RADIATION RESPONSE OF SOAKED BARLEY SEEDS

MATERIAL AND METHODSBarley (Hordeurn uulgure, hulless variety Himalaya CI 620) seeds (caryopses) were used in this study.Spikes were threshed by hand and only unbroken, fully-formed seeds with 8 per cent moisture (attained by storing in desiccators over dry calcium chloride) were used. Soaking treatmentsThe seeds were soaked for different time intervals (0, 2, 4, 6, 8, 10, 12, 20, and 24 hours) at 20' and 30' C while different gases (nitrogen or oxygen) were continuously bubbled through the water (KAMRA et nl., 1960).Control seeds were either not soaked or soaked in oxygen-free distilled water (pH approximately 5.8), which was boiled for at least 15 minutes and then cooled with nitrogen gas bubbling through it.The gases used in these experiments were obtained from commercially filled cylinders.Analysis of these was as follows: Oxygen=99.6"/.O,+0.4 % N, Nitrogen (water pumped) =99.6 % N,+0.4 "/.0, and CO,.After soaking, the seeds were quickly dried with fan-forced air.When air dry, the seeds were placed over a saturated solution of KNO, and NH,C1 in closed containers to bring the moisture content of the seeds to approximately 15 per cent before X-radiation. X-radiation of seedsThe seeds, embryos facing up, were placed in a single layer in petri dishes.The dishes were centered on a turn table situated 42 cms.from : i beryllium window ,4.E.G.50 Machlett X-ray tube operated at 34 kv and 25 ma.A thin Saran plastic film was draped over the dishes during X-radiation to reduce moisture changes in the seeds.These conditions provided 800 r/min. of soft X-rays (unfiltered) at the surface of the seed.Since the seeds were at 15 per cent moisture and hydrated immediately after exposure, the after effects of radiation are minimized (CALDECOTT, 1955 a ) . Effects measuredThe influences of the soaking treatments on X-ray sensitivity of seeds were measured by (A) height of M, seedlings (B) frequencies of chromosomal aberrations in shoot tips of M, seeds and frequencies of seedling chlorophyll mutation in M, populations.