ปริมาณโพรลีนและน้ำตาลเมื่อข้าวอยู่ในสภาวะแล้ง และการคัดเลือกข้าวทนแล้ง / วรัญญา คำปัน = Proline and sugar content in rice during drought stress condition and the selection of drought tolerance rice / Waranya Kampan
The selection of drought tolerance rice (Oryza sativa L cultivar RD23) line from somaclonal variation in tissue culture was done in vitro in two steps. First step was the selection in callus stage by subjecting the embryogenic calli to medium containing 125 grams/liter PEG6000 for one month. The survival calli were transferred onto normal medium and regenerated to complete plants. Total of 295 regenerated plants were planted in natural condition for seed collections. The second step of the selection was done at 7 day old seedling stage for 6 generations, by culturing the seedlings with 1 cm coleoptiles in nutrient solution containing 150 grams/liter PEG for one month under 1500 lux fluorescent light intensity, 12/12 hour photoperiod at 30-33 ํC. The survival plants were collected as the drought tolerant lines. The present project was the selection of the seedlings in R4 to R6 generations and the determination of the proline and sugar contents in their leaves when plants were grown in drought condition using PEG. The best drought tolerant lines from R5 and R6 generations have the survival rate of 99%. It was found that the tolerant lines accumulated higher levels of proline and sugar contents than the original RD23 line significantly under stress condition, while in the normal condition, the original RD23 line and the selected drought tolerance lines showed the same ability in proline and sugar accumulation. These data suggested that the ability in proline and sugar accumulation during drought stress were correlated to drought resistant. Other agronomic characteristics were also found from somaclonal variation, e.g. plant height, amount of tillers, heading date and seed production. The best variety selected from this experiment were TCRD23 2777-01-03-13-07 with survival rate of 99%. This line is more dwarf than original line and has the short heading date of 91 days with high yield.
