected in the sward trials, likely because survival and IVDMD have low correlations within populations. It should be feasible to continue to breed for high IVDMD in switchgrass but survival will need to be an additional selection criterion.
Aflatoxin Accumulation of White and Yellow Maize Inbreds in Diallel Crosses
Authors: Betrán F. J. , Isakeit T. , Odvody G. 
Published: July 2010

ABSTRACTPreharvest aflatoxin (AF) contamination is one of the main limitations for corn (Zea mays L.) production in the southern USA causing enormous economic losses and posing a risk to animal and human health. The objectives of this study were (i) to evaluate and compare hybrids of new and selected potential sources of AF resistance for AF accumulation under field conditions, (ii) to identify the inbreds with the most consistent expression of resistance under different hybrid combinations and growing conditions; and (iii) to estimate combining abilities of white and yellow inbreds for aflatoxin accumulation and secondary traits. Two diallels among six local and exotic white and six yellow maize inbreds were evaluated at three locations in Texas. Inoculation with Aspergillus flavus Link:Fr. isolate NRRL 3357, either directly through the silk channel or as infested kernels on the soil surface, was effective in promoting AF accumulation in hybrids. White hybrids with low aflatoxin were CML269 × TxX24 and CML269 × CML176. CML269, CML176, and CML322 were the white inbreds with the lowest most consistent AF in hybrids and had the best GCA for aflatoxin resistance. Yellow hybrids with low AF were FR2128 × Mp715, Tx772 × Mp715, and Tx772 × CML326. Tx772 and FR2128 had the best GCA for reduced AF across locations or at specific locations. Inbreds CML326 and Tx772 had consistently low aflatoxin accumulation in hybrids across environments. AF content was correlated with husk cover, ear rot ratings, and insect damage. Exotic inbreds have genetic factors that can contribute to the reduction of aflatoxin contamination.
Pollen Production, Pollination Dynamics, and Kernel Set in Maize
Authors: Uribelarrea M. , Cárcova J. , Otegui M. E. , Westgate M. E. 
Published: July 2010

ABSTRACTMaize (Zea mays L.) pollen production has been found not to limit kernel set, but there is scarce information on pollen production of modern hybrids and the effect that breeding for reduced tassel size has had on this trait. Our objectives were to study genotypic differences in pollen production and flowering dynamics, and to estimate pollen availability per exposed silk. Four F1 hybrids were grown at different plant densities (between 2.5 and 12.5 plants m−2) in two distinct environments (cool Midwest USA and temperate Argentine Pampa). Pollen availability was also modified by delayed plantings and detasseling treatments. We measured the dates of anthesis and silking of individual plants, the anthesis‐silking interval (ASI), the number of exposed silks per apical ear, the number of pollen grains per square meter (PGM), and kernel number per ear. The number of pollen grains produced per tassel (PGT) and per exposed silk were estimated. Increased plant density promoted an increase in ASI, matched by an enhanced interplant variability in this parameter, and a reduction in PGT. The latter was reduced from 10.3 × 106 or 11 × 106 at 2.5 plants m−2 to about 3 × 106 at 12.5 plants m−2 (USA), and from 9.7 × 106 or 11.3 × 106 at 3 plants m−2 to 4 × 106 or 3.6 × 106 at 9 plants m−2 (Argentina). We estimated two thresholds beyond which kernel set could be affected: (i) 227 pollen grains cm−2 d−1 at the end of pollen shedding and (ii) two pollen grains per exposed silk. Some cropping conditions were closer to the second threshold than others.
Yield and Growth Response of Cuphea to Sowing Date
Authors: Gesch Russ W. , Forcella Frank , Barbour Nancy , Phillips Bliss , Voorheees Ward B. 
Published: July 2010

ABSTRACTSelect germplasm of Cuphea, developed from an interspecific hybridization of C. viscosissima Jacq. and C. lanceolata f. Silenoides W.T. Aiton, shows good potential for commercial production in short‐season temperate climates. Cuphea seed oil could serve as a domestic source of medium‐chain fatty acids, which are in high demand by the chemical manufacturing industry. However, little is known about proper management practices for Cuphea agronomic production. A field study was conducted in west central Minnesota to determine optimum time of sowing in the northern Corn Belt region and describe influences of sowing date on growth and seed yield components of a semidomesticated germplasm line (PSR23). Seed was sown on 15 April, 1 May, 15 May, 1 June, and 15 June 1999 and 2000. Sowing in May resulted in greatest seed and seed‐oil yields, which were as high as 1.09 and 0.29 Mg ha−1, respectively. Seed yield declined as much as 31% when sown 15 April and 65% when sowing was delayed until 15 June. Plants developed from seed sown before June tended to form more branches and accumulated a greater amount of aboveground biomass. Typically, there was a distinct decrease in plant biomass accumulation and most seed yield components when sowing date was delayed until June. Cuphea PSR23 can be successfully grown in the northern Corn Belt, with early to mid May being the best time for sowing.
Embryo Drying Rates during the Acquisition of Desiccation Tolerance in Maize Seed
Authors: Cordova‐Tellez Leobigildo , Burris Joseph S. 
Published: July 2010

