Effect of proton ion and gamma-ray irradiation on radiosensitivity of M1 seedlings in Brassica napus

Effect of proton ion and gamma-ray irradiation on radiosensitivity of M1 seedlings in Brassica napus

2007

A:PS

This experiment was carried out to increase the cultivation area of rape (Brassica napus) and develop this plant as a biodiesel so dry seeds of 3 cultivars Naehan, Hanla and Tammi were irradiated with proton ion and gamma ray at range of 0 to 2000 Gy and the radiosensitivity of the M1 generation were investigated. The germination rate was more than 95.3% regardless of radiation source, dosage and cultivar. The emergence rate at 6 days after sowing decreased with increasing irradiation dosage, but emergence at 12 days was more than 91.7%. Survival rate under 1000 Gy and below at 7 weeks after sowing were similar but remarkably reduced by 38.1-84.1% under 1500 Gy and 2000 Gy. The length and area of cotyledon, and hypocotyl length in all 3 cultivars were significantly reduced with increasing dosage of proton ion and gamma-ray irradiation. Sensitivity responses were observed in following order: Naehan, Hanla and Tammi. On the other hand, the length and area of cotyledon were increased more at 100-200 Gy under proton ion treatment than the control in Tammi. Chlorophyll content, number of true leaves and leaf area at one month after sowing decreased with increasing radiation dosage regardless of radiation source. Cotyledons at one month after sowing showed chlorosis under treatments of more than 800 Gy, and chlorosis was particularly serious in Tammi. The number of true leaves was approximately 2.3 in the control and under low level of dosage, but cotyledon did not grow under 1500 Gy and above. The dosage in which leaf area was reduced to 50% compared to that of control was 800 Gy in Naehan, and 1500 Gy in Tammi and Hanla under proton ion treatment; and 400 Gy in Tammi, and 1500 Gy in both Naehan and Hanla, under gamma-ray. The fresh weight of tops than root was more sensitive to irradiation, and dosages in which fresh weight was reduced to 50% compared to that of control were: 600 Gy in Naehan, and 1000 Gy in both Tammi and Hanla. The growth of seedling decreased by over 50% under treatments higher than 1000 Gy. Results indicate that the proper dosage for mutation breeding in rape was 1000 Gy and below.

v.25(1):17-23, KOREAN JOURNAL OF HORTICULTURAL SCIENCE & TECHNOLOGY

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