Search Results
Abstract
Polyvinyl chloride columns (4 × 15 cm) containing by volume either 2 pine bark : 1 moss peat : 0 sand, 2 pine bark : 0 moss peat : 1 sand, 0 pine bark : 1 moss peat : 1 sand, or 2 pine bark : 1 moss peat : 1 sand amended with 3 kg m-3 of 32P-superphosphate (8.7% P) were leached daily with 16 or 32 ml of deionized water (pH 5.5) in 1 hour. Irrigation rate did not affect 32P leaching nor was there a media rate interaction or difference in the percentage total 32P and dissolved 32P leached. Medium 2:1:1 had the greatest percentage (76%) of 32P leached during the 3-week experimental period, however, 55% of the 32P amendment leached from each medium the 1st week.
Abstract
Increased soil moisture stress reduced growth and transpiration rate of Ficus benjamina. Leaf drop during indoor phase was greater for plants previously watered during production at 3 day intervals than for plants grown under the 6- and 9-day water regimes.
Abstract
Selected leaves on fruiting and non-fruiting plants of ‘Southern Cross’ cucumber (Cucumis sativus L.) were pulsed with 14CO2 for 30 minutes. After 24 hours, 4 to 6 times more 14C-labelled assimilates were recovered from fruiting than non-fruiting plants. Leaves on fruiting and non-fruiting plants exported 85% and 45% of the assimilated 14C, respectively. Leaf position had no effect on the amount of 14C recovered or on percent transported.
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
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.
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
Florida's ornamental horticulture industry, like the vegetable and fruit industries, has been shaped by Florida's long growing season, mild winters, and high light levels.
We are studying the horticultural performance of two model plant systems that carry a mutant gene that confers ethylene-insensitivity: Never Ripe tomatoes and petunia plants transformed with the mutant etr1-1 gene isolated from Arabidopsis thaliana. Having two model systems to compare side-by-side allows us to determine with greater certainty ethylene's role at different developmental stages. Presence of the mutant etr1-1 gene in transgenic petunias was determined using three techniques: PCR analysis, the seedling triple response assay (inhibition of stem elongation, radial swelling of stem and roots, and an exaggerated apical hook when grown in the dark and in the presence of ethylene), and the flower wilting response to pollination, which is known to be induced by ethylene. Flowers from ethylene-insensitive petunias took almost four times as long to wilt after pollination as wild-type plants. It is well known that fruit ripening in Never Ripe tomato is inhibited, and a similar delayed fruit ripening phenotype is observed in petunia plants transformed with etr1-1. In an effort to maintain ethylene-insensitive petunia plants by vegetative propagation, we observed that the rate of adventitious root formation was much lower with transgenic plants than in wild-type plants. In subsequent experiments on adventitious root formation in Never Ripe tomato, we observed the same result. Therefore, while ethylene-insensitive tomato and petunia plants appear phenotypically normal for many characters, other factors are altered by the presence of this mutation. The fact that these changes are present in two model systems helps to define the role of ethylene perception in plant growth and reproduction.
Abstract
Cultivars of Kalanchoe blossfeldiana Poelln. varied in number of long nights required for complete flower initiation and development. ‘Montezuma’ and ‘Texas Sunset’ requried 14 long nights, while ‘Pixie’, ‘Nugget’, ‘Cactus Candy’, ‘Goddess’, ‘Tobasco’, ‘Osage Orange’, ‘Toltec’, ‘Adobe Rose’ and ‘Rotkappchen’ required 15 to 28 nights. Height of apical meristems increased in ‘Montezuma’ after 7 long nights, but changes were not evident in ‘Pixie’ until 9 long nights. Scanning electron microscopic analysis showed first evidence of sepal primordia in ‘Pixie’ after 28 long nights—6 nights later than ‘Montezuma’. Differences in the number of long nights required for flower induction were related to delayed floral initiation rather than organogenisis or maturation.
Salvia (Salvia splendens F.), vinca (Catharanthus roseus L.), and pansy (Viola × wittrockiana Gams.) were examined to determine efficacy of growth retardants for inhibiting stem elongation of seedlings in the plug stage and after transplanting to 10-cm pots. Studies on salvia showed plugs sprayed with single applications of ancymidol at 10 or 20 ppm, paclobutrazol at 30 or 60 ppm, or daminozide/chlormequat tank mix at 2500/1500 ppm inhibited plug elongation by 17% to 22%. Pansy plugs were sprayed either once or twice with ancymidol at 5, 10, or 15 ppm. Number of applications was statistically significant with two applications reducing elongation by an average of 35%, whereas a single application resulted in a 23% average reduction. Ancymidol concentration was significant in reducing stem elongation with increasing rates in pansy; however, the concentration and application time interaction was not significant. In both pansy and salvia, plant size at flowering was similar to controls after transplanting. Vinca plugs were sprayed with ancymidol at 5, 10, or 15 ppm either the 3rd week, 4th week, or both weeks after sowing. As ancymidol concentrations increased, plug height decreased, and the concentration effect was greater week 3 than at week 4. Two applications of ancymidol was most effective in retarding stem elongation (36%) followed by one spray the 3rd week (29%) and one spray during week 4 (20%).