Compensation in spring-sown oil-seed rape (Brassica napus L.) plants in response to injury to their flower buds and pods

Abstract

SUMMARYThe extent and possible mechanism by which spring-sown oil-seed rape plants can compensate for insect or artificial injury to flower buds and pods were investigated by examination of the yield, and its components, of plants collected from commercial fields and those grown in field cages and glasshouses. Plants were able to compensate and in some instances overcompensate for all observed levels of M. aeneus injury or artificial bud removal by the production of more axillary racemes, which may be due to the loss of apical dominance. Artificial injury to the pods or infestation by C. assimilis larvae did not result in a significant reduction in the yield of seed and was compensated for partly by a slight increase in the number of axillary racemes and by slight increases in the number of pods on each axillary raceme and in the 1000-seed weight, and resulted mainly from the diversion of nutrients to other yield-bearing organs. Injury by D. brassicae larvae was partly compensated for in 1975 and at lower injury levels in 1974 and involved a similar mechanism to compensation for C. assimilis injury. These results are discussed in relation to the observed infestation levels in field surveys and current control practices.