ความคิดเห็นที่ 45
2.3. Stage properties
Leaf formation phases: Stage I apical meristem flat, leaf formation Stage II apical meristem round, leaf formation completed
Flower formation phase: Stage P1 the outer 3 perianth segments are formed Stage P2 the inner 3 perianth segments are formed Stage A1 the outer 3 anthers are formed Stage A2 the inner 3 anthers are formed Stage A2+ the gynoecium is visible, but still flat Stage G triangular swollen gynoecium Stage G+ all flower parts, including stamens, are clearly visible
2.4. Stage determination
The cold period may be started once stage G is reached and the treatment at the intermediate temperature has been completed. Unfortunately, no fixed date can be given for this period, as it depends on the stage development in that particular year and batch. A wide range of factors play a role in the development, such as weather conditions in the previous growing season, the time the bulbs were lifted, the temperature treatment after lifting, cultivar characteristics and bulb size. Use stage examination to determine whether or not the flower has developed fully. To do this, carefully cut open a bulb. Take out the apical meristem without damaging it and examine it with a binocular microscope (magnification of 25 to 30 times), or, if the flower has developed, a 10-x magnifying glass. The following botanical terms are used internationally for the flowers organs: P = perianth (petals) A = anther (stamen) G = gynoecium (pistil) The numbers indicate the various stages. Plus and minus signs after the stage indicate the transition between the stages.
3. Forcing 9°c (pre-cooled) and uncooled tulips in trays 3.1. Advantages of forcing in trays
Forcing in trays is the most commonly used forcing method for tulips. There are a number of reasons for this, including:
Ø forcing in trays allows for better planning, with-out being too dependent upon outside temperatures.
Ø forcing in trays allows better labour planning.
Ø relatively few diseases due to the low temperatures in the rooting room. This is an important advantage in view of likely future restrictions or even ban on the use of pesticides.
Ø reduced energy consumption due to shorter periods in the greenhouse.
Ø forcing in trays achieves a higher production of tulips per m2 per forcing season.
3.2. Cooling
The cold period ensures that the tulips develop a sufficiently long stem. It also promotes faster growth of the crop. When forcing in trays, the bulbs receive part of the cold period in the cold room as dry bulbs (9°C-(pre-cooled) tulips). After the bulbs are planted, they receive the remainder of the cold period in the rooting room or in a plunge bed. Alternatively, the bulbs receive the entire cold period as planted bulbs. These bulbs are called uncooled tulips. The duration of the cold period depends on the cultivar, the bulb size and the scheduled date for housing.
The minimum number of weeks at the intermediate temperature is based on bulb size 12/+. If bulb sizes 11/12 or 10/11 are used, the intermediate temperature must be extended by 1-1.5 or 2-3 weeks. The number of cold weeks also applies to bulb size 12/+. If bulb sizes 11/12 or 10/11 are used for early-mid or late forcing of a cultivar also suitable for early flowering, the cold period may be reduced by 0-1 or 1-2 weeks. In that case these smaller bulb sizes will produce somewhat shorter stems. As soon as the bulbs have had the necessary cold period, the trays can be placed in the green- house. Extending the cold period has both advantages and disadvantages. By extending the period by one week, the greenhouse period is shortened by three days, which reduces energy consumption. Associated disadvantages include:
Ø the development of long necks, especially in susceptible cultivars and smaller bulb sizes
Ø smaller blooms
Ø higher risk of topple
Ø limp leaves
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nok_tulip
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30 มี.ค. 52 01:23:56
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