Studies on Yield Determination of Taro Plant.

There are few data about the growth and development of taro plant, and it has poor yields in comparison with ather corms, For the experiment, 'Ishikawawase' were used. About its environmental facters, especially the photoperiod, the soil water, the soil temperature, and its growing behavior to get the fundamental data to improve its dry matter production, from the field of physiological and ecological vision. The examination results are as follows. 1. The leaf emergence rate of main culm increases under the short day treatment in the latter of its growth period, and decreases under little soil water and the high or cool temperature treatment. 2. The growing rate of the leaf area and the length of petiole increases under the long day treatment, and decreases under the short day treatment, the dry soil, the high degree of humidity, and the high or cool temperature treatment. 3. The life duration of the leaf blade becomes short under the short day rreatment and high or cool soil temperature treatment. 4. The best atmospheric temperature for photosynthesis is from 22゜c to 25゜c, and the best soil temperature is from 20゜c to 30゜c. 5. The photosynthetic capacity increases in proportion to its leaf area, and the photosynthetic rate increases in proportion to the density of nitrogen in the leaf blade. 6. The percentage of dry matter of corm becomes high in proportion to bearing and auxesis of the splitting from in mid-July, and dry matter partitioning ratio toward corm becomes high remarkably in the latter of the growth period. 7. The best soil water content (field capacity) for dry matter production is difforent on the ground and under the ground, the former is 60% and the latter is 80%. 8. The high soil temperature promotes the growth just only in early day of the vegetation period, and the growth is delayed under the cool soil tempereature from first to last.