Blog List

Friday, 30 December 2016

Fertilisation of Quercus seedlings inoculated with Tuber melanosporum: effects on growth and mycorrhization of two host species and two inoculation methods

Author

Sergi Garcia-Barreda (1-2)Corresponding author, Sara Molina-Grau (3), Santiago Reyna (4)

Abstract:

  Modern truffle cultivation is based on use of inoculated seedlings, which should exhibit highly colonised roots as well as a vegetative quality enhancing field plant performance. However, poor shoot and fine root growth has been a frequent issue in inoculated Quercus seedlings production. Fertilisation is a common solution in forest nurseries, but high fertilisation levels have been found to inhibit the formation of ectomycorrhizas of many fungal species. The influence of slow-release fertilisation (52 mg N, 26 mg P and 36 mg K per seedling) on growth and ectomycorrhizal status of Tuber melanosporum-inoculated seedlings was evaluated. Host species Quercus ilex and Quercus fagineaand inoculation methods involving root-dipping and root-powdering were tested. Fertilisation increased weight of both host species without significant detrimental effects on ectomycorrhizal colonisation, showing that it can be effectively used in inoculated seedlings production. Both host species showed similar response to fertilisation. The inoculation method affected seedling weight and ectomycorrhizal status, suggesting that some inoculant carriers are able to damage Quercus development and T. melanosporum colonisation. The study provided an important basis for fine-tuning the use of fertilisers in truffle-inoculated seedling production.

   
Introduction 

The European black truffle (Tuber melanosporum Vittad.) is an ectomycorrhizal (EM) fungus extensively cultivated due to its gastronomic value and decline of wild production ([25]). Each year, more than 2.000 ha of agricultural lands are afforested in southern Europe (mainly France, Italy and Spain) by entrepreneurs to produce black truffle, most of them with native Quercus as host plants ([25]). Modern truffle cultivation is based on planting nursery-inoculated seedlings on suitable lands, with appropriate edaphoclimatic environment for the fungus to complete its life cycle and with low EM inoculum potential ([30]).
High quality inoculated seedlings must exhibit a root system abundantly colonised by T. melanosporum ([1], [19]). The commercial production of these seedlings is customarily done with spore inoculum, either concentrating inoculum onto fine roots or incorporating it into substrate ([9], [22]). With the high price of sporocarps luring nurserymen into reducing inoculum application rates, selection of carrier materials providing close contact with fine roots and even distribution of inoculum is critical, especially when thousands of seedlings are produced ([2]). For Tuber species, little scientific information is publicly available on efficiency of the various inoculation methods or on their interaction with other nursery practices, often because of patents and confidentiality agreements ([7], [23]).
The quality of inoculated seedlings is determined not only by abundance of mycorrhizas but also by vegetative quality of seedlings ([14]). Large, nutrient-rich seedlings with high growth potential are likely to perform better in drylands with deep soils ([10]), such as the agricultural lands where truffle plantations are usually established in Spain ([16]). However, problems of scarce shoot development and stunted lateral root growth have been frequent in the commercial production of Quercus seedlings inoculated with T. melanosporum ([9], [2]). Some inoculation methods seem to exacerbate this problem ([6], [23]).
In forest nurseries a common solution for low vegetative quality of seedlings is fertilisation, which increases size, nutrient storage and root growth potential ([34]). However, Treseder ([32]) showed that nitrogen (N) and phosphorus (P) fertilisations decrease mycorrhizal abundance in the field. In nursery experiments, high fertilisation levels have been found to inhibit the formation of ectomycorrhizas of many fungal species including T. melanosporum ([13], [3], [37], [11]), although Castellano & Molina ([8]) noticed that some species are much more tolerant and that fertilisation effect was dependent on the application system, fertiliser type, dose and form. On the other side, Quoreshi & Timmer ([24]) and Rincon et al. ([26]) found fertiliser doses that increased growth of containerised conifer seedling without decreasing colonisation levels of inoculated fungi from various EM species.
In this study we inoculated Quercus ilex L. and Quercus faginea Lam. with T. melanosporum. We hypothesised that a moderate fertilisation regime could improve morphological quality of seedlings while maintaining EM colonisation levels suitable for commercial purposes. We assess the effect of fertilisation on growth and EM status of seedlings, applying a dose similar to that used by Rincon et al. ([26]). We compare the effect of fertilisation on Q. ilex and Q. faginea, a faster-growing species ([28]), and we evaluate the use of fertilisation in two inoculation methods, root-dipping and root-powdering, both applying inoculum onto roots, although with different carrier materials. We hypothesised that host species and inoculation method would affect fine root traits, thus influencing EM status and ability of seedlings to respond to fertilisation.

