Summer and autumn growth of rhizomatous birdsfoot trefoil

Abstract

A new population of birdsfoot trefoil (Lotus corniculatus L.) with rhizomes (RBFT) has been developed for greater persistence. No study has compared RBFT with a standard, non-rhizomatous cultivar of birdsfoot trefoil (BFT). Objectives were to: (i) compare RBFT with BFT for differences in shoot and root mass and total nonstructural carbohydrate (TNC) concentration of taproots in both clipped and non-clipped situations and (ii) describe rhizome production of clipped and non-clipped RBFT. 'Norcen' BFT and RBFT were grown in field plots near Columbia, MO, in 1994 and 1995. The study had four treatments: non-clipped RBFT, clipped RBFT, non-clipped BFT, and clipped BFT. Each treatment was replicated four times in a randomized complete block. Plots were sampled biweekly for shoot and root mass and taproot TNC from early-July until the first killing frost in October. In addition, length, mass, TNC, and number of rhizomes per plant were recorded for RBFT. From mid-September until the final sampling, the shoot mass for RBFT was about half that of BFT; however, RBFT's shoot mass was less affected by clipping than was BFT's. Taproot TNC was 20 to 40 g kg-1 greater for RBFT than BFT throughout both growing seasons. Nearly all RBFT plants exhibited rhizomes by mid-October both years. Clipping RBFT plants did not affect rhizome growth. Rhizome TNC concentration increased steadily during autumn, with a final concentration of approximately 220 g kg-1. The failure of clipping to decrease rhizome production, combined with higher levels of below-ground TNC, may give RBFT the ability to withstand frequent defoliation.