Abstract:
There is an increasing demand for traditional rice varieties due to their nutritional and
medicinal value. Standard germination test (SGT) used for rice seed testing, does not accurately
predict the field emergence (FE). Therefore, the objective of this study was to determine
whether the accelerated aging (AA) seed vigor test can be used to predict FE of nine popular
traditional rice varieties (Beheth Heenati, Herath Banda, Kahawanu, Madathawalu, Pachchei
Perumal, Pokkali, Sudu Heenati, Sulai and Suwandel). For the SGT, four replicates, each
containing 100 seeds, were germinated according to AOSA paper towel method. To calculate FE
of seedlings, four replicates of 400 pre-germinated seeds each from each variety were sown in 1
m2 plots in a paddy field at Pelwehera, Sri Lanka. To evaluate seed vigor, seeds from each variety
were aged at three different temperatures (42, 43 and 44 C) for two different time durations
(72 and 96 hours) in a water-jacketed incubator. Germination of aged seeds was tested
according to AOSA paper towel method. In each experiment, normal seedlings (%) were
calculated after seven days. Data were analyzed using proportion analysis. Normal seedlings (%)
in the SGT and FE test were >85% and >75%, respectively for all the tested varieties. In the two
varieties Beheth Heenati and Sulai, the normal seedlings (%) in FE test was similar to that of SGT
(P>0.05) while in other varieties, FE (%) was significantly lower than SGT (%) (P<0.05).
Pachchei Perumal and Sulai showed the highest vigor (>75%) under 44 °C for 96 hours, while
suwandel showed the lowest vigor (2±1%). For Beheth Heenati, Herath Banda, Madathawalu,
Pokkali, Sudu Heenati and Sulai, more than one AA treatment could predict FE. To predict the FE
of the tested varieties, AA conditions 43 °C for 72 hours, 44 °C for 96 hours and 42 °C for 72 can
be recommended for Herath Banda, Pachchei Perumal and the other tested varieties except
Kahawanu, respectively. To select the best AA parameters to predict FE of Kahawanu, more
combinations of temperature and time of exposure need to be tested.
