Germination and Viability of Seeds from 2,4-D Treated Sunflowers and Ragweeds

Abstract

Low dosages of 2,4-D increase yields of sunflower seeds but not seeds of ragweeds. This study was conducted to determine germination and viability of seeds produced by sunflowers and ragweeds exposed to low dosages of 2,4-D. Fewer seeds from sunflower plants dosed with 100 ppm of 2,4-D germinated than from plants dosed with 50 ppm or no 2,4-D. No differences were detected in germination rates of ragweed seeds from treated or untreated plants. No treatment-related effects were detected on seed viability. Pletscher and Robel (1979) reported increased yields of sunflower (Helianthus annuus) but not ragweed (Ambrosia artemnisiifolia) seeds after spraying plants with low dosages of 2,4-D. They theorized that low dosages of synthetic auxins might increase food supplies for granivores but they did not determine germination rates and viability of seeds produced by the plants they sprayed. This report presents results of germination and viability tests on seeds collected during the Pletscher and Robel (1979) study. MATERIALS AND METHODS The study of Pletscher and Robel (1979) was conducted on the Fort Riley Military Reservation in northeastern Kansas. Johnson and Robel (1968) described important plant associations on the Fort. We used ragweed and sunflower seeds produced on Pletscher and Robel's untreated (control) and treated plots, collected in the fall of 1976, stored frozen until April 1979, then removed from the freezer and held at room temperature until germination and viability tests were initiated in October 1979. Treatments were 50 and 100 ppm of 2,4-D sprayed at 0. 1 liter/m2 (approximately 0.05 and 0.10 kg acid equivalent per hectare or 10 to 20% of the recommended apI Contribution 80-414-J, Division of Biology, Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas 66506. The study was financed by the Kansas Agricultural Experiment Station. This content downloaded from 157.55.39.136 on Thu, 19 May 2016 04:55:53 UTC All use subject to http://about.jstor.org/terms VOLUME 84, NUMBER 4 217 Table 1. Germination rates and viability of sunflower and ragweed seeds produced by 2,4-D treated plants.