放射線에 依한 水稻新系統「密陽 10號」選拔에 關한 硏究

Studies on a New Selection of Rice MILYANG #10 Induced by Radiation

The study reported here was conducted using an old leading rice variety of japonica type, called PALKWENG. This is a high-yielding variety and grown on approximately 34 percent of the total area of paddy fields in southeastern Korea. But it has long culm and hence is liable to lodge and, moreover, it is moderately susceptible to blast disease. With a hope to improve upon these shortcomings and at the same time to retain favorable characters such as high yielding ability, seed treatments were made with X-ray and thermal neutrons. The mutant variety, MILYANG #10, has apparently short culm and higher resistance to lodging. However, it has the same yield potentiality as the original variety in spite of distinct reduction of culm length and panicle length. With the increased application of nitrogen, the mutant variety produced progressively higher yield than the original variety PALKWENG. It is clearly indicated that the mutant variety MILYANG #10 has a short stature and no lodging with erect type in contrast with the medium type of the original variety, involving the possibility of inducing favorable plant type by radiation treatment. Protein content of brown rice of the mutant variety MILYANG #10 was similar to that of the original variety and increased progressively in proportion to the increase of nitrogen up to 180㎏/㏊. However, lysine content of the mutant variety MILYANG #10 was less than that of the original variety. It is suggested that mutations with regard to short culm, resistance to lodging could be induced by radiation.