WELLINGTON, New Zealand (AP) ¿ China's seed and agriculture researcher Agria Corp. is to buy a 13 percent stake in New Zealand's largest rural services business, PGG Wrightson, with the aim of becoming a cornerstone shareholder, the companies said Friday. The two companies signed an agreement for Agria to invest 36 million New Zealand dollars ($27 million) in PGG Wrightson through a share placement and to form a strategic partnership. Agria's investment was conditional on it being satisfied that sufficient funds would be raised through equity raising and other sources for PGG Wrightson to repay a $149 million debt facility by March 31. A China-based agricultural solutions provider listed on the New York Stock Exchange, Agria is engaged in research and development, production and sale of upstream agricultural products. The companies said the partnership would cooperate on development and international commercialization of seed cultivars, development of livestock demand in China, exports of livestock from New Zealand, Australia, South America and other markets, and on establishing livestock trading systems in China using PGG Wrightson's auction expertise.