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- Author or Editor: Yin-Tung Wang x
Hibiscus rosa-sinensis `Jane Cowl' were pruned several weeks after receiving 0.1 mg/pot uniconazole soil drenches to retard the growth. Plants then received foliar sprays of GA3 (50 ppm), KIBA (200 ppm), or PBA (200 ppm) immediately after pruning or when the lateral shoots had three leaves. Application of the above growth regulators immediately after pruning had no effect on plant growth. When treatments were delayed until the three-leaf stage, GA3 completely restored leaf production rate and partially restored shoot elongation and pedicel length. GA3 also increased leaf area, and the leaf specific weight was similar to leaves on plants not receiving uniconazole. GA3 increased flower production 175% and 65% more than plants treated with uniconazole and the untreated plants, respectively. KIBA and PBA had no effect on altering the growth of uniconazole-treated plants. Foliar application of a combination of GA3, KIBA and PBA at the three-leaf stage had an effect similar to that of GA3 alone. However, the effect of GA3 on growth appeared to be transient and repeated application may be required to maintain the restored growth of uniconazole-treated plants.
Bare-root, vegetatively propagated plants (average 15-cm leaf spread) of a white-flowered Phalaenopsis Taisuco Kochdian clone were imported in late May and planted either in a mix consisting of three parts medium-grade douglas fir bark and one part each of perlite and coarse canadian sphagnum peat (by volume) or in chilean sphagnum moss. All plants were given 200 mg·L−1 each of nitrogen and phosphorus, 100 mg·L−1 calcium, and 50 mg·L−1 magnesium at each irrigation with 0, 50, 100, 200, 300, 400, or 500 mg·L−1 potassium (K). After 8 months, K concentration did not alter the number of new leaves on plants in either medium. Plants grown in moss produced four to five leaves, whereas those planted in the bark mix produced only two to three leaves. K concentration did not affect the length of the uppermost mature leaves when grown in the bark mix. However, in moss, plants had increasingly longer and wider top leaves as K concentration increased. The lower leaves on plants in the bark mix lacking or receiving 50 mg·L−1 K showed symptoms of yellowing, irregular purple spots, and necrosis after spiking and flowering, respectively. Yellowing and necrosis started from the leaf tip or margin and progressed basipetally. Symptoms became more severe during flower stem development and flowering. All of the plants lacking K were dead by the end of flowering. Leaf death originated from the lowest leaf and advanced to the upper leaves. K at 50 mg·L−1 greatly reduced and 100 mg·L−1 completely alleviated the symptoms of K deficiency at the time of flowering. However, by the end of flowering, plants receiving 50 or 100 mg·L−1 K had yellowing on one or two lower leaves. Plants grown in moss and lacking K showed limited signs of K deficiency. All plants in the bark mix bloomed, whereas none in sphagnum moss receiving 0 mg·L−1 K produced flowers. For both media, as K concentration increased, flower count and diameter increased. Flower stems on plants in either medium became longer and thicker with increasing K concentration. To obtain top-quality Phalaenopsis with the greatest leaf length, highest flower count, largest flowers, and longest inflorescences, it is recommended that 300 mg·L−1 K be applied under high N and high P conditions regardless of the medium.
Abstract
Compared to floriculture crops, relatively little research has evaluated the effects of growth retardants on production and interior quality of foliage plant species. Ancymidol decreased intemode length in several foliage plant species (1–3), but not china green or dieffenbachia (3). Ancymidol improved interior performance of Epipremnum aureum and Pilea depressa (2). This experiment was conducted to determine the effect of ancymidol on growth of Syngonium podophyllum ‘White Butterfly’ in production and simulated interior conditions.
Abstract
Ficus benjamina and Codiaeum variegatum ‘Gold Dust’ stem tip cuttings were rooted in a mist bed at 290 or 90 µmols·m–2 Photosynthetic photon flux (PPF) with or without 28° ± 1°C medium heating and then potted. Number of roots in C. variegatum was unaffected by either PPF or medium heating; however, both factors enhanced root elongation. Forty days after potting, cuttings rooted under 290 µmol·s–1·m–2 had more lateral shoots than those rooted under 90 µmol·s-1·m–2 PPF. Although cuttings rooted in heated medium under the lower PPF had roots more than twice as long as those on cuttings rooted in unheated medium under the high PPF, it had little effect on subsequent shoot growth. F. benjamina rooting was improved in heated medium and was not affected by PPF. Unheated cuttings rooted better under high than low PPF. Shoot growth 10 weeks after transplanting was unaffected by the initial differences in root grade.
Abstract
Viterra hydrogel at rates of 0, 1.75, or 2.50 kg·m−3 was tested for the production of three tropical ornamental plant species in two or all of the three media. These were a commercial peat-lite medium (SUN), a medium consisting of equal volumes of peatmoss, bark, and sand (PBS), and a mix containing equal volumes of peatmoss and bark (PB). Codiaeum was grown in SUN and PBS, Dieffenbachia was produced in all three media, and Hibiscus was planted in SUN and PB. Codiaeum variegatum (L.) Blume ‘Norma’ and Dieffenbachia ‘Camille’ grew more and required a longer time to reach initial wilting when grown in SUN than PBS. Hibiscus rosa-sinensis L. ‘Brilliant Red’ had similar growth in SUN and PB. In general, hydrogel had no beneficial effect on plant growth in a greenhouse. Hydrogel extended the time required to reach initial wilting of C. variegatum by 3 days (from 24 to 27 days), but had no effect on Dieffenbachia. Leachate from PBS had higher pH and lower electrical conductance (EC) than that from SUN. Hydrogel had no effect on leachate pH, but decreased EC of the leachate for C. variegatum used at the 2.5 kg·m−3 rate and for H. rosa-sinensis at both rates.
