Effects of sericea lespedeza root exudates on some perennial grasses

Abstract

Root exudates are substances released into the surrounding medium by healthy and intact plant roots. Research on root exudates has shown that root exudates can reduce seed germination and plant growth. There is no information on the effect of sericea lespedeza [Lespedeza cuneata (Dum. de Cours) G. Don.] root exudates on other plants. In a series of greenhouse experiments we studied (1) if sericea root exudates affect seed germination and seedling growth of the perennial grasses tall fescue (Festuca arundinacea Schreb.), bermudagrass [Cynodon dactylon (L.) Pers.], and bahiagrass (Paspalum notatum Flugge); and (2) if any such responses were cultivar dependent. The effects of the root exudates were measured in 2 experiments. In the first one, coarse perlite was used as a medium to measure seed germination and radicle and coleoptile growth. In the second experiment, soil was used as a medium to measure emergence and biomass. Root exudates from sericea lespedeza had no effect on germination and emergence of tall fescue and bahiagrass but reduced their radicle and coleoptile length and biomass. Germination, radicle, and coleoptile length, and emergence of bermudagrass decreased when exposed to the root exudates; however, biomass was not affected. Cultivars of the grass species differed in their response to the root exudates of sericea lespedeza. Thus, establishment of tall fescue in mixture with sericea lespedeza is not likely to be affected; however, its growth is likely to be decreased. Therefore, tall fescue contribution to total yield will be reduced. Conversely, establishment of bermudagrass is likely to be affected, but once established, its growth is expected to be similar to its grown alone.