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- Author or Editor: A.A. De Hertogh x
Abstract
Cell-free extracts which incorporated mevalonate-2-14C into terpenes were obtained from Tulipa gesneriana L. cv. Ralph and Iris hollandica Hoog cv. Wedgwood. The richest source of the enzyme system was the shoot, specifically the stamens, from tulip and the shoot from iris. Scale and root tissue of iris and scales of tulip were also active but to a lesser extent. Time-course studies with tulips showed that the system could be extracted as long as the flower was not aborted and at any time prior to placing the plants in the greenhouse (light). Similar studies with iris indicated that an active system could be obtained from the onset of precooling to anthesis.
Abstract
Flower development of tuberous-rooted Dahlia ‘Park Princess’ and ‘Miramar’ was studied during 2 forcing seasons using scanning electron and light microscopy techniques. Each cultivar had a flat, rectangular (0.2 × 0.1 mm) vegetative meristem which domed and increased in diameter as the last leaf primordia developed. Subsequently, 8 outer involucrate bract primordia were formed and the meristem bacame round with a diameter of approximately 0.35 mm. The first visible sign of floral initiation was the formation of inner involucrate bract primordia. The floret primordium developed after the subtending bract primordium. The first unpinched plants of ‘Park Princess’ were reproductive 20 days after planting and 100% were reproductive after 30 days. ‘Miramar’ was reproductive 10 days later with a corresponding delay in anthesis. Unpinched ‘Park Princess’ and ‘Miramar’ were reproductive when the 4th and 6th leaf pairs had separated, respectively. When pinched, over 80% of the lateral branches of ‘Park Princess’ and ‘Miramar’ were reproductive after 12 days.
Abstract
For the first 35 days following planting, the dry weights of the tuberous roots (TR) of Dahlia ‘Park Princess’ and ‘Miramar’ decreased, but simultaneously the dry weights of the fibrous roots (FR) and shoots increased. During the 2nd half of the forcing period shoot and TR dry weights increased rapidly. New TR developed from adventitious roots which formed at the basal nodes of the stem. Ancymidol (0.75 mg/plant) reduced shoot dry weight as well as total height but did not alter TR or FR growth. Plant quality measured by shoot dry weight was reduced when the distal half of each TR was removed before planting. It was not reduced where half of the TR were left intact or when only 1 cm was removed from each TR. The number of days to flower was inversely correlated with plant height measured at 14 and 28 days after planting but not with clump fresh weight.
Abstract
Pinching of forced tuberous-rooted Dahlia ‘Park Princess’ and ‘Miramar’ was evaluated as a method for increasing flower production and plant quality. Pinched plants produced more flowers, flowered later, had smaller flowers, and were taller than unpinched controls. On an individual plant basis, pinching at node 4 generally gave the best results, while pinching at node 2 resulted in the greatest delay and fewest flowers. The more distal the pinch, the greater the number of laterals formed on both cultivars and the higher the percent of laterals flowering on ‘Park Princess’. On a population basis, pinching only those plants with a single strong shoot at node 3 or 4 resulted in the best compromise between increased flower production and the deleterious delayed flowering and increased plant height.
Two experiments were conducted to determine the effects of applied ancymidol, chlormequat, daminozide, paclobutrazol, and uniconazole on early spring (March) and late (May) spring forcing of Dutch-grown Bleeding Heart [Dicentra spectabilis (L.) Lem.] as a flowering pot plant. Most of the plant growth regulator (PGR) treatments delayed flowering, however, the average time to flower after planting was from 17 to 21 days for untreated plants and delays were only 3 to 6 days with PGR treatments. Thus, the effect is not important commercially. Acceptable plant quality and height control not only at flowering but also 14 days later was obtained with two sprays of 3000 mg·L-1 (ppm) daminozide or two sprays of 50 mg·L-1 paclobutrazol. Uniconazole reduced total plant height, however, because the inflorescence did not elongate, plant quality was greatly reduced. Most ancymidol sprays were phytotoxic producing a chlorosis of the leaf margins. Media drenches of ancymidol or chlormequat did not control total plant height. Sprays and media drenches of ancymidol, daminozide, paclobutrazol, and uniconazole produced plants with a very deep green leaf color, but chlormequat did not. The total number of shoots per tuberous root, the number of shoots with flowers, and stem strength were not significantly affected by PGR treatments. If the tuberous roots have been properly cold treated, they initiate growth rapidly after planting. Thus, the first PGR spray must be applied immediately after shoot growth is initiated, which was 6 to 8 days after planting, followed by a second spray 5 days later. Two applications are necessary because of uneven shoot emergence and growth from the tuberous roots.
