Quantitative and geoecological Study on the Spatial Diffusion of Hybrid-variety (F_1) of Vegetables

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Seed and Seedling Industry, which provides and distributes the seed to farmers, grows now to Big business. Production and marketing of new variety of Hybrid-seeds(F_1)by seed companies increased rapidly in compasating the farm seeds.The purpose of this study intend to clarify quantitatively and geoecologically the diffusion process of Hybrid-variety(F_1)of vegetables. As a results, following items make clear.Generally speaking, vegetables were received severe damage with successive cropping. Thus, vegetable farmers tend to try the cultivation of new variety of Hybrid-seeds(F_1), which show superior property of anti-disease and insects. One of these example is the Taibyo soubuto(disease-resistance F_1 variety), Aokubidaikon(radish with green head)produced by Takii, the biggest seed company in Japan.Aokubidaikon, which introduced at first in suburban area of Okayama, diffuse to Hokuriku, and Kinki, then to Shikoku and Kyushuu. After that, it diffused to Hokkaido, and Tohoku and highland regions. Lastly it cultivated in lowland Kanto district. Aokubidaikon with good taste and high marketing price, produced at many seed companies, and cultivated throughout Japan.The authur identify the multi-nuclear diffusion of Aokubidaikon through big seed companies and their tributary networks. In a area it diffused fully within 4 years. Same patterns were observed in fresh tcmhato(F_1 variety ; Momotarou)and maize(F_1 variety ; Haney bandl= and sweet corn)production.