Annex White book.pdf

A1.5.1.2 Annual, biannual and triennial productionThe bulbs that will be used in forced cultivation should have alreadycarried flowers twice in the field. The vegetable material for bulbpropagation one year after planting is not suitable for forced cultivation.Its ability for flower production is very limited compared to thebiannual and triennial production, given the fact that the producedflowers correspond to the developed sprouts.A1.5.2 Cultivation in storage rooms under controlled microclimaticconditionsA1.5.2.1Bulb storageA1.5.2.1.1 Temperature conditionsWhen bulbs are stored at 0 o C, sprout production stops and no alterationis caused to the bulbs.Flowering takes place in bulbs with a diameter larger than 20 mmand at temperatures varying between 23 and 27 o C. Under such conditions,maximum flowering is achieved within 45 to 60 days of hatching(Valero et al, 2004).A1.5.2.1.2 Atmosphere modification and controlRelative humidity should vary between 70 and 80 % in order tohinder the development of microorganisms while causing very littleweight loss to the bulbs. The above temperatures vary according tostorage temperature, weight control and health condition of the bulbs.CO2 levels should not exceed 2500 ppm. Ethylene levels shouldbe controlled thoroughly because bigger concentrations may disturbbulb dormancy and cause flowering as well as physiological imbalances(Valero et al, 2004).A1.5.2.1.3 Storage durationBulbs may be stored in storage rooms that fulfill the above temperatureconditions (ventilation should be possible in containers or trays). At25 o C storage duration varies between 70 and 160 days. At 30 o C, storageshould not exceed 150 days – bulbs may begin sprouting and producehence a limited number of flowers (Valero et al, 2004). No duration limitis given if the storage temperature is kept at 0 o C.118