Evaluating the effect of glyphosate on the growth and photosynthetic characteristics of <italic>Rosa roxburghii</italic> seedlings on Yunnan Guizhou Plateau.

Taking 4-year-old <italic>Rosa roxburghii</italic> seedlings as the research object, the effects of glyphosate in orchards on the nutritional growth, leaf structure, photosynthetic characteristics, fluorescence characteristics and fruits were studied by soil application of glyphosate. The results show that new leaf morphology was deformed and yellowed, stomatal density and stomatal index were significantly decreased, MDA content was increased, and SOD, CAT and LOX activities were significantly increased after 15 days of glyphosate treatment. <italic>P</italic>N, <italic>G</italic>S, <italic>F</italic>v/<italic>F</italic>m, ABS/RC, TRo/RC, ETo/RC and DIo/RC of new leaves were significantly reduced with increasing glyphosate concentrations. New leaf photosynthetic organ development and photosynthetic pigment accumulation were affected under glyphosate, resulting in inhibition of photosynthesis, leading to a decrease in photosynthetic rate and ultimately affecting fruit development. The protective enzyme activity of new leaves was activated after glyphosate spraying, thereby enhancing its adaptability to adversity, while damage to PSII was reduced by increasing the energy dissipated through heat dissipation and reducing excess excitation energy under low dose glyphosate treatment. The adaptability of new leaf cell membranes could be improved, and thus the damage caused by glyphosate was mitigated in <italic>Rosa roxburghii</italic> orchards when glyphosate was applied at concentrations of less than 1.84 kg.ha-1. [ABSTRACT FROM AUTHOR]