Articles
OSMOTIC CONDITIONING OF SEEDS: PHYSIOLOGICAL AND BIOCHEMICAL CHANGES
Osmoconditioning of seeds such as lettuce, celery, parsley, onion, soybean, pea and sweet corn with polyethylene glycol offers an effective means for reducing the time required for germination and seedling emergence and for establishing a uniform seedling stand, particularly at sub-optimal temperatures (e.g., 8°, 10°, 10°–15°C). Inclusion of seed protectants and growth regulators in polyethylene glycol solution during the conditioning process aids further the performance of such seeds as lettuce, celery, parsley, legumes and cereals.
Biochemical studies show that osmoconditioning of lettuce seeds reduces the time of imbibition required for the onset of RNA and protein synthesis and polyribosome formation and increases the total amount of RNA and protein synthesized.
The activity of such enzymes as acid phosphatase and esterase increases by osmoconditioning.
The treatment causes qualitative changes in soluble proteins, acid phosphatases, esterases and 3-phosphogly ceraldehyde dehydrogenases as revealed by electrophoresis on polyacrylamide gels.
Osmoconditioning leads to complete disappearance of abscisic acid from lettuce seeds.
The data presented here suggest that increased synthesis of RNA, proteins and enzymes in treated seeds may be due to removal of certain inhibiting factors such as abscisic acid and/or to production of promotive factors.
The mobilization of storage materials such as sugars, fats and proteins by activation or de novo synthesis of key enzymes may underlie the mechanism of osmoconditioning.