Alternative pathway respiration in vivo of potato tuber callus grown at various temperatures

During incubation of potato tuber discs (Solanum tuberosum L. cv. Bintje) on a callus‐inducing medium at 28°C, a high capacity of in vivo alternative pathway respiration develops (75% of uninhibited respiration is azide‐resistant). When callus induction takes place at 8°C, only 45% of respiration is resistant to azide. In the lag phase of growth the activity of alternative pathway is low. during the exponential growth phase the activity reaches its maximal rate. This in vivo activity is of the same size at both culture temperatures. As a consequence a greater part of alternative pathway capacity is operating in uninhibited respiration during growth at low temperatures.