Cut Tulip Research Articles

Application of a Dynamic Growth Simulation Model to Hydroponic Production System for Cut Tulip

A previously developed dynamic growth simulation model for cut tulip production in a plant factory system which predicts forcing period and flower quality of cut tulips from duration of bulb chilling and forcing temperature was confirmed. In a 1993-1994 experiment in which bulbs were forced at 20°C, irrespective of the duration of their chilling period at 2°C, the simulated values of number of days from planting to anthesis, shoot (cut flower) fresh weight, perianth length and dry weight of the component parts at anthesis correlated well with the observed values. In a 1998-1999 experiment in which the forcing temperature was lowered with the extension of the duration of bulb chilling at 2°C, when the duration of bulb chilling was extended to 26 weeks or longer, shoot fresh weight, perianth length and dry weights of shoot and floral organs at anthesis were underestimated by the model, while the dry weight of daughter bulbs was overestimated. These differences were supposed to be caused by fluctuation in bulb properties and could be diminished by inputting the dry weights of the mother bulb and daughter bulbs at planting into the model.

ABSCISIC ACID IN RELATION TO DROUGHT-STRESS IN CUT TULIPS

Dry-storage of cut tulips during storage and transportation affects the vase-life of the tulips negatively (Swart, 1991). Tulips exposed to drought-stress for 8 days showed an approximate loss in fresh weight of about 10%. If these tulips were transferred to water, they were capable of regaining their original weight within 1.5h. In the upper green leaf of these tulips, the ABA level increased with a factor 2 to 8 during drought-stress, depending on the culltivar used. Although the turgidity was regained within 1.5h after replacement in water, the ABA levels remained at a constant level during this time period. Tulips stored in water under similar conditions did not show an increase in ABA, indicating that the increase was due to drought-stress and not to chilling stress. This renders ABA a possible parameter to test if tulips had been stored dry for such a time period that the quality of the vase-life was affected.

The Effect of Protein Synthesis Inhibition on Petal Senescence in Cut Bulb Flowers

Petal opening and senescence of cut Gladiolus, Iris, and Narcissus flowers was significantly inhibited by continuous treatment with 1 mm CHI. Vase life was doubled in individual flowers treated when half-open, and a similar effect was detected after pulsing cut gladiolus spikes with 1 mm CHI for 24 hours. Petal wilting was markedly inhibited in flowers treated with CHI and was confined to the outer 2 to 3 mm of petal margins as opposed to the entire petal in untreated flowers. These effects were not seen, however, in CHI-treated cut tulip flowers, where vase life was significantly reduced. CHI markedly inhibited protein synthesis in Gladiolus `New Rose' florets (a decrease of >60%). Treatment with a potent biocide, DICA, did not increase vase life; therefore, CHI was not prolonging flower longevity by preventing microbial growth in the vase solution. The results indicate that de novo protein synthesis is required for bulb flower development and opening and petal wilting and senescence. Chemical names used: cycloheximide (CHI), sodium dichloroisocyanuric acid (DICA).

Laboratory Exercises with Spring-flowering Bulbs1

Abstract Exercises are described to familiarize horticultural students with the ‘Standard Forcing’ of potted tulips, hyacinths, daffodils, Iris reticulata, Crocus and grape hyacinths as well as cut tulips and daffodils. Procedures are outlined for ‘Special Precooling’ of tulips and Dutch iris as cut flowers. In addition, a simplified list of readily available cultivars of the spring-flowering bulbs covered is provided. The exercises utilize Valentine’s Day as the marketing holiday.

Reduction in Last Internode Elongation of Cut Tulips by Growth Retardants1

Abstract The effects of several concn of growth retardant chemicals on the elongation of the last stem internode of cut tulips were studied. Compared to tap water, α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine-methanol (ancymidol) at 25 ppm reduced intemode growth by 31% with no detrimental effects on vase life or flower quality. The 2,4-dichlorobenzyl-tributylphos-phonium chloride (CBBP) was ineffective at 6-25 ppm. CBBP at 125 did reduce stem elongation but was toxic to the flower. Ancymidol in the vase solution retarded growth without altering water uptake by the stem.

Factors Affecting Floral Stalk Elongation of Flowering Tulips1

Abstract Factors affecting floral stalk elongation of tulips during the period from floral bud coloring (budded flower) to the senescence of the perianth were studied. All internodes elongated, however, the greatest elongation occurred in the internode directly beneath the flower and most of the elongation occurred in the upper two-thirds of the internode. Cut tulips elongated less than plants left in the forcing flats. Removal of the budded flower inhibited elongation of the last internode while removal of the leaves was stimulatory with some cultivars. With cut tulips, the perianth appeared to be the primary organ controlling floral stalk elongation followed by the gynoecium and androecium. When the flowers were left intact on the plant the gynoecium exerted the greatest control followed by the perianth and androecium. When the complete flower was removed and IAA or NAA was applied as a lanolin paste to replace the flower, the last internode elongated in a manner similar to the intact flower. Similar applications of kinetin and GA3 were ineffective.