Mycorrhizas on nursery and field seedlings of Quercus garryana

Oak woodland regeneration and restoration requires that seedlings develop mycorrhizas, yet the need for this mutualistic association is often overlooked. In this study, we asked whether Quercus garryana seedlings in nursery beds acquire mycorrhizas without artificial inoculation or access to a mycorrhizal network of other ectomycorrhizal hosts. We also assessed the relationship between mycorrhizal infection and seedling growth in a nursery. Further, we compared the mycorrhizal assemblage of oak nursery seedlings to that of conifer seedlings in the nursery and to that of oak seedlings in nearby oak woodlands. Seedlings were excavated and the roots washed and examined microscopically. Mycorrhizas were identified by DNA sequences of the internal transcribed spacer region and by morphotype. On oak nursery seedlings, predominant mycorrhizas were species of Laccaria and Tuber with single occurrences of Entoloma and Peziza. In adjacent beds, seedlings of Pseudotsuga menziesii were mycorrhizal with Hysterangium and a different species of Laccaria; seedlings of Pinus monticola were mycorrhizal with Geneabea, Tarzetta, and Thelephora. Height of Q. garryana seedlings correlated with root biomass and mycorrhizal abundance. Total mycorrhizal abundance and abundance of Laccaria mycorrhizas significantly predicted seedling height in the nursery. Native oak seedlings from nearby Q. garryana woodlands were mycorrhizal with 13 fungal symbionts, none of which occurred on the nursery seedlings. These results demonstrate the value of mycorrhizas to the growth of oak seedlings. Although seedlings in nursery beds developed mycorrhizas without intentional inoculation, their mycorrhizas differed from and were less species rich than those on native seedlings.     

Occurrence and types of ectomycorrhizae present in seedlings ofPicea glehnii in a natural forest in Hokkaido

Picea glehnii seedlings whose ages ranged from 2 to 5 years and which were growing in aP. glehnii-Abies sachalinensis natural forest where the surface had been scarified 6 years before, were assessed for the occurrence and types of ectomycorrhizae. Based on the macro- and microscopic characteristics, 34 types of ectomycorrhizae were classified. The basidiomycetes were clearly dominant and it was common to observe more than one type of mycorrhiza occurring in the same root tip. The diversity of mycorrhizal types and the presence of at least one type of ectomycorrhiza in a single seedling, observed in this work, indicate a very dynamic system of mycorrhizal formation inP. glehnii seedlings, which allows them to survive and grow in a forest surface subjected to soil scarification.     

Comparative effects of four mycorrhizal fungi on loblolly pine seedlings growing in a greenhouse in a Piedmont soil

Summary A greenhouse study was conducted to evaluate the effect of ectomycorrhizae on loblolly pine (Pinus taeda L.) growing in a Piedmont soil. Pine seedlings were inoculated with one of four species of fungi (Scleroderma aurantium, Pisolithus tinctorius, Thelophora terrestris, andRhizopogon roseolus). The seedlings were grown in pots containing a Cecil sandy clay loam amended to create a gradient of extractable P ranging from 5.9 to 52.5 g/g. After ten months, all colonized seedlings were significantly larger than control seedlings. However, of the four fungi,Scleroderma aurantium mediated a far superior shoot growth response to increasing levels of soil P; the seedlings were significantly larger than those colonized by any other fungus and also had the largest root systems and greatest degree of mycorrhizal colonization.     

Density dependent interactions between VA mycorrhizal fungi and even-aged seedlings of two perennial Fabaceae species

