EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON SHOOT, ROOT AND RHIZOME GROWTH IN 3 LOTUS-ULIGINOSUS SCHKUHR POPULATIONS

The growth of three populations of greater lotus (Lotus uliginosus Sch kuhr syn. L. pedunculatus Cav.) was compared at photoperiods of 10, 12 and 14 h at a maximum day/minimum night temperature of 21/16 degrees C and at maximum day/minimum night temperatures of 27/22, 21/16, 18/13 and 15/10 degrees C at a photoperiod of 12 h. Short days (10 h) favou red root and rhizome development compared to long days (14 h). A tempe rature regime of 15/10 degrees C restricted rhizome development compar ed to the 18/13 and 21/16 degrees C regimes. Shoot growth was restrict ed at the highest temperature regime (27/22 degrees C). The cultivar S harnae had fewer, but heavier, rhizomes than Grasslands Maku; this may indicate adaptation to the dry summers at its site of origin (Algarve , Portugal). The response of rhizome growth to temperature and photope riod explains part of the performance of greater lotus in the field at a wide range of latitudes. Grazing management to encourage the persis tence of L. uliginosus in pasture in temperate environments may includ e the exclusion of grazing livestock in autumn. In the sub-tropics, mo nitoring of rhizome production in the field would be required before d eciding the appropriate time interval between grazing. (C) 1998 Annals of Botany Company.