BIO1042 Lecture Notes - Lecture 12: Serotiny, Evaporative Cooler, Ice
31 Aug 2018
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Are there constraints: most favourable t range for metabolic function of plants is 10-25 c. Fluctuations in solar radiation (heating) and advection of cold air (cooling) make t fluctuate beyond these limits. Lethal limit -> t beyond which permanent injury occurs. Structural adaptations: to avoid high light stress e. g. , reflective surfaces, leaf orientation; evaporation) will also reduce heat overload; Structural adaptations to heat stress: tolerate the heat, most (cid:858)higher(cid:859) pla(cid:374)ts are heat se(cid:374)sitive a(cid:374)d ca(cid:374)(cid:374)ot survive half a(cid:374) hour at (cid:373)ore tha(cid:374) 30- 40 c: some plants from sunny and dry habitats can survive half an hour at up to 60 70 c, biochemical changes: changes in environmental temperature induce a number of changes in cellular composition (especially lipid composition of membranes) Plant adaptations to cold stress: chilling sensitive plants: suffer lethal damage a few degrees above freezing point. Freezing sensitive plants: suffer lethal damage as soon as ice forms within tissues.
