Navel centre. Manipura - governs the larger vital. 
NATURE (CHANGE OF)
Regulating moral habits.  The Niyamas are a discipline of the mind by regular practices of which the highest is meditation on the divine Being, and their object is to create a sattwic calm, purity and preparation for concentration upon which the secure pursuance of the rest of the Yoga can be founded. 
The Navel centre (Nābhipadma) commanding the larger life-forces and passions and larger desire-movements is the main seat of the centralised vital consciousness (dynamic centre) which ranges from the heart level (emotional) to the centre below the navel (lower vital, sensational desire centre). 
The navel is the vital centre in the physical body but the natural seat of the vital is in the vital sheath of the subtle body, which sheath it pervades; but for action through the gross body it is centred at the navel and below it.