Physiological responses to Nilaparvata lugens in susceptible and resistant rice varieties: allocation of assimilates between shoots and roots.

Nilaparvata lugens (Stål) is a typical vascular feeder, primarily sucking the phloem sap of host plants. Its feeding on rice, Oryza sativa L., plants changes the pattern of allocation of assimilates between roots and shoots, and the root:shoot (R/S) ratio of assimilates is often measured as an index of physiological responses to N.