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.
Key words: Flower quality, growth, low temperature storage, sprouting, tuberose