Abstract
Salinity severely constrains the expansion of cultivated areas and diminishes the productivity of rice lands in major irrigated paddy fields in the inland dry zone and coastal areas of Sri Lanka. The Angithathmkulam yaya is situated in the dry zone of Sri Lanka and is strongly affected by high salinity in paddy fields. As a result, rice cultivation is extremely difficult. Various technologies namely, preparation of drainage canals, deep plowing, land leveling, application of organic manure and maintenance of water level were implemented in paddy fields to reduce salinity, and salt tolerant rice varieties (Bg 5-110, Bg 11-139, Bg 4-91, At 354) as well as salt-sensitive variety (Bg 352) were examined to study their performance. In situ electrical conductivity was determined throughout the growing season, and Ca, Mg and Na contents in the soil were determined at planting and harvesting. It was revealed that paddy fields in Angiththamkulam yaya are mainly affected by salinity due to Na, Mg and Ca salts. Na, Ca and Mg contents of >800, >700 and >400mg kg^<-1>, respectively, were much higher than that required for normal growth of rice. Management practices reduced the Na and Mg contents resulting in a grain yield of 3t ha^<-1> from Bg 352, the salt-sensitive variety. The salt-tolerant rice variety Bg 11-139 recorded the highest yield of 7.0t ha^<-1> followed by Bg 5-110 and Bg 4-91, which produced yields of 6.4 and 6.1t ha^<-1>, respectively. These results suggest that adopting suitable management practices along with salt-tolerant rice varieties can potentially improve the productivity of saline paddy fields.
