Influence of the air and the soil temperature on the growth of potato tubers (Preliminary report)

Abstract

In order to obtain some knowledges on the influence of air and soil temperatures upon the growth, tuberization and starch accumulation in the tubers of potato plants, the present investigations were carried out using Early Rode variety, and their results are summerized as follows : 1) Under high air temperature (mean 21.4°C) there took place a marked top elongation with relatively poor leaf-stem ratio. Therefore the top growth was not normal resulting in distinct retardation of tuber development. The high temperature of either air or soil should delay the differentiation of tubers. 2) Under moderate air temperature (mean 17-19°C), the treatment with low soil temperature did not increase the tuber growth and starch content, however, the same treatment under high air temperature, partially reduced the retarding effect due to the high air temperature. 3) Even under the moderate air temperature, when the soil temperature rose to about 23-24°C, the starch content of tubers decreased, and at about 27-30°C, the secondary-growth of tubers was induced and the tuber growth was highly prevented. 4) The alternation of the soil temperature from high to low, or low to high resp. during the period of tuber thickening gave no significant effect upon the tuber growth. 5) The tuber yield fluctuation in soil temperature so far as it was within the range that does not prevent the tuber, growth. 6) The tubers treated with soil temperature at their earlier stage of growth revealed little or no pigmentation of tuber skin.