In the chandas (Vedas) the affix ghas (iya) comes in the sense of 'season has come for it' After the verbs the word ṛtu,
This debars अण्. As अयं ते योनिरृत्वियः ॥ Here there is no Guna by 6.4.146, because by sutra (1. 4. 16), ऋतु before the affix घस् gets the designation of पद, hence the guna rule which applies to भ (1.4. 18) does not apply.,