Summary The interaction of density and mycorrhizal effects on the growth, mineral nutrition and size distribution of seedlings of two perennial members of the Fabaceae was investigated in pot culture. Seedlings of Otholobium hirtum and Aspalathus linearis were grown at densities of 1, 4, 8 and 16 plants per 13-cm pot with or without vesicular-arbuscular (VA) mycorrhizal inoculum for 120 days. Plant mass, relative growth rates, height and leaf number all decreased with increasing plant density. This was ascribed to the decreasing availability of phosphorus per plant as density increased. O. hirtum was highly dependent on mycorrhizas for P uptake but both mycorrhizal and non-mycorrhizal A. linearis seedlings were able to extract soil P with equal ease. Plant size distribution as measured by the coefficient of variation (CV) of shoot mass was greater at higher densities. CVs of mycorrhizal O. hirtum plants were higher than those of non-mycorrhizal plants. CVs of the facultatively mycorrhizal A. linearis were similar for both mycorrhizal and non-mycorrhizal plants. Higher CVs are attributed to resource preemption by larger individuals. Individuals in populations with high CVs will probably survive stress which would result in the extinction of populations with low CVs. Mass of mycorrhizal plants of both species decreased more rapidly with increasing density than did non-mycorrhizal plant mass. It is concluded that the cost of being mycorrhizal increases as plant density increases, while the benefit decreases. The results suggest that mycorrhizas will influence density-dependent population processes of faculative and obligate mycorrhizal species.     

外生菌根菌对油松幼苗抗氧化酶活性及根系构型的影响

研究盆栽条件下,接种褐环乳牛肝菌(Suillus luteus)和红汁乳菇(Lactarius hatsudake)对油松(Pinus tabulaeformis)苗木生长,抗氧化酶活性和根系构型的影响。结果表明:(1)褐环乳牛肝菌和红汁乳菇均可与油松合成外生菌根,并显著提高苗木的苗高、地径、鲜重和干重。(2)接种褐环乳牛肝菌苗木针叶抗氧化酶(SOD、CAT、POD)活性分别比接种红汁乳菇苗木高14.77%、20.77%、34.68%;接种褐环乳牛肝菌苗木根系抗氧化酶(SOD、CAT、POD)活性分别比接种红汁乳菇苗木高8.54%,4.34%,33.31%;接种处理苗木抗氧化酶活性均显著高于不接种处理。接种处理苗木根长、表面积、体积、平均直径、根尖数、分叉数显著高于不接种处理;接种处理间苗木只有根尖数存在显著差异;接种褐环乳牛肝菌的油松根系分支成80°—90°的一级侧根数占23.81%,显著多于接种红汁乳菇和对照苗木。研究表明,接种褐环乳牛肝菌和红汁乳菇均能促进油松苗木生长,提高油松体内抗氧化酶活性,扩大苗木根系的吸收范围,其中褐环乳牛肝菌各方面的促进效果要优于红汁乳菇。     

Establishment of ectomycorrhizae on the roots of two species of Eucalyptus from fungal spores contained in the faeces of the long-nosed potoroo (Potorous tridactylus)

Abstract The long-nosed potoroo (Potorous tridactylus), a medium-sized, ground-dwelling marsupial, inhabits the foothills and coastal forests of southeastern mainland Australia. Faecal analysis confirmed the mycophagous habit of P. tridactylus at a eucalypt forest site in East Gippsland, Victoria; in one month, the spores of 33 different fungi were identified. The majority of species (27) were hypogeal or subhypogeal gasteromycetes that form ectomycorrhizae with forest trees and shrubs, and included the widespread and common Mesophellia pachytrix. The possible role of mycophagy in establishment of eucalypt-fungal mycorrhizae was investigated in several ways. Fungal spores were viable after passage through the gut of P. tridactylus; application of spore-bearing faeces to seedlings of Eucalyptus sieberi and Eucalyptus globoidea grown in sterile soil produced ectomycorrhizae. Spores of M. pachythrix were among the most common spores in these faeces and some of the resulting ectomycorrhizae were of the type expected from M. pachythrix. In contrast, direct application of M. pachythrix spores from sporocarp tissue to seedlings produced no ectomycorrhizae. Ectomycorrhizae also were established on seedlings grown in unsterilized forest soil, indicating that soil-borne spores had been conditioned, either by passage through the gut of a mammal or some other means, for reaction with the roots of eucalypts. Addition of faeces improved root and shoot growth of seedlings, although we could not determine whether this was primarily due to the formation of ectomycorrhizae, the addition of nutrients in the faeces, or a combination of both. Potorous tridactylus may enhance the re-establishment of mycorrhizal colonies in logged and/or burned forest sites by dispersing in its faeces, the spores of mycorrhizal fungi from sporocarps consumed within the disturbed area, as well as spores from sporocarps eaten in adjacent undisturbed habitat. In performing this function, P. tridactylus may also aid in the recovery of regenerating silvertop ash-stringybark forests.     

