Root Electrolyte Leakage Research Articles

Change of cold hardiness in bare-rooted Norway spruce planting stock during autumn and its effect on survival

The objective of this study was to test a method of measurements of electrolyte leakage for determining an optimal autumn lifting date. The second objective was to obtain information about the effects of different autumn lifting dates on survival of Norway spruce (Picea abies [L.] Karst.) plants. A significant difference was found between lifting dates for the values of root electrolyte leakage (REL) from unstressed plants, but without clear tendency. The values of electrolyte leakage from shoots (SEL) were very stable (11–13%). On the other hand, the electrolyte leakage from roots (REL) decreased in dependence on different lifting date after artificial frost stress. On the first lifting date (end of September) the REL values were 77%. On the last lifting date (8 November) the REL values were 56%. The same tendency was found for SEL values (decrease from 63% at the end of September to 17% on 8 November). Differences were also found in the survival of plants. The plants lifted on earlier dates had nearly 100% mortality, which decreased with later date of lifting. The results of this study showed that cold hardiness of planting stock increased during autumn and was higher for shoots than for roots. The first results showed that it is possible to optimize the autumn lifting date of spruce planting stock by measurements of electrolyte leakage from shoots after artificial frost test.    

Hypoxia affects root sodium and chloride concentrations and alters water conductance in salt-treated jack pine (Pinus banksiana) seedlings

The effects of NaCl were studied in 6-month-old jack pine (Pinus banksiana Lamb.) seedlings growing in solution culture under hypoxic (approximately 2 mg l−1 O2) and well-aerated (approximately 8 mg l−1 O2) conditions. The results showed that hypoxia led to further reduction of stomatal conductance (g s) in plants treated with 45 mM NaCl. This effect was likely due to a reduction in root hydraulic conductance by both stresses. When applied individually or together, neither 45 mM NaCl nor hypoxia affected cell membrane integrity of needles as measured by tissue electrolyte leakage. Hypoxia did not alter shoot Na+ and Cl− concentrations in NaCl-treated plants. However, root Na+ concentrations were lower in NaCl-treated hypoxic plants, suggesting that hypoxia affected the ability of roots to store Na+. Hypoxia also induced root electrolyte leakage from NaCl-treated and control plants. The higher root Cl− concentrations compared with Na+ and the positive correlation between root Cl− concentrations and electrolyte leakage suggest that Cl− played a major role in salt injury observed in jack pine seedlings. Roots of well-aerated plants treated for 1 week with NaCl contained almost two-fold higher concentration of total non-structural carbohydrates compared with plants from other experimental treatments and these concentrations decreased in subsequent weeks. We suggest that under prolonged hypoxic conditions, roots lose the ability to prevent Cl− uptake resulting in the increase in root Cl− concentration, which has damaging effects on root cell membranes.

Cytokinin Effects on Creeping Bentgrass Responses to Heat Stress: I. Shoot and Root Growth

Heat stress injury may involve inhibition of cytokinin biosynthesis in roots. The objective of this study was to examine whether application of a synthetic cytokinin, zeatin riboside (ZR), to the root zone would enhance tolerance of creeping bentgrass (Agrostis palustris L.) to high soil temperature or in combination with high air temperature. Grasses were exposed to three air and soil temperature regimes for 56 d in growth chambers: (i) optimum air and soil temperature (control), 20/20°C; (ii) optimum air but high soil temperature (20/35°C); and (iii) high air and soil temperatures (35/35°C). Four concentrations (0.01, 0.1, 1, and 10 μmol) of ZR or water (control) were injected into the 0–5 cm root zone on the day before heat stress (0 d) and 14 d after. Turf visual quality, canopy net photosynthetic rate (Pn), leaf photochemical efficiency (Fv/Fm), and vertical shoot extension rate decreased, whereas root mortality and root electrolyte leakage increased at 20/35 and 35/35°C, and to a greater extent at 35/35°C. Applications of 1 and 10 μmol ZR mitigated heat stress injury to shoots and roots during most of the experimental period, with 10 μmol ZR being more effective when applied at either 0 or 14 d of heat stress. Application of 0.1 μmol ZR was less effective than 1 and 10 μmol ZR. Application of 0.01 μmol ZR had no effects on shoot and root responses to high soil temperature alone or combined with high air temperature. Endogenous cytokinin content in both shoots and roots increased with the application of 1 and 10 μmol ZR. These results demonstrated that applying ZR at 1 or 10 μmol concentration to the root zone could alleviate heat stress injury of creeping bentgrass.

