Revista Brasileira De Herbicidas 2006; 5(1): 19-29
EFFECT OF GROWTH REGULATOR HERBICIDES APPLIED AT DIFFERENT STAGES OF DEVELOPMENT IN WHEAT
DOI: 10.7824/rbh.v5i1.41
The phytotoxicity level caused by hormonal herbicides that work as growth regulators in wheat plants is associated with the growth stage of the apical meristem. Applications of such herbicides when wheat plants are at double ridge and at terminal spikelet stages are very unlikely to cause damage to the ear and to the grain production. So, it is necessary to determine precisely the stages of plant development for having a secure use of these herbicides. However, small alterations may occur as a function of the environmental conditions, the mode of translocation of the herbicides, and tiller development. So, to determine the effect of the application of hormonal herbicide in two wheat cultivars (Embrapa 18 and BR 23), two field experiments were established. The application of hormonal herbicides at double ridge and at terminal spikelet stages did not cause any damage to the ears or to grain production. Applications before such stages caused deformities in the ears, flag leaves, and did no harm to grain yield. Applications after such stages reduced grain yield significantly for both cultivars, reaching the level of 60% reduction. The number of grains per ear was the component that mostly reduced grain yield for both cultivars.
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