Developmental Rates of Wild Oats (Avena fatua) and Wheat (Triticum aestivum)

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 521-524 ◽  
Author(s):  
David W. Cudney ◽  
Lowell S. Jordan ◽  
Chris J. Corbett ◽  
Warren E. Bendixen
Keyword(s):  
Floral Development ◽  
Developmental Stages ◽  
Developmental Rate ◽  
Base Temperature ◽  
Planting Dates ◽  
Wild Oats ◽  
Order Polynomial ◽  
Polynomial Expression ◽  
Developmental Rates ◽  
Developmental Scale

Prediction of the developmental stages of wheat and wild oats would be useful in order to: 1) correctly time the application of herbicides, and 2) accurately schedule research and cultural operations. The Haun developmental scale which numbers leaf development and describes floral development on the main stem of grasses was found to be suitable for describing the development of semidwarf wheat and wild oats in California. Haun developmental rates of wheat and wild oats were similar. Interference by wheat or wild oats in mixed cultures did not change the developmental rate of either species when grown with added nutrients and water. Degree days gave better correlations with development than calendar days when different planting dates, years, and locations were compared. A degree day model with a 5 C base temperature and a second-order polynomial expression gave accurate predictions of developmental stage, which correlated well with field data.

scholarly journals Embryonic communication in the nest: metabolic responses of reptilian embryos to developmental rates of siblings

2011 ◽  
Vol 279 (1734) ◽  
pp. 1709-1715 ◽  
Author(s):  
Jessica K. McGlashan ◽  
Ricky-John Spencer ◽  
Julie M. Old
Keyword(s):  
Developmental Stages ◽  
Incubation Temperature ◽  
Developmental Rate ◽  
Freshwater Turtle ◽  
Heart Rates ◽  
Developmental Rates ◽  
Environmentally Cued Hatching ◽  
Developmental Asynchrony ◽  
Developmental Conditions ◽  
Australian Freshwater

Incubation temperature affects developmental rates and defines many phenotypes and fitness characteristics of reptilian embryos. In turtles, eggs are deposited in layers within the nest, such that thermal gradients create independent developmental conditions for each egg. Despite differences in developmental rate, several studies have revealed unexpected synchronicity in hatching, however, the mechanisms through which synchrony are achieved may be different between species. Here, we examine the phenomenon of synchronous hatching in turtles by assessing proximate mechanisms in an Australian freshwater turtle ( Emydura macquarii ). We tested whether embryos hatch prematurely or developmentally compensate in response to more advanced embryos in a clutch. We established developmental asynchrony within a clutch of turtle eggs and assessed both metabolic and heart rates throughout incubation in constant and fluctuating temperatures. Turtles appeared to hatch at similar developmental stages, with less-developed embryos in experimental groups responding to the presence of more developed eggs in a clutch by increasing both metabolic and heart rates. Early hatching did not appear to reduce neuromuscular ability at hatching. These results support developmental adjustment mechanisms of the ‘catch-up hypothesis’ for synchronous hatching in E. macquarii and implies some level of embryo–embryo communication. The group environment of a nest strongly supports the development of adaptive communication mechanisms between siblings and the evolution of environmentally cued hatching.

scholarly journals Thermoprofile Parameters Affect Survival of Megachile rotundata During Exposure to Low-Temperatures

2019 ◽  
Vol 59 (4) ◽  
pp. 1089-1102 ◽  
Author(s):  
George D Yocum ◽  
Joseph P Rinehart ◽  
Arun Rajamohan ◽  
Julia H Bowsher ◽  
Kathleen M Yeater ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Survival Rates ◽  
Limited Range ◽  
Peak Temperature ◽  
Wave Form ◽  
Base Temperature ◽  
Megachile Rotundata ◽  
Lethal Effects ◽  
Delayed Emergence ◽  
Better Than

Abstract Insects exposed to low temperature stress can experience chill injury, but incorporating fluctuating thermoprofiles increases survival and blocks the development of sub-lethal effects. The specific parameters required for a protective thermoprofile are poorly understood, because most studies test a limited range of thermoprofiles. For example, thermoprofiles with a wave profile may perform better than a square profile, but these two profiles are rarely compared. In this study, two developmental stages of the alfalfa leafcutting bee, Megachile rotundata, eye-pigmented pupae, and emergence-ready adults, were exposed to one of eight thermoprofiles for up to 8 weeks. All the thermoprofiles had a base of 6°C and a peak temperature of either 12°C or 18°C. The duration at peak temperature varied depending on the shape of the thermoprofile, either square or wave form. Two other treatments acted as controls, a constant 6°C and a fluctuating thermal regime (FTR) with a base temperature of 6°C that was interrupted daily by a single, 1-h pulse at 20°C. Compared with constant 6°C, all the test thermoprofiles significantly improved survival. Compared with the FTR control, the thermoprofiles with a peak temperature of 18°C outperformed the 12°C profiles. Bees in the eye-pigmented stage exposed to the 18°C profiles separated into two groups based on the shape of the profile, with higher survival in the square profiles compared with the wave profiles. Bees in the emergence-ready stage exposed to 18°C profiles all had significantly higher survival than bees in the FTR controls. Counter to expectations, the least ecologically relevant thermoprofiles (square) had the highest survival rates and blocked the development of sub-lethal effects (delayed emergence).