The impact of storage, desiccation and planting date on seedling quality and survival of woody plant species

A comparative study of nine tree species was carried out to investigate the effects of ambient storage, desiccation and planting date on seedling quality. The ability of plant morphological and physiological indicators to detect damage and predict field performance after out‐planting was also tested. After lifting from the nursery bed, plants were either stored under ambient conditions or subjected to desiccation for 3 h, and seedling condition was assessed by measuring fine root electrolyte leakage, fine root moisture content, root moisture content, shoot moisture content and shoot water potential. Treated and control seedlings were planted in the experimental fields. Ambient storage affected the pre‐planting vitality indicators of some species, but no consistent and significant effects were found in survival between the control and stored planting stock. Pre‐planting measurements showed a significant effect of treatments on plant condition. Desiccation adversely affected the physiological parameters and survival of most plants. Seedlings planted in March showed reduced survival compared with those planted in February. Pre‐planting measurements were related to spring survival means but the results were very poor in autumn when survival was very low.

Influence of physiological condition at the time of lifting on the cold storage tolerance and field performance of ash and sycamore

Summary The physiological condition of ash (Fraxinus excelsior L.) and sycamore (Acer pseudoplatanus L.) seedlings sampled from the same nursery in Ireland was evaluated at periodic intervals from September to May, and after cold (1oC) storage from the time of lifting until May, in 1997/98. Shoot water potential (WP), root electrolyte leakage (REL) and root growth potential (RGP) were assessed. In addition, the survival and height increment of seedlings established in a field trial in tandem with the physiology work was determined after one growing season. Shoot WP of freshly lifted ash seedlings, but not sycamore, decreased to low values in the winter. REL and RGP values were generally also lower in ash than in sycamore on most lift dates. Furthermore, sycamore became more highly active earlier in the year (February/March) than ash (April/May). The effect of cold storage on physiological responses was not consistent. The survival of seedlings in the field was close to 100 per cent regardless of treatment. The height increment of freshly lifted sycamore was best for stock planted from September to early March, whereas ash grew best when planted early (October‐November) or late (after February) in the lifting season, although differences between most lift dates were small in ash. Under operational forestry conditions, planting during some of these periods may not be advisable due to the potential effect of handling damage. Cold-stored ash planted in May after cold storage performed well for seedlings lifted to the store from December to February, but the physiologically more active sycamore performed best when stored from February.

Cytokinin Effects on Creeping Bentgrass Responses to Heat Stress

Heat stress injury may involve inhibition of cytokinin biosynthesis in roots. The objective of this study was to examine whether application of a synthetic cytokinin, zeatin riboside (ZR), to the root zone would enhance tolerance of creeping bentgrass (Agrostis palustris L.) to high soil temperature or in combination with high air temperature. Grasses were exposed to three air and soil temperature regimes for 56 d in growth chambers: (i) optimum air and soil temperature (control), 20/20°C; (ii) optimum air but high soil temperature (20/35°C); and (iii) high air and soil temperatures (35/35°C). Four concentrations (0.01, 0.1, 1, and 10 μmol) of ZR or water (control) were injected into the 0–5 cm root zone on the day before heat stress (0 d) and 14 d after. Turf visual quality, canopy net photosynthetic rate (Pₙ), leaf photochemical efficiency (Fv/Fm), and vertical shoot extension rate decreased, whereas root mortality and root electrolyte leakage increased at 20/35 and 35/35°C, and to a greater extent at 35/35°C. Applications of 1 and 10 μmol ZR mitigated heat stress injury to shoots and roots during most of the experimental period, with 10 μmol ZR being more effective when applied at either 0 or 14 d of heat stress. Application of 0.1 μmol ZR was less effective than 1 and 10 μmol ZR. Application of 0.01 μmol ZR had no effects on shoot and root responses to high soil temperature alone or combined with high air temperature. Endogenous cytokinin content in both shoots and roots increased with the application of 1 and 10 μmol ZR. These results demonstrated that applying ZR at 1 or 10 μmol concentration to the root zone could alleviate heat stress injury of creeping bentgrass.

