THE EFFECTS OF CHRONIC GAMMA IRRADIATION ON THE APICAL MERISTEM AND BUD FORMATION OF TAXUS MEDIA

Technical Report · Mon Jan 01 04:00:00 EST 1962

OSTI ID:4772936

Miksche, J P; Sparrow, A H; Rogers, A F

Four-year-old plants of Taxus media cv. Hatfieldii were exposed to chronic gamma radiation from Co/sup 60/ at daily dose rates of 2.5, 3.75, 7.5, 15, and 30 r per 20-hour day. A dose response curve shows that dose rates as low as 3.75 r per day will reduce significantly the frequency of bud formation. At 12.5 r per day bud formation was reduced to 0.5% of the controls. Histological examination reveals that complete disorganization of the shoot apex occurs after an accumulation of 187.5 r at this low dose rate. Evidence for a pattern of differential sensitivity in the stem apex is presented. The decreasing order of radiosensitivity of the spical regions is: the apical initial layer, lateral initial layer, central mother-cell zone, transition zone, axillary cells and the pith meristem region. This pattern of radiation damage can be described as outer to inner, i.e., the outer cells are the first and the inmost cells are the last to show radiation damage. This response occurs at all dose rates studied above 2.5 r per day. A recovery mechanism frequentiy is observed at the lower dose rate (2.5 and 3.75 r per day) which leads to the occasional regeneration of a new operative apex from cells in or near the axillary regions. It is apparent from our data that T. media cv. Hatfieldii is one of the most radiosensitive of the higher plants yet studied. (auth)

• Research Organization: Brookhaven National Lab., Upton, N.Y.
• DOE Contract Number: AT(30-2)-GEN-16
• NSA Number: NSA-17-012122
• OSTI ID: 4772936
• Report Number(s): BNL-6203
• Country of Publication: United States
• Language: English

Related Subjects

BIOLOGY AND MEDICINE
BUDS
COBALT 60
CYTOLOGY
GAMMA RADIATION
PLANTS
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
RADIOSENSITIVITY
RECOVERY
TISSUES