Ammaz Omer Qureshi told the Oslo court that he had been "shocked" when he learned that his lover Yasmin Chaudhry, 28, filled the mouth the her 22-month-old daughter Huaina with chilli, and denied that he had instructed her to discipline the child.
"I thought it was hideous," he said. "It was not a punishment, but because it was funny. The baby made a face and its eyes filled with tears."
Qureshi is charged with giving Chaudhry instructions to "discipline" the child after it interrupted them during a late night chat session on MSN.
He allegedly instructed her to hold the baby by the ankles and dunk her head into a bucket of water.
After the girl was submerged the second time, she lost consciousness, after which Chaudhry called an ambulance. She died the next day in hospital.
Qureshi claimed that rather than encourage Chaudhry to do this, he had been appalled when it happened.
"I was stunned," he told the court. "'This must never do again, it is completely wrong,' I said. 'She's just a baby.'"
He has denied all the charges as "completely erroneous".
"The picture is drawn of me so far in this trial is entirely false, and I will try to show this as best I can," he told the court on Wednesday.
The duo, whose calls were monitored by the authorities, also stand accused of gagging the infant with adhesive tape, giving it cold showers and slapping it around the face.