Hydraulic conductance in aspen (Populus tremuloides) seedlings exposed to low root temperatures.

Low root temperatures significantly reduced root hydraulic conductivity and increased resistance to water flow through the roots of aspen (Populus tremuloides Michx.) seedlings. Increased resistance to water flow could not be fully explained by the corresponding increase in water viscosity at low temperatures. The shapes of Arrhenius plots of root water flow and the activation energies were dependent on the direction, sequence and extent of temperature change. The Arrhenius plots suggested that the effect of low root temperature on root water flow was mediated by an effect on root metabolism. The low root temperatures tested did not induce root electrolyte leakage normally associated with cell membrane injury. Although a decrease in root temperatures to 7 or 4 degrees C induced a reduction in stomatal conductance, this reduction lagged the decline in root water flow by several hours. In contrast, when soil temperatures were raised from 4 or 7 degrees C to 25 degrees C, root water flow presumably increased, and stomatal conductance responded rapidly and was temporarily higher than before the cold treatment was imposed.

Seasonal changes in physioloical status, cold storage tolerance and field performance of hybrid larch seedlings in Ireland

The physiological condition at the time of lifting between October and May, 1995/96 and 1996/97 (and after cold storage until May, 1996/97) of hybrid larch (Larix x eurolepis Henry) seedlings grown in Ireland was assessed. The seasonal pattern of cold hardiness acclimation and deacclimation was similar in 1995/96 and 1996/97, but deacclimation occurred 4-5 weeks earlier in the milder 1996/97 season. The pattern of change in shoot tip dry weight fraction was similar during the deacclimation phase each year, but there were differences during acclimation between years. Root electrolyte leakage (REL) declined and remained low from November to February, 1996/97; thereafter, REL increased until May. REL remained low during most of the November to April period in the colder 1995/96. The seasonal pattern of root growth potential (determined in a glasshouse) was similar each year; it declined and remained near zero from November to January, then increased rapidly to high values by March/April. The first-year field performance of seedlings planted soon after lifting in 1995/96 and 1996/97 (and after cold storage until May in 1996/97) was assessed. Similarly, field performance of seedlings from other nurseries planted in 1992/93 and 1994/95 was evaluated. Survival and/or height increment was best for stock that was freshly planted from about October until February/early March. Although survival was good, height increment was poor for cold-stored stock planted in May. Lifting for field planting under operational conditions should begin when cold hardiness (It20) is greater than -15 degrees C (in these experiments equivalent to late October/early November). Field planting should cease when plants deharden to temperatures warmer than this (equivalent to early February/early March).

The physiological basis for the establishment of bare-root larch seedlings

Data on physiological attributes and early forest performance of bare-rooted Japanese and hybrid larch in Britain are summarised. Physiological attributes included root growth potential (RGP), root membrane function, bud dormancy, shoot and root frost hardiness, resistance to desiccation, rough-handling and cold-storage, and sensitivity to insecticide. The survival pattern of freshly planted stock followed that of RGP, which was bimodal with peaks in October and March, whereas the survival pattern of cold-stored stock was more closely related to root membrane function at planting. Seasonal trends in bud dormancy and stress resistance are described. The optimum time for handling, as opposed to planting, larch was in December–February when shoots were hardy to about −30°C, roots were hardy to around −13°C, and root electrolyte leakage (REL) had fallen to about 10%. The optimum cold storage time varied from year to year but seemed to be generally best from mid-November to late December. Undercutting and wrenching improved survival. RGP was of major importance in determining establishment with fine root membrane function, root fibrosity and root:shoot ratio of secondary importance. Since the larches’ unique pattern of RGP seems related to their deciduous habit, it is probable that RGP will be an important determinant of survival in other species of larch.

