Seedling Injury Research Articles

Cacao (Theobroma cacao L.) Resistance Evaluation Againts Black Pod Diseaseand Effectiveness of Inoculation Methods

The general objective of this experiment was to standardize method of resistance evaluation of cacao germplasm against Phytophthora palmivora, the pathogen causing black pod disease in cacao. The sepecific objectives were to evaluate (1) effects of inoculum type and pod injury, (2) effects of inoculum type and seedling injury, and (3) effects of genetic background of cacao seedlings on infection of P. palmivora. In this experiment, effectiveness of either zoospora or mycellia was evaluated as inoculation sources for pod, leaf and stem of cacao clone GC 7 and Sca 12. Part of the tested cacao pods, leaves, and stems were injured prior to P. palmivora inoculation while the others were not. Observations were conducted on diameter of the necrosed symptoms on inoculated cacao pods, number of necrosed spot on inoculated leaf, and the length of necrosed symptoms on stem of tested cacao seedlings. Results of the experiment indicated inoculation using mycelia of P. palmivora was more effective than zoospora and injuring the tested cacao pods and seedlings before P. palmivora inoculation can be used to prediction the resistance of tested cacao clones against P. Palmivora infection. Results of resistance prediction using detached pod assay was similar to that of using seedling assay; therefore, seedling assay could be used as an alternattive method of resistance evaluation. Cacao F1 hybrids derived from TSH 858 x Sca 12 showed some resistance against P. palmivora and they might potentially result in high yielding lines.Key words: Phytophthora palmivora, cacao breeding, germplasm evaluation, inoculation standardization, pod assay, seedling assay.

Adaptive mechanism of Echinochloa crus-galli Beauv. var. formosensis Ohwi under salt stress: Effect of salicylic acid on salt sensitivity

Our previous study revealed that salicylic acid (SA) accumulates in salt-stressed rice ( Oryza sativa L. cv. Nipponbare) seedlings, and we hypothesized that the accumulation of SA might potentiate oxidative injury in rice seedlings since the inhibition of SA synthesis alleviated the growth inhibition under high salinity. To further clarify the action of SA under salt stress, we investigated the changes in the SA content, the activities of the antioxidative enzymes, and the effects of exogenous SA on barnyardgrass ( Echinochloa crus-galli Beauv. var. formosensis Ohwi), a gramineous weed which shows lower SA content and is more salt tolerant than rice. In E. crus-galli seedlings exposed to high salinity, neither free nor conjugated SA content showed any increase, while the fresh weight of the shoot and chlorophyll fluorescence ( Φ PSII) slightly decreased. When E. crus-galli seedlings were treated with salt after foliar application of SA, the absorbed SA resulted in the enhancement of the salt-induced growth inhibition and a striking reduction of the Φ PSII value. Catalase (CAT) and superoxide dismutase (SOD) activities of E. crus-galli seedlings were induced by the salt treatment. However, SA pre-treatment suppressed such an induction of CAT activity and further promoted SOD activity, both of which led to the elevation of the leaf hydrogen peroxide (H 2O 2) level. The present results suggested that enlargement of the cellular SA pool facilitates the generation of H 2O 2 through the suppression of CAT activity and through a remarkable promotion of SOD activity, and thereby enhances the oxidative injury caused by salt stress.

Ozone effects on visible foliar injury and growth of Fagus sylvatica and Viburnum lantana seedlings grown in monoculture or in mixture

Seedlings of Fagus sylvatica (beech) and Viburnum lantana (Viburnum) grown in monoculture and mixture were exposed to ambient and sub-ambient (charcoal-filtered) ozone concentrations in open-top chambers over the course of the 2003 and 2004 growing seasons at the WSL Lattecaldo open-top chamber facility in southern Switzerland. The aim of the study was to determine how the sensitivity to ozone in ambient air of these two species would differ between monocultures and mixtures in terms of growth and visible foliar injury development. Ambient ozone concentrations were consistently higher from the end of April to the middle of October in 2003 than in 2004 with seasonal peaks and means reaching 147 and 50 parts-per-billion (ppb) in 2003 compared to 124 and 40 ppb in 2004. Ambient AOT40 (ozone concentration accumulated over a threshold of 40 ppb during daylight hours with global radiation >50 W m −2) values from the end of April to the middle of October reached 48.3 and 26.8 parts-per-billon hours (ppm h) in 2003 and 2004, respectively. In general, Viburnum was a stronger competitor than beech over the course of this 2-year study. Seedlings of Viburnum benefited from interspecific competition in terms of both height growth and above-ground biomass accumulation at the expense of beech seedlings, which showed significantly reduced growth in the mixture as compared to the monoculture. However, as this was only the case for Viburnum growing in the charcoal-filtered treatment, ozone seemed to counteract the beneficial effect of interspecific competition on above-ground biomass accumulation in Viburnum, while at the same time decreasing relative biomass allocation to roots. Foliar sensitivity of the two species was also altered under interspecific competition suggesting that results based on seedlings of single species grown in monocultures may significantly over- or under-estimate foliar sensitivity to ozone. These results demonstrate that competition is an important factor affecting plant responses to ozone stress, but the direction and severity of these effects depend on the interacting species.

