Citrus dwarfing viroid reduces canopy volume by affecting shoot apical growth of navel orange trees grown on trifoliate orange rootstock

Abstract

Citrus dwarfing viroid (CDVd) infection of navel orange trees ( Citrus sinensis (L.) Osb.) on ‘Rich 16-6’ trifoliate orange ( Poncirus trifoliata (L.) Raf.) rootstock has been previously reported to reduce canopy volume by approximately 50%. We demonstrated that the reduction in tree size of CDVd-infected citrus resulted from a >20% reduction in the apical growth of individual shoots within the tree canopy. We also demonstrated that the reduced canopy volume of the CDVd-infected trees is a long lasting phenotype comparable to that of ‘Flying Dragon’ rootstock, which is known to reduce citrus tree size.