    
Materials and methods 

Fungal inoculum, plant material and inoculation

The sporocarps used as inoculum were acquired fresh and mature from plantations in Sistema Ibérico mountain range (eastern Spain). For each experiment, at least 20 sporocarps from five plantations were used in order to minimise spore germinability differences. They were surface sterilised with sodium hypochlorite solution, sliced thin, air dried under room conditions and homogenised with a coffee grinder ([22]).
We selected Q. ilex as host plant because it is the most used species in Spanish truffle plantations. It was compared to Q. faginea, which also produces truffles in the wild and is frequently used in Spanish truffle plantations. While having biological features similar to Q. ilex, Q. faginea is a faster-growing species whose nursery seedlings show more extensive lateral roots ([29], [28]). Acorns from the provenance regions Sistema Ibérico (for Q. ilex) and Sistema Ibérico Levantino (for Q. faginea) were acquired. They were surface sterilised with a 20% sodium hypochlorite solution for five minutes, and germinated in January in a tray with perlite and vermiculite. When seedlings had 6-8 leaves and had formed lateral roots (12 weeks after seedling emergence, in late April), they were removed from the tray, mechanically root-pruned at the tap root end to eliminate its defects ([22]), inoculated, and transplanted to Quick-pot® containers (650 ml, 18 cm deep).
The inoculation was performed by root-dipping, following a traditional method described by Hall et al. ([17]) as frequently used in Spain. The bare roots were dipped in a slurry of homogenised sporocarps in a sucrose solution (2:1 water: sucrose v/w) aimed to produce a high viscosity suspension. The spore concentration in the slurry was adjusted to obtain an application rate of 2.0 g fresh truffle per seedling (6×105 spores per seedling), although some variability between seedlings is impossible to avoid due to differing levels of fine root development. This method is compared to a root-powdering inoculation, also concentrating spores onto roots but with a solid carrier instead of a liquid one ([7]). A mix of talcum powder (hydrated magnesium silicate) and homogenised sporocarps was applied onto seedling bare roots, with spore concentration adjusted to obtain an inoculum rate of 2.0 g fresh truffle per seedling.
The potting substrate consisted of 12:6:1 (v/v) calcareous sandy loam soil, base-fertilised Sphagnum white peat (Kekkila® White 420 W), and limestone coarse sand. It was solarised during summer, and subsequently presented a pH of 7.9, conductivity (1:5) of 418 mS m-1, 1390 ppm N (Kjeldahl), 32 ppm P (Olsen) and 337 ppm K (ammonium acetate extraction), with pH and nutrient levels falling within the common range in Spanish wild truffle soils ([16]). A soil-based potting mix was selected because these are still used with good results in truffle nurseries and research ([7], [4]). Seedlings were cultivated in a greenhouse and sprinkle irrigated to saturation 2-3 times per week during summer and once each 7-14 days during winter.
Following the first shoot flush after inoculation (seven weeks after inoculating, in mid June), slow-release fertiliser Osmocote Exact Mini® (NPK 16-8-11, with a longevity of 3-4 months at 21 °C) was added in the surface of substrate at a dose 0.5 g L-1, providing 52 mg N, 26 mg P, 36 mg K, 6.5 mg Mg, 1.3 mg chelated Fe, 0.16 mg Mn and Cu, 0.07 mg B and Mo and 0.06 mg Zn per seedling. We selected a slow-release fertiliser because it is the most common in Spanish forest nurseries. The dose was selected following that used by Rincon et al. ([26]) for avoiding inhibition of EM formation in containerised Pinus seedlings.

