Changes in growth and chemical defences upon defoliation in maize

Abstract

The effect of defoliation on growth and on levels and allocation patterns of hydroxamic acids (Hx) in maize seedlings was evaluated 6 days after treatment. No significant differences were found between defoliated and nondefoliated plants for the Hx concentration, relative Hx content and Hx- aglucone to Hx-glucoside ratio in shoots, roots and root exudates, with the exception of Hx concentration in shoots, which decreased upon defoliation. However, growth of defoliated seedlings was considerably higher than that of nondefoliated ones. These results indicate that maize responds to defoliation by allocating its resources mainly tO growth rather than to defence. Since previous work described the opposite strategy in rye, responses to defoliation in both species are discussed in relation to current theories of plant defence.