Sodium and chloride distribution in salt-stressed Prunus salicina, a deciduous tree species

Measurements were made over four growing seasons of the Na(+) and Cl(-) content of leaves and woody tissues (twigs, branches, trunk and roots) of mature, fruit-bearing Prunus salicina Lindl. (on Marianna 2624 rootstock) trees irrigated during the growing season with water containing 3, 14 or 28 mM salt (2/1 molar ratio of NaCl and CaCl(2)). At the beginning of the study, the trees were 19 years old. Woody tissues of trees irrigated with water containing 14 or 28 mM salt accumulated Na(+) and Cl(-). Leaves of trees irrigated with water containing 14 or 28 mM salt accumulated Cl(-), but not Na(+), unless they had visible symptoms of salt injury. X-Ray microanalysis of leaf mesophyll cells indicated some ability of the cells to sequester Cl(-) in the vacuole. The data demonstrate a capacity for ion compartmentation among tissues and cell organelles in mature Prunus salicina, which may explain the ability of the species to survive low levels of salinity for several years in the field.     

Analysis of leaf water relations in leaves of two olive (Olea europaea) cultivars differing in tolerance to salinity

One-year-old rooted cuttings of olive (Olea europaea L. cvs. Frantoio and Leccino) were grown either hydroponically or in soil in a greenhouse. Plants were exposed to NaCl treatments (0, 100, and 200 mM) for 35 days, followed by 30 to 34 days of relief from salt stress to determine whether previously demonstrated genotypic differences in tolerance to salinity were related to water relations parameters. Exposure to high salt concentrations resulted in reductions in predawn water potential (Psi(w)), osmotic potential at full turgor (Psi(piFT)), osmotic potential at turgor loss point (Psi(piTLP)), and relative water content (RWC) in both cultivars, regardless of the growth substrate. Leaf Psi(w) and RWC returned to values similar to those of controls by the end of the relief period. The effect of salinity on Psi(pi) appeared earlier in Leccino than in Frantoio. Values for Psi(piFT) were -2.50, -2.87, and -3.16 MPa for the 0, 100, and 200 mM salt-treated Frantoio plants, respectively, and -2.23, -2.87, and -3.37 MPa for the corresponding Leccino plants. Recovery of Psi(pi) was complete for plants in the 100 mM salt treatment, but not for plants in the 200 mM salt treatment, which maintained an increased pressure potential (Psi(pi)) compared to control plants. Net solute accumulation was higher in Leccino, the salt-sensitive cultivar, than in Frantoio. In controls of both cultivars, cations contributed 39.9 to 42.0% of the total Psi(piFT), mannitol and glucose contributed 27.1 to 30.8%, and other soluble carbohydrates contributed 3.1 to 3.6%. The osmotic contribution of Na(+) increased from 0.1-2.1% for non-treated plants to 8.6-15.5% and 15.6-20.0% for the 100 mM and 200 mM salt-treated plants, respectively. The mannitol contribution to Psi(piFT) reached a maximum of 9.1% at the end of the salinization period. We conclude that differences between the two cultivars in leaf water relations reflect differences in the exclusion capacities for Na(+) and Cl(-) ions.     

6年生11种桉树无性系生物量与炭化研究

对雷州半岛6年生11种桉树无性系的林分生长量、生物量、炭化量进行了研究。结果表明:11种桉树无性系林分蓄积量大小排序为:GL4>GL9>DH32-22>LH5>DH201-2>LH1>M1>EC34>柳桉1>UC184-1>SH7,林分蓄积量最大的GL4是最小的SH7的2.12倍。11种桉树无性系各组分生物量变化不一致,但都以树干的最大,叶片的最小。LH5和GL4的林分生物量最大,均高于180t·hm-2,SH7和UC184-1林分生物量较小,均低于130t·hm-2,其它几种较为平均,在140~170t·hm-2之间。11种桉树无性系炭化量受林分生物量和炭化率影响,林分生物量和炭化率越大,炭化量越大。LH5、DH201-2、LH1和GL4的炭化率较高,均大于20%,UC184-1和SH7的炭化率最低。11种桉树无性系中LH5林分生物量最大,炭化率最高,故炭化量最高;其次为GL4和LH1,其炭化量均高于60t·hm-2,EC34、GL9、柳桉1、M1和DH32-22均大于50 t·hm-2,UC184-1的炭化量低于40 t·hm-2为最低。综合生长量、生物量和炭化率分析,GL4、LH5、GL9和DH32-224个无性系为一类,可作为薪炭林品系发展;LH1、EC34、DH201-2和M14个无性系划分为一类,作为薪炭林发展潜力较低;柳桉1、UC184-1和SH73个无性系为一类,不适合作为薪炭林发展。     