Experimental design

Two experiments were done independently. In 2009 an experiment to compare the effect of fertilisation on two host species (Q. ilex and Q. faginea) was conducted. Four treatments were established in a 2×2 factorial design, with 12 replicates per treatment: unfertilised Q. ilex, fertilised Q. ilex, unfertilised Q. faginea and fertilised Q. faginea. All seedlings were inoculated with root-dipping.
In 2010 an experiment to compare the effect of fertilisation on two inoculation methods was conducted. Four treatments were established in a 2×2 factorial design, with six replicates per treatment: unfertilised root-dipping, fertilised root-dipping, unfertilised root-powdering and fertilised root-powdering. The experiment was conducted with Q. ilex as plant host.

Data collection and analysis

The seedlings of the fertilisation and host species experiment were analysed 12 months after inoculation (in April-May), whereas the fertilisation and inoculation method experiment was analysed 11 months after inoculation (in March). The mycorrhizal status was assessed through a volumetric sampling. In each seedling a sample with 9% of the substrate volume (57 ml) was taken. To cope with heterogeneity across soil depth, every sample consisted of three subsamples: the depth of the container was divided into three equal parts, and in the centre of each third (4, 9 and 13.5 cm depth) a horizontal core (2 cm diameter) across the container was taken.
Samples were kept in water at 4°C. Length of fine roots (diameter <2 mm) was measured according to Tennant ([31]). Root tips were counted and classified as non-mycorrhizal, T. melanosporum ectomycorrhizas or contaminant ectomycorrhizas. Shoot dry weight, root dry weight, fine root dry weight, stem height and root collar diameter were measured after drying to constant weight at 80 °C.
Plant dry weight, shoot and root dry weight, stem height, root collar diameter, specific root length (SRL, ratio of root length to dry weight of fine roots), number of root tips and number of T. melanosporum tips per seedling were analysed by conventional ANOVA. Proportion of root tips colonised by T. melanosporum and frequency of occurrence of contaminants in seedlings were analysed through generalised (binomial) linear models. When model assumptions were violated, the response variable was transformed. In the model for proportion of roots colonised by T. melanosporum, fine root length was included as a covariate to account for within-treatment variability in fine root development.

    
Results 

Experiment 1: fertilisation/host species

Total dry weight of seedlings was positively affected by fertilisation (P<0.001), with no significant differences between host species (P=0.50 - Tab. 1). Both shoot and root dry weight followed the same pattern, with a positive effect of fertilisation (P<0.001 in both cases) and no significant differences between host species (P=0.59 and P=0.46, respectively - Tab. 1). Stem height was positively affected by fertilisation (P<0.001), with no significant differences between host species (P=0.69 - Tab. 1). Root collar diameter was positively affected by fertilisation (P<0.001) and higher in Q. faginea than in Q. ilex (P<0.001 - Tab. 1). SRL was higher in Q. faginea (P=0.001), with no significant effect of fertilisation (P=0.22 - Tab. 1). The number of root tips per seedling was higher in Q. faginea (P<0.001) and in fertilised seedlings (P=0.04 - Tab. 1).
Tab. 1 - Mean growth and mycorrhizal levels in Experiment 1: fertilisation/host species (95% confidence interval in parentheses). Letters indicate significant differences (α=0.05) between treatments according to the respective ANOVA or linear model. (§): Variables log-transformed.
Enlarge/Reduce
The inoculum of T. melanosporum formed mycorrhizas with all seedlings. The number of T. melanosporum mycorrhizas per seedling and the proportion of root tips colonised by T. melanosporum were higher in Q. faginea (P<0.001 and P=0.01, respectively), with no significant effect of fertilisation (P=0.59 and P=0.24, respectively - Tab. 1). The only contaminant EM species found in seedlings was Sphaerosporella brunnea Svrcek and Kubicka, showing a higher occurrence frequency on Q. ilex (P=0.02) and no significant effect of fertilisation (P=0.22 - Tab. 1). The mean proportion of root tips colonised by S. brunnea on Q. ilex was 2.5%.
The distribution of T. melanosporum colonisation levels along the depth profile did not show any significant (α=0.05) interaction with fertilisation.

