Many economists believe that the market for wheat in the United States is an almost perfectly competitive market. If one firm discovers a technology that makes its wheat taste better and have fewer calories than all other wheat offered in the market, the wheat market would become less competitive because

the products would no longer be similar in the wheat market.

Explanation:

A perfect competition is characterized by many buyers and sellers of homogenous goods and services. Market prices are set by the forces of demand and supply. There are no barriers to entry or exit of firms into the industry.  

In the long run, firms earn zero economic profit.  If in the short run firms are earning economic profit, in the long run firms would enter into the industry. This would drive economic profit to zero.  

Also, if in the short run, firms are earning economic loss, in the long run, firms would exit the industry until economic profit falls to zero.  

the products would be different because the wheat of the firm that made the discovery would taste better and have less calories. this would make the wheat market would become less competitive because a key characteristic  of perfect competition is homogeneity of products.