Pyrethrum Breeding: A Progress Report

Abstract

In order to obtain the maximum efficiency from a field of pyrethrum it is necessary to plant intrinsically good material. In this connection, a considerable amount of work is being carried out by the Plant Breeding. Services at Njoro on the selection and breeding of high yielding strains of good toxic qualities. Before, however, attempting the synthesis of high test types, it is necessary to determine whether pyrethrin content is a factor that is inherited or whether it is controlled entirely by environment, fluctuating according to, say, rainfall and altitude. If the latter is found to be the case the selection and building up of high content lines will be impossible: breeding work can then do no more than accomplish the production, valuable though this would be, of high yielding strains with desirable agronomic characteristics such as resistance to lodging, production of large flowers, and longevity. The toxicity of such plants would then depend, in a given season, on the environment in which they were growing. But, if toxicity is just as much part and parcel of a plant as is a particular type of flower or a certain habit of growth, then the possibility of isolating or synthesizing highpyrethrin strains falls within the scope of the plant breeder.