%0 Book %1 SakaiLarcher_87 %A Sakai, A. %A Larcher, R. %D 1987 %E Billings, W. D. %E Golley, F. %E Lange, O. L. %E Olson, J. S. %E Remmert, H. %I Springer %K bibtex-import citeulikeExport %T Frost survival of plants - responses and adaptation to freezing stress

@book{SakaiLarcher_87, added-at = {2019-03-31T01:14:40.000+0100}, author = {Sakai, A. and Larcher, R.}, biburl = {https://www.bibsonomy.org/bibtex/261e269d4576d456094ad67090090d67d/dianella}, citeulike-article-id = {1524007}, comment = {(private-note)Call number:qk756.s235 The Freezing Process in PLants: "The number and size of crystallisation units depend on the rate of crystal growth and the rate of nucleation. Both of these are effected by cooling rate and concentration of the medium" in pure water the freezing exotherm goes sharply up to 0oC, and stays there until all the ice is frozen, then drops off. in a solution the exotherm peak is more rounded as it reaches the top, the top (the freezing point) is lower than 0oC. It's curvy because as ice forms, the freezing point gets further and further depressed in the remaining solution. At the eutectic point, hydrated crystals form. "cooling suddenly to below the eutectic point causes amorphous solidification of the solution becoming a glass doesn't protect you. On thawing, glass crystallises. migratory recrystallisation can occur. Ice microscopy in cells references therein glaciers references therein microcinematography references therein "frost plasmolysis" slightly supercooled water freezes in discoid and fern-shaped crystals "Intracellular freezing is lethal as a rule because of destruction of biomembranes (they quote maximov 1914) PLant cells can survive intracellular freezing if the crystals are small enough and melt before they can grow too much but this only happens if cooling is ultrarapid. Hatakeyama and Kato 1965 " The ice grew at the expense of water migrating from the unfrozen roots" cites LT50 and LT0 and LT100 of various mountain plants pp219-221: temperate ericaceous mountain shrubs leaves: -25 to -70 TYPES OF EXOTHERMS AND FREEZING PATTERNS Continuous freezing happens in uniform tissues. There's a broad exotherm. Sequential freezing occurs in non-uniform tissues eg. vessels freeze first Steep but very brief fise in temperature as vessels freeze, then a broader exotherm as cells freeze Discontinuous freezing when part of the tissue exhibits a deep supercooling but the other parts don't 2 exotherms Tsc = the lowest temperature before ice forms in a plant tissue Modlibowska '56 divides freezing responses into "transient" supercooling and "persistent" supercooling ( when even at ver low temperatures, things don't freeze) Effective supercooling is more likely to occur if 1. small cell size 2 little space for intercellular nucleation 3 low water content 4 no internal nucleators 5 barriers against external nucleators 6. dispersion of cells into independently freezing units 7 antinucleator substances (Levitt 1980, Hong and Sucoff 1980, Ishikawa 1984) 8. whether the plant sufface is wet or dry Polylepis sericea (trop alp) has persistent supercooling (-10 to -12) and has densely packed small cells (Larcher '75, larcher and wagner 76, goldstein et al 1985, rada et al 1985a) Bamboo supercools (cryomicroscopic studies) "compartments of tissue bordered by longitudinal and transverse veins froze at random" froze at -20 to -24 ishikawa 1984 the exotherm was gradual because of this. "presumably the structure of palm and bamboo leaves might be responsible for the maintenance of such a high supercooling ability" @Q: is a P. foliosa leaf more compartmentalised than P. hothamensis? Are the veins more likely to be connected to both leaf sides with fibres? In trees ice normally forms in the xylem first (high freezing point, dilute sap) zimmmermann 1964 but "the xylem fraction of supercooled water us found to be very stable to -35oC (george and Burke 19777a) but they're probably talking about the xylem parenchyma of trees. FREEZING DAMAGE 1. Non-equilibrium freezing of sensitive cells semipermeability of membranes lost 2. following dehydration of freezing-tolerant cells occurs at lower temperatures determined by dehydration tolerance phospholipid degradation (Rodinov et al '73, wilson and Rhine 76, Horvath 79) affects active transport properties (palta et al 82) FROST MITIGATION Nyctinasty eg bean insulation eg tussocks heat storage eg cacti heat uptake from surrounds (conduction fron soil) eg rosettes, prostrates, cushions heat production during freezing (of leaf bases, sheaths, attached litter) eg. cushion plants metabolic thermogenesis eg. Araceae FROST EXCLUSION hiding under snow/soil/water WINTER DESSICCATION is also a problem. Transpiration doesn't stop entirely, and root water uptake can be severely diminished. (eg due to membrane changes and or soil freezing). Could this be why foliosa is xerophytic? EXPERIMENTAL DESIGN Frost treatment: If you're simulating natural conditions, a natural rate of cooling is 1 to 2 K hr'1 @@?? At temperatures below -30 to -40oC ice formation proceeds very slowly. A good conclusion... "winder hardiness may reflect a very long history of adaptation to climate with cold winters such hardiness, once acquired can persist in mild climates where it is no longer appropriate. This was demonstrated for Salix safsaf and Salix tetrasperma (Sakai 1978c cf p75)}, editor = {Billings, W. D. and Golley, F. and Lange, O. L. and Olson, J. S. and Remmert, H.}, interhash = {e964f4686fd4ac64b2c82287e8ce301b}, intrahash = {61e269d4576d456094ad67090090d67d}, keywords = {bibtex-import citeulikeExport}, posted-at = {2007-07-31 07:02:15}, priority = {2}, publisher = {Springer}, timestamp = {2019-03-31T01:16:26.000+0100}, title = {{Frost survival of plants - responses and adaptation to freezing stress}}, year = 1987 }