| Popis: |
Different nursery beds of 1-year-old jack and loblolly pines, 2-year-old white pine, and 3-year-old red pine were sprayed in September, October, and March with naphthaleneacetic acid in concentrations of 200, 400, 600, 800, or 1000 mg. per liter of 1% Dowax emulsion. Other blocks of seedlings were toppruned at such a height as to remove most of the terminal buds and about 50% of the foliar surface. Chief results were: 1. Seedlings of white pine and red pine were not perceptibly affected by growth-regulator treatments. An explanation for this failure to respond is offered. 2. Jack pine seedlings sprayed in September with 800 and 1000 mg./l. were inhibited to the extent that on May 1 they had produced only 42% as much new shoot growth as controls. October and March sprayings, and September sprayings of lower than 800 mg./l., produced no discernible effects. 3. Loblolly pine seedlings sprayed in September responded to all concentrations above 200 mg./l., the degree of inhibition increasing with concentration... |
