Appraisal of root leakage as a method for estimation of root viability

Figures & data

Figure 1. Schematical representation of root electrolyte leakage test methodology (adapted from Ritchie and Landis, 2006).

Figure 2. Root electrolyte leakage (REL) with time measured after 1, 2, 3, 4, and 5 h from the time of adding distilled water to root samples of Quercus robur L. seedlings grown in an Irish nursery. Oak roots were previously exposed to four desiccation treatments with durations of 0, 4, 6, and 8 h, according to the methodology outlined in Mortazavi et al. (2004).

Figure 3. Root electrolyte leakage of Sitka spruce (Picea sitchensis B) seedlings at time of lifting over three lifting seasons in Ireland. Vertical bars on the symbols indicate standard errors, at 5% LSD of the means. (Adapted with permission from O'Reilly et al., 2000. © 2000 Springer).

Figure 4. Root electrolyte leakage (REL) of fine roots (open circles) and woody roots (solid circles) of Scots pine seedlings after exposure to a series of declining temperatures in a phase during cold acclimation in hydroponics. Frost hardiness, defined as the inflection point of the sigmoid curves fitted to the data, was −4.1 and −3.8°C for fine and woody roots, respectively (Redrawn from Ryyppö et al., 1998).

Figure 5. Time course of temperature causing 50% electrolyte leakage of fine roots of Japanese larch (Larix leptolepis (Sieb. and Zucc.) Gord.) (•) and hybrid larch (Larix × eurolepis Henry) (▪) in 1990 – 91 (―) and 1991 – 92 (‐‐‐). (Adapted with permission from McKay & Morgan, 2001. © 2001 Elsevier).

Figure 6. The relative electrolyte leakage for taproots of ash (Fraxinus excelsior L.), oak (Quercus petraea Liebl.), and sycamore (Acer pseudoplatanus L.) seedlings after exposure to 45°C for different durations (from 0 to 8 h) at different lifting dates during the annual cycle. (Adapted with permission from Mortazavi et al., 2004. © 2004 Springer).

Figure 7. Leakage of amino acids (determined by the ninhydrin reaction) from ficus (Ficus rubiginosa) aerial roots following dehydration treatment.

Figure 8. Leakage of amino acids (determined by the ninhydrin reaction) from ficus (Ficus rubiginosa) aerial roots following dehydration treatment.

Appendix 1. Published data on REL application, information provided about type of stress, applied treatments, species, age, and tissue types used