Sodium chloride improves photosynthesis and water status in the succulent xerophyte Zygophyllum xanthoxylum

Zygophyllum xanthoxylum, a C(3) woody species, is a succulent xerophyte that is well adapted to arid environments. Our previous investigations showed that Na(+) has a positive effect on the growth of Z. xanthoxylum under drought conditions, which was closely related to high Na(+) accumulation in leaves. To reveal the physiological mechanisms underlying how Na(+) accumulation improves the drought resistance of Z. xanthoxylum, 3-week-old seedlings were treated with a series of additional external NaCl concentrations (5-150 mM) in sand culture experiments. Seedlings were also subjected to water deficit (30% of field water capacity) in the presence or absence of additional NaCl (50 mM) in pot experiments. The results indicated that 50 mM NaCl could mitigate deleterious impacts of water deficit on the growth of Z. xanthoxylum, by improving the relative water content, inducing a significant drop in leaf water potential and, concomitantly, increasing leaf turgor pressure and chlorophyll concentrations resulting in an enhancement of overall plant photosynthetic activity (i.e., photosynthetic rate and water use efficiency). Furthermore, NaCl (50 mM) could alleviate the inhibitory effect of water deficit on the activity of photosystem II in Z. xanthoxylum. The contribution of Na(+) to the total osmotic potential varied from 8% in the control to 13% in plants subjected to water deficit and, surprisingly, to 28% in plants grown in the presence of 50 mM NaCl under water deficit; however, the contribution of K(+) significantly decreased from 13 to 8%. These findings suggest that, under arid environments, Z.?xanthoxylum is able to accumulate a high concentration of Na(+) in its leaves and use it directly for osmotic adjustment, which was coupled with an improvement in leaf hydration and photosynthetic activity.     

Micropropagation of Pinus densiflora and the evaluation of nematode resistance of regenerated microshoots in vitro

To accelerate the breeding and selection of Pinus densiflora Siebold and Zucc. resistance to pine wilt disease, a micropropagation system was established and nematode resistance evaluated in vitro. Cotyledon-hypocotyl explants from 28-day-old seedlings were first cultured on Gresshoff and Doy medium supplemented with 4.0 mg L^-1 6-benzyladenine and 0.2 mg L^-1 a-naphthaleneacetic acid(NAA) to stimulate the formation of buds. Induced buds were subsequently subcultured on Gupta and Durzan medium supplemented with 0.1%(w/v)activated charcoal for elongation. Stem sections derived from shoots were used as explants for the further multiplication. Roots were formed from shoots transferred to woody plant medium containing 0.2 mg L^-1 NAA for4 weeks. The nematode resistance test showed that symptoms in micropropagated shoots after infection with pine wood nematode(PWN) were similar to those in plants infected in the field. The wilting rate varied from 20 to100% among different clones 18 days after inoculation.The most susceptible clone was Clone 6-4 with a 100%wilting rate, while Clone 8-4 showed a relatively high resistance with a 20% wilting rate. The number of nematodes recovered from Clone 8-4 shoots was significantly lower(P = 0.05) than from Clones 5-10 and 16-4. This work contributes to the breeding of PWN resistance in P.densiflora.     

