Temperature effect on chiasma frequency in the bluebell endymion nonscriptus

Abstract

1. Experiments have been conducted with the bluebell, Endymion nonscriptus (L.) Garke to determine the effect of temperature on chiasma frequency using a proposed standardizing procedure by which (a) the material used is known to be homogeneous for chiasma frequency, and (b) just enough time is used at each temperature as is required for meiosis to be completed. These experiments showed a consistent but gradual decrease in mean chiasma frequency with increasing temperature. 2. A decrease in mean chiasma frequency is shown to be associated with an increase in inter-nuclear variance (see also Rees and Thompson 1956). 3. Constant temperature seems to be more deleterious to chiasma formation than fluctuating temperature. 4. In the light of the present experimental results it has been possible to evaluate some of the apparently conflicting results of previous workers. 5. It is expected that future experiments along the lines of the present one would allow legitimate comparison of results from different materials.