Comparative Evaluation and Economic Potential of Ecorational Versus Chemical Insecticides for Crucifer Flea Beetle (Coleoptera: Chrysomelidae) Management in Canola

From 2001 to 2004, field studies were conducted to evaluate the effect of the ecorational insecticides SpinTor (spinosad), BotaniGard (Beauveria bassiana), Neemix (azadirachtin), and Surround (kaolin) against crucifer flea beetle on canola, Brassica napus L., at the cotyledon stage. The ecorational treatments were compared with a standard foliar chemical insecticide, Capture (bifenthrin), and the chemical seed treatment insecticide Helix XTra (thiamethoxam). This study indicated that flea beetle injury was lower for Helix XTra, Capture, and the ecorational insecticide SpinTor. SpinTor was less effective when flea beetle populations were relatively high (200-300 per trap-week). Yields for chemical insecticide treatments were always greater than SpinTor, with differences being the smallest (68-374 kg/ha) at low levels of flea beetle feeding injury. Differences were greatest when canola seedling injury was high (775-1,364 kg/ha). Yield differences between the conventional insecticides and BotaniGard, Neemix, and Surround were 119-439 and 61-2,248 kg/ha at low and high flea beetle feeding injury, respectively. Although yield differences between SpinTor and chemical insecticides were relatively small at lower levels of flea beetle injury, net losses ranged from $47 to $151/ha when SpinTor was used as an alternative to a standard chemical seed treatment, Helix XTra. This suggests that SpinTor would not be a viable alternative to the chemical insecticide. Net losses ranged from $30 to $266/ha when BotaniGard, Neemix, and Surround were used as alternatives to the seed treatment.

CYSTATIN ACCUMULATION IN TOMATO LEAVES AFTER METHYL JASMONATE TREATMENT OR MECHANICAL INJURY

The elicitation of cystatin accumulation in tomato leaves was studied with mature and seedling cv. Bonnie Best. Repetitive mechanical injury (MI) or methyl jasmonate (MJ) treatment of seedlings elicited plentiful cystatin accumulation in the leaves when plants were held at 30C under continuous lighting. Cystatin accumulation in leaves of MI seedlings decreased by 50% when incubated at a reduced light period of 12 h light/day. Cystatin accumulation in MJ treated plants was not influenced by reducing the light period from 24 h to 12 h/day. Cystatin accumulation after MJ treatment was optimal at 35C and negligible at 40C. At ambient field conditions (I8–33C), MJ treated seedlings still accumulated a significant amount of cystatin; however, very little cystatin accumulated in leaves of MI seedlings under these conditions of lower temperature and light exposure. The leaves of mature plants accumulated less cystatin after MJ or MI treatment than did those of seedlings.

Pre-Exposure to Ozone Predisposes Oak Leaves to Attacks byDiplodia corticolaandBiscogniauxia mediterranea

