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  • 1970-1974  (3)
  • 1965-1969
  • 1950-1954
  • 1973  (3)
Material
Years
  • 1970-1974  (3)
  • 1965-1969
  • 1950-1954
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 43 (1973), S. 18-22 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A study was made of the nature of variation and changes in association for characters related to yield, development and disease resistance in two sets of progenies one set derived through biparental mating (A-series) and the other by traditional inbreeding (selfing) from the F2 onwards (T-series), in a 22 × 22 diallel of dwarf derivatives of Pennisetum typhoides S & H. Comparison of means and variances within and between the two groups of progenies (A and T-series) and with those of released hybrids (HB-1, HB-2, HB-3, HB-4) for seventeen characters (six related to development, six to productivity, three to vegetative growth and one each to earliness and disease incidence) showed significant variation among the lines of the two series for synchrony of tillering, earliness, disease incidence, chlorophyll depth, grain hairiness, tiller number, plant height, length of earhead, grain yield and grain weight. The A-series selections were significantly superior to the T-series for most of the characters, indicating the effectiveness of selection in biparental matings compared with selection in selfed progenies for these traits. Many of the A-series (220 out of 800) selections were also superior to the existing released hybrids. Changes in the magnitude and nature of association among twelve important characters in the two populations were more favourable in the biparental matings: of 66 possible correlation coefficients examined, 25 cases were found with changes in favour of selections from biparental matings (A-series). These changes were probably due to the breakage of unfavourable linkages and changes in phase of linkage, and indicate the usefulness of biparental matings in the simultaneous improvement of the population for several attributes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 84 (1973), S. 205-226 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The heart rate ofAnabas is about 40 beats/min when breathing water and air. Tachycardia occurs as the fish takes an air breath and the rate declines as the breath holding continues but water breathing stops. Bradycardia is observed during this later phase. By the time the next air breath is taken, the heart rate has dropped to 15–30 beats/min. The heart rate of a fish breathing normoxic water but prevented from surfacing is about 42/min. Bradycardia occurs in hypoxic water under similar conditions. Tachycardia is observed in active fish when breathing hypercarbic water and air. On exposure to air bradycardia is found in resting fish but tachycardia occurs during activity. In air,Anabas usually repeats a breath when the heart rate drops to 15–25 beats/min. Tachycardia occurs immediately following an air breath. Heart rate then returns over a period of 3–6 mins to the normal resting level of 30 beats/min. The gas composition of the suprabranchial chambers has been measured and its relationship with the occurrence of an air breath, tachycardia and bradycardia is described. The experimental results are discussed in relation to the anatomy of the blood supply to the respiratory organs. The possible role of respiratory gases and pH in the control of breathing and perfusion is also discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 44 (1973), S. 602-607 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: The rate of recombination between linked inversions of the third chromosome of Drosophila ananassae has been investigated by means of the salivary gland smear technique. Different homozygous strains of the species were utilised during the present investigation. The data show that the crossover rate between heterozygous inversions of the third chromosome of D. ananassae varies among different strains. This suggests that recombination between heterozygous inversions is influenced by genic (strain) factors.
    Type of Medium: Electronic Resource
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