Weed Control and Physiological Responses in Poplar Plantations: Assessing Glyphosate’s Impact

The presence of weeds and changes in temperature and precipitation due to global climate change can negatively affect the growth, development, and adaptation of poplars to new places. Experiments were conducted at the Experimental Estate of the Institute of Lowland Forestry and Environment to test glyphosate’s efficacy and phytotoxicity and to assess the impact of glyphosate on physiological parameters in different stages of poplar plantations. A test with glyphosate was set up by a random block system with four replications at three localities, each characterized by different physical soil properties. Glyphosate efficacy was evaluated after 15 and 30 days, while phytotoxicity was evaluated according to the EWRC scale. Net photosynthesis (A), stomatal conductance (gs), transpiration rate (E), and intercellular CO2 concentration (Ci) were measured, and water use efficiency (WUE) was computed. Annual and perennial broadleaf weeds, grasses, and woody shrubs and bushes were identified. The dominant weed species across all poplar plantations were Solidago gigantea L., Solidago speciosa L., and Poa pratensis L. Glyphosate was highly effective against the major weed species, with the total efficacy ranging from 94.29 to 97.67%. The results showed significant differences in all observed gas exchange parameters, except for transpiration rate (E), between the different-aged poplar plantations. The younger poplars showed lower gas exchange rates in the treatment under the environmental conditions of the studied sites. Weed suppression resulted in altered microhabitats for poplar development at various ages, causing variation in the physiological parameters compared to the control.