Experiment 2: fertilisation/inoculation method

Total dry weight of seedlings, shoot dry weight and root dry weight were higher in root-powdering inoculation than in root-dipping (P=0.004, P=0.003 and P=0.02, respectively). No significant effect of fertilisation was found (P=0.08, P=0.14 and P=0.08, respectively), although the trend with respect to fertilisation was the same as in the fertilisation/host species experiment (Tab. 2). Stem height was not significantly affected by either fertilisation (P=0.28) or inoculation method (P=0.26 - Tab. 2). Root collar diameter was positively affected by fertilisation (P=0.02), with no significant differences between inoculation methods (P=0.16 - Tab. 2). Neither SRL nor number of root tips per seedling were significantly affected by fertilisation (P=0.54 and P=0.39, respectively) or inoculation method (P=0.59 and P=0.12, respectively - Tab. 2).
Tab. 2 - Mean growth and mycorrhizal levels in Experiment 2: fertilisation/inoculation method (95% confidence interval in parentheses). Letters indicate significant differences (α=0.05) between treatments according to the respective ANOVA or linear model. (§): Variables log-transformed.
Enlarge/Reduce
The inoculum of T. melanosporum formed mycorrhizas with all seedlings. The number of T. melanosporum mycorrhizas per seedling and the proportion of root tips colonised by T. melanosporum were higher in root-powdering inoculation (P=0.009 and P=0.049, respectively), with no significant effect of fertilisation (P=0.46 and P=0.68, respectively - Tab. 2). The only contaminant EM species found was S. brunnea, showing a higher occurrence frequency in root-dipping inoculation (P=0.004) and no significant effect of fertilisation (P=0.56 - Tab. 2). The mean proportion of root tips colonised by S. brunnea in root-dipping inoculation was 5.2%.
The distribution of T. melanosporum colonisation levels along the depth profile did not show any significant (α=0.05) interaction with fertilisation.

