Vienna — Two developments point to a potentially critical period ahead for Poland's government, and call into question its ability to contain popular reaction in the coming months:
* Lech Walesa has announced he plans to lay flowers and speak Dec. 16 at the Gdansk memorial for the shooting of workers in the 1970 food-price riots.
* Trybuna Ludu, Poland's Communist Party newspaper, candidly revealed Monday that 77 percent of Poles interviewed expressed hostility to the price increases slated for Jan. 1.
The authorities still disdain giving Mr. Walesa any part in the ''consultation'' process they offered Poles a fortnight ago. The public was asked to make suggestions about how to handle the price rises, which will be 15 percent and more.
But to the worker rank and file, the ''former chairman'' of ''a former trade union'' is still the leader of the unprecedented East-bloc labor movement.
A year ago Walesa planned a speech for the 1970 commemoration. It was to call for an ''open'' rather than underground pursuit of Solidarity's original aims, and for a conciliatory dialogue with the government.
Gen. Wojciech Jaruzelski's regime was on the verge of ending martial law, but decided to take no chances with Walesa. Instead it decided to take him out of circulation - in police custody, though not in jail - until after the time of his planned appearance at the shipyard memorial.
The official attitude on him has not changed. In the last few months, Walesa has felt compelled to shift his position from dialogue to open support - for the first time in a year - of underground calls for direct action to protest the price rises and to demand higher wages before they come into effect.
So far not even Walesa's identification with Solidarity's underground has seemed to elicit any overt response. But can the government be sure that in six weeks' time the ''big protest actions'' and strikes forecasted by the underground union will not come about?
In mid-November the authorities opened the price issue to public discussion, with phone-in facilities to radio and television. Both held strong, adverse opinions. They also claimed that some Poles understand why the increases are unavoidable.
But the admission by the party's own newspaper that three out of four people polled are against the price increases is the hard reality that Jaruzelski still faces.