Comparative floral development reveals novel aspects of structure and diversity of flowers in Cannabaceae

2020 ◽  
Vol 193 (1) ◽  
pp. 64-83 ◽  
Author(s):  
Flávia M Leme ◽  
Jürg Schönenberger ◽  
Yannick M Staedler ◽  
Simone P Teixeira
Keyword(s):  
Floral Development ◽  
Developmental Stages ◽  
Cannabis Sativa ◽  
Glandular Trichomes ◽  
Flower Morphology ◽  
Ovule Development ◽  
3D Reconstructions ◽  
Development Stages ◽  
Broad Base ◽  
Trema Micrantha

Abstract Species of Cannabaceae are wind pollinated, have inconspicuous and reduced flowers that are pistillate, staminate and apparently perfect on the same individual or on different individuals, with a single-whorled perianth and a pseudomonomerous gynoecium. Our objective is to understand the developmental processes that lead to such a reduced flower morphology and polygamy in Cannabis sativa, Celtis iguanaea and Trema micrantha. Floral buds and flowers were processed for surface, histological examinations and 3D reconstructions of vasculature. The single-whorled perianth is interpreted as a calyx because the organs are robust, have a broad base, an acute apex and quincuncial aestivation and are opposite the stamens. Petals are absent from inception. The dicliny is established at different development stages: stamens or carpels are absent from inception (Cannabis sativa), initiated and aborted during early (Trema micrantha, before sporo/gametogenesis) or late (Celtis iguanaea, after sporo/gametogenesis) development. Furthermore, in all species studied the carpels are congenitally united and the pseudomonomerous nature of the gynoecium is confirmed. Glandular trichomes are distributed on the bracts, sepals, anther connective and receptacle. Special floral features shared by species of Cannabaceae include precocious ovule development and sepals that are each vascularized by one bundle. The reduced flowers of Cannabaceae are the result of the absence from inception and/or abortion of organs and even of a whole whorl at different developmental stages, which were probably selected in response to pressures exerted by the similar pollination mechanism.

scholarly journals Estimating the development of landrace and improved maize cultivars as a function of air temperature

2016 ◽  
Vol 46 (10) ◽  
pp. 1737-1742
Author(s):  
Josana Andreia Langner ◽  
Nereu Augusto Streck ◽  
Genei Antonio Dalmago ◽  
Lia Rejane Silveira Reiniger ◽  
Angelica Durigon ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Block Design ◽  
Sowing Date ◽  
Maize Cultivars ◽  
Randomized Block Design ◽  
Sowing Dates ◽  
Developmental Rates ◽  
Cardinal Temperatures ◽  
Santa Maria ◽  
Emergence Phase

ABSTRACT: The objective of this study was to determine the maximum development rates for the phases of emergence, vegetative and reproductive, and to test the performance of the Wang and Engel (WE) model for simulating the development of landrace and improved maize cultivars sown on different dates. Model calibration was with data collected from a field experiment with a sowing date on December 13, 2014, and the model was tested with independent data from experiments with five sowing dates (August 20 and November 4, 2013, February 3 and August 15, 2014, and January 7, 2015) in Santa Maria, RS. The experiment was a complete randomized block design with four replicates. The dates of emergence (EM), silking (R1), and physiological maturity (R6) of two landraces ('Cinquentinha' and 'Bico de ouro') and two improved maize cultivars ('BRS Planalto' and 'AS 1573PRO') were recorded. Maximum daily developmental rates varied among cultivars from 0.2400 to 0.3411 d-1 for the emergence phase, from 0.0213 to 0.0234 d-1 for the vegetative phase, and from 0.0254 to 0.0298 d-1 for the reproductive phase. The WE model adequately estimated the developmental stages of landraces and improved maize cultivars with a mean error of 3.7 days. The cardinal temperatures used in the WE model were appropriate to estimate the developmental stages of landraces and improved maize cultivars.

scholarly journals An Improved Analysis for the Harmonic Distortion of MOS Voltage-Controlled-Resistors