Abstract
Croton (Codiaeum variegatum Blume cv. Craigii) cuttings, enclosed in polyethylene bags, were placed in light (20 μmol·s−1·m−2) or darkness at 15°, 20°, or 30°C for 5, 10 or 15 days (simulated shipping) and then placed in a mist bed to root for 4 weeks. Final leaf loss in most of the treatments was <7%. Cuttings in simulated shipping for 15 days at 30° in darkness and light had 31% and 56% final leaf drop, respectively. These cuttings also produced fewer roots than controls. Root length increased with increased shipping duration and shipping temperature from 15° to 20°, without further increase at 30°. Regardless of temperature and duration in simulated shipping, cuttings shipped in darkness had roots 2.5 to 5 cm longer than those shipped in the light.
Abstract
Removing 33% or 100% of the Easter lily (Lilium longiflorum Thunb. ‘Nellie White’) mother scales when flower buds were 1.3 cm in length, in conjunction with flower bud removal at the 3-cm stage, increased daughter bulb dry weight by 21% and 45%, respectively, when plants were harvested after 13 weeks. Size of the remaining mother scales in partially de-scaled plants was estimated to be 30% larger than their counterparts in intact bulbs. Growth of the Easter lily bulb is likely limited by source carbon supply.
Bare-root Phalaenopsis Blume orchids are frequently shipped by air freight intercontinentally. It was not known how temperature and duration in shipping affect their subsequent performance during greenhouse production. On 15 Sept., container-grown plants of vegetatively propagated Phalaenopsis (Atien Kaala Group) ‘TSC 22’ were removed from pots and individually weighed immediately. These bare-root plants were packed in cartons with shredded newspaper and placed in growth chambers at 15, 20, 25, or 30 °C in darkness. After 4, 7, and 14 days, one-third of the plants were removed from each temperature treatment, weighed, planted in pots, and then placed in a greenhouse. Weight loss increased with increasing air temperature and duration in storage. Chilling injury (CI) was more severe at 15 °C than 20 °C storage temperature and was progressively more severe as storage duration increased from 4 to 14 days. Plants had no sign of CI at 25 °C or 30 °C regardless of storage duration. Leaf loss was most severe on plants stored at 15 °C for 7 days (three leaves) or 14 days (five leaves) or at 30 °C for 14 days (three leaves). Storing plants 14 days or less between 15 °C and 25 °C did not affect the time of spiking (emergence of the flowering shoot), but at 30 °C, spiking was delayed by 5 to 8 days regardless of the duration. Storage resulted in reduced flower count, but not flower size, regardless of temperature and duration. In a second experiment, potted Phalaenopsis plants of the same clone were thermal-acclimatized in growth chambers in mid-September for 10 days at 25 °C followed by another 10 days at 20 °C before being stored in pots or bare-root at 15 °C, 20 °C, 25 °C, or 30 °C for 10 days. Thermal acclimatizing at 25 °C and 20 °C reduced the severity of CI and leaf loss after being stored for 10 days at 15 °C either bare-root or in pots, but did not reduce leaf loss resulting from heat at 30 °C. Repotting or storing bare-root plants did not affect spiking or flowering date under otherwise similar conditions. Nondisturbed plants in pots stored at temperatures between 20 °C and 30 °C for 10 d had higher flower count as compared with bare-root plants that were similarly stored. Spiking of nonacclimatized, bare-root plants was delayed after 10 days at either storage temperature, whereas flowering was delayed by 15 °C and 30 °C only. Bare-root Phalaenopsis orchids should be shipped near 25 °C during the warm period of the year and between 25 °C and 15 °C in the late fall through early spring to avoid CI or heat stress.
Results of a series of experiments showed that the ground, noncomposted woody stem core of kenaf (Hibiscus cannabinus L.) can be used successfully as a container medium amendment for producing potted tropical foliage and woody nursery crops. The growth of Brassaia actinophylla Endl., Hibiscus rosa-sinensis L. `Jane Cowl', and Pittosporum tobira (Thunb.) Ait. `Wheeler's Dwarf' in 70% or 80% kenaf (by volume, the balance being peatmoss or perlite or vermiculite and other nutrients) was similar to or greater than growth in two popular commercial mixes. Undesirable shrinkage of certain kenaf-amended media during plant production was reduced greatly by mixing it with at least 30% peatmoss or by using a coarser kenaf grind. As the portion of peatmoss increased from 0% to 30%, noncapillary porosity and water-holding capacity per container increased. A medium consisting of 50% kenaf, 40% peatmoss, and 10% vermiculite held as much water as a commercial medium. However, plants in most kenaf-amended media required more-frequent irrigation than those in the commercial media.