|Bentz, Jo Ann|
Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2004
Publication Date: 7/3/2004
Citation: Roh, M.S., Bentz, J., Wang, P., Li, E., Koshioka, M. Maturity and temperature stratification affect the germplasm of Styrax japonicus seeds. Journal of Horticultural Science & Biotechnology. 2004. v:79(4), pp:645-651. Interpretive Summary: According to the literature, Styrax seeds needed to be stored for 3 to 5 months at moist and warm (70 degree F) environments and then stored at low temperature (40 degree F) for 3 or 4 months. For seed to germinate, seeds should be mature. However, it is not fully understood when seeds become mature. Seeds harvested 12 to 14 weeks after flowering germinated well. Based on these results, it is concluded that seeds should be harvested 12 to 14 weeks after flowering. Further, the results of these experiments revealed that germination was improved when seeds received warm moist treatment for 1 month followed by 2 to 3 months of cold treatment. Gibberellic acid treatment did not improve seed germination, if seeds received warm moist treatment for 1 month followed by 2 to 3 months of cold treatment. If non-mature seeds are harvested, seeds will not germinate. Also, seeds that are sown immediately after collection may germinate by the following spring, suggesting that non fresh seeds may take longer to germinate. Seed maturity was studied using magnetic resonance imaging technique and it was concluded that seeds harvested 11 to 13 weeks after flowering are considered mature and able to germinate. It is recommended that Styrax seeds should be harvested 12 to 14 weeks after flowering and receive 1 month of warm and moist treatment followed by 2 months of cold treatment to improve germination percentage and to induce rapid germinations.
Technical Abstract: The effect of seed maturity, warm (18oC) or cold (5.5oC) temperature, and gibberellic acid (GA3) on seed germination of Styrax japonicus Sieb. et. Zucc was investigated. Seed maturity and morphological changes were observed using magnetic resonance (MR) imaging (MRI). Fruits harvested on July 22, i.e., 8 weeks after flowering showed early development of cotyledons and endosperm of the seeds. Fruits harvested 11 to 13 weeks after flowering, formed cotyledons and endosperm that were observed by MRI. These seeds germinated when sown, indicating that the seeds were mature. Internal seed structures were identified using MR image and the fruits showed several tissues that contained water with different mobility in early growth stages, thus fruits were actively developing. The endosperm of seeds harvested on July 7 and 22 had low water mobility, while developing cotyledons had high water mobility. While the water mobility in the seed coat declined, the pericarp maintained high water mobility. In the pericarp, T1 was increased with maturation of the seed, indicating the termination of the physiological role of the pericarp and increased degradation in metabolisms. Magnetic resonance imaging is a nondestructive tool that facilitates studying the structural development. Germination increased when cold stratification (CS) was given to seeds after 1 month of warm stratification (WS). Treating seeds with GA3 at 3,000 or 6,000 ppm promoted germination, as compared to seeds treated only with CS. The maximum percent germination was 98%, after 2 months of WS followed by 3 months of CS. Also, seed germination was high (> 92%) when seeds were treated with 3,000 ppm GA3, regardless of WS duration. At least 2 months of CS were required to improve germination more than 81%. The highest germination was obtained when seeds were treated with 3 months of CS without or with 3,000 ppm GA3. Gibberellin promoted germination when seeds received sub-optimal levels of WS and CS.