The Distribution of Assimilates in Lolium multiflorum Lam. Following Differential Defoliation

Abstract

In seedling plants of Lolium multiflorum Lam. the tillers were defoliated but the main shoot was left intact. Radiocarbon as 14CO2 was supplied to this shoot at different times following tiller defoliation and the pattern of distribution of labelled assimilates was determined quantitatively. It was found that a greater proportion (approximately 10–20 per cent) of exported assimilate was translocated to the cut tillers but although the proportion supplied to the root system was less the total radiocarbon incorporated by the roots was unchanged. This was brought about by a large increase in the export of radiocarbon fixed by the intact shoot—up to 100 per cent following one treatment. These alterations in the organization of the defoliated plant lead to a greater efficiency in the carbon economy and are discussed in relation to the stress imposed by defoliation.