W. J. C. Lawrence
Articles written in Journal of Genetics
Volume 21 Issue 2 August 1929 pp 125-159
Volume 22 Issue 2 May 1930 pp 153-163
Odd multiple polyploids are relatively infertile, consequently in fruits such as
In apples a very low proportion of fruit to flowers is sufficient to give a yield. The apple has ten embryos, and often a single seed is sufficient for the development of a fruit, and even this seed may be imperfect. This approaches parthenocarpy and renders fruit production still less dependent on the formation of seeds. Fruitfulness in apples may therefore be maintained in spite of a high degree of generational sterility.
Triploidy in apples is another example of the occurrence of sterile forms in species where a substitute has been found (either in nature or in cultivation) for normal seed and fruit production. The substitution in apples is more complex than usual for, while sexual reproduction is now replaced by grafting, the necessity for the stimulus of seed growth in the formation of a fruit is largely evaded. Therefore triploids are able to fruit although incapable as a rule of yielding offspring of any value.
The offspring of triploids, whether derived from selling or crossing with diploids, lack vigour, presumably owing to their aneuploid constitution (cf. Darlington and Moffett). Consequently triploid varieties are likely to be of little value in practical breeding as the necessary vigour and fertility would rarely be obtained in the resulting offspring.
Volume 24 Issue 1 February 1931 pp 97-107
Volume 24 Issue 2 April 1931 pp 243-255
Volume 24 Issue 3 July 1931 pp 257-306
Volume 24 Issue 3 July 1931 pp 307-324
Volume 28 Issue 2 December 1933 pp 265-296
Volume 30 Issue 2 March 1935 pp 155-226
Volume 38 Issue 1-2 July 1939 pp 299-306
An account is given of the flower colours, chromosome numbers and flower pigments of cultivated species and hybrids of
The origin of the garden strain is recounted and the results of breeding experiments within the strain are shown to agree with the known origin of the garden forms.
The action of the flower colour genes is as follows.
Volume 48 Issue 1 April 1947 pp 16-30
When the two dominant genes
Mutations and chimaeras are described. One of the latter gave rise to tetraploids, the first to be recorded in garden
It is considered doubtful whether these genes can play a part in speciation.
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