毛乌素沙地优势灌丛对两种松树幼苗的保育作用

选择毛乌素沙地优势灌丛柠条(Caragana intermedia)、紫穗槐(Amorpha fruticosa)和沙柳(Salix psammophila)作为保育植物,选择2年生油松(Pinus tabulaeformis)和樟子松(Pinus sylvestris)幼苗作为目标植物,将其分别种植在开阔地、柠条、紫穗槐和沙柳4种微生境下,连续3a监测油松和樟子松幼苗的存活和生长动态,从而确定毛乌素沙地优势灌丛是否对植物幼苗的定居有促进作用。结果表明:柠条、紫穗槐和沙柳冠层下光照强度、大气温度和土壤温度都显著低于开阔地,致使土壤湿度增高,油松幼苗总存活率均显著高于开阔地,而樟子松幼苗总存活率仅紫穗槐冠层下显著高于开阔地(P0.05)。紫穗槐冠层下油松和樟子松幼苗总存活率均最高(P0.05),外来种紫穗槐可选为保育植物。保育灌丛下松树幼苗的主枝生长良好,并未受到抑制,但第1年主枝生长长度最小。光照强度和土壤湿度是决定主枝生长长度的重要因素。保育灌丛高度和冠幅面积与油松和樟子松幼苗存活率呈显著正相关(P0.05)。固氮灌丛(紫穗槐和柠条)对松树幼苗存活有持续的促进作用,但柠条冠幅结构紧密,可能因为对光的竞争,减弱了促进作用。沙柳灌丛下松树幼苗的存活率较低。油松幼苗具有一定程度的耐阴性,樟子松幼苗喜光性强,保育灌丛下油松幼苗存活率显著高于樟子松幼苗(P0.05)。总的来说,保育灌丛对松树幼苗的定居有促进作用,保育植物技术可作为一种有效的恢复措施,应用在毛乌素沙地的植被恢复中来。但是,保育灌丛的选择要考虑是本土种或外来种,以及灌丛的高度、冠幅大小、冠幅结构和化学效应,恢复物种的选择要考虑其自身的生物学特性及其与保育植物的相互作用。     

In vitro ectomycorrhizal formation in Picea glehnii seedlings

 Twenty isolates of ectomycorrhizal fungi – 3 from Picea glehnii, 12 from other coniferous trees, and 5 from decidous trees – were tested for the ability to form mycorrhizae with P. glehnii, using an in vitro synthesis technique. Macroscopically, mycorrhizal formation was observed 3 months after inoculation, when the lateral roots began to grow. Mycelial growth was observed in all inoculated treatments, generally around and along the roots. Six months after inoculation, seedlings were harvested and the mycorrhizae were observed microscopically. Fourteen of the 20 isolates formed ectomycorrhizae with a dense sheath and a deep Hartig net; 1 formed ectendomycorrhizae with a rudimentary mantle, a well-developed Hartig net and intracellular hyphae; 3 formed pseudomycorrhizae with a mantle but without the Hartig net; and only 2 of the fungi tested, Chalciporus pipeparatus 5/92 and Lyophyllum sp. 61/92, did not form mycorrhizae at all. P. glehnii was a good host species since it had low specificity to ectomycorrhizal fungi isolated from trees other than P. glehnii. Accepted: 6 May 1996     

An in vitro method for establishing mycorrhizae on coniferous tree seedlings

Summary A method for in vitro synthesis of mycorrhizae on coniferous tree seedlings is described. Tree seedlings (Larix decidua Mill., Picea abies (L.) Karst, and Pinus sylvestris L.) and fungi Amanita muscaria (L. ex Fr.) Hooker, Piloderma croceum Erikss. et Hjorst., Pisolithus tinctorius (Pers.) Coker et Couch, and Suillus grevillei (Klotzsch) Singer were maintained under sterile conditions in petri dishes. Typical ectomycorrhizae were established within 2–3 weeks after inoculation and within 2 months after germination of seedlings. Eventually a high percentage of mycorrhizal root tips was obtained.     

