Periods of sensitivity to chilling in germinating cotton.

Cotton seedlings were subjected to a 96 hour chilling treatment (5 degrees or 10 degrees ) after periods of germination at 31 degrees ranging from 0 to 48 hours. Inhibition of subsequent growth at a favorable temperature by chilling was dependent on level of low temperature and stage of seedling development when chilled. Two periods of chilling hypersensitivity were observed during germination: 1) coincident with subjection of seed to a germination environment; and 2) after 18 to 30 hours of germination at 31 degrees . Subsequent growth of seedlings chilled after 12 to 18 hours or 48 hours of germination at 31 degrees was relatively unaffected. It is suggested that chilling alters specifically timed events that occur at the initiation of germination and after 18 to 30 hours of germination, and that alteration of these germination processes is visited on long term subsequent growth of the plant.