    
Discussion 

In modern truffle cultivation the use of inoculated seedlings is fundamental ([17]). The abundance of T. melanosporummycorrhizas in the early years after plantation establishment has been found positively related to mycorrhizal abundance in the nursery and to plant performance after planting ([5], [15]). Nursery practices must be fine-tuned to encourage colonisation by T. melanosporum, but also to improve vegetative quality of seedlings. However, in nursery fertilisation experiments a conflict between optimal seedling growth and EM colonisation has been reported for many EM fungi ([8], [37], [11]). Two mechanisms have been suggested to explain this conflict: (i) the host reducing carbon supply to the fungus due to a greater carbon demand by growing shoots, or (ii) the fungus requiring most carbon received from the plant to assimilation of the greater N uptake ([38]).
The fertilisation dose used in the present study increased growth as well as vegetative quality according to Spanish standards ([35], [36]), while maintaining T. melanosporum colonisation levels. In the fertilisation/host species experiment, fertilisation increased seedling biomass by 70%, stem height by 49% and root collar diameter by 22%, without significant detrimental effects on fine root traits or EM colonisation levels. In the fertilisation/inoculation method experiment, fertilisation increased Q. ilex root collar diameter by 13%. The lower magnitude of the fertilisation effect in the latter experiment could be due to differences in acorn size ([20]), spore germinability ([22]) or greenhouse climatic conditions from year to year, although it could also be related to the lower number of replicates decreasing the accuracy of estimation.
Our results disagree with previous experiments with containerised Quercus seedlings. Beckjord et al. ([3]) inoculated Quercus alba L. and Quercus rubra L. with Pisolithus tinctorius (Pers.) Coker & Couch and Scleroderma citrinum Pers. and found that N and P fertilisation doses suitable for mycorrhizal colonisation were much lower than those needed to promote seedling growth. Dupré et al. ([13]) inoculated Quercus humilis Mill. with T. melanosporum and found that P fertilisation doses with increased seedling growth did not correspond with higher mycorrhizal colonisation. In Q. ilexinoculated with Paxillus involutus (Batsch) Fr., Hebeloma mesophaeum (Pers.) Quél. and Cenococcum geophilum Fr., Oliveira et al. ([21]) found that a fertiliser dose moderately higher than ours decreased mycorrhizal colonisation, with no significant increase in plant biomass or shoot height. On the other hand, Rincon et al. ([26]), Quoreshi & Timmer ([24]) and Khasa et al. ([18]) found fertilisation levels that improved conifer growth without damaging colonisation levels by various inoculated EM fungi, supporting that at least in some cases they can be reconciled.
The contrast between our results and other Quercus experiments could be due to differences in sensitiveness of EM species to fertilisers ([8], [38]), differences in the response of host species to fertilisation, differences in fertilisation implementation or differences in other cultivation practices. The response of non-inoculated Q. ilex seedlings to fertilisation follows a pattern similar to other Mediterranean Quercus such as Q. faginea, but different from Quercusfrom other biomes which show lower sufficiency levels ([33]). Castellano & Molina ([8]) warned that response of EM fungi to fertilisation was influenced not only by the dose but also by fertiliser type and form, as well as application system (timing, rate and method).
In our study, Q. ilex and Q. faginea showed very similar biomass and response to fertilisation, as expected for species with similar biological features and agreeing with results of Sanz-Pérez et al. ([28]) for non-inoculated seedlings fertilised with 50 mg N. We found the main differences between these species in fine root traits and EM status, with Q. faginea showing higher SRL, number of root tips and number of mycorrhizas. This agrees with findings of Domínguez-Núñez et al. ([12]) and Silla & Escudero ([29]) in young plantations. The former found more root tips and EM tips in Q. faginea than in Q. ilex seedlings inoculated with T. melanosporum, whereas the latter found higher SRL in Q. fagineathan in Q. ilex non-inoculated seedlings. Our results agree with the accepted view that Q. faginea root system is more branched and extensive.
The distinct fine root traits of Q. ilex and Q. faginea went along with differences in EM status. This could be due to the inoculation method delivering somewhat more spore inoculum to seedlings with higher SRL, to inoculum being more evenly distributed within seedling fine roots, or to seedlings recovering before from transplantation. However no interaction in the response of fine root traits to fertilisation was found, suggesting that differences between Q. ilex and Q. faginea did not affect ability of seedlings to respond to fertilisation.
The inoculation method influenced seedling weight and EM status, with root-dipping showing worse characteristics. Pruett et al. ([23]) found that adding hydrogel in a water slurry for root-dipping inoculation had negative effects on Quercus robur L. survival, root development and Tuber aestivum Vittad. colonisation. Cartié et al. ([6]) found that using an alginate solution for root-dipping inoculation provoked an important Q. ilex mortality and a low T. melanosporumcolonisation. These results suggest that inoculant carriers forming a sticky coating around the complete root system are able to damage Quercus development and Tuber colonisation.
However, Cartié et al. ([7]) found no detrimental effects of alginate solution when the inoculant was applied in a bilayer, firstly dipping roots in alginate solution and then powdering them with a mixture of inoculum and talcum. Pruett et al. ([23]) found no detrimental effect of root-dipping inoculation when it was performed without hydrogel. All this suggests that the damage was due to the combination of sticky carrier and spores in close contact with roots.
Our results show that seedling characteristics and inoculation effectiveness can be affected not only by host species but also by inoculation method. Further research would help to know if fertilisation or inoculation method interact with other nursery practices.
The only EM fungi found in our study other than T. melanosporum was the pioneer, nursery adapted S. brunnea ([27]). As expected, its occurrence was higher in treatments with lower T. melanosporum colonisation levels, thus suggesting that it was related to gaps left by the latter.
The inoculation and fertilisation procedures used in the present study proved effective for obtaining EM seedlings with quality levels comparable to commercial standards. All seedlings bore T. melanosporum mycorrhizas, with all treatments showing mean colonisation levels analogous to those in commercial nurseries ([1]). All seedlings met the morphology standards established in relevant regulation on forest seedlings marketing (European Directive 1999/105/CE for Q. ilex and Spanish RD 289/2003 for Q. faginea).

    
Conclusions 

This study showed that a dose of slow-release fertiliser is able to improve growth and morphological quality of Quercusseedlings while maintaining commercial T. melanosporum colonisation levels under greenhouse conditions. Quercus ilex and Q. faginea showed differences mainly in fine root traits and EM status, but in spite of them both species showed similar response to the fertilisation dose. The inoculation method proved able to influence not only EM status but also seedling growth. The study provided an important basis for fine-tuning use of fertilisation in commercial production of T. melanosporum-inoculated seedlings, but showed that inoculation effectiveness can be altered by other cultural practices, hence the improvement of these practices should be addressed jointly.

    
Acknowledgements 

This work was funded by Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA, Government of Spain) project PET2007-13-C07-04.

