Abstract

GALON, L. et al. Influence of herbicides on the photosynthetic activity of sugarcane genotypes. Planta daninha [online]. 2010, vol.28, n.3, pp. 591-597. ISSN 0100-8358.  http://dx.doi.org/10.1590/S0100-83582010000300016.

The objective of this study was to evaluate the effects of herbicides on the photosynthetic activity of sugarcane genotypes, under field conditions. An experiment was arranged in a randomized block design with split-plots and four replications.The following herbicides were allocated in the main plot: ametryn (2.000 g ha^-1), trifloxysulfuron-sodium (22.5 g ha^-1), mixture of ametryn + trifloxysulfuron-sodium (1,463 + 37 g ha^-1) and a hoed treatment without herbicide. In the subplots, six sugarcane genotypes (RB72454, RB835486, RB855113, RB867515, RB947520 and SP80-1816) were allocated. At 70 days after planting and 15 days after herbicide application, evaluations of stomatal gas flow rate (U - μmol s^-1), sub-stomatal CO₂ concentration (Ci - μmol mol^-1) , photosynthetic rate (A - μmol m^-2 s^-1) and CO₂ consumed (ΔC - μmol mol^-1) were conducted on the first plant leaf with visible ligule. Ametryn caused significant damage to the physiological characteristics related to sugarcane photosynthetic activity compared to the trifloxysulfuron-sodium. Sugarcane genotypes show differential sensitivity to herbicide treatments, with the most susceptible to ametryn being RB835486 and RB867515, and the most tolerant RB72454, RB855113, RB947520, SP80-1816 and RB867515. Regarding the evaluated characteristics, there was no difference between the genotypes treated with trifloxysulfuron- sodium and the mixture of ametryn + trifloxysulfuron-sodium.

Keywords : Saccharum spp.; ametryn; trifloxysulfuron-sodium; IRGA.