Which beans produce more crema Arabica or Robusta ?
Is it the same for Espresso and Turkish ?
I don't know the exact answer of your question. However, I can say that whichever bean has more sugars, it should produce more crema.
I deduce this such that, crema is composed of three things: some irregularities in coffee (e.g. microscopic ground particles) to trigger bubble production, CO2 to fill into the bubble, and finally some oil that's extracted from the grounds during brewing to jail the CO2 inside.
Thus, I assume, the initial amount of hydrocarbons and correct roasting is the key factor. Note that, if you leave beans for long, the trapped CO2 will eventually be released so you cannot have proper crema with stale beans.
And about the brewing method. The crema production is, for sure, affected by the brewing method. Espresso always has more homogeneous crema as it is made by a proper machine and Turkish crema should be marbled that reflects the several phases of brewing. But, the basic bubble formation is always the same.
I hope this helps. Let's wait for another answer that may compare the crema characteristics of Arabica and Robusta.