Effects of Temperature and Osmotic Priming on Germination of Spinach (Spinacia oleracea L.) Seeds
Hsiao-Hua Wang, Wen-Chuan Chung and Tsai-Fa Shen
Seed Improvement and Propagation Station, Taichung,Taiwan, R.O.C.
Summary
Five germination temperatures (10, 15, 20, 25, and 30℃) were tested for their effects on the final germination percentage (FGP) and the mean germination time (MGT) of the seeds of four spinach (Spinacia oleracea L.) cultivars ('Shiluo No.1', 'Derei', 'Ballet' and 'Taiwan jyuelih' ). The results indicated the FGP of seeds was significantly decreased with increasing temperature on all cultivars. Higher temperature also shortened MGT. The optimum temperatures for germination were different among cultivars. FGP was improved significantly by priming and the MGT was reduced more than 50% on all cultivars. Priming the seeds at -0.85 and -0.95 MPa appeared to be optimum for 'Shiluo No.1' which reached 89% germination as opposed to 8% in the control.
Key words: spinach, osmotic priming, seed
Effects of Seed Size on Emergence and Vigour of Water Convolvulus (Ipomoea aquatica Forssk.) Seeds
Tsung-Dao Liou, Kan-Shu Chen and Shuo-Peng Li
Director, Associate Scientist and Assistant Researcher of Fengshan Tropical Horticultural
Experiment Station, TARI, Fengshan, Kaohsiung, Taiwan 830, ROC.
Summary
Seeds of two cultivars of water convolvulus, 'Pingtung Green Stem' (pointed leaf) and 'White Stem' (broad leaf), were classified into four fractions, which were <4.0, 4.0, 4.5 and > 4.5φmm, by standard round sieves. Unsorted seeds were served as control. Vigour of different fraction seeds were tested by topographical tetrazolium test. Emergence and seedling growth of different fraction seedswere tested at constant temperature of 30℃ in a growth cabinet and in the field with different sowing dates respectively. The results indicated that the time to seed emergence, emergence percentage and seedling growth were not significantly influenced by seed size. Similar results were obtained in the field experiment. Seed size did not affect time to seed emergence, emergence percentage and seedling growth of these two cultivars under field condition.
Key Words：water convolvulus, seed size, vigour, emergence
The Asynchronous Dormancy Acquisition in Epicotyl and Radicle during Zygote Embryogenesis of Fringe Tree （Chionanthus retusus Lindl.）
Tsung-Dao Liou, Kan-Shu Chen and Shuo-Peng Li
Director, Associate Scientist and Assistant Researcher of Fengshan Tropical Horticultural
Experiment Station, TARI, Fengshan, Kaohsiung, Taiwan 830, ROC.
Summary
The seed of fringe tree (Chionanthus retusus Lindl.) is characterized with strong epicotyl dormancy. Embryos of various developmental stages were cultured on half strength MS medium containing malt extract 500 mg/l, glutamine 100 mg/l and sucrose 2%. It was showed that the germinability of immature embryos dramatically increased from 1.5 to 7.2 mm, and achieved 85-95% by approximately 110 days after anthesis. Thereafter, the frequency of epicotyl emergence declined down to 30% in the middle mature period. In the meanwhile, the intact seeds exhibited 100% epicotyl dormancy. The imposition of epicotyl dormancy started right before full expansion of cotyledon, but the onset of radicle dormancy, which was conditional dormancy in nature and which occurred in lower frequency than epicotyl dormancy, appeared lately. The addition of 2.0 ppm GA3 stimulated the germination of the smaller embryos, increased the precocious germination percentage, overcome primary epicotyl dormancy, and relieved the ABA inducing secondary dormancy. Histological feature indicated that the GA treatment is able to initiate apical and sub-apical meristem activity rapidly, and differentiate neo-epicotyl axis with leaf primordia within 4-5 days. The de-rooted treatment also had pronounced effect on overcoming epicotyl dormancy, resemble to GA treatment. The exogenous 0.5 ppm ABA induced the secondary epicotyl dormancy of young embryos, enforced the primary epicotyl dormancy of mature embryos, and retarded the cotyledon greening, rather than radicle protrusion. In contrast, both epicotyl and radicle emergence, and cotyledon greening were totally inhibited by 2.0 ppm ABA. It is suggested that the asynchronously epicotyl-radicle dormancy may be caused by their differential sensitivity to endogenous ABA level, and the surrounding tissue and protruding radicle may be also involved in regulation of persistent epicotyl dormancy.
