In agricultural products, interregional competition is apt to shift to cutthroat competition, being retarded resource mobility, by competitive strategy be willing to increase market occupation percentage among producing areas. In the case of market performance going so wrong that individual farm can not reproduct under the cutthroat competition in long period, product differentiation as a competitive strategy is effective to improve the marketing performance in the marketing theory. But whether its effect can be maintained or not in initial producing area depends on whether rivals of tile producing area can adapt or not a uniform competitive strategy. If rivals can adapt it easily and, in the next, begin to enter into the market which initial producing area have achieved to the high profitable products by demand creation, initiator's actions become standard practice and the effect of product differentition will decline.
In order to maintain this effect, producing areas are willing to compete largely on the basis a combination of the geographic and technical advantage with minimum cost. In this sense, lligl~land vagetables marketing may be a representive example of maintaining the effect of product differentiation. Its marketing activity may be summarized as follows during the 1930's to 1960's.
1. The life cycle of Cabbage and Chanisse Cabbage as industry products have begun in the Meigi era and a rapid growth accured as many buyers rushed into the market in the Taisho era in response to the business upturn. So that Hokkaido and Touhoku districts could enter the market easily by the evolution of transport in spite of long distance, The producing areas near large consumer cities regressed in the result of the interregional competition.
2. Highland vegetable areas entered into the competition by adapting product differentiation in the early years of Showa era, in spite of the depressed economy that market price decline continuously. However the market price of Cabbage and Chinese Cabbage in the highland vegitable areas was high because of the off-crop season and virture of demand creation. But, as the scale of market became limited in an early stage of 1970's in spite of the demand creation by the efforts of marketing organizations, first of all, Cabbage last the market power by shift to overproduction.
3. As the producing areas in Nagano prefecture are located in a wide range from 500m to 1500m above the sea level, patterns of farm organization and outlet-season in each producing area are so various by the difference of temperature and production structure that market share from July to September for Chinese Cabbage, Tomato, Japanese radish, Lettuce and Celery was high. Diviation from the cutthroat competition within Nagano prefecture made each producing area conduct product differentiation as a competitive strategy.
4. From the 1950's to the 19607s, the exit of Miyagi prefecture from Chinese Cabbage production and Iwate prefecture from Cabbage production as the result of interregional competition between highland vegetable producing areas, so that highland vegetable areas could expand with market price going up.