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  • Author or Editor: Ming Chen x
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Abstract

Papaya (Carica papaya L.), a climacteric fruit, became progressively less susceptible to chilling injury as it ripened. Symptoms of chilling injury included skin scald, hard areas in the pulp around the vascular bundles, and water soaking of tissue. Mature green fruit were most sensitive to chilling and began showing injury after 10 days of storage at 2°C. Chilling injury symptoms began to occur after 20 days at 7.5°. Fruit that showed 60% yellowing could be kept at 2° for 17 days without developing injury. Preconditioning papaya fruit for 4 days at 12.5° before storage for 12 or 14 days at 20° reduced chilling sensitivity. The decrease in chilling sensitivity with preconditioning was associated with partial fruit ripening. Waxing and wrapping papaya with polyethylene reduced chilling injury, but the fruit had an off-flavor. Controlled atmospheres of low oxygen (1.5% to 5%) with or without high C 02 (2% or 10%) delayed ripening, but did not reduce chilling injury symptom development. Calcium treatment led to increased chilling injury of papaya fruit. Delaying storage until the fruit ripened decreased chilling susceptibility and increased storage life at chilling temperatures. Shipping 60% yellow fruit at 2° could provide a procedure for achieving fruit fly disinfestation. Differences in cultivar response to chilling injury were noted.

Open Access

Stock plants of tea [Camellia sinensis (L.) Kuntze cv. Chin-shin Oolong] were sprayed three times at weekly intervals with benomyl before taking cuttings. The survival rate of cuttings was increased from 3.3% in the nontreated controls to 76% in 1986 and from 6.4% to 83% in 1987. The treatment also greatly improved the subsequent growth of cuttings. Soaking cuttings in benomyl solution before sticking slightly improved survival and subsequent growth of cuttings. Chemical name used: methyl[1-[(butylamino)carbonyl]-1H-benzimidazol-2-yl]carbamate (benomyl).

Free access

Chrysanthemums have beautiful flowers with high ornamental value and rich genetic diversity. Amplified fragment length polymorphism (AFLP) markers were used to detect the relationships among 12 wild accessions and 62 groundcover chrysanthemum cultivars. Nineteen EcoRI/MseI primer combinations revealed 452 informative polymorphic bands with a mean of 23.8 bands and 71.5% polymorphic rate per primer pair. Jaccard’s coefficient of similarity varied from 0.64 to 0.89, indicating much genetic variation in chrysanthemums. The 74 accessions were classified into two major groups by unweighted pair group method with the arithmetic averages (UPGMA). The dendrogram showed that AFLP variability was closely correlated with both geographic distribution and traditional classification of the wild accessions. Among all accessions, genetic relationship was the most relevant factor in AFLP-marker clustering, whereas petal type was also informative. AFLP technology could be very efficient for discriminating species of chrysanthemum and its related genera and reconstruct their genetic relatedness.

Free access

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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The main purpose of this research was to explore individuals' attitudes toward horticultural activities. The research was conducted in two stages. First, open-ended interviews were used to conceptualize attitudes toward horticultural activities, and seven themes and several subthemes of attitudes were induced. Based on the results, a questionnaire was then designed and a quantitative survey was conducted to identify the dimensions of attitudes toward horticultural activities and their interrelationships. Five dimensions of attitudes toward horticultural activities were extracted: increasing positive mood, improving the environment, leisure belief, improving social relationships, and escaping. These dimensions of attitudes toward horticultural activities had activity-based attributes that differed to some extent from those of general leisure. The dimension of improving the environment was particularly salient for horticultural activities. Propositions and recommendations to stimulate future research about developing a valid measurement instrument are offered.

