Abstract:
Submergence poses a major challenge to rice cultivation, significantly reducing
harvest outcomes. Therefore, the adoption of rice varieties with enhanced tolerance
to submergence is crucial. This study examines how water quality and
environmental conditions influence the submergence tolerance of selected
improved rice varieties (Oryza sativa L.) in Sri Lanka. After 24 hours pretreatment
procedure, LD 376, LD 253, LD 368, and LD 408 selected rice varieties were
submerged for 12 days with Well water, Canal water and Chlorinated tap water
from 6 different locations. During the pretreatment, each sample was submerged
in corresponding water of each location for 24 hours followed by the weight
treatment for 24 hours. Then, cultivation was carried out using Well water obtained
from Walasmulla (L1) and Udugama (L2) locations, Canal water from
Embilipitiya (L3) and Hambantota (L4) locations and chlorinated tap water from
Tangalle (L5) and Galle (L6) locations. SPAD readings were obtained from
randomly selected rice plants after 12 days, while bud length was measured daily
with respective water samples. According to analyzed data, LD 408 variety showed
the highest bud growth rate in Canal water which has high conductivity values and
also LD 408 rice sample which was submerged in Canal water in Location 3 & 4
has relatively high SPAD values. Thus, LD 408 rice variety exhibited resilience to
Canal water with high conductivity, resulting from dissolved soil minerals such as
NaCl and CaSO₄ as well as sewage, maintaining rapid bud growth and elevated
SPAD values, which indicates strong tolerance to submergence and ionic stress. It
implies its suitability for cultivation in flash-flood-prone areas and other marginal
environments with saline or nutrient-rich water in Sri Lanka.
