EFFECT OF SUBSEQUENT STORAGE OF TUBEROSE (POLIANTHES TUBEROSA L.) BULBS AFTER LOW TEMPERATURE PRE - TREATMENT IMPROVES GROWTH, PERCENT SPROUTING AND CUT FLOWER QUALITY

During  peak  planting  time  in  commercial  tuberose  cut  flower  production  lack  of seed  materials occasionally  occur.  Most  producers  also  source  planting  materials which have not been adequately stored resulting in poor performance of the crop. For  improved  productivity  in  tuberose  cut  flower  value  chain,  ways  of  increasing the availability of planting materials and improving the growth performance need attention.  This  study  examined  the  effects  of  subsequent  warm  temperature storage after  low  temperature treatment of  tuberose  bulbs  on  growth,  sprouting and  flower  quality.  The  experiment  was  laid  in  a  split  plot  arrangement  in  a completely randomized design. Tuberose bulbs were stored in a biotron at 5oC or 10oC  for  3  months with  subsequent  temperature  storage  of  20oC  for  0,  2,  4  or  6 weeks.  The  main  effects  were  pre‐treatment  temperatures  at  5  or  10oC,  whilst subsequent  temperature  storage  treatments  constituted  the  sub‐effects.  Days  to sprouting were significantly earlier ( 14.9) when tuberose bulbs were pretreated at 10oC followed by 20oC subsequent temperature storage for 6 weeks compared to 51.1  at  5oC  pretreatment  with  no  subsequent  temperature  storage.  The  highest percent sprouting (99.2%) was obtained with 10oC pretreatment followed by 20oC thawing  for  6  weeks.  Pre‐treating  tuberose  bulbs  at  either  5oC  or  10oC  then planting directly resulted in 69.3% and 88.3% sprouting, respectively, whilst similar pretreatments  resulted  in  70.0%  and  81.2%  flowering.  The  number  of  days  to flowering  were  significantly  (P<0.05  )  reduced  (110.8)  at  10oC  pre‐treatment followed  by  20oC  subsequent  thawing  for  6  weeks  compared  to  143.1  at  5oC pretreatment  with  no  thawing respectively.  Stem  length  of  inflorescences significantly  (P<0.05)  improved  to  106.8  cm  at  10oC  with  thawing  at  20oC  for  6 weeks  compared  to  98.2  cm  at  5oC  pretreatment  and  no  thawing  respectively. Number of florets per spike also significantly (P<0.05) increased to 42.4 compared to  34.9  for  similar  treatments.  Storage  of  tuberose  bulbs  at  low  temperatures followed  by  warm  subsequent  storage  for  2,  4  or  6  weeks  besides  improving sprouting and quality of flowers could enhance the availability of planting materials for  crop  production.  The  planting  materials  could  be  bulked  with  possibility  of commercial exploitation.