In a pot culture experiment, gibbereliins/abscisic acid GA/ABA ratio in shoots of three high tern perature adapted potato genotypes (Desiree, LT-2 and DTO-33) was found to be low (0.02 – 0.10) when grown under high day/night temperature (36/25°C) during the period of tuber induction. Under similar conditions, the ratio was markedly higher (0.21 – 0.24) in heat sensitive genotypes (Kufri Jyoti and Kufri Chandramukhi). GA-like substances decreased in shoots and tended to accumulate in the roots of heat sensitive genotypes during tuber bulking stage, whereas a substantial amount of GA like substances remained in the shoots of heat tolerant genotypes. It is suggested that tuberization at high temperature may be related with high levels of ABA like inhibitors in the shoots during tuber induction followed by low GA-like activity in roots at later stage of tuber growth.
