Identification of Accelerated Aging Conditions for Seed Vigor Test in Rice (Oryza sativa L.)

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AUTHOR: Suraj Chhetri and Thawatchai Teekachunhatean 


ABSTRACT

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.

KEY WORDS:

rice seeds, seed vigor tests, accelerated aging test, conductivity test.

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