Effects of root residues on growth ofPinus radiata seedlings and a mycorrhizal fungus

The height of Pinus radiata Don seedlings grown on soils incorporating different proportions of root tissues (25 and 50%) was shown to be reduced by 20–80%. Seedlings watered with aqueous extracts from soil/root mixtures also showed a significant reduction in growth. This growth-retarding effect was partially overcome by the addition of nutrients or by soil sterilisation. It is postulated that growth retardation was caused not only by nutrient deficiency resulting from the addition of organic matter with a high C/N ratio, but also by phytotoxic substances present in the root tissue. The effect of water extracts of roots from old P. radiata trees on the growth of young P. radiata seedlings and on a mycorrhizal fungus (Rhizopogon sp.) under aseptic conditions was also studied. Extracts from the inner bark of roots caused complete growth inhibition of the mycorrhizal fungus as well as root necrosis and wilting of P. radiata seedlings. A water-soluble substance or substances, toxic both to the roots of P. radiata and to its mycorrhizal fungus, is postulated as the causal agent.     

Aluminum-mycorrhizal interactions in the physiology of pitch pine seedlings

Aluminum (Al) in the rhizosphere adversely affects plant nutrition and growth. Although many conifer species, and pitch pine (Pinus rigida) in particular, have evolved on acidic soils where soluble Al is often high, controlled environment studies often indicate that Al interferes with seedling growth and nutrient relations. Under normal field conditions, conifer roots grow in a symbiotic relationship with ectomycorrhizal fungi, and this association may modulate the effects of Al on root physiology. To investigate the influence of mycorrhizal infection on Al toxicity, pitch pine seedlings were grown with or without the ectomycorrhizal symbiont Pisolithus tinctorius and were exposed to low levels of Al in sand culture. Aluminum at 50 μM reduced nonmycorrhizal seedling growth and increased foliar Al concentrations, but did not alter photosynthetic gas exchange or other aspects of seedling nutrition. Nonmycorrhizal seedlings exposed to 200 μM Al exhibited decreased growth, increased transpiration rates, decreased water use efficiency, increased foliar Al and Na levels, and reduced foliar P concentrations. Seedlings inoculated with P. tinctorius exhibited unaltered growth, physiological function, and ionic relations when exposed to Al. The fungal symbiont evidently modulated ionic relations in the rhizosphere, reducing Al-P precipitation reactions, Al uptake, and subsequent root and shoot tissue Al exposure.     

Synergistic effect of colonization with arbuscular mycorrhizal fungi improves growth and drought tolerance of Plukenetia volubilis seedlings

The objective of this study was to investigate the effects of arbuscular mycorrhizal fungus (AMF) inoculation on plant growth and drought tolerance in seedlings of a promising oilseed crop, Sacha Inchi (Plukenetia volubilis L.), under well-watered or drought conditions. AMF inoculation was applied in four treatments: without AMF inoculation, Glomus versiforme, Paraglomus occultum, or combination of both microorganism inoculations. The results showed that AMF colonization significantly enhanced the growth of Sacha Inchi seedlings regardless of soil water conditions, and the greatest development was reached in plants dually inoculated under well-watered conditions. G. versiforme was more efficient than P. occultum. Plants inoculated with both symbionts had significantly greater specific leaf area, leaf area ratio and root volume when compared with the uninoculated control, G. versiforme, and P. occultum treatments alone, indicating a synergistic effect in the two AMF inoculation. Photosynthetic rate and water-use efficiency were stimulated by AMF, but not stomatal conductance. Inoculation with AM fungus increased antioxidant enzymes activities including guaiacol peroxidase and catalase, thus lowering hydrogen peroxide accumulation and oxidative damage, especially under drought stress conditions. However, proline content showed little change during drought stress and AMF colonization conditions, which suggested that proline accumulation might not serve as the main compound for osmotic adjustment of the studied species. These results indicate that AMF inoculation stimulated growth and enhanced drought tolerance of Sacha Inchi seedlings, through alterations in morphological, physiological and biochemical traits. This microbial symbiosis might be an effective cultivation practice in improving the performance and development for Sacha Inchi plants.     