Effects of desiccation and freezing on vitality and field performance of broadleaved tree species

) and freezing (–5 °C, darkness).The effect of stress factors on seedling quality was assessed using root electrolyte leakage, water potential and moisture content offine roots. After treatments, seedlings were outplanted in a field site. The effects of desiccation and freezing on planting stock quali-ty and field performance varied and depended upon the length of exposure and species. Root electrolyte leakage values were signifi-cantly related to field performance rates of seedlings exposed to both stress factors. Root moisture content and root water potentialwere related to survival only in the case of desiccation treatment. seedling quality / survival / planting stock / desiccation / freezingResume – Effets du dessechement et de la congelation sur la vitalite et la performance des plants d’especes arborees platy-phylles. Des plants d’Acer pseudoplatanus L., Fraxinus ornusL. et Castanea sativa Miller, ont ete soumis a des traitements condi-tionnes controles de dessechement (15 °C, 50 % HR, mouvement d’air 0.3 ms

Effect of warm storage and date of lifting on the quality of Douglas-fir seedlings

The effect of warm storage (15 °C)for up to 21 days on the vitality of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings lifted on four occasions from October to January wasassessed using fine root electrolyte leakage (REL). After 0, 7 and 21 days warm storage, additionalseedlings were potted and placed in a controlledgreenhouse environment to determine root growthpotential (RGP) after 4 weeks and survival after 8weeks. REL was a poor indicator of survival potential;REL increased after 7 days storage, despite the factthat RGP and survival were unaffected. REL increased further during the remainder of the 21-days storage period, but values were often not greatly different from those following 7days storage. Storage for up to 21 days greatlydecreased RGP and survival. Seedlings lifted inOctober and November were most affected by storagetreatments, but differences among lifting dates wererelatively small.

Seed lot, nursery, and bud dormancy effects on root electrolyte leakage of Douglas-fir (Pseudotsuga menziesii) seedlings

The effects of seed lot, nursery culture, and seedling bud dormancy status on root electrolyte leakage (REL) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were assessed to determine if these factors should be considered when interpreting REL for seedling quality. The relationships of REL to survival, net photosynthesis (Pn), stomatal conductance (gwv), mid-day shoot water potential (Ψmid), root growth capacity (RGC), and relative height growth were determined for each factor. Nursery culture had no effect on the relationship between REL and all other measured attributes. Seed lot affected the relationship between REL and Pn, Ψmid, and survival. However, critical REL (i.e., lowest value associated with detectable root damage) and PS80 REL (i.e., level associated with an 80% probability for survival) were similar between seed lots. Bud dormancy status affected the relationship between REL and survival, RGC, and relative height growth. Control levels of REL, critical REL, and PS80 REL decreased as the number of days required for 50% terminal bud break declined. Thus, terminal bud dormancy status must be known before REL can be used to assess seedling quality. If the bud dormancy status of Douglas-fir populations is known, then critical and PS80 REL levels may be useful as indices of root damage.

Seed lot, nursery, and bud dormancy effects on root electrolyte leakage of Douglas-fir (<i>Pseudotsuga menziesii</i>) seedlings

The effects of seed lot, nursery culture, and seedling bud dormancy status on root electrolyte leakage (REL) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were assessed to determine if these factors should be considered when interpreting REL for seedling quality. The relationships of REL to survival, net photosynthesis (Pn), stomatal conductance (gwv), mid-day shoot water potential (Ψmid), root growth capacity (RGC), and relative height growth were determined for each factor. Nursery culture had no effect on the relationship between REL and all other measured attributes. Seed lot affected the relationship between REL and Pn, Ψmid, and survival. However, critical REL (i.e., lowest value associated with detectable root damage) and PS80 REL (i.e., level associated with an 80% probability for survival) were similar between seed lots. Bud dormancy status affected the relationship between REL and survival, RGC, and relative height growth. Control levels of REL, critical REL, and PS80 REL decreased as the number of days required for 50% terminal bud break declined. Thus, terminal bud dormancy status must be known before REL can be used to assess seedling quality. If the bud dormancy status of Douglas-fir populations is known, then critical and PS80 REL levels may be useful as indices of root damage.

