PRELIMINARY DATA ON RELATIVE RADIORESISTANCE OF THE APEX OF THE SHOOT AND THE ROOT APEX OF BARLEY SEEDS

Journal Article · Fri Jan 01 04:00:00 EST 1960 · Genetica Agraria (Italy)

OSTI ID:4831253

Avanzi, S

Dry seeds of barley were irradiated with 3 doses of x rays and 3 doses of thermal neutrons after equilibration in an atmosphere of 60% relative humidity at 20 deg C. Seedling growth analysis was performed in water culture at 18 to 19 deg C by germinating the seeds on vertical sheets of puffed polystyrol, which allowed a very precise measurement of both shoot and root length at the eight day. For the study of chromosomal damage, the first mitotic cycle in both the shoot and the root appex was analysed. Since no statistical difference between the two classes was ascertained, the pooled data are reported in the tables. Results show that thermal neutrons are able to inhibit root growth much more strongly than shoot growth, while an almost identical degree of growth inhibition in the two organs is observed in the x-rays series. These data are in agreement with Ehrenberg and Wettstein's (1955) observations on the dry matter content of barley seedlings from seeds irradiated with x rays and fast neutrons. In order to compare the relation of chromosomal damage to growth inhibition in the shoot and in the root, for each radiation dose, an index was established by calculating the number of chromosomal breaks corresponding to a 10% inhibition. For one and the same organ, either shoot or root, the index seems to keep constant irrespective of the radiation used, the value of the shoot index being nearly four times greater than that of the root. This indicates that growth ii'hibition in the root is dependent on a consistently lower chromosomal damage as compared with shoot growth inhibition. At the highest doses of x rays and thermal neutrons used, a significantly greater number of chromosome breaks was observed in the shoot tips as coi pared with the root tip. The frequency of chromosomal breaks observed in the present experiments is clearly lower than that reported by previous investigators in irradiated barley seeds. The discrepancy might be explained by assuming a delay in mitosis initiation of cells with a higher degree of chromosomal damage. This hypothesis is being tested in a series of expcriments in progress. (auth)

• Research Organization: C.N.R.N., Rome
• NSA Number: NSA-16-001525
• OSTI ID: 4831253
• Report Number(s): CNEN-81; 0016-6685
• Journal Information: Genetica Agraria (Italy), Journal Name: Genetica Agraria (Italy) Vol. Vol: 13; ISSN GEAGA
• Country of Publication: Country unknown/Code not available
• Language: Italian

Related Subjects

BIOLOGY AND MEDICINE
CEREALS
CHROMOSOMES
FAST NEUTRONS
MEASURED VALUES
MITOSIS
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
ROOTS
SEEDS
THERMAL NEUTRONS
X RADIATION