Weedy rice (Oryza sativa L.) is one of the most problematic weeds of rice cultivation worldwide. An effective control technique is the application of the stale seedbed which consists of preparing the field early in the season and then flooding it to stimulate weed germination. After the seedlings have emerged, they are destroyed by using herbicides such as glyphosate. The efficacy of this technique could be affected by variability in weedy rice sensitivity to the herbicide applied. The aim of the study was to evaluate the sensitivity to glyphosate of 90 weedy rice populations, collected in fields located in the major Italian rice cultivation area, and selected on the basis of their phenotypic features.The experiment was carried out in 2011 and 2012 in greenhouse by seeding weedy rice in alveolar trays (3 seeds/alveolus) with 3 replications. Weedy rice seedlings (3-leaf stage) were sprayed with glyphosate at the field rate (1400 g a.s./ha). Shoot biomass was assessed 15 days after treatment and data were expressed as percent of weight reduction of untreated plants. Visual rating of weed control was also recorded. The results showed that the tested populations had a variable level of sensitivity towards glyphosate, resulting in a visual weed control always exceeding 69%. Weedy rice biomass reduction ranged between 35% and 86%. In spite of this large variability, the sensitivity to glyphosate did not vary significantly among awnless, awned and mucronate populations and was not correlated with hull coloration.
Glyphosate sensitivity in Italian weedy rice
FOGLIATTO, SILVIA;VIDOTTO, Francesco;ANDRES, ANDRE;FERRERO, Aldo
2013-01-01
Abstract
Weedy rice (Oryza sativa L.) is one of the most problematic weeds of rice cultivation worldwide. An effective control technique is the application of the stale seedbed which consists of preparing the field early in the season and then flooding it to stimulate weed germination. After the seedlings have emerged, they are destroyed by using herbicides such as glyphosate. The efficacy of this technique could be affected by variability in weedy rice sensitivity to the herbicide applied. The aim of the study was to evaluate the sensitivity to glyphosate of 90 weedy rice populations, collected in fields located in the major Italian rice cultivation area, and selected on the basis of their phenotypic features.The experiment was carried out in 2011 and 2012 in greenhouse by seeding weedy rice in alveolar trays (3 seeds/alveolus) with 3 replications. Weedy rice seedlings (3-leaf stage) were sprayed with glyphosate at the field rate (1400 g a.s./ha). Shoot biomass was assessed 15 days after treatment and data were expressed as percent of weight reduction of untreated plants. Visual rating of weed control was also recorded. The results showed that the tested populations had a variable level of sensitivity towards glyphosate, resulting in a visual weed control always exceeding 69%. Weedy rice biomass reduction ranged between 35% and 86%. In spite of this large variability, the sensitivity to glyphosate did not vary significantly among awnless, awned and mucronate populations and was not correlated with hull coloration.
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