Leaf Abscission in Cotton. IV. Effects of a Natural Promoter and Amino Acids on Abscission in Cotyledonary Node Explants

1. The presence of a natural abscission-promoting factor(s) in pulvinoids of debladed cotton leaves was demonstrated. 2. The unidentified thermostable factor was extractable with ether and ethanol but not with water. It was slightly inhibitory to elongation of Avena coleoptile sections and gave a negative Salkowski reaction. 3. Although not identified, the abscission factor is probably a growth inhibitor similar to others reported in the literature. 4. Amino acids were found to be poor promoters of abscission.