Abstract
Metribuzin is the only herbicide registered in Israel for postemergence weed control in tomatoes. Field observations have shown that under certain circumstances the herbicide causes severe damage to the crop, especially when applied before, during or following cloudy days; the injuries varied in severity and quite often led to crop death. The aims of this study were to examine in a controlled environment and under field conditions the response of tomato seedlings to light-stress and its interactions with the metribuzin treatment. Plants at the 4- to 5-leaf stage were grown in pots in a growth cabinet under the following conditions:25/160C day/night temperatures, 14-h photoperiod, and light intensity of 500 ktE s-lm -2.
Light-stress was imposed by exposing the plants to light intensities of 100, 250 and500 p.E s-lm -2, either for 3 days before or after metribuzin (0.35 kg/ha) application, orcontinuously for 6 days. Field trials were conducted in both seeded and a'ansplanted tomatoesgrown for processing, in a commercial field at Kibbutz Alumim (northern Negev). Lightintensity was reduced by using a plastic net which transduces 20% of the prevailing naturallight intensity. The plants were shaded either for 2 days before or after metribuzin application or continuously for 4 days. The results of both field and controlled environment experiments showed clearly that metribuzin did not injure tomato plants grown under high lightinten sities. However, plants grown for a short period under light-stress, before or after exposure to metribuzin, were injured by the herbicide. Metribuzin-treated plants which were exposed to a continuous low light intensity, rapidly developed severe necrotic spots on theleaves and died within a few days. These data confirm the early observations that meta'ibuzinselectivity in tomatoes is light-intensity dependent. Studies aimed at the elucidation of the biochemical mechanism(s) involved in this phenomenon are now in progress
Light-stress was imposed by exposing the plants to light intensities of 100, 250 and500 p.E s-lm -2, either for 3 days before or after metribuzin (0.35 kg/ha) application, orcontinuously for 6 days. Field trials were conducted in both seeded and a'ansplanted tomatoesgrown for processing, in a commercial field at Kibbutz Alumim (northern Negev). Lightintensity was reduced by using a plastic net which transduces 20% of the prevailing naturallight intensity. The plants were shaded either for 2 days before or after metribuzin application or continuously for 4 days. The results of both field and controlled environment experiments showed clearly that metribuzin did not injure tomato plants grown under high lightinten sities. However, plants grown for a short period under light-stress, before or after exposure to metribuzin, were injured by the herbicide. Metribuzin-treated plants which were exposed to a continuous low light intensity, rapidly developed severe necrotic spots on theleaves and died within a few days. These data confirm the early observations that meta'ibuzinselectivity in tomatoes is light-intensity dependent. Studies aimed at the elucidation of the biochemical mechanism(s) involved in this phenomenon are now in progress
| Original language | American English |
|---|---|
| Pages (from-to) | 352-353 |
| Journal | Phytoparasitica |
| Volume | 20 |
| State | Published - 20 Jan 1992 |