Vegetative Regeneration of Panicum racemosum from Rhizome Fragments on Southern Brazilian Coastal Dunes

Abstract

The sand-building grass Panicum racemosum, the dominant species in foredune habitats in southern Brazil, are subject to severe damage during winter storms. Consequently, rhizomes of P. racemosum are exposed and fragmented into different sizes. Each rhizome fragment has the potential to produce a new shoot, root or rhizome. Plants excavated on seaward fore dunes revealed that 48% of new shoots had originated from rhizome fragments and none of them were from seedlings. Rhizome fragments with 3-nodes were more successful in sprouting new shoots than 2- and 1-node, in both laboratory and field conditions. The effect of sand burial on production of new shoots showed that rhizome fragments with 3-node were more effective than 2- and 1-node fragments. Panicum racemosum shows similar behavior to other coastal dune grasses with high regenerative capacity of rhizome fragments and clonal propagation. The success in development of new shoots from rhizome fragments is related to nitrogen content, size of fragment, and seasonality. This regenerative capacity is an important strategy in the maintenance of local populations after strong storms.