   
References

(1) 
Andres-Alpuente A, Sanchez S, Martin M, Aguirre AJ, Barriuso JJ (2014). Comparative analysis of different methods for evaluating quality of Quercus ilex seedlings inoculated with Tuber melanosporum. Mycorrhiza 24: S29-S37.
::CrossRef::Google Scholar::
(2) 
Averseng P, Rouch P (2001). Quatre étapes de l’amélioration d’un produit au travers d’un quart de siècle de coopération entre l’INRA et Agri-Truffe [Four steps for the improvement of a product in a quarter of century of cooperation between INRA and Agri-Truffe]. In: Proceedings of the "Vè Congrès International Science et Culture de la Truffe" (Sourzat P ed). Aix-en-Provence (France), 4-6 March 1999. Fédération Française des Trufficulteurs, Marseille, France, pp. 293-295. [in French]
::Google Scholar::
(3) 
Beckjord PR, Melhuish Jr JH, McIntosh MS (1985). Effects of nitrogen and phosphorus fertilization on growth and formation of ectomycorrhizae of Quercus alba and Q. rubra seedlings by Pisolithus tinctorius and Scleroderma auranteum. Canadian Journal of Botany 63: 1677-1680.
::Online::Google Scholar::
(4) 
Benucci GMN, Gógán Csorbai A, Baciarelli Falini L, Bencivenga M, Di Massimo G, Donnini D (2012). Mycorrhization of Quercus robur L., Quercus cerris L. and Corylus avellana L. seedlings with Tuber macrosporum Vittad. Mycorrhiza 22: 639-646.
::CrossRef::Google Scholar::
(5) 
Bourrières D, Coves H, Tixier R, Ricard JM (2005). Effects of the initial level of mycorrhization of young plants inoculated with Tuber melanosporum. In: Abstracts book of “IV International Workshop on Edible Mycorrhizal Mushrooms (IWEMM4)”. Murcia (Spain) 28 Nov - 2 Dec 2005. Universidad de Murcia, Murcia, Spain, pp. 32.
::Google Scholar::
(6) 
Cartié G, Palazón C, Barriuso JJ, Delgado I (1996). Un nuevo método de inoculación de Quercus ilex L. por Tuber melanosporum Vitt. [A new method of Quercus ilex L. inoculation by Tuber melanosporum Vitt.]. Revista Montes 46: 40-43. [in Spanish]
::Google Scholar::
(7) 
Cartié G, Palazón C, Delgado I, Barriuso JJ (2001). Influencia del método de inoculación, del tipo de substrato y de la procedencia de la trufa, en la micorrización de Quercus ilex L. por Tuber melanosporum Vitt. y en la supervivencia de las plantas [Influence of inoculation method, kind of substrate and origin of truffle on Quercus ilex L. mycorrhization by Tuber melanosporum Vitt. and plant survival]. In: Proceedings of the “Vè Congrès International Science et Culture de la Truffe” (Sourzat P ed). Aix-en-Provence (France) 4-6 March 1999. Fédération Française des Trufficulteurs, Marseille, France, pp 296-299. [in Spanish]
::Google Scholar::
(8) 
Castellano MA, Molina R (1989). Mycorrhizae. In: “The Container Tree Nursery Manual, Vol. 5. The biological component: nursery pests and mycorrhizae” (Landis TD, Tinus RW, McDonald SE, Barnett JP eds). USDA Forest Service, Washington, USA, pp. 101-171.
::Google Scholar::
(9) 
Chevalier G, Grente J (1978). Application pratique de la symbiose ectomycorhizienne: production a grande echelle de plants mycorhizes par la truffe (Tuber melanosporum Vitt.) [Practical application of ectomycorrhizal symbiosis: large-scale production of plants mycorrhized by truffle]. Mushroom Science 10: 483-505.
::Google Scholar::
(10) 
Cortina J, Vilagrosa A, Trubat R (2013). The role of nutrients for improving seedling quality in drylands. New Forests 44: 719-732.
::CrossRef::Google Scholar::
(11) 
Diaz G, Carrillo C, Honrubia M (2010). Mycorrhization, growth and nutrition of Pinus halepensis seedlings fertilized with different doses and sources of nitrogen. Annals of Forest Science 67: 405.
::CrossRef::Google Scholar::
(12) 
