Particle Systems wont stop/play

I'm working on a project that visualizes data from a Graphml using Force directed graph algorithm. The nodes are created with their own material and particle system. When I want to distinguish communities of nodes by a Dropdown button, the non-selected nodes need to fade. I managed to make the nodes transparent. But I cannot disable the particle system.

This is the code. The nodes are properly selected because the material loses opacity correctly. It's the particle system what I cannot disable. What do you guys think?

I'll just show the piece of code where the problem is. If you need more info, I'll update the post.

 public class DropdownComm : MonoBehaviour {
         public TextAsset xmlRawFile;
         public Dropdown dropdown;
     
         void Start () {
             commList();
 
             dropdown.onValueChanged.AddListener(delegate {
                 DropdownValueChanged(dropdown);
             });
 
         }
         public void DropdownValueChanged(Dropdown change)
         {
             foreach (Node node in StaticUtil.NodeList)
             {
                 if (!(dropdown.captionText.text == node.modularClass.ToString() || dropdown.value == 0))
                 {
                     node.GetComponent<Renderer>().material.color= new Color(1, 1, 1, 0.01f);
                     node.GetComponent<Renderer>().material.DisableKeyword("_EMISSION");
                     node.GetComponent<ParticleSystem>().Stop();
                 }
                 else
                 {
                     node.GetComponent<Renderer>().material.EnableKeyword("_EMISSION");
                     node.GetComponent<Renderer>().material.color = new Color(1, 1, 1, 1f);
                     node.GetComponent<ParticleSystem>().Play();
                 }
             }
         }
 }

Group of nodes Not selected

Group of nodes Selected (As you see, the material is transparent but the particle system is still running)

Thanks a lot!