七株外生菌根真菌与三种松苗菌根的形成能力

松树外生菌根菌资源丰富,但实际应用的种类不多。为筛选出与松苗形成菌根能力较强的菌种,采用播种接菌和芽苗截根移栽接菌两种方法,对7株外生菌根真菌与马尾松、湿地松和黑松3种松苗的菌根合成进行了研究。结果表明：形成的菌根以二叉分枝状为主,棒状菌根相对较少,多叉状菌根以马尾松较多。PC2形成的菌根表面菌丝厚且紧密,504、EG、Pt,形成的菌根表面菌丝紧密程度中等,而505、ZJ和HX形成的菌根其表面菌丝则比较稀疏;Pt1、Pt2、EG形成的菌根外延菌丝较长,而505、HX形成的菌根外延菌丝极短。截根接菌时的感染率和感染指数要高于播种接菌。504形成菌根的能力最强,在3种松苗上的菌根感染率都达100％,感染指数最高可达90,最低也达70;Pt2和EG与马尾松和黑松形成菌根的能力较强;而505和HX仅与马尾松形成菌根的能力较强;Pt1形成菌根的能力较差,在3种松苗上菌根感染率和感染指数都较低。在3种松苗中,马尾松的菌根化状况最好,其次为黑松,湿地松的菌根化状况较差。     

Ectomycorrhizal fungal exoenzyme activity differs on spruce seedlings planted in forests versus clearcuts

Key message

Ectomycorrhizal (ECM) fungal community structure and potential exoenzymatic activity change after clearcut harvesting, but functional complementarity and redundancy among those ECM fungal species remaining support growth of regenerating seedlings.

Abstract

Ectomycorrhizal (ECM) fungal community composition is altered by forest harvesting, but it is not clear if this shift in structure influences ECM fungal physiological function at the community level. In this study, we characterized activities of extracellular enzymes in the ectomycorrhizospheres of Picea engelmannii seedlings grown in forest and clearcut plots. These exoenzymes are critical for the breakdown of large organic molecules, from which nutrients are subsequently absorbed and translocated by ECM fungi to host plants. We found that ectomycorrhizae on seedlings planted in forests had different exoenzyme activity profiles than those on seedlings planted in clearcuts. Specifically, the activities of glucuronidase, laccase, and acid phosphatase were higher on forest seedlings (P ≤ 0.006). These differences may have been partly driven by soil properties. Total carbon, total nitrogen (N), extractable phosphorus, extractable ammonium-N, and mineralizable N were higher, while pH was lower in forest plots (P ≤ 0.01). However, we also found that enzyme activity only shifted where community composition also changed. Functional complementarity can be inferred within ECM fungal communities in both forests and clearcuts because ectomycorrhizae formed by different species in the same environment had distinct enzyme profiles (P < 0.0001). However, ectomycorrhizae of Thelephora terrestris exhibited high levels of N- and P-mobilizing exoenzyme activities. Seedling biomass did not differ between forest and clearcut environments, so the high abundance of T. terrestris ectomycorrhizae in the clearcuts may have sustained nutrient acquisition by clearcut seedlings even in soils with lower N and P and with reduced ECM fungal species richness.

     