One-year-old cork oak (Quercus suber) and turkey oak (Q. cerris) seedlings were exposed to ozone (110 ppb, 5 h day˗1, for 30 days) and were inoculated with Diplodia corticola and Biscogniauxia mediterranea, respectively, by spraying a suspension of spores on the leaves. Both fungi are endophytic and may act as weak parasites, contributing to oak decline. Ozone exposure stimulated leaf attacks after inoculation, although the physiological, visible, and structural responses of both oaks to O3 exposure were weak. In fact, steady-state gas exchange, leaf waxes, and wettability were not significantly affected by O3. In Q. cerris, O3 altered the structure of stomata, as observed by scanning microscopy, and reduced the leaf relative water content. No hyphal entry through stomata or growth towards stomata was, however, observed. Inoculations were performed in a humid chamber at low light; stomata were likely to be closed. When Q. cerris was inoculated in natural conditions, i.e., in a forest infected by B. mediterranea, seedlings pre-exposed to the enhanced O3 regime had a higher number of B. mediterranea isolates than the controls. This suggests that pre-exposure to O3 predisposed Q. cerris leaves to attacks by B. mediterranea independent of stomata. The hyphae of both fungi were able to enter the leaf through the cuticle, either by gradual in-growth into the cuticle or erosion of a hollow in the cuticle at the point of contact. The primary cause of increased leaf injury in O3-exposed seedlings appeared to be higher germination of spores than on control leaves.

Patterns of peroxidative ethane emission from submerged rice seedlings indicate that damage from reactive oxygen species takes place during submergence and is not necessarily a post-anoxic phenomenon

Using ethane as a marker for peroxidative damage to membranes by reactive oxygen species (ROS) we examined the injury of rice seedlings during submergence in the dark. It is often expressed that membrane injury from ROS is a post-submergence phenomenon occurring when oxygen is re-introduced after submergence-induced anoxia. We found that ethane production, from rice seedlings submerged for 24-72 h, was stimulated to 4-37 nl gFW(-1), indicating underwater membrane peroxidation. When examined a week later the seedlings were damaged or had died. On de-submergence in air, ethane production rates rose sharply, but fell back to less than 0.1 nl gFW(-1) h(-1) after 2 h. We compared submergence-susceptible and submergence-tolerant cultivars, submergence starting in the morning (more damage) and in the afternoon (less damage) and investigated different submergence durations. The seedlings showed extensive fatality whenever total ethane emission exceeded about 15 nl gFW(-1). Smaller amounts of ethane emission were linked to less extensive injury to leaves. Partial oxygen shortage (O(2) levels <1%) imposed for 2 h in gas phase mixtures also stimulated ethane production. In contrast, seedlings under anaerobic gas phase conditions produced no ethane until re-aerated: then a small peak was observed followed by a low, steady ethane production. We conclude that damage during submergence is not associated with extensive anoxia. Instead, injury is linked to membrane peroxidation in seedlings that are partially oxygen deficient while submerged. On return to air, further peroxidation is suppressed within about 2 h indicating effective control of ROS production not evident during submergence itself.

Comparing weed and crop seedling response to pre-emergence pendimethalin application in Corchorus olitorius and Abelmoschus esculentus

Field experiments and bioassay tests were carried out to evaluate the relative response of the crops, tossa jute ( Corchorus olitorius L.) and okra [ Abelmoschus esculentus (L.) Moench], and their associated weeds to pre-emergence application of pendimethalin at 0.33, 0.66, 0.99, 1.32 kg ai ha −1 and a pendimethalin+atrazine tank mixture at 1.32+2.05 kg ai ha −1. Bioassay tests were carried out using herbicide solutions of corresponding concentrations and herbicide-treated soil. Field application of pendimethalin at ⩾0.66 kg ai ha −1 and the herbicide mixture in both crops effectively controlled most seedling weeds including Rottboellia cochinchinensis. Euphorbia heterophylla and Calopogonium mucunoides, which persisted from 2 weeks after treatment (WAT) were not controlled. Herbicide application during crop establishment markedly inhibited the growth of both seedling weeds and crops. The mixture caused the highest weed and crop injury. Pendimethalin at 0.33 kg ai ha −1 had minimal effect on these crops. Weed growth, weed tolerance of herbicide treatment and crop seedling injury were higher in tossa jute than that in okra, under the conditions of this study. The use of low pendimethalin doses in an integrated weed management system will ensure effective control of seedling weeds, and prevent crop injury and residue accumulation in edible plant produce.

