Mechanisms of frequency-dependent advantage in wheat

1977 ◽  
Vol 28 (2) ◽  
pp. 187 ◽  
Author(s):  
TK Phung ◽  
AJ Rathjen
Keyword(s):  
Grain Yield ◽  
Genetic Polymorphisms ◽  
Competitive Ability ◽  
Low Frequency ◽  
F1 Hybrids ◽  
Soil Factors ◽  
Frequency Dependent ◽  
Weak Competitor ◽  
The Relationship ◽  
Test Plants

The relationship between frequency-dependent advantage (f.d.a.) and competitive ability in wheat was investigated by growing F1 hybrids and their parents in paired combinations at two frequencies, 6.25% and 25%. The results indicated that a strong competitor had an increased yield at a low frequency when grown in a stand of a weak competitor (thus exhibiting f.d.a.); however, the weak competitor was not significantly reduced when it was grown at low frequency. One hybrid (Warimek*Tirngalen) did not show f.d.a, when grown in either parent, which indicated that heterozygosity did not necessarily lead to f.d.a. The strong competitor, Timgalen, also showed f.d.a, in a mixture of other varieties, which suggested that the mechanism which resulted in f.d.a. in this genotype was specific to this genotype. The physical basis of f.d.a, was studied in an experiment designed to permit assessment of relative competition for aerial and soil factors. The results indicated that f,d.a. was mainly associated with soil factors. Furthermore, there was a positive correlation between grain yield per plant and distance between the test plants, which suggested that f.d.a. was probably due to the interaction between roots of the same genotype in the exploitation of the environment in a slightly different way from that by other genotypes. The significance of f.d.a, in the maintenance of genetic polymorphisms is discussed.

scholarly journals Assessment of the relationship of yield and its contributing traits in wheat

2022 ◽  
pp. 4-10
Keyword(s):  
Grain Yield ◽  
Genetic Material ◽  
Spike Length ◽  
F1 Hybrids ◽  
Path Coefficient ◽  
Cereal Crop ◽  
Thousand Grain Weight ◽  
Path Coefficient Analysis ◽  
Relationship Of ◽  
The Relationship

Wheat is an essential source of nutrition for humans and an important cereal crop of Pakistan due to its widespread use as food. To fulfill the nutrition needs of boosted population, crop yield must be improved. In this perspective, we conducted the experiment reported in this paper to achieve correlation and path coefficient attributes given by yield-related traits. Our study enables to understand the association and contribution of nine traits toward grain production. The genetic material was comprised of seven parents and twelve F1 hybrids. Correlation analysis showed that grain yield per spike, thousand grain weight, spike length, and number of tillers per plant have positive and significant correlation with grain yield per plant, at both genotypic and phenotypic level. Path coefficient analysis revealed that direct effects of number of tillers per plant, grain yield per spike, and spike length were positive. This data persuaded that selection based on these traits could be useful for breeding purposes to higher grain yield.

Associated growth of wheat and annual ryegrass. III. Effects of early competition on wheat

1980 ◽  
Vol 31 (6) ◽  
pp. 1057 ◽  
Author(s):  
K Rerkasem ◽  
WR Stern ◽  
NA Goodchild
Keyword(s):  
Competitive Ability ◽  
Total Density ◽  
Annual Ryegrass ◽  
Nitrogen Application ◽  
Soil Factors ◽  
Wheat Roots ◽  
Ear Development ◽  
Competitive Relations ◽  
Shoot Weight ◽  
The Relationship

The effects of four factors applied in factorial combination, viz. nitrogen application, time of ryegrass germination relative to wheat, roots together or separate and species proportion, were studied during the first few weeks of the associated growth of wheat and annual ryegrass. The experiment was conducted in boxes in a glasshouse at a total density of 355 plants m-2. Many plant variates were measured at 7, 28 and 49 days from sowing. Nitrogen content was determined at 28 and 49 days. Even at 7 days, measurable treatment effects on root and shoot weights of wheat could be detected. The effects could be discerned subsequently in terms of root length, tillering patterns, shoot weight, and ear development. Effects on ear development were observed in the last tiller and on the most recently developed florets. Some of these responses involved interactions of two or more of the factors studied. Treatments modified the relationship between competitive ability and yield in pure culture, more in ryegrass than in wheat. Although nitrogen effects appeared to have a strong influence on the competitive relations between the species, it is suggested that competition for soil factors other than nitrogen may also have been involved.

