Induced mutations as a method of obtaining iron toxicity resistant and high quality rice cultivars

Summary

Iron toxicity, a nutritional disorder of rice plants typical of acid soils rich in iron oxides, has been detected as a yield reducing factor in several countries of Asia, Africa and South America. Iron toxicity in Santa Catarina, Brazil, has been responsible for yield reductions up to 80%. Soil amendments and cultural practices are not recommended to correct the problem. Tolerant or medium resistant cultivars are the best solution to be used. An attempt to obtain germplasm resistant to iron toxicity and good quality rice has been made using induced mutations. Gamma rays (120–240 Gy) were used as a physical mutagen to improve ‘EMPASC 105’, an iron susceptible and poor grain quality rice cultivar. Plants from M3 up to M6 were field screened for tolerance to iron toxicity. Agronomic characteristics, milling yield and cooking quality were also evaluated. One mutant line, SCM 7-12-4, from EMPASC 105 was selected for its medium resistance to iron toxicity, lodging resistance, high milling yield and good cooking qualities. The mutant line was evaluated in the first year, of the three-year regional trials, under six different soil and climatic conditions.