Abstract:
Submergence tolerance is an important trait where short term flash flooding
damages rice. Due to the heterogeneity in flood-prone ecosystem, many
different types of traditional rice cultivars are grown by the farmers. Present
study was conducted to explore the submergence tolerance traditional rice
cultivars in traditional rice collections in Sri Lanka. Twenty Sri Lankan
traditional rice cultivars were screened for complete submergence tolerance
at two week old seedling stage. Experiment was carried out according to the
randomized complete block design with 4 replicates and 20 plants were
included into each replicate. After the complete submergence stress,
desubmerged plants were allowed to recover for 14 days at normal growth
conditions. Data were collected on the number of survival plants, plant
height before and after the submergence stress and plant height after the two
week recovery period. Control experiment was also carried out parallel to
treatment. Among tested rice cultivars 45% rice cultivars elongated during
complete submergence period while 55 % of rice cultivars reduced their
height compared to that of control plants during 14 day submerged period.
Among evaluated 20 traditional rice cultivars, all the cultivars died after two
week recovery period followed by 14 day completely submergence stress
except rice cultivar Sudu Wee. It also recorded 51% survival rate. Sudu Goda
Wee and Dik Wee 328 recorded the highest gained plant height during
submerged period. Only Sudu Wee which elongated (5.45 cm) during
submergence stress was able to survive at submerged conditions at seedling
stage. There was no significant correlation (r = 0.16, α=0.5) between height
gain during 14 day submergence stress and survival percentage of rice
cultivars at seedling stage.