I've been listening to some sarod recently, and what struck me is how much more rhythmic even the alaap of sarod performances tends to be than vocal or other instrumental performances. This seems to be because of certain stylistic conventions -- sarod players seem to strum certain base (fundamental? not wise in the music-theoretic ways) notes almost simultaneously with the melodic lines, which yields not only to a very virtuosic effect, but also much more rhythmically focused music (even without, say, a tabla). See, for example, Ustad Amjad Ali Khan's Raga Bageshwari (specifically see 8:00 or 17:00-24:00) or Ustad Ali Akbar Khan's Manjh Khamaj.
I was wondering if there's a name for this technique, and more importantly whether this is simply the usual method of playing sarod or whether this is a style unique to a specific gharana, or to khayal, etc.