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

IMPROVEMENT OF SPRING DURUM WHEAT SELECTION METHODOLOGIES UNDER CLIMATE CHANGE CONDITIONS

1970 ◽  
pp. 33-36
Author(s):  
А. I. Grabovets ◽  
V. P. Kadushkina ◽  
S. А. Kovalenko
Keyword(s):  
Grain Yield ◽  
Durum Wheat ◽  
Correlation Coefficient ◽  
Harvest Index ◽  
Unit Area ◽  
Correlation Coefficients ◽  
Chemical Mutagenesis ◽  
Main Method ◽  
The Relationship ◽  
Selection Of

With the growing aridity of the climate on the Don, it became necessary to improve the methodology for conducting the  breeding of spring durum wheat. The main method of obtaining the source material remains intraspecific step hybridization. Crossings were performed between genetically distant forms, differing in origin and required traits and properties. The use of chemical mutagenesis was a productive way to change the heredity of genotypes in terms of drought tolerance. When breeding for productivity, both in dry years of research and in favorable years, the most objective markers were identified — the size of the aerial mass, the mass of grain per plant, spike, and harvest index. The magnitude of the correlation coefficients between the yield per unit area and the elements of its structure is established. It was most closely associated with them in dry years, while in wet years it decreased. Power the correlation of the characteristics of the pair - the grain yield per square meter - the aboveground biomass averaged r = 0.73, and in dry years it was higher (0.91) than in favorable ones (0.61 - 0.70) , between the harvest and the harvest index - r = 0.81 (on average). In dry years, the correlation coefficient increased to 0.92. Research data confirms the greatest importance of the mass of grain from one ear and the plant in the formation of grain yield per unit area in both dry and wet years. In dry years, the correlation coefficient between yield and grain mass per plant was on average r = 0.80; in favorable years, r = 0.69. The relationship between yield and grain mass from the ear was greater — r = 0.84 and r = 0.82, respectively. Consequently, the breeding significance of the aboveground mass and the productivity of the ear, as a criterion for the selection of the crop, especially increases in the dry years. They were basic in the selection.

scholarly journals Optimizing Grain Yield and Water Use Efficiency Based on the Relationship between Leaf Area Index and Evapotranspiration

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 313
Author(s):  
Guoqiang Zhang ◽  
Bo Ming ◽  
Dongping Shen ◽  
Ruizhi Xie ◽  
Peng Hou ◽  
...  
Keyword(s):  
Grain Yield ◽  
Water Use Efficiency ◽  
Leaf Area Index ◽  
Water Use ◽  
Plant Density ◽  
Maize Yield ◽  
Area Index ◽  
Irrigation Level ◽  
Use Efficiency ◽  
The Relationship

Achieving optimal balance between maize yield and water use efficiency is an important challenge for irrigation maize production in arid areas. In this study, we conducted an experiment in Xinjiang China in 2016 and 2017 to quantify the response of maize yield and water use to plant density and irrigation schedules. The treatments included four irrigation levels: 360 (W1), 480 (W2), 600 (W3), and 720 mm (W4), and five plant densities: 7.5 (D1), 9.0 (D2), 10.5 (D3), 12.0 (D4), and 13.5 plants m−2 (D5). The results showed that increasing the plant density and the irrigation level could both significantly increase the leaf area index (LAI). However, LAI expansion significantly increased evapotranspiration (ETa) under irrigation. The combination of irrigation level 600 mm (W3) and plant density 12.0 plants m−2 (D4) produced the highest maize yield (21.0–21.2 t ha−1), ETa (784.1–797.8 mm), and water use efficiency (WUE) (2.64–2.70 kg m−3), with an LAI of 8.5–8.7 at the silking stage. The relationship between LAI and grain yield and evapotranspiration were quantified, and, based on this, the relationship between water use and maize productivity was analyzed. Moreover, the optimal LAI was established to determine the reasonable irrigation level and coordinate the relationship between the increase in grain yield and the decrease in water use efficiency.

scholarly journals Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, Candoia aspera

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 672
Author(s):  
Bruce A. Young ◽  
Skye Greer ◽  
Michael Cramberg
Keyword(s):  
Cerebrospinal Fluid ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Mean Amplitude ◽  
The Body ◽  
Body Waves ◽  
Lower Amplitude ◽  
Lateral Undulation ◽  
Recovery From Anesthesia ◽  
The Relationship