Domínguez-Núñez JA, Selva-Serrano J, Rodríguez-Barreal JA, Saiz de Omeñaca JA (2006). The influence of mycorrhization with Tuber melanosporum in the afforestation of a Mediterranean site with Quercus ilex and Quercus faginea. Forest Ecology and Management 231: 226-233.
::CrossRef::Google Scholar::
(13) 
Dupré C, Chevalier G, Morizet J, Leblevenec L (1982). Influence de l’azote et du phosphore sur la mycorhization de Quercus pubescens Willd. par Tuber melanosporum Vitt. en conditions contrôlées [Influence of nitrogen and phosphorus on mycorrhiza formation by Quercus pubescens Willd. and Tuber melanosporum Vitt. under controlled conditions]. In: “Les mycorhizes, partie intégrante de la plante: biologie et perspectives d’utilisation”. (Gianinazzi S, Gianinazzi-Pearson V, Trouvelot A eds). INRA seminar no. 13, INRA, Dijon, France, pp. 147-154. [in French]
::Google Scholar::
(14) 
Fischer CR, Colinas C (1996). Methodology for certification of Quercus ilex seedlings inoculated with Tuber melanosporum for commercial application. In: Abstracts booklet of “1st International Conference on Mycorrhizae (ICOM1)” (Szaro TM, Bruns TD eds). Berkeley (California, USA) 4-9 Aug 1996. University of California, Berkeley, California, USA, p 34.
::Google Scholar::
(15) 
Garcia-Barreda S, Reyna S (2013). Cultivation of Tuber melanosporum in firebreaks: short-term persistence of the fungus and effect of seedling age and soil treatment. Fungal Biology 117: 783-790.
::CrossRef::Google Scholar::
(16) 
Garcia-Barreda S, Reyna S, Pérez-Badía R, Rodríguez-Barreal JA, Domínguez-Núñez JA (2007). Ecología de la trufa y las áreas truferas [Ecology of truffle and truffle areas]. In: “Truficultura: Fundamentos y Técnicas” (Reyna S ed). Ed. Mundi-Prensa, Madrid, Spain, pp. 153-208. [in Spanish]
::Google Scholar::
(17) 
Hall I, Brown GT, Zambonelli A (2007). Taming the truffle. Timber Press, Portland, USA, pp. 304.
::Google Scholar::
(18) 
Khasa PD, Sigler L, Chakravarty P, Dancik BP, Erickson L, McCurdy D (2001). Effect of fertilization on growth and ectomycorrhizal development of container-grown and bare-root nursery conifer seedlings. New Forests 22: 179-197.
::CrossRef::Google Scholar::
(19) 
Murat C (2015). Forty years of inoculating seedlings with truffle fungi: past and future perspectives. Mycorrhiza 25: 77-81.
::CrossRef::Google Scholar::
(20) 
Navarro FB, Jiménez N, Ripoll MA, Fernández-Ondoño E, Gallego E, De Simón E (2006). Direct sowing of holm oak acorns: effects of acorn size and soil treatment. Annals of Forest Science 63: 961-967.
::CrossRef::Google Scholar::
(21) 
Oliveira RS, Franco AR, Vosátka M, Castro PML (2010). Management of nursery practices for efficient ectomycorrhizal fungi application in the production of Quercus ilex. Symbiosis 52: 125-131.
::CrossRef::Google Scholar::
(22) 
Palazón C, Barriuso JJ (2007). Viveros y producción de planta micorrizada [Nurseries and production of mycorrhizal plants]. In: “Truficultura: Fundamentos y técnicas” [Trufficulture: Principles and Techniques] (Reyna S ed). Ed. Mundi-Prensa, Madrid, Spain, pp. 209-236.
::Google Scholar::
(23) 
Pruett GE, Bruhn JN, Mihail JD (2008). Colonization of Pedunculate oak by the Burgundy truffle fungus is greater with natural than with pelletized lime. Agroforesty Systems 72: 41-50.
::CrossRef::Google Scholar::
(24) 
Quoreshi M, Timmer VR (2000). Growth, nutrient dynamics, and ectomycorrhizal development of container-grown Picea mariana seedlings in response to exponential nutrient loading. Canadian Journal of Forest Research 30: 191-201.
::CrossRef::Google Scholar::
(25) 
Reyna S, Garcia-Barreda S (2014). Black truffle cultivation: a global reality. Forest Systems 23: 317-328.
::CrossRef::Google Scholar::
(26) 
Rincon A, Parlade J, Pera J (2007). Influence of the fertilisation method in controlled ectomycorrhizal inoculation of two Mediterranean pines. Annals of Forest Science 64: 577-583.