1997 ◽  
Vol 19 (4) ◽  
pp. 253-260
Author(s):  
Muhammad Taher Abuelma'atti
Keyword(s):  
Fourth Order ◽  
Harmonic Distortion ◽  
Voltage Characteristic ◽  
Current Voltage Characteristic ◽  
Mos Transistor ◽  
Current Voltage ◽  
Order Polynomial ◽  
Polynomial Expression ◽  
Analytical Expressions ◽  
Fourth Order Polynomial

In this paper, a fourth-order polynomial expression is obtained for the nonlinear current-voltage characteristic of a MOS transistor operating in the triode region. Using this expression, closed-form expressions are obtained for the second-, third- and fourth-harmonic distortion of a MOS voltage-controlled- resistors. The analytical expressions obtained in this paper can be used for a quantitative study of the effect of different parameters of the performance of MOS voltage-controlled-resistors.

Temperature thresholds and statistical modelling of larval Wuchereria bancrofti (Filariidea: Onchocercidae) developmental rates

Parasitology ◽  
1997 ◽  
Vol 114 (2) ◽  
pp. 123-134 ◽  
Author(s):  
F. LARDEUX ◽  
J. CHEFFORT
Keyword(s):  
Wuchereria Bancrofti ◽  
Developmental Rate ◽  
Statistical Modelling ◽  
Original Method ◽  
Frequency Data ◽  
Larval Stages ◽  
A Value ◽  
Temperature Thresholds ◽  
Developmental Rates ◽  
Aedes Polynesiensis

Developmental rates for Wuchereria bancrofti larvae maturing in the vector Aedes polynesiensis were estimated by analysing stage-frequency data consisting of counts of larval stages in mosquitoes reared at 20, 22·5, 25, 27·5, 30 and 32 °C. Base temperatures (i.e. low temperature thresholds) for W. bancrofti development were estimated by the x-intercept method and the model of Lactin et al. (1995). Resulting values were similar with both methods and were ≈12·5 °C for microfilariae (mf) in thorax, ≈17 °C for L1, 15·5 °C for L2 and 16·5 °C for L3. Upper thresholds estimated by the Lactin et al. model were 29·3 °C for mf, 29·1 °C for L1, 32·2 °C for L2 and 31·5 °C for L3. In addition, an original method was devised for computing the L3 upper threshold, by modelling L3 length shrinkage with temperature. It gave a value of 31·4 °C. At 32 °C, L2 and L3 stages exhibited altered morphology, larvae being shorter and wider than expected. The model of Lactin et al. described adequately the non-linear relationship between developmental rate and temperature, but a linear degree-day approach may be applied for temperatures below 27–28 °C.

Floral development of Aponogeton natans and A. undulatus

1977 ◽  
Vol 55 (9) ◽  
pp. 1106-1120 ◽  
Author(s):  
V. Singh ◽  
R. Sattler
Keyword(s):  
Cell Division ◽  
Developmental Stage ◽  
Floral Development ◽  
Developmental Stages ◽  
Point Of View ◽  
Stages Of Development ◽  
The Third ◽  
Procambial Strand ◽  
Tunica Layer

The primordia of the floral appendages are initiated in an acropetal succession. Members of the same whorl appear nearly simultaneously. The gynoecial whorl and the two staminal whorls are trimerous, whereas the perianth consists only of two anteriolateral tepals. However, the posterior (adaxial) tepal may be present as an extremely reduced buttress whose growth becomes arrested immediately after its inception. If this somewhat questionable tepal rudiment is included we have a perfectly trimerous and tetracyclic flower with alternation of successive whorls. Subtending bracts of the flowers are completely missing in all developmental stages. While the tepal primordia are dorsiventral from their inception, the stamen and pistil (carpel) primordia originate as hemispherical mounds which become dorsiventral in subsequent stages of development. Each pistil (carpel) primordium becomes horseshoe shaped. As the margins grow up and contact they fuse postgenitally. No cross zone is formed. Placentation is submarginal. In A. natans eight ovules are formed and in A. undulatus only two arise; all ovules are bitegmic. The floral apices have a two-layered tunica up to the stage of pistil formation. The inception of all floral appendages (including the ovules) occurs by periclinal cell division in the second tunica layer. The third layer (corpus) may contribute to the formation of the stamens and pistils. Each appendage primordium receives only one procambial strand which begins to differentiate after the inception of the primordium. The questionable rudimentary tepal buttress lacks a procambial strand. Apparently it does not reach the developmental stage at which procambial induction occurs. From the point of view of floral development, the two species of Aponogeton differ drastically from members of the Alismatales studied so far. Among the Helobiae, the Aponogetonaceae appear to be most closely related to the Scheuchzeriaceae and the Juncaginaceae (Triglochinaceae).