黄龙林区引进瑞典能源柳的适应性及生长调查

以黄龙林区引种的8个瑞典能源柳无性系为研究对象,开展了形态学特征、物候、病虫害与日灼、1a生苗木生长量等调查。结果表明,1a生瑞典能源柳无性系扦插苗,以瑞能A、瑞能C和瑞能E高径生长量最大;病虫害和日灼对引种能源柳危害比较小;瑞典能源柳在3月中下旬开始叶芽萌动,展叶期一般为1周左右,多数开花无性系花期超过1月;瑞能2和瑞能4花期长,观赏价值高,更适于作为园林绿化树种;清水浸泡插穗以瑞能A和瑞能成活率最高,分别为96%和93%,其它6个无性系成活率介于73%～89%之间。     

Spatial distribution of leaf morphological and physiological characteristics in relation to local radiation regime within the canopies of 3-year-old Populus clones in coppice culture

Spatial distributions of leaf characteristics relevant to photosynthesis were compared within high-density coppice canopies of Populus spp. of contrasting genetic origin. We studied three clones representative of the range in growth potential, leaf morphology, coppice and canopy structure: Clone Hoogvorst (Hoo) (Populus trichocarpa Torr. & Gray x Populus deltoides Bartr. & Marsh), Clone Fritzi Pauley (Fri) (Populus trichocarpa Torr. & Gray) and Clone Wolterson (Wol) (Populus nigra L.). Leaf area index ranged from 2.7 (Fri and Wol) to 3.8 (Hoo). The clones exhibited large vertical variation in leaf area density (0.02-1.42 m2 m-3). Leaf dry mass per unit leaf area (DM(A)) increased with increasing light in Clones Hoo and Fri, from about 56 g m-2 at the bottom of the canopy to 162 g m-2 at the top. In Clone Wol, DM(A) varied only from 65 to 100 g m-2, with no consistent relationship with respect to light. Conversely, nitrogen concentration on a mass basis was nearly constant (around 1.3-2.1%) within the canopies of Clones Hoo and Fri, but increased strongly with light in Clone Wol, from 1.4% at the bottom of the canopy to 4.1% at the top. As a result, nitrogen per unit leaf area (N(A)) increased with light in the canopies of all clones, from 0.9 g m-2 at the bottom to 2.9 g m-2 at the top. Although a single linear relationship described the dependence of maximum carboxylation rate (17-93 micromol CO2 m-2 s-1) or electron transport capacity (45-186 micromol electrons m-2 s-1) on N(A), for all clones, Clone Wol differed from Clones Hoo and Fri by exhibiting a higher dark respiration rate at low N(A) (1.8 versus 0.8 micromol CO2 m-2 s-1).     

不同基因型细叶桉生长特征的变异性

Eighteen clones of Eucalyptus tereticornis (Sm.) were evaluated for three years by adopting randomized block design for various growth parameters at Hoshiarpur, Punjab, India and compared with two checks. Significant variations were recorded for height, diameter at breast height (DBH) and clear bole height (CBH). The broad sense heritability was low to moderate for both height and CBH. The genetic gain for height and CBH increased substantially per se with the increase in age of trees. The average genetic gain for three years was recorded maximum for height (159.60%) followed by DBH (110.97%) and CBH (70.34%). Clone 17 attained maximum DBH over other genotypes for second and third year followed by clones 14 and 11. Clone 5 showed an upward trend for DBH and maintained its superiority for CBH as the age of the tree increased. Similarly, clone 11 changed its ranking from 9th to 8th to 3rd for DBH and from 9th to 4th to 2nd for CBH, respectively for the age of one, two and three years. Nonetheless, clones 6 and 10 performed poorly for all the characters studied. Clones 17, 14 and 5 were found to be the most promising clones for commercial deployment.     

Gas exchange, water relations and osmotic adjustment in Phillyrea latifolia grown at various salinity concentrations