Key words：fringe tree, embryo culture, precocious germination, epicotyl dormancy, hormones
Micropropagation of Eustoma grandiflorum by Axillary Bud Culture
Fure-Chyi Chen1) * , Shu-Chung Hsu2), Lih-Hsieng
Ke1) and Ming-Che Wu3)
1) Department of Plant Industry, National Pingtung University of Science and
Technology, Neipu, Pingtung, Taiwan 91207.
2) Undergraduate student, NPUST.
3) Council of Agriculture, Division of Horticulture, Taipei, Taiwan.
* Correspondening author
Summary
Axillary buds of Eustoma grandiflorum cultivars ‘Heidi Blue’ and ‘Echo Blue’ were cultured in vitro on modified Murashige and Skoog (MS) media. Multiple shoots were obtained in the media containing various concentration of benzyladenine (BA) alone or with low concentration of a -naphthalene acetic acid (NAA). Callus formation at the basal part of the shoots was observed when cultured in the media containing both growth regulators. Crowded multiple shoots occurred in the media containing BA at 1.0 mg/l or higher. Gibberellic acid (GA3) at 0.1-1.0 mg/l with 1.0 mg/l BA induced less crowded but more multiple shoots. The optimal medium for rooting was MS medium containing 1 mg/l IBA and 0.01 mg/l NAA. Sucrose seemed to be helpful for root formation, but the addition of activated charcoal inhibited rooting. When in the container with air-permeable Milliseal membrane, the plantlets were shorter than those without Milliseal membrane. Two batches of rooted plantlets were acclimatized under mist and grown in the experimental farm. They flowered normally during May and June.
Key words: Eustoma grandiflorum, axillary bud culture, rooting, acclimatization
Tetrazoloium Test for the Seed of Carica papaya L.
Chia Hong Shie1) and Warren H.J. Kuo2)
Department of Agronomy, National Taiwan University, Taipei 107, Taiwan.
1) Present address: Taiwan Tea Experiment Station, Taoyaun, Taiwan.
2) Corresponding author.
Summary
Non-dormant papaya seeds subjected to different accelerated-aging levels are used to evaluate the pattern of the TTC-stained embryo. The procedure of TTC testing for papaya seeds is proposed as follow: Soak the seeds in water over night, then remove the testa and endosperm. Stain the de-coated embryo by 0.5% TTC solution at 37.5℃ for 3 hours. Twelve categories are sorted out from the patterns of TTC staining. (fig 1) Halve of the embryo of a seed lot which containing only 2.5% viable seeds stained red, which deviate from viable one only by a slightly tint of opaque. (fig 2) The viability status of each category is determined by the calculation of minimum root mean square method. (table 1) The criteria for the evaluation of staining pattern thus determined predict the germination percentage of papaya seeds of different sources and cultivars accurately. (table 2) In order to harmonize with the ISTA rules, it is suggested that, the maximum area of unsuccessful staining for a viable papaya seed to be 1/3 radicle, with a remark that the red colour with an opaque or glassy appearance should be considered as dead.
Key Words: Carica papaya L., seed, TTC, TZ test
The Physiological Study of Seed Germination and Seedling Growth of Haemaria discolor var. dawsoniana
Ling-chin Chou1)and Doris Chi-Ning Chang2)
1)Graduate student, Department of Horticulture, National Taiwan University
2) Professor, Department of Horticulture, National Taiwan University, Taipei,
Taiwan
Summary
Jewel orchid (Haemaria discolor var. dawsoniana Rchb. F.) seeds of 30-45 days after hand pollination and only the unbroken capsules were collected. Effects of various kinds of media on the in vitro seed germination and seedling growth of jewel orchid were studied. Seed germination and seedling growth of jewel orchid were higher in 1/1 MS and 1/2 MS medium with 2-3 ppm of BA. This experiment confirmed that the growth of jewel orchid seedling were better in Hyponex #3 could better than those in Hyponex #1. It was suggested that for seed germination and seedling growth of jewel orchid, Hyponex #3 could replace MS medium and adding 2-3 ppm of BA could produce healthy seedling ready for transplanting into plugs or small pots within one year.
Key words：Haemaria discolor var. dawsoniana, seed germination, seedling growth