Evaluation of Level of Drought Tolerance in Traditional Rice Cultivars in Sri Lanka at the Seedling Stage

Abstract

Rice consumes more water than any other commercially valuable crop. In the phase of increasing water shortage, introduction of rice cultivars with less water consumption is needed. Sri Lankan traditional rice cultivars were evaluated for drought stress tolerance at the seedling stage to find out comparatively better drought resistant varieties within the gene pool. Forty three traditional rice cultivars collected from the Plant Genetic Resource Centre, Gannoruwa, Sri Lanka and known drought tolerant modern rice variety Bg 352 were used for the study. The experiment was conducted at Faculty of Agriculture, Mapalana. Dormancy broken seeds were allowed to germinate at 35°C and the germinated seeds were planted in plastic boxes (15 cm X 7.5 cm X 15 cm) filled with homogenized soil up to ¾ of the total depth according to completely randomized block design with 20 plants per replicate. Four weeks after planting water supply was restricted. Five days after 80% of the plants were completely withered plants were re watered once for recovery. Plant survival percentage was recorded 10 days after re-watering. After data recording, plants were under gone a second cycle of drought stress. Plants were re-watered five days after 80% of the rest of the plants were completely withered. Ten days after re-watering plants were evaluated by measuring green plant length, root length and dry matter weight of the recovered plants. According to the results significantly highest (p<0.05) survival percentages were observed in Mas samba, Kottamalli, Bathkiri el, Kollikuttu, Kahata samba, and Rankirial cultivars. Significantly highest root lengths were recorded in Yakada wee, Dewaradderi, Masuran, Moddai karuppan, Rathu heenati and Rathel over other accessions, while significantly highest shoot lengths were recorded in Seedevi, Kolikuttu, Sivuru wee, Rathel, Dewaradderi and Masuran. The significantly highest (p<0.05) dry shoot weight was recorded in Kollikuttu, Seedevi and Dewaredderi accessions. The significantly highest dry root weight was recorded in Kollikuttu, Kahata samba and dewaredderi accessions. These cultivars must be further studied under drought stress at other growth stages.