Seed dormancy and germination of five tropical montane species belonging to the family Fabaceae in Sri Lanka

Abstract

The  family  Fabaceae  consists  of  economically  and  ecologically  important  plant  species   (as crops,  cropwild  relatives,  cover  crops,  shade  crops,  weeds,  and  invasive  species  and  as  members  in   m a n yi m p or t a n t   p l a n t   c o m m u n i t i e s ).    Information  on   s e e d   d or m a n cy   a n d   germination  is  essentialin  propagation  of  useful  species  and  in  eradication  of  unwanted species.  However,  information  onseed  dormancy  and  germination  is  rare  on the  species  belongs  to  Fabaceae  family  occurring  in tropical  montane  forests.  Thus,  the  objective  of  the  study  was  to  investigate   the  seed  dormancy  type  offive species  of   Fabaceae  family  ie.    Tadehagi  triquetrum,  Calpurnea  aurea,  Clotelaria scabrella,  Erithriasubumbrans  and  Cassia  didymobotrya.  Available  information  suggested  that  seeds  of these  species  havePhysical  Dormancy  (PY),  Physiological  Dormancy (PD),  combinational   dormancy  and  non  dormancy. Seeds  were  collected  from  various  montane  forests  in  Sri  Lanka.  Seed  moisture  content  (SMC),imbibition  and  germination  of non  scarified  (NS)  and  manually  scarified  (MS)  seeds  were determinedfor  each  species separately.SMC  of  T. triquetrum,  C.  aurea, C. scabrella  and  C.  didymobotrya  was  ≤15%  indicating  that seeds  areOrthodox.  However,  SMC  of  E.  subumbrans   was  34%,  suggesting  that  they  are recalcitrant.  Significantlyhigher  mass  increment  was  observed  in  MS  seeds  than  that  of  NS seeds  of  all  the  species  except  for  E.subumbrans.  Thus,  it  reveals  that  seeds  of  these  four species  have  PY.  The  germinating  test  inlight/dark  condition  confirmed  the  PY  of  these  four species.  MS  seeds  of  C.  aurea  C.  scabrella  and  C.didymobotrya  germinated  >50  %  while,  NS  seeds  only  germinated  to  <  15  %.  Although,  within  first  14days  only  <  50  %  of  the  NS seeds  of  T.  triquetrum  germinated,  within  30  days  it  germinated  >  90%indicating  that  they  have  a  slight   dormancy.  Interestingly,  both  NS  and  MS  seeds  of  E.  subumbransimbibed  water   and  >  90%  of  them  germinated  during  the  30  day  germinated  within  14  days.  Thus, seeds of E. subumbrans have no dormancy.

Key words: orthodox seeds, physical dormancy, recalcitrant seeds