A bimodal germination response to temperature in cocklebur seeds. I. Cyanide‐sensitive and cyanide‐resistant respirations

摘要: Abstract. Pre-imbibed cocklebur (Xanthium penn-sylvanicum Wallr.) seeds displayed bimodal germination-temperature responses with two optima at 8 and 33° C. Such germination occurred subsequent to respiration-temperature upsurges lower higher temperature regions. At temperatures, respired predominantly through a cyanide-sensitive cytochrome pathway. A rise in resulted marked increase flux via an alternative pathway, propyl gallate- (PG) or benzohydroxamic-acid- (BHAM) sensitive thus resulting the ratio of this pathway relative Both increased capacity for were obtained when pre-imbibed exposed either 33°C short period. The effects low reduced as exposure time was prolonged beyond 3d, reduction germination. Neither PG nor BHAM had inhibitory effect on chilling-induced germination, but germination-stimulating high temperatures less pronounced presence BHAM. other hand, KCN NaN3 ineffective or, rather, slightly inhibited It concluded that exert their by essentially similar manner which increases fluxes both and, especially, result, raises latter former.