Leaf gas exchange, water relations and osmotic adjustment were studied in hydroponically grown Phillyrea latifolia L. plants exposed to 5 weeks of salinity stress (0, 80, 160, 240 and 320 mM NaCl) followed by 5 weeks of treatment with half-strength Hoagland solution. Whole-plant relative growth rate and root/shoot and lateral/structural root ratios were also evaluated. Net CO2 assimilation rate, stomatal conductance and transpiration rate were markedly decreased by all of the salt treatments. Growth was also strongly depressed by all salt treatments, especially lateral root growth. Leaf water potential decreased soon after salinity stress was imposed, whereas there was a lag of several weeks before leaf osmotic potential decreased in response to the salt treatments. After 5 weeks of salinization, leaf turgor of salt-treated plants was similar to that of controls. Although Na+ + Cl- contributed little to the salt-induced changes in osmotic potential at full turgor (Psi(piFT)), the contributions of K+, mannitol (Man) and glucose (Glc) to Psi(piFT) markedly increased as external salinity increased. Salt accumulation was negligible in the youngest leaves, which mostly accumulated soluble carbohydrates and K+; in contrast, old leaves served as storage sinks for Na+ and Cl-. Photosynthetic performance of salt-treated plants fully recovered once salt was leached from the root zone, with the recovery rate depending on the severity of the salt stress previously experienced by the plants. Recovery of gas exchange occurred even though the leaves still had a salt load similar to that detected in leaves at the end of the 5-week salinity period, and had markedly lower concentrations of K+ and soluble carbohydrates than control leaves. We conclude that salt-induced water stress primarily controlled gas exchange of salt-treated P. latifolia leaves, whereas the salt load in the leaves did not cause irreversible damage to the photosynthetic apparatus.     

Photosynthetic productivity of aspen clones varying in sensitivity to tropospheric ozone

Rooted cuttings from three aspen (Populus tremuloides Michx.) clones (216, 271 and 259, classified as high, intermediate and low in O(3) tolerance, respectively) were exposed to either diurnal O(3) profiles simulating those of Michigan's Lower Peninsula (episodic treatments), or diurnal square-wave O(3) treatments in open-top chambers in northern Michigan, USA. Ozone was dispensed in chambers ventilated with charcoal-filtered (CF) air. In addition, seedlings were compared to rooted cuttings in their response to episodic O(3) treatments. Early in the season, O(3) caused decreased photosynthetic rates in mature leaves of all clones, whereas only the photosynthetic rates of recently mature leaves of the O(3)-sensitive Clone 259 decreased in response to O(3) exposure. During midseason, O(3) caused decreased photosynthetic rates of both recently mature and mature leaves of the O(3)-sensitive Clone 259, but it had no effect on the photosynthetic rate of recently mature leaves of the O(3)-tolerant Clone 216. Late in the season, however, photosynthetic rates of both recently mature and mature leaves of Clone 216 were lower than those of the control plants maintained in CF air. Ozone decreased the photosynthetic rate of mature leaves of Clone 271, but it increased or had no effect on the photosynthetic rate of recently mature leaves. Photosynthetic response patterns of seedlings to O(3) treatment were similar to those of the clones, but total magnitude of the response was less, perhaps reflecting the diverse genotypes of the seedling population. Early leaf abscission was observed in all clones exposed to O(3); however, Clones 216 and 259 lost more leaf area than Clone 271. By late August, leaf area in the highest O(3) treatment had decreased relative to the controls by 26, 24 and 9% for Clones 216, 259 and 271, respectively. Ozone decreased whole-tree photosynthesis in all clones, and the decrease was consistently less in Clone 271 (23%) than in Clones 216 (56%) and 259 (56%), and was accompanied by declines in total biomass of 19, 28 and 47%, respectively. The relationship between biomass and whole-tree photosynthesis indicates that the negative impact of O(3) on biomass in the clones was determined largely by lower photosynthetic productivity of the foliage, rather than by potential changes in the carbon relations of other plant organs.     

Tolerance of citrus rootstock seedlings to saline stress based on their ability to regulate ion uptake and transport

Forty-five-day-old seedlings of sour orange (Citrus aurantium L.) and Citrus macrophylla Wester, the most commonly used rootstocks in lemon orchards, were grown in nutrient solutions containing 1 (control), 10, 20, 30 or 60 mM NaCl for 14 days. The effects of salinity on growth, uptake, transport and accumulation of Cl- and Na+ ions in leaves, stem and four root segments were studied. The 60 mM NaCl treatment reduced leaf dry mass more in C. macrophylla (40%) than in sour orange (20%), whereas it reduced root dry mass more in sour orange (36%) than in C. macrophylla (20%). In C. macrophylla, Cl- and Na+ uptake rates were high at the beginning of the saline treatments, but low at the end of the 14-day experiment. In contrast, sour orange showed high uptake rates at the beginning and end of the experiment. In response to increasing salinity, root and shoot concentrations of Cl- and Na+ increased in sour orange, but not in C. macrophylla. Different loading characteristics of Cl- and Na+ were observed between young and old segments of the root system. In general, old root segments reached quasi-steady-states later than young root segments. These results suggest that sour orange and C. macrophylla have different regulatory mechanisms for uptake and transport of Cl- and Na+.     