Reference	Type of stress	Treatment	Environment type	Species	Age	Tissue type
Apostol & Zwiazek, 2003	Salinity, hypoxia, aeration	0 and 45 mM NaCl, 8 mg 1^−1 O2, (well aerated) and 2 mg 1^−1 O2, (hypoxic)	Root trainers, controlled environment after 6 months solution culture	Pinus banksiana	6-month-old	Shoots, roots (both 0.45 g fresh weight)
Bronnum, 2005a	Freezing	Temperatures between −5 and −20°C	In wax-coated paper bag at +2°C storage	Quercus robur, Pinus sylvestris	2-year-old	Fine roots (bare root)
Bronnum, 2005b	Desiccation	4°C, 20°C, RH 40%, photo flux density 220 μmol m^−2s^−1	Controlled environment	Abies procera	2-year-old	Fine roots
Bigras, 1997	Freezing	Temperatures between −5 and −22.5°C	Controlled environment	Picea mariana	6-month-old	Fine roots, coarse roots, whole root system
Cabral & O'Reilly, 2005	Desiccation	Warm storage 15°C, cold storage 1 – 2°C	Controlled environment	Quercus robur	2-year-old	Fine roots and tap roots
Chiatante et al., 2002	Cold	2°C	Controlled environment	Pinus nigra	1- and 2-year-old	Fine roots
Chiatante et al., 2005	Drought, heat	100 days under water stress	Mimic natural drought before heating	Quercus ilex	2-year-old	Fine roots
Chiatante et al., 2006	Drought, heat	100 days under water stress	Mimic natural drought before heating	Quercus pubescens, Fraxinus ornus	l-year-old	Fine and tap roots
Coursolle et al., 2000	Freezing	Down to −36, to −30, to −30°C for species respectively (with gradual descending of temperature)	Controlled environment	Picea glauca, Picea mariana, Pinus banksiana	2-year-old	Whole root
Epron & Dreyer, 1992	Desiccation	0 – 6 h dehydration (air drying)	Ambient conditions	Quercus petrae	30-year-old	Leaf disks
Folk et al., 1999	Heat	Root damage, warm water 57°C	Controlled environment	Pseudotsuga menziesii	l-year-old	Fine roots
		1. Seed lots
		2. Nursery culture
		3. Bud dormancy
Garriou et al., 2000	Cold	0,2, or 4 weeks in gunny bags and 4 weeks in polythene bags, 1.4°C	Nursery	Quercus robur, Quercus rubra, Pinus nigra	2-year-old	Fine roots
Genere et al., 2004	Cold	1.8°C, RH 82%	Controlled environment	Quercus robur, Quercus rubra	2-year-old	Fine roots
Harper & O'Reilly, 2000	Warm storage, cold storage	15°C, 0 – 2°C (21 days)	Controlled environment	Pseudotsouga menziesii	2-year-old	Fine roots
McKay, 1992	Cold storage	1°C	Controlled environment	Picea sitchesis, Pseudotsuga menziesii	2-year-old	Fine roots, cut roots
McKay et al., 1993	Mechanical stress (dropping)	0 – 135 times from height of 10, 100, 300 cm on concrete floor, storage at 1°C/4°C and 20°C	Controlled environment for growth	Picea sitchesis, Pseudotsuga menziesii	2-year-old	Fine roots
McKay, 1998a	High illumination	20°C	Clear felled site, glyphosate, hand weeding	Picea sitchesis, Pseudotsuga menziesii, Larix eurolepis, Larix kaempferi, Pinus sylvestris, Pinus nigra var. maritima, Rubus fruticosus, Betula pendula, Quercus robur	2-year-old	Fine roots
McKay, 1998b	Cold storage	1°C	Controlled environment	Picea sitchesis, Larix kaempferi, Larix x eurolepis	2-year-old	Fine roots
McKay & White, 1996	Desiccation	20°C	Controlled environment	Picea sitchesis, Pseudotsuga menziesii	2-year-old	Fine roots (bare rooted)
McKay & Milner, 2000	Desiccation, mechanical stress (rough handling)	Dropping from 3 m (equivalent impact), air stream 1 – 1,4 m/s for 5 h at 15°C	Natural environment	Picea sitchensis, Pseudotsuga menziesii, Larix kaempferi, Pinus sylvestris	2-year-old	Fine roots
McKay & Morgan, 2001	Cold storage, freezing, desiccation	Temperatures between −2 and 1°C	Controlled environment	Larix kaempfer, Larix x eurolepis	2-year-old	Fine roots (bare root)
Mena-Petite et al., 2001	Cold storage, desiccation	RH 80%, 4 and l0°C	Controlled environment	Pinus radiata	9-month-old	Fine roots (containerized seedlings)
Mena-Petite et al., 2003	Cold, desiccation	RH 80%, 4 and l0°C	Controlled environment	Pinus radiata	9-month-old	Fine roots (containerized seedlings)
Mortazavi et al., 2004	Heat	45°C for 0, 4, 8, or 24 h	Nursery	Fraxinus excelsior, Quercus petrae, Acer pseudoplatanus	2-year-old	Taproots (bare root)
O'Reilly et al., 2000	Cold, freezing	Shoots at −20°C or lower than −30°C, seedlings 1 – 2°C	Nursery	Picea sitchensis	2 + 1	Excised roots
O'Reilly et al., 2001	Cold storage	1 – 2°C	Nursery	Larix x eurolepis	2-year-old	Fine roots (bare root more than 90%, undercut, not wrenched)
O'Reilly et al., 2002	Cold storage	1 – 2°C	Nursery	Fraxinus excelsior, Acer pseudoplatanus	2-year-old	Fine roots (bare root)
Perks et al., 2001	Cold, freezing	Temperatures between −2 and 0.5°C	From nursery transplanted in field	Pseudotsuga menziesii	3-year-old	Fine roots <2 mm
Radoglou & Raftoyannis, 2001	Desiccation, freezing	15°C, 50% RH −5°C	Outdoors bare roots (containerized)	Acer pseudoplatanus, Fraxinus ornus, Castanea sativa	l-year-old	Fine roots
Radoglou & Raftoyannis, 2002	Desiccation	Outdoor storage (one month) Warm storage (l5°C, RH 50%, one month)	Nursery controlled environment	Acer pseudoplatanus, Catalpa bignonioides, Celtis australis, Cercis siliquastrum, Hibiscus syriacus, Fraxinus ornus, Koelreuteria paniculata, Platanus orientalis, Sophora japonica	2-year-old	Fine roots (bare root)
Radoglou et al., 2003	Rough handling (through transplanting)	Field performance	Outdoors	Castanea sativa, Quercus frainetto	2-year-old	Fine roots (containerized seedlings)
Ryyppö et al., 1998	Freezing	Different hardening conditions Different freezing temperatures (from 5 to −48°C)	Greenhouse, hydroponic culture, controlled environment	Pinus sylvestris	l-year-old	Fine roots, woody roots, needle tips, needle bases
Sarvas, 2003	Freezing	−16°C for 20 h	Controlled environment	Picea abies	2 + 3	Fine and taproots (bare root), shoots
Sarvas, 2004	Freezing	−16°C for 20 h	Controlled environment	Abies alba, Larix decidua	4-year-old	Fine and taproots (bare root), shoots
Schaberg et al., 2005	Freezing	Down to −60°C	Controlled environment	Chamaecyparis nootkatensis, Tsuga heterophylla	2-years-old	Fine roots, needles
Shalata & Neumann, 2001	Salinity	300 mM NaCl, 5 – 9 h	Controlled environment	Lycopersicon esculentum Mill. cv. M82	14-day-old	Roots
Stattin & Lindstrom, 1999	Freezing	Different temperatures between −5 and −25°C	Controlled environment	Pinus sylvestris	l-year-old	Fine and woody roots
Stattin et al., 2000	Cold, freezing	5.5 and −4.6°C at 2-week intervals	Outdoors	Picea abies	4-year-old	Fine roots

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