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Chao-Yi Lin and Der-Ming Yeh

Guzmania lingulata (L.) Mez. ‘Cherry’ plants were grown in coconut husk chips. All plants were given 8 mm nitrogen (N), 2 mm phosphorus (P), 4 mm calcium (Ca), and 1 mm magnesium (Mg) at each irrigation with potassium (K) concentration at 0, 2, 4, or 6 mm. After 9 months, K concentration did not alter the number of new leaves, and shoot and root dry weights. Increasing K concentration did not affect the length but increased the width of the most recently fully expanded leaves (the sixth leaves). Plants under 0 K exhibited yellow spots and irregular chlorosis on old leaves being more severe at the middle of the blade and leaf tip. Numbers of leaves with yellow spots or chlorosis decreased with increasing K concentration. Chlorenchyma thickness was unaffected by K concentration, whereas water storage tissue and total leaf thickness increased with increasing K concentration. Leaf N concentration in the sixth or 10th leaf was unaffected by solution K concentration. However, plants at 0 mm K had higher N concentration in the 14th leaf than those in sixth and 10th leaves. Leaf P, Ca, and Mg concentrations decreased with increasing solution K concentration. K concentrations were higher in the sixth leaf than the 14th leaf in plants at 0, 2, or 4 mm K, whereas leaf K concentration was 15 g·kg−1 on dry weight basis in the sixth, 10th, or 14th leaves in plants treated with 6 mm K.

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Chin-Mu Chen, Tzu-Yao Wei and Der-Ming Yeh

A double-flowered periwinkle [Catharanthus roseus (L.) G. Don.] mutant TYV1 was identified and the morphology and inheritance of the double-flowered phenotype was studied. TYV1 has an outer salverform whorl of petals and an additional inner funnel-shaped whorl of petals originating from the apex of the corolla. The apex of corolla tube forms a narrow opening. There are hairs under the opening at the apex. The stigma in this mutant is set below the anthers. The overlap between the top end of the pistil and bottom ends of anthers in TYV1 flowers at 1 to 2 days after anthesis is 0.56 ± 0.01 mm. TYV1 could be used as either the male or female parent in crossing. Self-pollinated TYV1 produced all double-flowered progeny compared with self-pollinated single-flowered cultivars Little Pinkie and Titan Burgundy, which produced all single-flowered progeny. F1 plants between TYV1 and ‘Little Pinkie’ or ‘Titan Burgundy’ were all single. Three F2 populations segregated into 3 single: 1 double ratio. Backcrossing F1 to seed parents also indicated that a double-flowered form was controlled by a recessive allele. A single dominant gene expressed in the homozygous or heterozygous state resulted in the single-flowered phenotype. All the young seedlings of self-pollinated TYV1 and double-flowered progeny had distorted leaves before the sixth pair of leaves emerged.

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Chang-Tsern Chen, Ching-Lung Lee and Der-Ming Yeh

Growth and photosynthetic parameters were measured in Eustoma grandiflorum (Raf.) Shinn. ‘Umihonoka’ grown hydroponically under nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), or magnesium (Mg) deficiency in 1/2 strength of modified Johnson’s solution. Plant height, node number, and leaf area were all reduced under N, P, K, and Ca deficiencies but not under Mg deficiency as compared with plants grown in the complete nutrient solution. Shoot and root dry weight were reduced in the N-, P-, K-, and Ca-deficient treatments, whereas root but not shoot dry weight was lowered by Mg-deficient treatment. Shoot-to-root dry weight ratio decreased under N and P deficiencies, increased under K and Mg deficiency, but was not altered under Ca deficiency. Decreased net photosynthetic rate (Pn) of N-, P-, and K-deficient leaves was all related to lower stomatal conductance (g S), whereas N-deficient leaves also accompanied by a higher intercellular carbon dioxide concentration (Ci). The Mg-deficient treatment did not alter chlorophyll fluorescence Fv/Fm, maximal fluorescence (Fm), or minimal fluorescence (Fo). Decreased Fv/Fm of N-, P-, K-, and Ca-deficient leaves was all related to lower Fm, whereas N- and P-deficient leaves also accompanied by lower Fo. A key was developed for the identification of N, P, K, Ca, and Mg deficiency symptoms.