Toxicidade do herbicida S-metolachlor em plantas de milho provenientes de sementes com diferentes formatos e dimensões

Este trabalho teve como objetivo avaliar a toxicidade do herbicida S-metolachlor em plantas de milho oriundas de sementes com diferentes características morfológicas. O experimento foi conduzido em casa de vegetação, localizada no município de Capão do Leão, RS. Os tratamentos foram compostos pelas combinações de três grupos de tamanhos de sementes, classificadas em peneiras de crivo oblongo [sementes retidas nas peneiras de largura 14/64" (peneira 14), 18/64" (peneira 18) e 21/64" (peneira 21)], de dois formatos de sementes (chata e redonda) e de cinco doses do herbicida S-metolachlor (0,00; 0,48; 0,96; 1,44; e 1,92 kg ha-1), totalizando-se 30 tratamentos. O delineamento experimental utilizado foi o de blocos casualizados em esquema fatorial (3 x 2 x 5), com quatro repetições. Após a separação e classificação das sementes, procedeu-se à semeadura em vasos preenchidos com solo homogeneizado. Em cada vaso foram semeadas oito sementes de milho, na profundidade de 3,0 cm, realizando-se, 24 horas depois, a aplicação do S-metolachlor em pré-emergência. Foram realizadas as seguintes avaliações: velocidade de emergência das plântulas; número total de plântulas emergidas; toxicidade visual e altura de plantas aos 7, 14 e 21 dias após a emergência (DAE); e biomassa seca das raízes e da parte aérea aos 21 DAE. O formato das sementes se mostrou fator importante na tolerância das plantas aos efeitos tóxicos do herbicida S-metolachlor, aplicado em pré-emergência, quando as sementes de milho são de menor tamanho, sendo observada maior toxicidade quando as plantas eram provenientes de sementes redondas. O aumento das doses aplicadas do S-metolachlor ocasionou reduções na aquisição de biomassa seca tanto da parte aérea como das raízes de plantas de milho, porém maior decréscimo se observou quanto ao acúmulo de biomassa seca das raízes.

Effect of seed pre-treatment by low-dose gamma-ray radiation on reducing ultraviolet-B-induced injury in ryegrass seedlings

SummaryRyegrass (Lolium perenne L., cv. ‘Victorian’) seedlings from seed pre-treated by low-dose gamma irradiation (LDG) were exposed to 6.5 kJ m–2 d–1 UV-B radiation under controlled environmental conditions. The high level of UV-B radiation caused serious plant injury, such as accelerated senescence, growth inhibition and lipid oxidation in cell membranes, but UV-B-induced injury was alleviated significantly by LDG-pretreatment, in particular by 20 Gy and 30 Gy (1 Gy = 1 J kg–1). Both ascorbic acid and UV-absorbing compounds were increased by LDG-pretreatment, and the latter were further increased 2-fold by UV-B irradiation. During UV-B exposure, the levels of photosynthetic pigments remained high in seedlings from seed pre-treated with 30 Gy. We suggest that increased plant tolerance to UV-B damage, caused by LDG-pretreatment, may be due, in part, to higher contents of ascorbic acid and UV-absorbing compounds, and the ability to maintain high levels of photosynthetic pigments. The possible implications of these observations are discussed.

Carbon sink limitation and frost tolerance control performance of the tree Kageneckia angustifolia D. Don (Rosaceae) at the treeline in central Chile

The decrease in temperature with increasing elevation may determine the altitudinal tree distribution in different ways: affecting survival through freezing temperatures, by a negative carbon balance produced by lower photosynthetic rates, or by limiting growth activity. Here we assessed the relative importance of these direct and indirect effects of altitudinal decrease in temperature in determining the treeline in central Chile (33°S) dominated by Kageneckia angustifolia. We selected two altitudes (2000 and 2200 m a.s.l.) along the treeline ecotone. At each elevation, leaf non-structural carbohydrates (NSC) and gas exchange parameters were measured on five individuals during the growing season. We also determined the cold resistance of K.␣angustifolia, by measuring temperatures that cause 50% seedling mortality (LT50) and ice nucleation (IN). No differences in net photosynthesis were found between altitudes. Although no differences were detected on NSC concentration on a dry matter basis between 2000 and 2200 m, when NSC concentration was expressed on a leaf area basis, higher contents were found at the higher elevation. Thus, carbon sink limitations may occur at the K. angustifolia’s upper altitudinal limit. For seedlings derived from seeds collected at the 2200 m, LT50 of cold-acclimated and non-acclimated plants were −9.5 and −7 °C, respectively. However, temperatures as low as −10 °C can frequently occur at this altitude during the end of winter. Therefore, low temperature injury of seedlings seems also be involved in the treeline formation in this species. Hence, a confluence of global (carbon sink limitation) and regional (freezing tolerance) mechanisms explains the treeline formation in the Mediterranean-type climate zone of central Chile.