In the viper boa (Candoia aspera), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.66 Hz) pulses with a mean amplitude of 1.2 mmHg that correspond to the cardiac cycle. Manual oscillations of anesthetized C. aspera induced propagating sinusoidal body waves. These waves resulted in a different pattern of CSF pulsations with frequencies corresponding to the displacement frequency of the body and with amplitudes greater than those of the cardiac or ventilatory cycles. After recovery from anesthesia, the snakes moved independently using lateral undulation and concertina locomotion. The episodes of lateral undulation produced similar influences on the CSF pressure as were observed during the manual oscillations, though the induced CSF pulsations were of lower amplitude during lateral undulation. No impact on the CSF was found while C. aspera was performing concertina locomotion. The relationship between the propagation of the body and the CSF pulsations suggests that the body movements produce an impulse on the spinal CSF.

scholarly journals On the Relationship between Regional Ocean Heat Content and Sea Surface Height

2017 ◽  
Vol 30 (22) ◽  
pp. 9195-9211 ◽  
Author(s):  
John T. Fasullo ◽  
Peter R. Gent
Keyword(s):  
Time Scales ◽  
Low Frequency ◽  
Heat Content ◽  
Sea Surface Height ◽  
Ocean Heat Content ◽  
Ocean Dynamics ◽  
Sea Surface ◽  
Altimeter Data ◽  
Model Control ◽  
The Relationship

Abstract An accurate diagnosis of ocean heat content (OHC) is essential for interpreting climate variability and change, as evidenced for example by the broad range of hypotheses that exists for explaining the recent hiatus in global mean surface warming. Potential insights are explored here by examining relationships between OHC and sea surface height (SSH) in observations and two recently available large ensembles of climate model simulations from the mid-twentieth century to 2100. It is found that in decadal-length observations and a model control simulation with constant forcing, strong ties between OHC and SSH exist, with little temporal or spatial complexity. Agreement is particularly strong on monthly to interannual time scales. In contrast, in forced transient warming simulations, important dependencies in the relationship exist as a function of region and time scale. Near Antarctica, low-frequency SSH variability is driven mainly by changes in the circumpolar current associated with intensified surface winds, leading to correlations between OHC and SSH that are weak and sometimes negative. In subtropical regions, and near other coastal boundaries, negative correlations are also evident on long time scales and are associated with the accumulated effects of changes in the water cycle and ocean dynamics that underlie complexity in the OHC relationship to SSH. Low-frequency variability in observations is found to exhibit similar negative correlations. Combined with altimeter data, these results provide evidence that SSH increases in the Indian and western Pacific Oceans during the hiatus are suggestive of substantial OHC increases. Methods for developing the applicability of altimetry as a constraint on OHC more generally are also discussed.

NEW ETIOLOGICAL FACTORS OF OCCUPATIONAL HEARING LOSS

2021 ◽  
Author(s):  
V.B. Pankova ◽  
◽  
М.F. Vilk ◽  
◽  
◽  
...  
Keyword(s):  
Hearing Loss ◽  
Low Frequency ◽  
Evidence Base ◽  
Frequency Noise ◽  
Labor Intensity ◽  
Etiological Factors ◽  
Hearing Organ ◽  
The Relationship ◽  
Vascular Stria ◽  
Occupational Hearing Loss

Annotation. On the example of railway and air transport, a number of new issues of occupational hearing loss are shown, requiring study and subsequent implementation in practical health care, as new etiological factors in the development of hearing loss. This concerns the factor of labor intensity, which has a potentiating, pathogenetic significance, along with noise, in the development of hearing loss due to the formation of chronic stress, leading to additional ischemia of the vascular stria and damage to the neuroepithelium of the inner ear. There is a need, along with the development of a methodology for assessing the factor of labor intensity for SOUT of workplaces, to determine the criteria for its negative action when used for the examination of the connection between the disease of the organ of hearing and the profession. In the «List of occupational diseases» in clause 2.4.2. indicated diseases associated with exposure to infrasound (IZ), among the manifestations of which, called sensorineural hearing loss bilateral. However, IZ, as well as low-frequency noise (LFN), were not previously considered as significant adverse factors in relation to the hearing organ in mass clinical trials, therefore, there are no expert criteria for the relationship between hearing loss and their impact, which could be applied in practice, which requires accumulation of evidence base for the subsequent substantiation of an independent nosological form of a disease of the organ of hearing, associated with mechanoacoustic exposure.

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