Laboratory germination of seeds from 10 British species of Potamogeton

Factorial laboratory germination experiments were carried out on fruits from 10 British species of Potamogeton (Potamogetonaccae). Fruits had all been placed in a dry-room maintained at 15% RH and 15 degrees C for 3-6 months from the time of collection. Maximum levels of germination ranged from 13% (P polygonifolius) to 90% (P. berchtoldii). Whilst for some species, there was some germination across all the conditions tested, for others germination was significantly increased under specific conditions. The single most important factor for promoting germination was cold stratification prior to placing at the germination temperature. Logistic regression analysis indicated that there was a positive effect of applying a cold stratification treatment in R filiformis, R gramineus, and R natans. Scarification (removal of some of the fruit) also resulted in increases in the number of seeds that germinated for all species. It is suggested that the initial conditions which should be tried for germinating seeds from temperate Potamogeton species are 15-20 degrees C with a 12 h photoperiod, anaerobic conditions, following a cold stratification treatment. If high levels of germination are not observed, the fruits should be scarified to remove the mechanical restriction of the fruit coat. (c) 2008 Elsevier B.V. All rights reserved.