Mr Parrikar, who is being treated at the Lilavati Hospital in Mumbai for a pancreatic ailment since February 15, would not attend the session, said BJP MP Narendra Sawaikar.
The session will begin tomorrow with Governor Mridula Sinha's address.
It was scheduled to end in mid-March, but now it would end in three days owing to Mr Parrikar's illness, Mr Lobo said.
The state budget, scheduled for February 22, will now be presented on February 20, the deputy speaker said, adding that the Business Advisory Committee will meet tomorrow afternoon to take a formal decision on cutting the session short.
"The questions, which were supposed to be discussed in the current session, would be postponed to the next session," Mr Lobo said.
Legislature sources said minister Sudin Dhavalikar of the Maharashtrawadi Gomantak Party will table the budget as Parrikar, who holds the finance portfolio, will not be able to attend the session.
"On the advice of his doctors, Chief Minister Manohar Parrikar will be continuing with the treatment for (the ailment of) pancreas in Mumbai," BJP MP from South Goa Narendra Sawaikar told reporters.
"Expert doctors are taking a good care of him," the MP said.
Main opposition Congress said it had no objection to the curtailment of the session.
"We have no objection if the Assembly is curtailed to three days as the chief minister is genuinely ill," said Leader of Opposition Chandrakant Kavlekar, who is also a member of the Business Advisory Committee.
The BJP's Goa legislature wing will be holding a special meeting tomorrow morning before the start of the session to decide who will be its leader in the House in Parrikar's absence.
Party sources said Union AYUSH Minister Shripad Naik would also attend the meeting.
Mr Parrikar underwent a check-up at the Goa Medical College Hospital on February 14 after he complained of stomach pains. The next morning, he was admitted to the Lilavati Hospital in Mumbai, where the doctors said he was suffering from a "mild pancreatitis".
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