AUTHOR: Suraj Chhetri and Thawatchai Teekachunhatean
The accelerated aging conditions commonly practiced in Thailand as seed vigor test in rice is not accurate and no recommended accelerated aging test conditions for rice seed is prescribed in international seed vigor testing handbooks. The main objective of this study was to investigate accurate combinations of temperature and time for the accelerated aging conditions for seed vigor test in rice. The minor objective was to explore for efficient vigor tests for rice seeds other than accelerated aging test. Twenty four rice seed lots of 3 common Thai varieties (Chai Nat1, Khao Dok Mali 105 and Phitsanulok1) of different vigor levels from different seed centers and research centers in Thailand were used in the experiment. The following tests were conducted: standard germination, field emergence, seedling root length, seedling shoot length, total seedling length, seedling growth rate, conductivity and accelerated aging at 42, 43 and 44 oC for 72, 96 and 120 hrs at each temperature. In the multiple correlation analyses, all tests showed highly significant correlations (p < 0.01) with field emergence (r = 0.55** to 0.82**). The three single vigor test that provided highest correlation with field emergence were conductivity test (r = -0.82**), accelerated aging test at 44 oC for 72 hrs (r = 0.78**) and seedling shoot length (r = 0.75**), respectively. Among conductivity test and 9 accelerated aging conditions the highest correlation (r = -0.71**) was observed between conductivity and accelerated aging at 44 oC for 72 hrs. Based on the result obtained it can be concluded that the accelerated aging condition at 44 oC for 72 hrs and conductivity test should be generally recommended for vigor test in rice seeds of Thai varieties.
rice seeds, seed vigor tests, accelerated aging test, conductivity test.
Association of Official Seed Analyst (AOSA). (1983). Seed Vigor Testing Handbook. Contribution No. 32. Association of official Seed Analysts. Lincon, NE., USA. .
Bradford, K. J. (1988). Rice Seed–88. 1988 Annual report. Department of Vegetable Crops,UC Davis. Available source: http://www.carrb.com/ 88rpt/RiceSeed.htm. June 27, 2009.
Chea, S. (2006). Seed Vigour Tests and Their Use in Predicting Field Emergence of Rice. M. Sc. Thesis, Khon Kaen University, Thailand.
Delouche, J. C. and C. C. Baskin. (1973). Accelerated aging techniques for predicting the relative storability of seed lots. Seed Sci. & Technol. 1: 427-452.
Egli, D. B. and D. M. TeKrony. (1995). Soybean seed germination, vigor and field emergence. Seed Sci. & Technol. 23: 595-607.
International Seed Testing Association (ISTA). (1995). Handbook of Vigour Test Methods. 3rd edition. Internaitonal Seed Testing Association. Zurich. Switzerland. 117 p.
ISTA. (1999). International Rules for Seed Testing. 1999. Seed Sci. & Technol. 27 (Suppl.) 333 p.
Komba, C. G., B. J. Brunton and J. G. Hamptton. 2006. Accelerated ageing vigour testing of kale (Brassica oleracea L. var. acephala DC) seed. Seed Sci. & Technol. 34: 205-208.
Mavi, K. and I. Demir. (2007). Controlled deterioration and accelerated ageing tests to predict seedling emergence of watermelon under stressful conditions and seed longevity. Seed Sci. & Technol. 35: 445-459.
Patin, A. L. and T. J. Gutormson. (2009). Evaluating rice Oryza sativa L. seed vigor. CABI
Abstract. Available source: http://www.cababstractsplus.org/abstracts/ Abstract.aspx?AcNo=20053186670. June 27, 2009.
Santipracha, W, Q. Santipracha and V. Wongvarodom. (1997). Hybrid corn seed quality and accelerated aging. Seed Sci. & Technol. 25: 203208.
Siddique, S. B., D. V. Seshu and W. D. Pardee. 1988. Rice cultivar variability in tolerance for accelerated aging of seed. IRRI Research Paper Series No. 131: 1-7.
Singkanipa, V. (2008). Personal communicaition. Head of Seed Quality Control Group, Nakhon Ratchasima Rice Seed Center, Nakhon Ratchasima, Thailand. Tomer, R. P. S. and J. D. Maguire. (1990). Seed vigour studies in wheat. Seed Sci. & Technol. 18: 383-392.