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United States Department of Agriculture

Agricultural Research Service

Research Project: Conservation, Genetic Analyses, and Utilization of Subtropical/Tropical Fruit Crops, Sugarcane, and Miscanthus Genetic Resources

Location: Subtropical Horticulture Research

Title: Breaking seed coat dormancy with physical and chemical methods in tamarind (Tamarindus indica L.) seeds

Authors
item Ayala-Silva, Tomas
item Gubbuk, Hamide -
item Gordon, Garry -

Submitted to: Journal of Agriculture of the University of Puerto Rico
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 5, 2013
Publication Date: October 1, 2013
Citation: Ayala Silva, T., Gubbuk, H., Gordon, G. 2013. Breaking seed coat dormancy with physical and chemical methods in tamarind (Tamarindus indica L.) seeds. Journal of Agriculture of the University of Puerto Rico. 97(1-2):87-96.

Interpretive Summary: THE EFFECTS OF MECHANICAL AND CHEMICAL TREATMENTS ON ENHANCING SEED GERMINATION OF TAMARIND (Tamarindus indica L.) SEEDS Tomas Ayala-Silva1*, Hamide Gubbuk2 and Garry Gordon1 1 National Germplasm Repository System, Subtropical Horticulture Research Station, Miami, FL, USA 2 Department of Horticulture, Faculty of Agriculture, Akdeniz University, Antalya 07058, Turkey, *Email: tomas.ayala-silva@ars.usda.gov Interpretative summary Tamarind (Tamarindus indica L.) is an important tree crop in Africa and Asia. It is mainly propagated by seeds and grafting, which requires the generation of rootstock material. Tamarind seeds have water-resistant seed coat and need pre-treatment before germination. In this study, tamarind seeds collected from sweet tamarind trees in Miami, FL. were submitted to various mechanical treatments (bottom cutting (BC), both side cutting (BSC), and bottom cutting + both side cutting (BC+BSC)), and sulfuric acid (SA) treatments (soaking for 25, 50, 75, 100 or 125 minutes) with a control. After pretreatments, seeds were planted in coconut peat and perlite media (50/50) in 40 cell trays. The experiment was carried out in the greenhouse at 25-28 oC degrees. Germination percentage, germination index, germination energy, and mean germination time were evaluated in accordance with the pre-treatments. In addition, root, radicle, and hypocotil length, leaf number and seedling (root, radicle, hypocotil, stem and leaf) fresh and dry weight also were determined. Results showed that all investigation measures were statistically different in accordance with the pre-treatments. Grinding of the seeds enhanced seed germination percentage in all treatments. However, soaking seeds in sulfuric acid more than 25 minutes reduced seed germination significantly. Germination percentage was between 27.50 and 100%. The highest germination energy was observed in Sulfuric acid at 25 minutes and the lowest in the 125 minutes SA treatment. Same results were obtained for the germination index. The results showed that BC, BSC, BC+BSC, and soaking in SA for 25 minutes are the best treatments for promoting germination of tamarind seeds. Key words: Tamarind, seed, dormancy, pre-sowing treatment, germination

Technical Abstract: Tamarind (Tamarindus indica L.) is an important tree crop in Africa and Asia. It is primarily propagated by grafting, which involves the generation of rootstock material. Tamarind seeds have an impermeable seed coat and need scarification for improved germination. In this study, tamarind seeds collected at the Subtropical Horticulture Research Station (SHRS) in Miami, FL, were submitted to various mechanical and sulphuric acid treatments: Control, bottom cutting (BC), both sides cutting (BSC), bottom cutting + both sides cutting (BC+BSC), and soaking in sulphuric acid (SA) treatments for 25, 50, 75, 100 and 125 minutes. After pretreatments, seeds were sowed in coconut peat and perlite media in 40-cell trays and arranged in a RCBD with four replications. Germination percentage, germination index, germination energy, mean germination time were evaluated for each treatment. Root, radicle, and hypocotyl length, leaf number, and seedling (root, radicle, hypocotyl, stem and leaf) fresh and dry weights were also determined. All mechanical scarification treatments enhanced seed germination. However, soaking the seeds in sulfuric acid more than 50 minutes significantly reduced seed germination percentage. Germination percentage ranged between 27.50 and 92.50%. Total fresh weight was higher in the BSC and BC+BSC, however, total dry weight was higher in the 25 minutes sulfuric acid treatment. We recommend soaking in SA for 25 minutes to break dormancy in tamarind. Key words: tamarind, fresh and dry weight, germination, scarification, seed, sulfuric acid

Last Modified: 9/21/2014
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