::CrossRef::Google Scholar::
(27) 
Sánchez S, Gómez E, Martín M, De Miguel AM, Urban A, Barriuso J (2014). Experiments on the life cycle and factors affecting reproduction of Sphaerosporella brunnea provide evidence for rapid asexual propagation by conidiospores and for homothallism in an ectomycorrhizal competitor of cultivated truffle species. Fungal Ecology 8: 59-65.
::CrossRef::Google Scholar::
(28) 
Sanz-Pérez V, Castro-Díez P, Valladares F (2007). Growth versus storage: responses of Mediterranean oak seedlings to changes in nutrient and water availabilities. Annals of Forest Science 64: 201-210.
::CrossRef::Google Scholar::
(29) 
Silla F, Escudero A (2004). Nitrogen-use efficiency: trade-offs between N productivity and mean residence time at organ, plant and population levels. Functional Ecology 18: 511-521.
::CrossRef::Google Scholar::
(30) 
Sourzat P (2008). Principe de précaution en trufficulture [The principle of precaution in truffle cultivation]. Station d’Expérimentation sur la Truffe, Le Montat, France, pp 72. [in French]
::Google Scholar::
(31) 
Tennant D (1975). A test of a modified line intersect method of estimating root length. Journal of Ecology 63: 995-1001.
::CrossRef::Google Scholar::
(32) 
Treseder KK (2004). A meta-analysis of mycorrhizal responses to nitrogen, phosphorus, and atmospheric CO2 in field studies. New Phytologist 164: 347-355.
::CrossRef::Google Scholar::
(33) 
Uscola M, Salifu KF, Oliet JA, Jacobs DF (2015). An exponential fertilization dose-response model to promote restoration of the Mediterranean oak Quercus ilex. New Forests 46: 795-812.
::CrossRef::Google Scholar::
(34) 
Villar-Salvador P, Planelles R, Enríquez E, Peñuelas-Rubira J (2004). Nursery cultivation regimes, plant functional attributes, and field performance relationships in the Mediterranean oak Quercus ilex L. Forest Ecology and Management 196: 257-266.
::CrossRef::Google Scholar::
(35) 
Villar-Salvador P, Nicolás-Peragón JL, Heredia-Guerrero N, Uscola M (2012a). Quercus ilex L. In: “Producción y manejo de semillas y plantas forestales. Tomo II” [Production and handling of forest seeds and seedlings. Vol. II] (Pemán J, Navarro-Cerrillo RM, Nicolás-Peragón JL, Prada-Sáez MA, Serrada R eds). Organismo Autónomo Parques Nacionales, Ministerio de Agricultura, Alimentación y Medio Ambiente, Madrid, Spain, pp. 226-250. [in Spanish]
::Google Scholar::
(36) 
Villar-Salvador P, Oliet J, Heredia-Guerrero N, Uscola-M, Goicoetxea P (2012b). Quercus faginea Lam. - Quercus humilis Mill. In: “Producción y manejo de semillas y plantas forestales. Tomo II” [Production and handling of forest seeds and seedlings. Vol. II] (Pemán J, Navarro-Cerrillo RM, Nicolás-Peragón JL, Prada-Sáez MA, Serrada R eds). Organismo Autónomo Parques Nacionales, Ministerio de Agricultura, Alimentación y Medio Ambiente, Madrid, Spain, pp. 206-225. [in Spanish]
::Google Scholar::
(37) 
Walker RF, Walker RF, McLaughlin SB, Amundsen CC (2003). Interactive effects of mycorrhization and fertilization on growth, nutrition, and water relations of sweet birch. Journal of Sustainable Forestry 17: 55-80.
::CrossRef::Google Scholar::
(38) 
Wallander H (1995). A new hypothesis to explain allocation of dry matter between mycorrhizal fungi and seedlings in relation to nutrient supply. Plant and Soil 168-169: 243-248.
::CrossRef::Google Scholar::

For further details log on website :
http://www.sisef.it/iforest/contents/?id=ifor2096-009
at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Advantages and Disadvantages of Fasting for Runners

Author BY   ANDREA CESPEDES  Food is fuel, especially for serious runners who need a lot of energy. It may seem counterintuiti...