A technique for the study of floral development

1968 ◽  
Vol 46 (5) ◽  
pp. 720-722 ◽  
Author(s):  
Rolf Sattler
Keyword(s):  
Floral Development ◽  
Developmental Stages ◽  
Three Dimensional ◽  
Serial Sectioning ◽  
Direct Study ◽  
Floral Buds ◽  
Dimensional Picture

When floral buds are studied by serial sectioning, the obtained three-dimensional picture of the buds is a reconstruction which involves some theoretical elements. In contrast to this reconstructive method, the described technique permits the direct study of the three-dimensional developmental stages of flowers. Protoderm cells of floral apices and primordial appendages can be demonstrated.

A TEMPERATURE-DEPENDENT MODEL OF EGG DEVELOPMENT OF THE WESTERN CORN ROOTWORM, DIABROTICA VIRGIFERA VIRGIFERA LECONTE (COLEOPTERA: CHRYSOMELIDAE)

1991 ◽  
Vol 123 (6) ◽  
pp. 1183-1197 ◽  
Author(s):  
A.W. Schaafsma ◽  
G.H. Whitfield ◽  
C.R. Ellis
Keyword(s):  
Simulation Model ◽  
Diabrotica Virgifera Virgifera ◽  
Base Temperature ◽  
Diabrotica Virgifera ◽  
Degree Days ◽  
Egg Development ◽  
Egg Hatch ◽  
Developmental Threshold ◽  
Soil Temperatures ◽  
Developmental Rates

AbstractDevelopmental rates of post-diapause eggs of Diabrotica virgifera virgifera LeConte were compared in the laboratory at six constant temperatures, 12, 16, 20, 24, 28, and 32°C. Linear and nonlinear models were fitted to temperature versus developmental data and were used to predict egg hatch in the field. A four-parameter model fitted to median developmental rates (r2 = 0.99) indicated that development was linear between 16 and 28°C, optimal at 28°C, and decreased at 32°C. The lower development threshold (± SE) (10.5 ± 0.1°C) was determined by linear regression and the x-intercept method. Completion of post-diapause egg development required 258 ± 3 degree-days (± SE) above the base temperature. This compared well with the mean degree-days accumulated to 50% hatch (± SE) of 265 ± 24 which we observed in the field at several locations over 3 years using a degree-day model incorporating an 11°C developmental threshold and soil temperatures at 5- and 10-cm depths. A stochastic simulation model, incorporating a nonlinear developmental function dependant on soil temperatures taken every 2 h also predicted 50% hatch within 2 days. This model was validated in the field with 19 independent records of soil temperatures for several locations at two depths in the soil over 3 years. The simulation model accurately predicted time of 5 and 95% hatch, which indicates that this model has broad application in predicting the pattern of egg hatch for pest management.

scholarly journals Different co-culture systems have the same impact on bovine embryo transcriptome

Reproduction ◽  
2017 ◽  
Vol 154 (5) ◽  
pp. 695-710 ◽  
Author(s):  
A Vitorino Carvalho ◽  
E Canon ◽  
L Jouneau ◽  
C Archilla ◽  
L Laffont ◽  
...  
Keyword(s):  
Early Development ◽  
Embryo Development ◽  
Developmental Stages ◽  
Developmental Rate ◽  
Cell Types ◽  
Culture Conditions ◽  
Bovine Embryo ◽  
Culture Systems ◽  
Beneficial Impact ◽  
Reduce Cell Survival

During the last few years, several co-culture systems using either BOEC or VERO feeder cells have been developed to improve bovine embryo development and these systems give better results at high oxygen concentration (20%). In parallel, the SOF medium, used at 5% O2, has been developed to mimic the oviduct fluid. Since 2010s, the SOF medium has become popular in improving bovine embryo development and authors have started to associate this medium to co-culture systems. Nevertheless, little is known about the putative benefit of this association on early development. To address this question, we have compared embryo transcriptomes in four different culture conditions: SOF with BOEC or VERO at 20% O2, and SOF without feeders at 5% or 20% O2. Embryos have been analyzed at 16-cell and blastocyst stages. Co-culture systems did not improve the developmental rate when compared to 5% O2. Direct comparison of the two co-culture systems failed to highlight major differences in embryo transcriptome at both developmental stages. Both feeder cell types appear to regulate the same cytokines and growth factors pathways, and thus to influence embryo physiology in the same way. In blastocysts, when compared to culture in SOF at 5% O2, BOEC or VERO seems to reduce cell survival and differentiation by, at least, negatively regulating STAT3 and STAT5 pathways. Collectively, in SOF medium both blastocysts rate and embryo transcriptome suggest no influence of feeder origin on bovine early development and no beneficial impact of co-culture systems when compared to 5% O2.

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