6种外生菌根真菌对西南桦幼苗的接种效应

【背景】西南桦是兼具内生、外生菌根的典型菌根营养型树种,菌根化育苗是其壮苗培育的有效措施。【目的】揭示外生菌根真菌对西南桦无性系幼苗生长和养分含量的影响,为其菌根化育苗筛选优良外生菌根真菌提供科学依据。【方法】以BY1、FB4、FB4+和A5等4个西南桦优良无性系为研究对象,选用土生空团菌(Cenococcumgeophilum)、松乳菇(Lactariusdeliciosus)、黄硬皮马勃(Scleroderma flavidum)、多根硬皮马勃(S. polyrhizum)、褐环乳牛肝菌(Suillus luteus)和红绒盖牛肝菌(Xerocomuschrysenteron)6个外生菌根真菌进行盆栽接种试验,分析接种处理间及无性系间苗高、地径、生物量以及养分含量差异。【结果】6个菌种均能与西南桦无性系幼苗形成外生菌根共生体,接种多根硬皮马勃与黄硬皮马勃显著促进了幼苗生长和养分吸收(P0.05),说明其与幼苗的亲和力明显优于其它菌种。尽管菌根侵染率在4个无性系之间无显著差异(P≥0.05),但各菌种对FB4、BY1幼苗生长的促进作用显著强于其它2个无性系。【结论】多根硬皮马勃和黄硬皮马勃可作为西南桦菌根化育苗的优选菌种。     

Growth and gas exchange responses of Hevea brasiliensis seedlings to inoculation with Glomus mosseae

 The beneficial effect of arbuscular mycorrhizal (AM) fungi on plant growth is well known, but the physiological processes involved are still discussed. The purpose of this study was to determine if Glomus mosseae affects the growth of Hevea brasiliensis seedlings and, if it is the case, if it could be associated with variations in leaf CO₂ and H₂O gas exchange. H. brasiliensis rubber trees were grown for 9 months in a medium containing either propagules of G. mosseae or sterilized inoculum. Plant size, root collar diameter and leaf area, as well as net CO₂ assimilation, stomatal conductance (g_s) and water-use efficiency of photosynthesis were evaluated during the first 5 stages of growth. At stage 2, a growth depression occurred in the mycorrhizal seedlings coincident with the first AM infections. Then, at stage 5, Glomus mosseae-inoculated plants had moderate colonization (47% of root length) and were taller than control plants with a larger root collar diameter and an enhanced leaf organogenesis. This enhanced growth was accompanied by increased photosynthesis, transpiration, and stomatal conductance. After 9 months, dry weights of shoots and roots of inoculated plants were greater than those of controls by 27 and 17%, respectively. Received: 10 May 1997 / Accepted: 9 September 1997     

Salinity effects on germination,growth, and seed production of the halophyte Cakile maritima

The growth ofEucalyptus regnans seedlings in forest soil is enhanced when it has been air-dried. In undried forest soil seedlings grow poorly and develop purple coloration in the foliage, indicating P deficiency. This paper reports the results of pot experiments designed to investigate the relationship between growth and P acquisition, ectomycorrhizal infection and age of seedlings grown in air-dried and undried soil. The effect on seedling growth of their inoculation with air-dried or undried soil or with ectomycorrhizal roots from plants growing in air-dried or undried soil was also investigated. Ectomycorrhizal root tips were detected in 3-week-oldE. regnans seedlings in both air-dried and undried soil, and from then on the frequency of ectomycorrhizal root tips increased rapidly. In air-dried soil, seedlings were fully ectomycorrhizal at 9 weeks, and the occurrence of maximum ectomycorrhizal infection coincided with enhanced P acquisition and the initiation of rapid seedling growth. In undried forest soil, seedling growth remained poor, even though the seedlings had well-developed ectomycorrhizae and the incidence of ectomycorrhizal root tips was the same as in air-dried soil. The dominant ectomycorrhizae in airdried soil were associated with an ascomycete fungus, whereas in undried, undisturbed soil they were commonly associated with basidiomycete fungi. Inoculation of sterile soil/sand mix with washed ectomycorrhizal roots from air-dried soil increased the P acquisition and growth of the seedlings significantly compared with controls, whereas ectomycorrhizal inocula from undried soil had no effect on seedling growth, although both inocula resulted in a similar incidence of ectomycorrhizal root tips. Similarly, addition of a small amount of air-dried soil into sterile soil/sand mix resulted in a significantly greater increase in the P content and dry weight of the seedlings, compared with the control, than addition of undried soil. In both treatments, the incidence of ectomycorrhial root tips was similar. As (i) the differentiation in seedling growth between air-dried and undried soil occurred after seedlings became ectomycorrhizal, (ii) the dominant ectomycorrhizae in air-dried soil were different from those in undried soil, and (iii) inocula from air-dried soil, but not from undried soil, stimulated seedling growth in sterile soil/sand mix, it is concluded that development of particular ectomycorrhizae may be involved in seedling growth stimulation and enhanced P acquisition associated with air drying of forest soil.     

