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Tropentag, September 17 - 19, 2014 in Prague, Czech Republic

"Bridging the gap between increasing knowledge and decreasing resources"


Overcoming Seed Germination Problems of Traditional Vegetables after Cold Storage

Andreas Wilhelm Ebert, Tien-Hor Wu

AVRDC - The World Vegetable Center, Genetic Resources and Seed Unit, Taiwan


Abstract


The experiments described here address the constraints of hard-seededness of fresh and stored seed of okra (Abelmoschus esculentus (L.) Moench) and water spinach (Ipomoea aquatica Forssk.). Freshly harvested fruits of two water spinach and two okra accessions were dried for two weeks in a screenhouse prior to manual seed extraction and cleaning. Cleaned seed was dried to 6% seed moisture content in a dehumidified drying room for 8 days at 18oC and 15% RH. The two accessions of both crops showed a marked difference in initial germination rate prior to storage. The water spinach accession from Thailand (VI050476) had a very low initial germination rate of 4% compared to 77% for the accession from Taiwan (VI054533). Okra seeds of an accession from Thailand (VI046536) had an initial germination rate of 26% compared with 90% for the accession from Zambia (VI050598). Seed priming was conducted after 6 months of storage at 5oC and -15oC. The germination rate of water spinach seed from Thailand (VI050476) remained very low at 4% and 1% after 6 months of storage at 5oC and -15oC, respectively (T1; control). Partial removal of the seed coat followed by 24 h soaking in water (T3) elevated the germination rate substantially to 82% and 85% after 6 months of storage at 5oC and -15oC, respectively. The germination rate of seed from Taiwan (VI054533) increased from 77% prior to storage to 92% and 93% after 6 months of storage at 5oC and -15oC, respectively. Seed priming of the latter did not have any additional beneficial effect on the germination rate. Storage temperature of okra seed had a major impact on the germination rate. While the germination rate of seed stored for a 6-month period at 5oC was low for the accessions from Thailand (18%) and Zambia (20%), the germination rate reached 99% and 96%, respectively, when seed was stored at -15oC. Seed priming was highly beneficial for seed stored at 5oC (T3), but was not required when seed was stored under sub-zero temperatures.


Keywords: Cold storage, germination rate, hard-seededness, okra, seed priming, water spinach


Contact Address: Andreas Wilhelm Ebert, AVRDC - The World Vegetable Center, Genetic Resources and Seed Unit, P.O. Box 42, Shanhua, 74199 Tainan, Taiwan, e-mail: andreas.ebert@worldveg.org


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