Yin-Tung Wang

Effects of six fertilizers on vegetative growth and flowering of phalaenopsis orchids

Abstract One of six water-soluble fertilizers, 10N-13.1P-16.6K, 15N-4.4P-24.9K, 15N-8.7P-20.8K, 20N-2.2P15.8K, 20N-4.4P-16.6K, and 20N-8.7P-16.6K (10-30-20, 15-10-30, 15-20-25, 20-5-19, 20-10-20, and 20-20-20 in N-P2O5-K2O, respectively), was applied to young seedlings of Phalaenopsis Tam Butterfly at concentrations of 200 or 100 mg N l−1. After seven months, leaf span, leaf size, total leaf area, and shoot and root fresh weight were not different among various fertilizers within either concentration. However, plants had a wider leaf spread, produced more and larger leaves, and had greater total leaf areas in response to the higher fertilizer concentration, regardless of which fertilizer was used. The different fertilizers had a small but significant effect on leaf number. The 10N-13.1P-16.6K fertilizer caused a lower medium pH than the others. Medium fertigated with the 10N-13.1P-16.6K or 15N-8.7P-20.8K fertilizer always had higher EC than that receiving the 20N-8.7P-16.6K fertilizer. In a second experiment, the same fertilizers at the 200 mg N l−1 concentration were used on mature plants in late August, with either municipal water (EC = 1.4 dS m−1) or water from a reverse osmosis system (RO, EC = 0.03 dS m−1). Regardless of which fertilizer was used, flowering date, flower size and number, as well as plant width were unaffected. The 10N-13.1P-16.6K fertilizer resulted in 12% more leaves than 20N-8.7P-16.6K by May the following year. Plants fertigated with RO water had slightly larger flowers and longer leaves.

Partitioning of 14C-assimilate in Easter Lily as affected by growth stage and flower removal

Abstract Three weeks before anthesis, flower buds of Easter Lily plants received 47 and 12% of 14C translocated from Leaf 5 (upper) and 25 (middle), respectively, whereas the bulb received 5 and 52%, respectively. Flower bud removal increased the fraction in the bulb to 52% (Leaf 5) and 63% (Leaf 25). At anthesis, the flowers received 78% (Leaf 5) and 65% (Leaf 25) of translocated 14C-assimilate, nearly all of which was in the second flower which was still expanding. Less than 5% of the 14C from either leaf moved to the bulb in intact flowering plants, but upon flower removal, the bulb received 26 and 59% of the labelled assimilate from Leaf 5 and 25, respectively. Five weeks after anthesis, nearly 85% of the 14C-assimilate from either leaf was in the bulb. The fraction of 14C moving into the daughter bulb increased from less than 10%, 3 weeks before, to over 50%, 5 weeks after anthesis. Regardless of treatment, sink activity of the daughter scales was 2- to 12-fold higher than that of the mother scales. Although much of the current assimilate from the upper half of the intact lily shoot moves to flowers before anthesis, flower-bud removal is an effective way to increase carbon supply to the bulb.

Modification of hibiscus growth by treating unrooted cuttings and potted plants with uniconazole or paclobutrazol

Unrooted cuttings ofHibiscus rosasinensis L. “Seminole Pink” were soaked for 5 s in a solution containing 25, 50, 75, or 100 mg L−1 uniconazole or paclobutrazol, rooted, and then potted and allowed to grow without pinching. Uniconazole was more effective than paclobutrazol in suppressing stem growth and number and length of lateral shoots. Uniconazole and paclobutrazol, at the 25 mg L−1 concentration, resulted in stem growth 75 and 25%, respectively, of the control, with further reduction at higher rates. Flowering was delayed by the highest rate of uniconazole but not paclobutrazol. Flower number was reduced by both retardants, without any effect on flower size. Plants treated with uniconazole had short pedicels regardless of the rates, whereas paclobutrazol did not affect pedicel length. A second experiment used unrooted cuttings being soaked in a solution containing 0, 12.5, 25, or 50 mg L−1 uniconazole or having the lower 2.5 cm of the stem dipped in a solution containing 0, 50, 100, or 200 mg L−1 uniconazole. Plants were pinched after potting. Soaking resulted in more efficient height control than dipping. Lateral shoot number was reduced by soaking but not dipping. All treated plants had smaller stem diameters. Flower size was unaffected regardless of method of treatment and the type of retardant applied. In a third experiment, soil drenches with uniconazole at a rate as low as 0.05 mg/pot resulted in excessive growth retardation. Soil drenches with paclobutrazol at 0.05–0.20 mg/pot reduced shoot growth, flower number, and pedicel length, but did not affect days to bloom.