Alternative Agents for Control of European Corn Borer and Corn Flea Beetle on Sweet Corn

ABSTRACT Small plot field trials were conducted in 2002 and 2003 to compare European corn borer (ECB) (Ostrinia nubilalisHübner) control using currently recommended insecticides, carbofuran (FURADAN® 480F) and lambda-cyhalothrin (MATADOR® 120EC), with spinosad (SUCCESS® 480SC) and Bt-sweet corn (ATTRIBUTE®). In both years, foliar applications of spinosad, lambda-cyhalothrin or carbofuran, or Bt-sweet corn significantly reduced the number of ECB stalk tunnels, percent damaged plants and number of damaged kernels, tunnels and larvae on ears at harvest compared to the untreated control. More marketable ears were harvested from plots treated with the insecticides and Bt-sweet corn treatments than from untreated controls. Small plot field trials also were conducted to investigate the efficacy against corn flea beetle (CFB) (Chaetocnema pulicaria Melsheimer) of the seed treatment insecticides, imidacloprid (GAUCHO® 480FS) and clothianidin (PONCHO® 600F). Imidacloprid was evaluated in both 2002 and 2003, clothianidin in 2003 only. Seed treatment with either insecticide significantly reduced numbers of CFB feeding damage marks compared to untreated controls. Clothianidin provided more effective control of CFB than imidacloprid. Overall, the results demonstrated that spinosad or Bt-sweet corn provided ECB control comparable to carbofuran and lambda-cyhalothrin, while imidacloprid or clothianidin seed treatments reduced sweet corn seedling injury from CFB.

Insect injury and mortality of seedlings of field penny-cress (Thlaspi arvense L.).

During 1997–1999 the injury caused by insect herbivors and mortality of plants of field penny-cress (Thlaspi arvense L.) was studied on an early fallow field at Prague-Ruzyně. The highest abundance of the weed (102 plants per m2) was recorded in 1999, the lowest (27 plants/m2) in 1998. Nearly all plants (100% in 1997 and 1998, 94% in 1999) were injured by flea beetles (Phyllotreta spp.). Injury was greatest (&gt; 50%) in younger seedlings. Mortality was low in 1997 (17.1%) and 1999 (15.8%), but high in 1998 (94%) because of concurrent drought. Herbivory and drought may kill a large proportion of seedlings and thus change the composition of the weed community.

Protective effect of exogenous polyamines on root tonoplast function against salt stress in barley seedlings

Salinity stress is one of the most serious factors limiting the productivity of agricultural crops. A possible survival strategy of plants under saline conditions is to sequester excess Na+ in the vacuole by vacuolar Na+/H+ antiport using a pH gradient generated by H+-ATPasc (EC 3.6.1.35) and H+-Pyrophosphatase (H+-PPase; EC 3.6.1.1) to maintain a higher K+/Na+ ratio in cytoplasm. The effect of exogenously applied polyamines (PAs) in stabilizing root tonoplast integrity and function against salt stress in the barley (Hordeum vulgare L.) seedlings was investigated. The NaCl-induced reductions in the contents of phospholipids and PAs in tonoplast vesicles isolated from barely seedling roots, as well as the activities of H+-ATPase, H+-PPase and vacuolar Na+/H+ antiport were all partially restored by the application of 0.5 mM putrescine and 0.5 mM spermidine, especially the former. The above results indicated that one of the mechanisms involved in attenuating salt injury in barley seedlings by exogenous PAs application was to maintain tonoplast integrity and function under saline conditions. Moreover, the possible mechanism involved in counteracting detrimental effects of salt on the barley seedlings by the application of exogenous PAs was discussed.

Long-Term Effects of Simulated Acid Fog on Visible Injury, Growth, Chlorophyll and Nitrogen Content of Japanese Cedar, Red Pine and Beech Seedlings

Long-Term Effects of Simulated Acid Fog on Visible Injury, Growth, Chlorophyll and Nitrogen Content of Japanese Cedar, Red Pine and Beech Seedlings

Oat cover cropping and soil insecticides in an integrated sugarbeet root maggot (Diptera: Otitidae) management program.