Free access

Tuber production of calla lily (Zantedeschia elliottiana Spreng cv. Super Gold) was investigated using three size ranges (7-10, 4-7, and <4 mm shoot diameter) of in vitro plantlets acclimated in either pots or soil beds in a protected house. The shoots and tubers of large plantlets exhibited higher rates of dry-matter accumulation than did those of small plantlets. The diameter of tubers harvested from pots ranged from 0.67 to 4.1 cm with median values of 2.7, 2.1, and 1.9 cm for the plants derived from large, medium, and small plantlets, respectively. Plants grown in soil beds, regardless of size, produced larger tubers than did those grown in pots. Tubers >3 cm in diameter developed on 25% and 52% of plants grown in pots and soil beds, respectively. Our results suggest that improved calla lily production could be realized by using larger in vitro plantlets as the source material and growing them in soil beds in a protected house.

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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.

Free access

Nitrogen and potassium are two crucial nutrient elements that affect the yield and quality of crops. The aim of this study was to quantify the impacts of potassium on growth dynamics and quality of muskmelon, so as to optimize potassium management for muskmelon in a plastic greenhouse, and develop a coupling model of nitrogen and potassium. For this purpose, four experiments (two experiments with different levels of potassium treatment and planting dates, and the other two experiments with different ratios of nitrogen and potassium, and planting dates) on muskmelon (Cucumis melo L. ‘Nanhaimi’ and ‘Xizhoumi 25’) were conducted in a plastic greenhouse located at Sanya from Jan. 2014 to Sept. 2015. The quantitative relationship between leaf potassium content and growth dynamics and yield of muskmelon was determined and incorporated into a photosynthesis-driven crop growth model (SUCROS). Independent experimental data were used to validate the model. The critical leaf potassium content at the flowering stage for muskmelon ‘Nanhaimi’ and ‘Xizhoumi 25’ were 55.0 and 46.0 mg·g−1. The result showed that the coefficient of determination (r 2) between the predicted and measured values of leaf area index (LAI), direct weight of shoot (DWSH), direct weight of stem (DWST), dry weight of leaf (DWL), dry weight of fruit (DWF), fresh weight of fruit (FWF), soluble sugar content (SU), soluble protein content (PR), vitamin C (Vc), and soluble solids content (SO) of potassium model were 0.93, 0.98, 0.83, 0.96, 0.98, 0.99, 0.94, 0.94, 0.89, 0.85, and 0.90, respectively; and the relative root-mean-squared error (rRMSE) were 10.8%, 19.6%, 30.3%, 21.1%, 11.9%, 17.2%, 13.9%, 27.8%, 20.6%, and 10.1%, respectively. The two ways of nitrogen and potassium coupling (multiplicative coupling and minimum coupling) were compared, and the multiplicative coupling was used in model development finally. The r 2 between the predicted and measured values of LAI, DWSH, DWST, DWL, DWF, FWF, SU, PR, Vc, and SO of nitrogen and potassium coupling model were 0.78, 0.91, 0.93, 0.94, 0.83, 0.89, 0.92, 0.95, 0.91, and 0.93, respectively; and their rRMSE were 9.2%, 12.4%, 11.8%, 43.2%, 6.6%, 7.2%, 6.85%, 4.98%, 6.61%, and 4.35%, respectively. The models could be used for the optimization of potassium, nitrogen, and potassium coupling management for muskmelon production in a plastic greenhouse.

Free access

Nuclear DNA contents were estimated by flow cytometry in 18 Phalaenopsis Blume species and Doritis pulcherrima Lindl. DNA amounts differed 6.07-fold, from 2.74 pg/diploid nuclear DNA content (2C) in P. sanderiana Rchb.f. to 16.61 pg/2C in P. parishii Rchb.f. Nuclear DNA contents of P. aphrodite Rchb.f. clones, W01-38 (2n = 2x = 38), W01-41 (2n = 3x = 57), and W01-22 (2n = 4x = 76), displayed a linear relationship with their chromosome numbers, indicating the accuracy of flow cytometry. Our results also suggest that the 2C-values of the Phalaenopsis sp. correlate with their chromosome sizes. The comparative analyses of DNA contents may provide information to molecular geneticists and systematists for genome analysis in Phalaenopsis. Endoreduplication was found in various tissues of P. equestris at different levels. The highest degree of endoreduplication in P. equestris was detected in leaves.

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