Persistence of 2,4-D Stimulus in Cotton Plants with Reference to Its Transmission to the Seed

Abstract

Sixty-day-old cotton plants were treated with the Na salt of 2,4-D in acid-equivalent amts. of 0.1, 1 or 10 mg. to detn. the effect of large amts. of 2,4-D on translocation of the stimulus into seed embryos formed prior to appln. and on its persistence within the plant as shown by injury to embryos subsequently formed. Cotton plants at the developmental stages of seedling, floral primordia, and anthesis were treated with 2,4-D acid-equivalent amts. of 0.01 or 0.04 mg. to detn. effect of plant age on transmission of the 2,4-D stimulus into seeds developed subsequent to the appln. All seeds from bolls (1-15 days old) set prior to treatment with 0.1 mg. or 1.0 mg. produced seedlings which exhibited symptoms of 2,4-D injury. Bolls in the 10 mg. series failed to develop. Some seedlings from seeds produced in bolls initiated 8 wks. after appln. in the 0.1-, 1.0-, and 10.0-mg. series exhibited 2,4-D injury. Seeds formed 14 weeks after appln. did not yield malformed seedlings in any series. Plants treated with 0.01 or 0.04 mg. of 2,4-D at the seedling or floral primordia stage showed no significant transmission of the stimulus into the seed embryos. Seed embryos formed in bolls initiated in a 5-wk. period subsequent to appln. at the anthesis stage showed significant 2,4-D injury.