This was weaker than the 4.5% fall forecast by City analysts for the 13 weeks to May 4.
The Bradford-based chain is planning to invest £1 billion over the next three years cutting prices and will also launch a new loyalty card scheme.
Last week, Morrisons launched an "I'm Cheaper" campaign which cut prices across 1,200 products by an average of 17%.
Morrisons chief executive Dalton Philips said: "The plans we set out at our results in March are on track.
"The reaction of our customers to the 1,200 'I'm Cheaper' price cuts we announced last week has been very positive.
"Although it will take time for their full impact to be felt, we are confident that these meaningful and permanent reductions in our prices will enable our clear points of difference to resonate strongly with consumers."
Morrisons has 63 stores in Scotland, around a third of that of market leader Tesco.
It also now behind J Sainsbury with 82 stores.
Having long been ahead of J Sainsbury in Scotland, thanks to the purchase of Safeway in 2004, Morrisons fell behind after Sainsbury's got a head start in opening convenience stores.
Four of Morrisons' Scottish stores are M Local convenience outlets. The group plans to double the number of these to 200 UK-wide this year, although most will be in the south of England, where Morrisons has little presence.
Clive Black, analyst at Shore Capital, said: "Morrison's pricing initiatives can be expected to 'deflate' its top-line to some degree, a process that we expect to increasingly to see across the trade as pricing activities of various sorts comes to into play. Quite what deflation turned out to be for Morrison's in Q1 remains to be seen but it is clear that the overall top-line is shrinking apace and against very favourable comparatives too."
Morrisons maintained its guidance towards underlying full-year profit before tax range of £325m to £375m
Britain's fourth biggest supermarket posted a £176m annual loss in March and issued a profits warning, sending its shares tumbling.
Yesterday, the stock regained some poise to close up 8.1p or 4.3% at 198.9p.