Effects of Photoperiod and Temperature on Shoot, Root and Rhizome Growth in ThreeLotus uliginosusSchkuhr Populations

Abstract

The growth of three populations of greater lotus (Lotus uliginosusSchkuhr syn.L. pedunculatusCav.) was compared at photoperiods of 10, 12 and 14 h at a maximum day/minimum night temperature of 21/16 °C and at maximum day/minimum night temperatures of 27/22, 21/16, 18/13 and 15/10 °C at a photoperiod of 12 h. Short days (10 h) favoured root and rhizome development compared to long days (14 h). A temperature regime of 15/10 °C restricted rhizome development compared to the 18/13 and 21/16 °C regimes. Shoot growth was restricted at the highest temperature regime (27/22 °C). The cultivar Sharnae 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 photoperiod explains part of the performance of greater lotus in the field at a wide range of latitudes. Grazing management to encourage the persistence ofL. uliginosusin pasture in temperate environments may include the exclusion of grazing livestock in autumn. In the sub-tropics, monitoring of rhizome production in the field would be required before deciding the appropriate time interval between grazing.