Physiological evaluation of tolerance of elite rice breeding lines for iron (Fe) toxicity using Fe-excluding power
2004
Rodriguez, R.C. | Nozoe, T.,International Rice Reseach Inst., Los Banos, 4030 Laguna (Philippines). Crop, Soil and Water Sciences Div. | Yanagihara, S. | Fukuta, Y. | Agbisit, R.
Rice varieties differ in their reaction to Fe toxicity. The Fe-excluding power of the roots is a mechanism by which plants may overcome Fe toxicity. It is determined by exposing 35 d-old plants grown in solution culture to FeSO4 solution for 24 h and measuring the amount of Fe absorbed and the amount of remaining solution. Two near-isogenic lines (NILs) of IR64 (FTB7-3 and FTB11-5) and two elite breeding lines (Fe0013 and Fe0014) with different Fe-excluding powers were selected for evaluation during 2003 wet season in San Dionisio, Iloilo [Philippines], in a rainfed site known for its acidic soil and high Fe toxicity. The Fe-excluding powers of the entires are as follows: Fe0013 (48 percent), FTB11-5 (33 percent) Fe0014 (20 percent), FTB73 (2 percent), check variety (IR64) (35 percent). Experimental results revealed that the high Fe content and low soil and water pH at the site caused the significant reduction in leaf area index, dry matter production, tiller number, root dry weight, plant height and grain yield of the five entries. Among the entries, Fe0013 and Fe0014 showed better visual Fe tolerance ratings until flowering and maturity. IR64 and the two NILs were susceptible to high Fe toxicity. On the basis of better plant growth and Fe tolerance, Fe0013 and Fe0014 were the best performers. Their differences in Fe-excluding power, however, suggests that for Fe0014, Fe-excluding power may not be the tolerance mechanism involved. Further studies are needed to better understand the tolerance mechanisms of promising elite lines and to assists the breeders in developing better Fe-tolerant rice varieties.
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