ABSTRACTMaize (Zea mays L.) seed quality is often reduced because of drying injury, although the causes and impairment mechanisms are poorly understood. In this study, we investigated changes in embryo drying rates and their effect on the acquisition of desiccation tolerance in maize seed. Ears of hybrid maize [B73 × (H99 × H95)] were harvested at about 550, 500, 400, and 320 g H2O kg−1 fresh weight (fw) and subjected to preconditioning (PC) (ear drying at 35°C and 0.47 m s−1 airflow rate) for 0, 12, 24, 36, and 48 h before fluidized bed (FB) drying (shelled seed, 35°C and 5.10 m s−1 airflow rate) treatments to decrease moisture content (MC) to about 130 g H2O kg−1 fw. Additionally, ears were entirely dried under PC (35C) and unheated‐air (NH) conditions. At the four harvests, different drying rate phases were evident in embryos of seed dried entirely at PC (35C) conditions. A slower drying phase coincided with the PC period, which increased with increasing maturation. Under FB drying, embryo MC declined at a faster rate down to about 400 g H2O kg−1 fw, followed by an intermediate drying rate down to about 200 g H2O kg−1 fw, and a slower drying rate below this point. As embryo MC declined to 400 g H2O kg−1 fw at slower drying rates, either with PC or field drying, the ability to withstand the faster drying rates of the FB progressively increased. This effect was illustrated by lower cell solute leakage and better performance in germination and vigor tests. We conclude that slow embryo drying rates to threshold levels may be crucial to acquire their ability to withstand higher drying rates without detrimental effect on seed germination and vigor.
Changes in Membrane Polar Lipid Fatty Acids of Seashore Paspalum in Response to Low Temperature Exposure
Authors: Cyril J. , Powell G. L. , Duncan R. R. , Baird W. V. 
Published: July 2010

ABSTRACTSeashore paspalum (Paspalum vaginatum Sw.) is a warm‐season turfgrass, best known for its superior salt tolerance. Plants are subject to injury during winter conditions along the northern boundary of their zone of adaptation. New cultivars that are more tolerant to low temperatures are needed for use in the transition zone. Cold tolerance has been correlated with the degree of unsaturation in membrane lipid fatty acids. Unsaturated fatty acids are thought to aid in maintaining membranes in a fluid state necessary for biological functioning (homeophasic adaptation). The primary objective was to characterize fatty acid composition of membrane lipids in three genotypes differing in cold tolerance. A second objective was to investigate changes in fatty acid content in these genotypes during exposure to low temperatures. Cold‐treated plants were exposed to a 10‐h photoperiod at 8°/4°C day/night temperatures and light intensity of 250 μmol m−2 s−1 photosynthetic photon flux density for 3 wk. Rhizomes and crowns were harvested at 7‐d intervals. Total lipids were extracted and the polar lipids separated by thin‐layer chromatography. Fatty acids were identified by gas chromatography (GC) and mass spectroscopy. In all three genotypes, the two saturated fatty acids, palmitic acid and stearic acid, did not change during cold treatment. The triunsaturated linolenic acid increased significantly during low temperature exposure. The magnitude of change was greater in the finer‐textured and more cold‐tolerant PI 509018‐1 (‘SeaIsle1’) than in the intermediately cold‐tolerant ‘Adalayd’ or in the cold‐susceptible, coarse‐textured PI 299042. These findings suggest that accumulation of linolenic acid partly explains the differential response in their cold tolerance.
Freezing Tolerance of Chicory and Narrow‐Leaf Plantain
Authors: Skinner R. Howard , Gustine David L. 
Published: July 2010

ABSTRACT‘Ceres Tonic’ and ‘Grasslands Lancelot’ narrow‐leaf plantain (Plantago lanceolata L.) and ‘Grasslands Puna’ chicory (Cichorium intybus L.) have received considerable interest as potential new forages for the northeastern USA because of their reported drought tolerance and high forage quality. However, all three cultivars were developed under New Zealand conditions and may not have sufficient winter hardiness to survive northeastern USA winters. Growth chamber and field studies were conducted to determine the freezing tolerance and winter survival of these new forages under well‐watered and drought conditions. Winter survival of chicory in the field ranged from 73% of marked plants in the wet treatment to 93% following summer drought. Likewise, winter survival of plantain in the field increased from 3% in the wet treatment to 41% in the dry treatment. Survival of Lancelot plantain in the growth chamber increased from 4% in the well‐watered to 16% in the drought treatment. However, survival of Tonic plantain and Puna chicory in the growth chamber was not affected by drought. Chicory survival was greater than survival of plantain in both controlled and field environments. Puna chicory appears to have sufficient winter hardiness to survive winters in the northeastern United States. Although Lancelot had slightly greater survival than Tonic, neither plantain cultivar had sufficient freezing tolerance to be recommended for use in the northeastern USA. Improved cultivars will need to be developed from populations that have evolved under more severe winter conditions before plantain can become a viable forage for most of this region.