I made simple particle system (source, gravity, collision, color) and faced with a problem: Color node have no influence on alpha of particles. I tried to use Param and Ramp tab in Alpha tab, but it don't work. Param and Ramp tab in color tab works normally. This also applies to other projects with particles that I have tried to make or open, in particular, project from lesson #13 from Introduction to dynamics in Houdini by Digital Tutors.
What is the problem? (houdini 10.0.528)

To verify that the POP is correctly setting the Alpha attribute, you can use the RMB menu to open a spreadsheet and examine the attributes. Most likely the attribute is there, but the viewport will not take the Alpha attribute into account unless there is also a Cd (color) attribute present on the geometry.

Thank you! Spreadsheet displays that alpha and Cd are present. Moreover, if I turn viewport to sprite mode it displays alpha. When I add Sprite node to Color node it works normally. One wonder why in the above lesson did not need to switch viewport to sprite mode (they used Houdini 9).