The influence of pruning, topping, and defoliation on the morphology of cannabis

"Pruning techniques play a crucial role in cannabis cultivation systems, offering potential benefits for plant design. However, scientific understanding of the effects of pruning on plant architecture remains limited." Therefore, a recent study aimed to investigate the effects of different pruning techniques on the plant architecture of cannabis.

The experiment
A greenhouse experiment was conducted at the University of Hohenheim, Germany, from January to April 2022. Cannabis strain Canada (KAN) was grown, with five pruning treatments (C, P, P+T, DL, DH) being applied in three replicates. The pruning treatments that were applied: control (C), pruning (P), pruning + topping (P+T), low defoliation (DL), and high defoliation (DH).

According to the researchers, height response to different treatments is critical in indoor cultivation due to limited resources and the need for canopy uniformity. "Controlling plant height is essential to avoid burning plants with grow lights and to ensure efficient light distribution. Canopy uniformity plays an important role in indoor environments as it helps to prevent mutual shading and maintain uniform light exposure."

Of the five treatments, control (C) plants had the tallest height, followed by low defoliation (DL) and high defoliation (DH), while pruning (P) and pruning with topping (P+T) resulted in progressively shorter heights. "Topping, in particular, proved to be highly effective in reducing plant height while promoting the development of equally long branches," the researchers add.

"In our study, topping not only reduced plant height but also led to a substantial increase in mean branch length by nearly 100%. The combination of reduced height and equally long branches makes topped plants an ideal choice for indoor growers, as they provide
more well-positioned branches than untopped plants. Therefore,
topping as a height control technique can contribute to achieving a more uniform canopy, optimize light distribution, and ensure the overall success of indoor cultivation practices," the researchers conclude.

To read the complete study, go to www.researchgate.net