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Yuan-Tsung Chang, Der-Ming Yeh and Wen-Ju Yang

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Shu-Ting Fan, Der-Ming Yeh and Tsu-Tsuen Wang

This study determined the sensitivity of two Aglaonema cultivars to ethylene and evaluated the effectiveness of 1-methylcyclopropene (1-MCP) to protect sensitive cultivars. Plants of ‘White Tip’ and ‘Chalit's Fantasy’ were exposed to various ethylene concentrations for 7 days during dark storage at 15 °C. Poststorage performance, measured as number of chlorotic leaves and quality rating, was recorded after the plants were placed in the indoor environments for 14 days. Exposure to 4.5 μL·L−1 ethylene resulted in increased chlorotic leaves and reduced quality rating in ‘White Tip’ but did not affect poststorage performance in ‘Chalit's Fantasy’. Exposure to 4.5 μL·L−1 ethylene reduced both the soil plant analytical development-502 (SPAD-502) and variable fluorescence/maximal fluorescence (Fv/Fm) values of the lowest leaves in ‘White Tip’ but not in ‘Chalit's Fantasy’. Chlorotic leaf number increased; the SPAD-502 value, Fv/Fm, and Fm of the lowest leaves decreased in ‘White Tip’ as ethylene concentration increased from 0 to 4.1 μL·L−1. Plants of ‘White Tip’ pretreated with 300 or 900 nL·L−1 1-MCP for 6 h had fewer chlorotic leaves, higher Fv/Fm, and SPAD-502 values and better postproduction quality than those without 1-MCP pretreatment in response to treatment with 1.1 μL·L−1 ethylene during storage.

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Ching-Hsueh Wang, Der-Ming Yeh and Chian-Shinn Sheu

Flowering of many chrysanthemum [Dendranthema ×grandiflora (Ramat.) Kitam.] cultivars is reduced or delayed under high temperatures. Identification and rapid selection of heat-tolerant and flowering-heat-delay-insensitive chrysanthemum genotypes for commercial production is desirable. An electrolyte leakage technique was used to measure cell membrane thermostability of chrysanthemum cultivars. The relationship between the relative injury (RI) value occurring in leaf tissue discs and the treatment temperature was sigmoidal. The RI values at the approximate midpoint of the sigmoid response curve occurred at 47 to 53 °C for summer- and fall-flowering cultivars and at 45 to 46 °C treatments for winter- and spring-flowering cultivars. Regressing the delay in days to flowering for the cultivars grown at day/night temperature of 30/25 °C compared with those grown at 20/15 °C versus their associated RI values at 50 °C treatment showed a linear relationship. Reduced RI was more apparent in the heat-tolerant ‘Kaa Luoh-Lii’ than the heat-intolerant ‘Repulse’ after 30/25 °C treatment for 24 to 27 days. When 30/25 and 20/15 °C treatments were compared, the former did not alter leaf malondialdehyde (MDA) content in ‘Kaa Luoh-Lii’ but increased MDA content in ‘Repulse’.

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Yuan-Tsung Chang, Shyh-Shyan Wang, Der-Ming Yeh and Wen-Ju Yang

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Huan-Keng Lin, Tzu-Yao Wei, Chin-Mu Chen and Der-Ming Yeh

Stem anatomy and modulus of elasticity (MOE) were compared between upright and trailing cultivars of periwinkle [Catharanthus roseus (G.) Don.]. The inheritance of growth habit and flower form was also studied. Internode cross sections revealed that phloem fiber was distributed at the inner cortex in upright cultivars but not in trailing cultivars. Except the youngest internode, the upright ‘Vitesse Pink’ had the highest MOE throughout the 1st–13th internodes above the cotyledon. The more trailing ‘Cora Cascade Strawberry’ had consistently lower MOE than a less trailing ‘Cora Cascade Polka Dot’. All F1 plants between upright and trailing cultivars were upright, and the F2 generation derived from self-pollinating F1 fit a 3 upright : 1 trailing segregation ratio. All F1 plants between upright/double-flower and trailing/single-flower exhibited upright and single-flowers, whereas plants in the F2 generation fitted a 9 upright/single-flower : 3 trailing/single-flower : 3 upright/double-flower : 1 trailing/double-flower ratio. New double-flowered periwinkle selections with trailing growth habit were successfully developed from the F2 population.