In vitro selection for improved seedling vigour in birdsfoot trefoil (Lotus corniculatus L.)

Establishment of productive stands of birdsfoot trefoil (Lotus corniculatus L.) is often difficult due to poor seedling vigour. Objectives of this study were to evaluate the relative effectiveness of in vitro selection conditions for seedling vigour and to choose the best lines for further evaluation. Birdsfoot trefoil seedlings from cvs. Leo and Upstart were selected on the basis of in vitro rate of germination at 5, 12 and 20 degrees C and subsequent seedling growth at 20 degrees C. Two cycles of recurrent selection were carried out. Progeny from both cycles of selection were evaluated under controlled and field conditions. In general, selection temperatures did not significantly affect emergence, individual shoot dry matter production or total shoot dry matter production. Emergence and total shoot dry matter yield were higher for selections within cv. Upstart than for selections within cv. Lee. Seedling vigour of cycle-2 selections was not superior to cycle-1 selections. Failure to make gains during the second cycle of selection is believed to be due to seed sterilization procedures during cycle-2 selection. Germplasms chosen for further evaluation include the 12 degrees C and 20 degrees C cycle-1 selections and the 20 degrees C cycle 2 selection from cv. Upstart.