Uniconazole controls growth and yield of greenhouse tomato

Abstract Tomato ( Lycopersicon esculentum cultivar ‘Summer Flavor’) seedlings received a single uniconazole soil drench at 0, 12.5, 25, 50, 100, 200 or 400 μg per plant at the five-leaf stage. After 2 weeks of growth, plant height, length and area of the fifth leaf, and plant fresh and dry weights progressively decreased with increasing rates of uniconazole. The rate of leaf production was unaffected at low rates of the retardant. Another group of seedlings received soil drenches at the above rates at the onset of flowering. Uniconazole applied at both stages resulted in short final plant height at all rates. Total fruit yield was reduced by uniconazole at the 12.5 μg per plant rate, with further reduction as rates increased. Yields of large fruits (≥ 110 g) increased at the two lower rates of uniconazole. The incidence of blossom-end rot (BER) was nearly eliminated by this retardant at all rates. Foliar application of uniconazole at the flowering stage with rates of 0, 25, 50, 100, 250, 500, 750 or 1000 μg per plant had less control on plant height compared with their respective rates as a soil drench. Total fruit yield was not affected until the rate exceeded 100 μg per plant. The incidence of BER decreased sharply with increasing rates of uniconazole. The number and weight of fruits ≥ 110 g were doubled at rates between 25 and 250 μg per plant. Plant fresh and dry weights were lower as a result of uniconazole foliar spray. Fruit number was reduced regardless of the rate and stage of uniconazole application.

Effect of GA4+7 on growth and cellular change in uniconazole-treated hibiscus

Hibiscus rosa-sinensis ‘Jane Cowl’ in 1.5–1 pots were given a soil drench of 0.2 mg uniconazole, pruned 2 weeks later, and treated with a foliar application of GA4+7 at 0, 25 (once or four times every 2 weeks), 50 (once or twice every 4 weeks), or 100 mg L-1. One application of GA4+7 at 100 mg L-1, two applications at 50 mg L-1, and four applications at 25 mg L-1 were more active in partially restoring stem elongation and caused nearly normal leaf production than other GA treatments, but promoted the abscission of the lower leaves. The size of the individual leaves, but not stem diameter, increased following GA4+7 application. Multiple applications of GA4+7 stimulated flowering of the retarded plants. Uniconazole resulted in short pedicels bearing short cells with increased diameter, as well as larger pith, vascular, and cortical tissues than the untreated control. Four applications of 25 mg L-1 GA4+7 to uniconazole-treated plants resulted in long pedicels, having long cells similar to the control. Results of the histological study suggest that uniconazole either slowed cell division or caused cell division to cease early.

Effect of stock plant shading, developmental stage and cytokinin on growth and lateral branching of Syngonium podophyllum ‘White Butterfly’

Abstract Syngonium podophyllum Schott. ‘White Butterfly’ cuttings which received a 5-min dip in 400 or 800 mg l −1 PBA had faster initial growth but produced smaller plants with fewer leaves and basal shoots, less total leaf area, and smaller shoot and root dry weights than controls. Light intensities of 650 and 1200 μmol s −1 m −2 on stock plants did not affect the subsequent growth of cuttings. Foliar sprays of 0, 250, 500, 750 or 1000 mg l −1 BA on plants had no effect on lateral branching and growth of plants propagated from cuttings when applied at the 1-leaf stage. However, when treated with the same concentrations and with 2000 mg l −1 at the 3- and 5-leaf stages, increasing BA concentration induced earlier development of basal lateral shoots and decreased the elongation of the main shoot, resulting in bushier plants. The total number of lateral shoots at final harvest, however, was not increased by BA. BA application at the 3-leaf stage was more effective in reducing the length of the main shoot than application at the 5-leaf stage. BA caused an increased fraction of the total dry weight to be partitioned to the lateral shoots and less to the main shoot, although total plant dry weight remained unchanged among treatments. Leaf number was unaffected by BA. BA foliar spray at 200, 400, 600 or 800 mg l −1 on plants which had already started natural basal branching had no effect on plant growth except that total length of the top 3 internodes on the main shoot was reduced by 25% at the 3 higher concentrations.