Interactive effects of nitrogen and genotype on maize rough dwarf disease

Nitrogen and genotype play vital roles in modulating plant disease resistance. Maize (Zea mays L.) rough dwarf disease (MRDD) is a global viral disease that has caused serious yield losses. However, it is not clear how nitrogen and genotype interact to affect MRDD. We conducted field experiments in 2011 and 2013 to investigate the MRDD incidence, yield, and yield loss rate of 59 maize hybrids under high nitrogen (HN) and low nitrogen (LN). Compared with HN, the MRDD incidence and yield loss rate of S-sensitive hybrids (nitrogen significantly influenced MRDD incidence in susceptible genotypes) could be significantly reduced by 50.6% and 35.5%, respectively, in LN without compromising maize yield. In contrast, R-insensitive types (resistant hybrids in which MRDD incidence was unresponsive to nitrogen treatment) could maintain high MRDD resistance and yield at HN. US hybrid 78599 and inbred line Dan340 were the main parental resources of the resistant genotypes, and inbred lines Huangzao4 and Ye478 were the main parental resources of the susceptible genotypes. The physiological mechanism leading to increased MRDD incidence was thought to be higher nitrogen concentrations in the stalks. This study provided theoretical support for using reasonable nitrogen management to control MRDD and breeding MRDD-resistant maize hybrids.