Adventitious sprouting of Pinus leiophylla in response to salt stress

Context

Although adventitious shoots are produced in many tree species in response to injury, little is known about the effects of salinity on sprouting.

Aims

The main objective was to examine the sprouting capacity of Pinus leiophylla seedlings in relation to injury and physiological changes induced by NaCl.

Methods

Seedlings were grown in controlled-environment growth rooms and treated with 0, 100, 150, and 200 mM NaCl. Numbers of adventitious shoots were recorded and growth and physiological parameters measured after 64 days of treatments and following a 30-day recovery period.

Results

NaCl treatments triggered sprouting of adventitious shoots, mainly in the lower parts of the stems. However, fewer sprouts were induced by 200 mM NaCl compared with the lower concentration treatments. These changes were accompanied by needle necrosis, decreased chlorophyll concentrations, seedling dry mass, and stem diameter. Stomatal conductance, net photosynthesis, and root hydraulic conductance decreased with increasing NaCl concentrations and did not return to the control levels after 30 days of stress relief.

Conclusions

Pinus leiophylla has the regeneration potential when exposed to salinity. However, very high salt concentrations induce severe physiological impairments and, consequently, a decrease of this regeneration potential.     

桉树对青枯病抗性与过氧化物酶及同工酶关系的研究

对７个具有不同青枯病抗性的桉树品系的叶部和根部的过氧化物酶活性进行了测定,对同工酶进行了电泳分析。酶活性测定结果表明,桉树各品系叶部的过氧化物酶活性显著高于根部。对青枯病具有不同抗性的７个桉树品系,其叶部的过氧化物酶活性存在着显著差异。对青枯病抗性较弱的Ｆ１１和Ｅ１３品系体内的过氧化物酶显著比其它抗性品系体内的酶活性低。同工酶电泳分析表明,桉树对青枯病不同抗病性品系之间的同工酶谱带,在条带数和各条     

Post-fertilization physiology and growth performance of loblolly pine clones

The physiological processes leading to enhanced growth of loblolly pine (Pinus taeda L.) following fertilization are not clearly understood. Part of the debate revolves around the temporal response of net photosynthetic rate (A(n)) to fertilization and whether the A(n) response is always positive. We measured light-saturated photosynthetic rate (A(sat)), dark respiration rate, growth and crown silhouette area in eight clones of loblolly pine before and after nitrogen (N) fertilization (112 kg ha(-1)) to track the initial physiological changes prior to any changes in growth. Overall, there were positive photosynthetic and growth responses to fertilization; however, there were pronounced physiological and growth differences among clones, even among clones with the same parents. Clones 4, 6 and 7 showed large volume growth and A(sat) responses to fertilization. Clone 1 and Clone 8 (a full-sibling of Clone 7) mainly showed a volume growth response, whereas Clone 2 (full-sibling of Clone 1) showed an A(sat) response only. Clone 5 (full-sibling of Clone 6) showed little response to fertilization, whereas Clone 3 (full-sibling of Clone 4) showed a negative A(sat) response. Thus, within-family variation warrants further study to ensure that relatively expensive clonal material is used efficiently.     

Stable carbon isotope discrimination: an indicator of cumulative salinity and boron stress in Eucalyptus camaldulensis

Saplings of Eucalyptus camaldulensis Dehn. Clone 4544, irrigated with water of differing salinities (2 to 28 dS m-1) and boron concentrations (1 to 30 mg l-1), integrated the history of these stresses through the discrimination of stable isotopes of carbon in leaf and woody tissues. Carbon isotope discrimination (delta) was reduced primarily by salinity. Decreases in discrimination in response to boron stress were detected in the absence of salinity stress, but the decreases were significant only in leaf tissues with visible boron injury. Sapwood core samples indicated that salinity- and boron-induced reductions in delta increased with increasing tree age. Absolute values of delta varied with location of leaf or wood tissue, but relative effects of salinity on the relationship between delta and transpiration efficiency (W) were similar. In response to increasing salinity stress, relative decreases in delta paralleled relative decreases in biomass and both indices yielded similar salt tolerance model parameters. The strong correlations between delta, tree fresh weight, leaf area and W suggest that delta is a useful parameter for evaluating salt tolerance of eucalyptus     