Sugarbeet, Beta vulgaris L., producers occasionally establish cereal cover crops to minimize early-season soil erosion, wind abrasion, and mechanical injury of seedlings. We evaluated the use of living oat, Avena sativa L., cover cropping as a cultural tactic to minimize feeding injury from sugarbeet root maggot, Tetanops myopaeformis (Röder), larvae at five field sites during 1996, 1998, and 1999. Sweep-net sampling yielded 4.8-, 11.2-, and 7.2-fold more flies from oat cover-cropped chlorpyrifos, terbufos, and untreated control plots, respectively, than in noncover counterparts. However, larval feeding injury in terbufos-treated plots was reduced when cover-cropped (383 seeds/m2) at St. Thomas in all years. A reduced oat seeding rate (224 seeds/m2) also enhanced root protection in terbufos-treated plots at St. Thomas in 1999. Less root injury was sustained in cover-cropped chlorpyrifos plots than in noncover counterparts at St. Thomas in 2 study yr. Oat cover cropping also frequently resulted in reduced T. myopaeformis feeding injury in the absence of a soil insecticide. Although trends toward increased yields were often evident, significant yield benefits were limited to a 6.8% root yield increase in oat cover plots when compared with noncover treatments overall at St. Thomas in 1996 and an 18.4% sucrose yield increase in terbufos-treated plots at St. Thomas in 1999. These findings suggest that beneficial interactions between planting-time soil insecticides and cereal cover crops are achievable in areas infested by T. myopaeformis. Demonstrated reductions in root feeding injury, combined with additional agronomic benefits, may warrant use of this production practice as part of an integrated management program for this key insect pest of sugarbeet.

Imported longhorned weevil (Coleoptera: Curculionidae) injury to soybean: physiological response and injury guild-level economic injury levels.

The imported longhorned weevil, Calomycterus setarius Roelofs, is an occasional pest of soybean, Glycine max (L.), and can cause substantial defoliation of seedling soybean when the weevil is present in large numbers. Because weevil populations can reach high levels, the potential exists for significant seedling injury, so economic injury levels (EILs) are needed for imported longhorned weevil on seedling soybean. Because the bean leaf beetle, Cerotoma trifurcata (Forster), also is present on seedling soybean, injury by this insect should be included in EIL calculations. This study was conducted to (1) determine daily soybean consumption rates of imported longhorned weevil; (2) compare soybean injury responses between weevil injured and noninjured soybeans; and (3) develop multiple species EILs for imported longhorned weevil and bean leaf beetle. Field and laboratory studies were conducted in 1997 to determine weevil daily consumption rates. Field experiments were conducted in 1998 to examine physiological responses of soybean to weevil injury. Field and laboratory consumption rates were 0.16 and 0.21 cm2 per day, respectively. There were no significant differences in physiological responses (i.e., photosynthetic rates, stomatal conductance, and transpiration rates) between noninjured soybean leaflets (caged) and weevil-injured leaflets. Multiple-species EILs were developed for imported longhorned weevil and bean leaf beetle on VC through V3 soybean.

Safening effects of dymron and fenclorim on pretilachlor injury in rice seedlings under water leakage conditions

Safening effects of dymron and fenclorim on pretilachlor injury in rice seedlings under water leakage conditions

Sucking Injury of Rice Seedlings by the Lygaeid Bug, Nysius plebeius

Sucking Injury of Rice Seedlings by the Lygaeid Bug, <I>Nysius plebeius</I>

Growth and elemental composition of jack pine (Pinus banksiana) seedlings treated with sodium chloride and sodium sulfate

Mining activities in the boreal regions can increase levels of Na+, Cl– and SO4 2– in the forest soil. In the present study, we compared the effects of NaCl and Na2SO4 on the nutrient status of jack pine (Pinus banksiana). Germinated seedlings were grown in sand culture for 28 weeks before adding salts over a period of 3 days to treatment concentrations of 60 mM NaCl and 60 mM Na2SO4, which were maintained for 10 weeks. Salt treatments decreased shoot dry weights and shoot elongation rates. Growth and injury of seedlings were more affected by NaCl than equimolar Na2SO4. Plants treated with NaCl exhibited a delay in flushing of the terminal buds, reduced carotenoid content, extensive needle necrosis, and elevated levels of K, Mg, Mn, N and P in the shoot. Treatment with Na2SO4 resulted in reduced shoot Ca and K concentrations, while those of N and P increased. Necrosis was correlated with tissue Na only in NaCl-treated plants, and no relationship was found between growth or necrosis, and tissue levels of Cl or nutritional elements. We conclude that the greater toxicity of NaCl in jack pine is not due to nutrient deficiency.