Interaction of soil filamentous fungi affects needle composition and nutrition of Norway spruce seedlings

The effects of the interactions of soil filamentous fungi (including saprotrophic, mycorrhizal and endophytic fungi) on several morphological and physiological parameters of Norway spruce seedlings [Picea abies (L.) Karst.] were studied in a pot experiment. Both mycorrhizal variants (Hebeloma bryogenes and Cadophora finlandica) were slightly inhibited with respect to the accumulation of aboveground biomass. However, these variants exhibited significantly improved foliar content of N, P, and Ca (H. bryogenes variant also K), compared to controls. The presence of the saprotrophic fungus Setulipes androsaceus attenuated the positive effect of mycorrhizal fungi on Ca, P, and K content, but did not reduce the positive effect of mycorrhizal fungi on the N content of the seedlings’ needles. Raman spectroscopy revealed that both mycorrhizal fungi increased the foliar content of carotenoids compared to the controls, but the effect diminished in the presence of S. androsaceus. In contrast, in the presence of the dark septate endophyte Phialocephala fortinii, needles exhibited significantly higher wax content and lower carotenoid content compared to the mycorrhizal variants. The presence of the saprotrophic isolate Serpula himantoides resulted in a decrease in needle waxes in comparison to controls. The needles’ carotenoid concentration was positively correlated with the levels of needle nutrients (N, P, K, Ca, Mg), while correlation of needle nutrients (N, P) with the needle wax concentration was negative. We conclude that not only individual fungi but also their interactions profoundly affect the nutrition and needle composition of Norway spruce seedlings.     

The Effects of Simazine, Applied for Weed Control, on the Mycorrhizal Development of Pinus Seedlings

The herbicide Simazine is widely used in forestry nurseries.Its effect on the incidence of ectomycorrhizae on pine seedlingroot systems was investigated. Under field (nursery) conditions,at routine rates of application, Simazine does not inhibit mycorrhizaldevelopment in Pinus sylvestris and P. nigra, and it may, undersome conditions, actually enhance mycorrhizal formation. Sucha stimulatory effect was also obtained with pot-grown seedlingstreated with the herbicide. It is suggested that soil type andclimatic factors might be involved in determining the responseto Simazine. The mode of stimulation of mycorrhizal developmentby this herbicide is not understood, but it is not via suppressionof weed growth. Pinus sylvestris, Pinus nigra, pine seedlings, ectomycorrhizae, Simazine     

水引发对油松种子和幼苗的生理效应及其作用机理

为了解决油松种子在直播造林中发芽率低、幼苗抗旱性差的问题,研究了油松种子水引发的方法及引发对其种子和幼苗的生理效应,并对水引发后幼苗的抗旱机理进行了探索。结果表明:油松种子水引发的最佳条件为10℃,闭光条件下分批给种子加水,加水总量为种子初始质量的30%,引发10 d。水引发可显著(P0.05)降低种子的半数发芽天数和硬实率,显著提高种子的发芽指数、最终发芽率和活力指数;水引发种子的可溶性糖及可溶性蛋白含量相比对照也得到提高。水引发可增加油松幼苗的茎粗、鲜重及根长,降低其相对苗高;并极显著(P0.01)提高了幼苗过氧化氢酶、过氧化物酶和根内脱氢酶活性,降低了游离氨基酸含量。干旱胁迫下,引发种子的幼苗脯氨酸和可溶性糖含量分别高于对照39.6%、118.9%,丙二醛含量低于对照93.4%,均达极显著水平。综合分析认为,水引发提高了种子可溶性糖及可溶性蛋白含量为种子萌发提供了保障,从而提高了种子发芽率,并通过增强幼苗抗氧化酶活性、降低丙二醛含量,进而增强幼苗抗氧化系统的功能,最终明显提高其抗旱性。