Photoinhibition of photosynthesis in needles of two cypress (Cupressus sempervirens) clones

Photoinhibition of photosynthesis and photosynthetic recovery were studied in detached needles of cypress (Cupressus sempervirens L.) Clones 52 and 30 under controlled conditions of high irradiation (about 1900 micromol m(-2) s(-1) for 60 min; HL treatment), followed by 60 min in darkness. The degree of photoinhibition was determined based on the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm), which is a measure of the potential efficiency of photosystem II (PSII), and on electron transport measurements. The Fv/Fm ratio declined in needles of both clones in response to the HL treatment. Minimal fluorescence (Fo) increased in HL-treated needles of both clones. The HL treatment decreased rates of whole-chain and PSII activity of isolated thylakoids more in Clone 52 than in Clone 30. In needles of both clones, PSI activity was less sensitive to photoinhibition than PSII activity. In the subsequent 60-min dark incubation, fast recovery was observed in needles of both clones, with PSII efficiencies reaching similar values to those in non-photoinhibited needles. The artificial exogenous electron donors diphenyl carbazide (DPC), hydroxylamine (NH2OH) and manganese chloride (MnCl2) failed to restore the HL-induced loss of PSII activity in needles of Clone 30, whereas DPC and NH2OH significantly restored PSII activity in photoinhibited needles of Clone 52. Quantification of the PSII reaction center protein D1 and the 33-kDa protein of the water-splitting complex following HL treatment of needles revealed pronounced differences between Clone 52 and Clone 30. The large decrease in PSII activity in HL-treated needles was caused by the marked loss of D1 protein and 33-kDa protein in Clone 30 and Clone 52, respectively.     

Methods of inoculation and evaluation of Erwinia psidii in eucalypt

The dieback and wilting caused by Erwinia psidii are emerging eucalypt diseases that have been observed since 2014 in the south and central‐south regions of Brazil. Field observations have shown variability in disease severity resistance among Eucalyptus spp. clones and species. It is hypothesized that this variability is due to genetic resistance. To confirm this hypothesis, inoculations in genetically distinct eucalypt plants are necessary. However, lack of an inoculation method and disease assessment makes difficult to select resistant genotypes for use in commercial plantations or genetic breeding programmes. Three inoculation methods were tested on eight clones of Eucalyptus spp. Among them, inoculum deposition with bacteria‐impregnated toothpick on the axillary buds was the simplest and most effective, capable to reproduce the disease symptoms observed under conditions of natural infection. We also developed a rating scale for disease assessment. Among eight clones tested, only Clone 1 (Eucalyptus saligna) and Clone 2 (Eucalyptus urophylla) were resistant.     

First report of bacterial wilt caused by Ralstonia solanacearum on eucalypts in South Africa

Ralstonia solanacearum, the causal agent of bacterial wilt, has one of the widest host ranges of all phytopathogenic bacteria. This pathogen was first reported on Eucalyptus spp. in the late 1980s in Brazil. Since then, there have been reports of its occurrence on this host in Australia, China and Venezuela. Early in 1997, an 18‐month‐old clonally propagated Eucalyptus grandis × Eucalyptus camaldulensis (GC) hybrid in Zululand, KwaZulu/Natal, showed signs of wilting. The vascular tissue of infected trees was dicoloured and bacterial exudation was produced from cut surfaces. The bacterium was consistently isolated from diseased tissue, purified and identified as R. solanacearum biovar 3 race 1, using the BioLog bacterial identification system. Inoculation trials were conducted on three E. grandis × E. camaldulensis clones (GC515, GC550 and GC505). Clone GC550 displayed wilting after 3 days and all cuttings subsequently died. Clones GC515 and GC505 appeared to be less susceptible with cuttings not showing signs of disease until 7 days after inoculation. After 14 days, 90 and 80%, respectively, of cuttings of these two clones had died. This is the first report of bacterial wilt on Eucalyptus in South Africa.