Mesa Petroleum Co. Chairman T. Boone Pickens Jr. today called a proposal by Unocal Corp. to increase its stock value by putting its largest oil and gas reserves into a limited partnership "too little, too late."

Pickens also said he will not be deterred in his attempt to gain control of the big oil company.

And in an appearance before Unocal shareholders, investment analysts and institutional investors, he called for stockholder approval of his proposal to adjourn, or postpone, Unocal's annual meeting to two months from its scheduled April 29 date to give him time to put his takeover strategy into place.

"I urge you all to vote for adjournment" of the meeting, Pickens told the overflow crowd of more than 300 in a ballroom of the Waldorf-Astoria Hotel. "You've got nothing to lose . . . well, maybe with one exception -- maybe the Unocal people will be a bit cool to you."

When a stockholder expressed confusion over the conflicting proposals and deadlines given by Pickens' investor group and Unocal's management, Pickens said "that's why we need the adjournment -- it will take 60 days to sort all this out."

Pickens, who heads an investor group that owns 13.6 percent of Unocal, is offering $54 a share for 51 percent of the company. Shareholders have until Friday to accept that offer. But Unocal -- the former Union Oil Co. of California -- has countered with a number of defensive tactics, including an offer under which, should Pickens succeed in acquiring 51 percent of the stock, remaining shareholders would received $72 a share for their stock. To qualify for that offer, shareholders must agree to accept it by next week. That offer has been described by analysts as a "poison pill" because it would put the company heavily into debt.

Yesterday Pickens won a critical court battle that would allow him to use the additional time profitably. The Delaware Chancery court blocked a February change in Unocal's bylaws that would have prevented Pickens from using the additional time to propose alternate slates for election to Unocal's board, or to bring other proposals before shareholders -- two options that could be helpful in Pickens' bid to take over the company.

Unocal said the ruling was a preliminary one and that it hoped to have it overturned when the case goes to trial.