2011 年 21 巻 4 号 p. 268-271
The ‘Hakuto’ (white peach) produced in Okayama prefecture is very famous in Japan due to its distinctive quality. The name of ‘Hakuto’ is not only from its white color of flesh or skin but also expressing the whole images of white peach. The original variety ‘Hakuto’ was derived from growing seedlings of Chinese varieties in Meiji period. The debut of this cultivar might be one of the main reasons why the white peach production in Okayama became famous in Japan. In addition to that, the character of the farmers with challenging spirit as well as the suitable climate and soil condition made it possible to raise Okayama as a main white peach producing area.
It is known that the cultivation technique such as fruit bagging and pruning has been changed in Okayama in peach production, however; the biggest change was brought by the utilization of nondestructive sugar content measurement by using near-infrared absorbance method. It has changed into the quality valuing in recent years, though only outside looking were valued a lot before. As peach grower had to pay much more attention to the internal quality, it was required to build a new standard on the growth and nutritional status of peach tree and soil condition. After the investigation mainly done by the research institute for agriculture, it was succeed to prepare the new standard and to reflect the data measured by the nondestructive sugar content measurement for improving through the correction of cultivation condition.
The June drop (physiological fruit drop) is serious problem in the varieties such as ‘Hakuto’ and ‘Shimizuhakuto’. It is from the sprit pit due to the excessive uptake of water from root system. To control it, the mulching by plastic film under the canopy is tested and turned out be effective. Besides that, a breeding method has been taken to obtain the better quality and lower June drop ratio. The new variety ‘Okayamayumehakuto’, for example, is the best result of breeding which promises the higher sugar content of mature fruit and the fewer June drop ratio than ‘Shimizuhakuto’.
Further endeavor should be taken to keep ‘Hakuto’ as a leading commodity in Okayama toward the future. All we need to do is to keep producing the peach with an outstanding quality by succeeding and improving the technique from the predecessors.