Vol. 70 No: 3

Title:
The Inheritance of Red, Salmon, Rose-Pink and Soft-Pink Flower Colours in Zonal Pelargoniums

Authors:
R.A.E. TILNEY-BASSETT, A.A. MUNSHI, A.B. ALMOUSLEM and N.S. NASSER

pp: 499-508

Abstract:
The inheritance of red flower colour in zonal pelargoniums is controlled by the interaction of two complementary genes, R1/r1 and R2/r2. In the absence of one or both dominant genes, the flower has a non-red colour. When a plant has a genotype in which R2 is present and R1 absent the flower colour is salmon, and when it is R1 that is present and R2 absent the flower colour is rose-pink. When a plant has a genotype in which both R1 and R2 are missing, the flower colour is soft-pink. Owing to genetic heterogeneity with respect to modifying genes, the variation in the expression of these colours may lead to problems of classification. There are four genotypes for red, two for salmon, two for rose-pink and one for soft-pink flower colours. These conclusions were supported by the goodness of fit between the observed segregations after 32 different crosses within a wide range of cultivars or hybrids, and the expected Mendelian segregations from a matrix of crosses between the nine genotypes proposed. Examples of all expected genotypes were identified. There was some data which raised the possibility that the two R genes were linked. Four variegated-leaf chimeras were shown to be chimeras for flower colour.

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