The effect of pre-planting desiccation stress and root pruning on the physiological condition and subsequent field performance of one year old Prunus avium and P. cerasifera seedlings

SummarySevere desiccation of dormant seedlings of wild cherry (Prunus avium) and cherry plum (P. cerasifera) did not affect their immediate survival, but caused significant reductions in subsequent shoot growth and root volume which were not recovered in a single growing season. Damage to the fine roots, as indicated by the physiological plant quality measures of tetrazolium absorbance and root electrolyte leakage, increased rapidly over drying periods of ca. 6 h, further damage requiring progressively longer periods of desiccation. Root pruning prior to planting did not mitigate desiccation damage and severe pruning was highly injurious to subsequent growth. Generally the removal of the fine roots was equivalent to a relatively short desiccation period, but pruning of fine roots prior to, instead of after, desiccation in P. cerasifera resulted in more lateral shoots, possibly indicating the production of growth retardant substances by the dried root systems. All measures of physiological plant quality at the beginning of the growing season were effective as predictors of plant performance at the end. In the species tested, the most cost-effective routines are likely to be fine root electrolyte leakage and root moisture content, with tetrazolium testing and stem water potential measurements requiring both greater reproducibility and more sophisticated equipment.

Root electrolyte leakage and root growth potential as indicators of spruce and larch establishment

The relationship between the condition of bare-rooted 2-year-old seedlings of Sitka spruce and larch at the time of planting and their survival and growth after 2 years was examined. Data were analysed for 2 experiments using seedlings lifted and stored at +1 °C throughout the winter for planting in April and also for 2 experiments using seedlings planted directly on different dates without cold storage. Electrolyte leakage from the fine roots of spruce was closely correlated to survival following direct planting at different times from September to April and fine root leakage was a more accurate indicator of spruce performance than root growth potential. However the pattern of larch survival of directly planted stock was more closely related to root growth potential than to root leakage. When seedlings were cold-stored, root electrolyte leakage and root growth potential were modified during storage and following cold storage, the performance of both species was more closely related to root electrolyte leakage than root growth potential. These results are interpreted as meaning that successful establishment of bare-rooted seedlings requires a functional nursery root system that is capable of both supplying adequate water for a limited period immediately after transplanting and of producing roots to meet the seedling’s increased water demand later in the growing season.

Optimal planting times for freshly lifted bare-rooted conifers on the North York Moors

Two-year-old Picea sitchensis (Queen Charlotte Islands and Oregon provenances), Pseudotsuga menziesii, Larix kaempferi, Larix eurolepis, Pinus sylvestris and Pinus nigra var. maritima were lifted at intervals during two winters and planted within 24 h on a nearby second rotation site. Physiological condition at planting, measured by root growth potential and fine root electrolyte leakage, and outplanting performance were significantly influenced by lifting date. There were consistent differences in the species' response to lifting date. Planting out in September resulted in poor survival. Survival of P. sitchensis lifted in October until April was >90 per cent. Pinus sylvestris and P. nigra had survivals of >90 per cent when lifted in November and January respectively until March. There was no clear pattern in P. menziesii performance. Both L. kaempferi and L. eurolepis had two periods of good survival—October and March—with significantly poorer survival and growth associated with mid-winter planting. The double peak in larch performance was closely related to root growth potential; low mid-winter establishment was associated with root growth potentials of <5 even though the nursery root systems were in excellent condition as assessed by electrolyte leakage.

