1. 1) Garner, W. W. and Allard, H. A., Further studies in photoperiodism, the response of plants to relative length of day and night. J. Agric. Research, 23, 871 (1923).
2. .
1943.
3. 3) Gregory, L., Some factors for tuberization in the potato plant. Amer. J. Bot., 43, 281-288 (1956).
4. 4) Chapman, H. W., Tuberization in the potato plant. Physiol. Plant, 11, 215-224 (1958).
5. 5) Koda, Y. and Okazawa, Y., Detection of Potato Tuber-Inducing Activity in Potato Leaves and Old Tubers. Plant Cell Physiol., 29, 969-974 (1988).