The role of the cotyledon on the flowering behaviour of Pisum Sativum : a physiological study.

This thesis doesn't have an abstract. Included here is the first 2 paragraphs of chapter 1 (genetics and physiology). Genetics The present knowledge concerning the genetic control of flowering in peas has recently been reviewed by Murfet (1971a). Rowlands (1964), who used as his criterion FT (the number of days between sowing of the seed and opening of the first flower) and Barber (1959), who recorded the flowering response in terms of NF (the node at which the first flower is initiated), both concluded that flowering was fundamentally under the control of one major gene,.dominant for late flowering. Barber used the symbol Sn, first proposed by Tedin and Tedin (1923), to designate this gene. The effect of Sn is increased under S.D. (short day) conditions, and subject to modification by a system of polygenes. Barber also suggested a second polygene system working outside the orbit of the Sn gene. More recently, Wellensiek (1969) has suggested the presence of a multiple allelic gene system controlling flowering behaviour in peas, with alleles for late, intermediate and early flowering such that each later gene is incompletely dominant over the earlier one. Physiology TECHNIQUES AND ENVIRONMENTAL VARIABLES With regard to the physiological approach towards flowering in peas, the two most common variables used have been photoperiod and vernalization. In addition, the two techniques of cotyledon removal and grafting have been commonly employed. These environmental variables and techniques are explained in greater, detail in the following chapter. 1.