A review of the effect of stresses between lifting and planting on nursery stock quality and performance

This paper presents the experimental evidence on the effects of desiccation, low and high temperatures, rough handling, root loss and storage between lifting and planting on plant quality and performance. The review concentrates on the impact of these stresses on outplanting performance; their effect on seedling properties, such as root growth potential and root electrolyte leakage, is also described. Stresses most often happen in combination but there is relatively little information on their interactions. Examples of desiccation plus rough handling, cold storage plus desiccation, frost damage plus freeze storage and the triple stress of desiccation, heating and rough handling are presented. The limited evidence on the cumulative effect of stresses suggests tentatively that damage from rough handling does not accumulate in the same way as damage from desiccation and prolonged storage. Factors affecting stress resistance are briefly reviewed. There are three impediments to producing a critical review of the literature: experimental treatments, particularly of desiccation and rough handling, can rarely be directly compared; the impact of stress treatments can be modified by a large number of factors, and the levels of stress have seldom been quantified in normal forestry practice. The first two problems also make it difficult to formulate general statements concerning critical thresholds for the stresses. However, instruments are now available for measuring and monitoring stresses between lifting and planting and it is, in theory, possible to model the effects of these stresses to take account of the many factors that modify their impact on seedling survival and growth. This offers the possibility of significant improvements in our ability to predict the effect of stresses between lifting and planting on seedling performance.

Fine root electrolyte leakage and moisture content: indices of Sitka spruce and Douglas-fir seedling performance after desiccation

In spring 1992, 2-year-old bare-rooted seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were exposed for 0, 0.5, 1.0, 1.5, or 3 h in a controlled environment room at 20°C. Plants were desiccated in batches during February and March; 100 seedlings of each species were planted in 5 20-plant plots at each of 6 planting sites using the normal planting times and methods of each area. The effect of exposure was assessed within 24 h of desiccation on a subsample of plants by measuring fine root moisture content and electrolyte leakage and, in a limited number of cases, needle water potential. These measures were related to survival and growth after the first and second growing seasons.

Morphological and physiological differences in Scots pine seedlings of six seed origins

Summary One-year-old seedlings of Scots pine (Pinus sylvestris L.) of four native seed origins (Loch Maree Islands, Glengarry/Glen Morriston, Glen Affric and Abernethy), a commercial British seedlot, and a seedlot from Hedesunda, in middle Sweden, were compared at monthly intervals from October 1993 to April 1994. Seedling morphology, root condition, root frost hardiness and bud dry matter were determined at each date. There were clear morphological differences among seed origins. Seedlings raised from the commercial seedlot (A70) were larger but had a poorer root:shoot ratio than the other seed origins. Of the native pines tested, the Loch Maree Islands origin allocated a larger proportion of its photosynthate to fine roots and needles and smaller proportion to woody structures. Seedlings raised from the commercial British seedlot tended to have poorer bud lignification than the other origins and also, in autumn, higher electrolyte leakage rates from its fine roots. During winter, the Swedish origin had the lowest fine root electrolyte leakage. Seedlings of all origins showed a progressive increase in fine root hardiness towards mid-winter with maximum hardiness (—7°C) in January. Dehardening occurred over subsequent months reaching -3°C in April. Differences among origins were evident. The Swedish seedlot developed greater frost resistance than the other origins, hardening began earlier in autumn and dehardening began later in spring. The commercial seedlot hardened later than the other origins but reached a similar level of frost hardiness by January. Of the native pines, seedlings of the Loch Maree Islands origin were slowest to develop root hardiness.

Seasonal Cold-acclimation Patterns of Sedum spectabile × telephium L. `Autumn Joy' and Sedum spectabile Boreau. `Brilliant'

Electrolyte leakage and regrowth were measured from September through January to determine cold hardiness of Sedum spectabile × telephium L. `Autumn Joy' and Sedum spectabile Boreau. `Brilliant' plants grown outdoors in central Iowa. Crowns were subjected to 0, –3, –6, –9, –12, –15, –18, –21, –24, or –27C. Regrowth tests were performed on whole crowns and electrolyte leakage was determined on excised tuberous root and crown tissue. Both cultivars were killed at –3C in September, but they acclimated gradually through January. Maximum hardiness was achieved in January, with killing temperatures of –27C for `Autumn Joy' and –21C for `Brilliant'. Regrowth quality ratings were significantly correlated with crown and tuberous root electrolyte leakage measurements, although the relationship was stronger for `Autumn Joy'.