Abstract
The starch content of the bulb scales and the ethanol-soluble sugars of the bulblets and bulb scales of Tulipa gesneriana L. cv. Preludium declined with development. In contrast, the starch content of the bulblets increased rapidly. Calculations indicated that the total soluble sugars initially in the bulb scales could account for all the soluble sugars in the bulblets at harvest. However, the initial starch content of the bulb scales could account for only 17% of the starch present in the matured bulblets. It was surmised that the remaining 83% of the starch in the matured bulblets was derived from photosynthesis.
Potted Lilium Asiatic hybrids `Aristocrat', `Horizon', and `Polka' were evaluated following 3, 6, or 9 days of transport at 2, 7, or 13C. `Aristocrat' and `Horizon' withstood transport with little or no effect on floral bud opening. `Polka' was the most sensitive cultivar to transport, where bud opening decreased 33% when transported at 13C for 9 days. Most floral buds opened on `Aristocrat' (90% to 98%), while fewer buds opened on `Horizon' (37% to 56%) and `Polka' (52% to 90%). Individual flower longevity and diameters were largely unaffected by transport. Plant longevity was reduced 4 to 7 days when transported for 9 days at ≥7C or for >3 days at 13C. Plant longevity averaged 16 days for `Aristocrat' and `Polka' and 12 days for `Horizon'. `Aristocrat' and the Oriental potted hybrid lily `Star Gazer' were maintained at postproduction conditions of 18, 21, or 24C at 7 or 14 μmol·m–2·s–1 after being commercially transported for 4 days at 5 ± 2C. Postproduction conditions had no effect on floral bud opening of `Aristocrat' (98% to 99%), while bud opening of `Star Gazer' was reduced 17% at 24C compared to 18C. Plants lasted 4 and 9 days longer at 18C than at 21 or 24C, respectively. Foliar discoloration was greatest at 24C. Irradiance level had no effect on the variables evaluated.
Abstract
Intact stem apices of Lilium longiflorum Thunb. cv. ‘Ace’ were prepared for scanning electron microscopy to determine floral initiation and differentiation by viewing topographical changes. The apices, after removal of leaves under running water, were frozen in liquid N2, freeze-dried on carbon discs and coated with carbon prior to viewing. Electron photomicrographs were taken of vegetative, transitional and reproductive apices. This method of tissue preparation permitted microscopic evidence of flower bud initiation and differentiation to be obtained in less than 9 hr after removal of the apex from the plant. The apices retained their in vivo configuration, but as dry, permanent, 3-dimensional mounts. Cell net studies of the apical meristem are possible with this technique. This method of preparation is also adaptable to light microscopy.
Simulated transport (ST) of `Aristocrat', `Polka' and `Horizon' flowering Lilies was conducted at 2, 7 or 13C for 3, 6 or 9 days, then plants were held at 21±2C at 10 μmol ·s-1 ·m-2 for postproduction evaluations. Number of open flowers was reduced for `Polka' at ST of 9 days at 13C, while `Aristocrat' and `Horizon' were unaffected. Differences in individual flower longevity were found between the first and last open flowers. First open flower longevity was reduced by ST of 9 days and last open flower longevity was reduced by ST of 7 and 13C for both `Polka' and `Horizon'. ST for 9 days at 13C increased flower diameter and decreased whole plant longevity.
Exp. 2. Postproduction evaluation of `Stargazer' and `Aristocrat' were conducted using 18, 19.5 or 21C at 8 or 16 μmol ·s-1 ·m-2. Number of open flowers was unaffected by treatments, while flower longevity and whole plant longevity were greatest at 18C.
Postproduction evaluations of two cultivars each of Amaryllis (Hippeastrum), calla lily, Freesia, lily, and paperwhite Narcissus were conducted under postproduction temperatures of 18, 21 and 24C and irradiance levels of 7 or 14 μmol·m-2·s-1. Amaryllis longevity ranged from 10 to 24 days, with an increase of 7 to 10 days at 18C. Excessive stem elongation occurred and was greatest at 24C. Calla lily longevity ranged from 33 to 68 days, with up to a 25-day increase at 18C and 14 μmol·m-2·s-1. Freesia lasted 24 to 33 days with an increase of 6 to 9 days at 18C. Leaf yellowing and stalk elongation was a common problem of Freesia, especially at 24C. Lilies lasted 17 to 31 days, with an increase of 9 to 11 days at 18C. Asiatic lilies were superior to Oriental lilies. Paperwhite Narcissus lasted 13 to 27 days, increasing up to 10 days at 18C. Cultivar differences in longevity and quality were observed. Optimum postproduction conditions ranged from 18 to 21C at an irradiance of 14 μmol·m-2·s-1 for best quality and longevity.