ITAQ940002A1 - PROCEDURE FOR THE PRODUCTION OF TRUFFLE PLANTS - Google Patents

Description

DESCRIPTION

of the industrial invention entitled: PROCEDURE FOR THE PRODUCTION OF TRUFFLE PLANTS

from:

The present invention relates to an innovative process of proven efficacy for the nursery production of mycorrhizal plants (trees and shrubs) with various species of Tuber, to be used in the indirect cultivation of truffles of commercial interest: "black truffle of Norcia and Spoleto" "truffe du Périgord "Tuber melanosporum Vitt.," white truffle from Alba and Acqualagna "Tuber magnatimi Pico," summer truffle "" truffe de Bourgogne "Tuber aestivum Vitt. and Tuber uncinatum Chatin, "bianchetto" Tuber borchii Vitt., "Bagnoli truffle" Tuber mesentericum Vitt., "smooth black truffle" Tuber macrosporum Vitt. and "black winter truffle" Tuber brumale Vitt.

Three different processes are currently used:

1) sterile produced seedlings that are transferred to a phytocell or pot with soil containing the truffle inoculum;

2) sterile produced seedlings whose root system is immersed in a dense suspension of inoculum before potting;

3) "mother plant system", ie the use of mycorrhizal plants with one of the two previous systems as a source of secondary infection on other sterile plants;

The inoculum usually consists of an aqueous homogenate or a flour of ripe truffles. Rarely, or for limited experiences, mycelial cultures are used.

The first two procedures are those most used for the production of truffle plants, which at the moment involve a large market, mainly active in Italy, France and Spain, which exceeds five hundred thousand plants sold a year.

The soil for the pot or phytocell phase is usually represented by soil from truffle areas or a mixture of crushed pine peel, lignite ash, peat and slow release fertilizer, called MELFERT (MELange FERTilisé), made by CHEVALIER GERARD (1984) Agronomies 4: 211.

The inconveniences attributable to the proceedings in progress concern:

a) production costs;

b) the results obtainable in mycorrhizal synthesis;

c) the results on the field.

By correctly carrying out the indications for the mycorrhization systems indicated above as 1) and 2) the quantity of truffle needed for each plant is about 3-5 gr. In fact, to obtain better results, even the method n.2, immersion of the root system in a spore suspension, provides for the distribution of at least another cubic centimeter of spore suspension around the collar of the potted plant. The cost of the truffle inoculum alone is several thousand lire, which varies in relation to the species of truffle used and the cost of the truffle in the year of nursery production. In the current year (1994) the inoculum cost for what concerns the most valuable species was Lit. 2,000—3.000 for Tuber melanosporum and Lit. 9.000-15.000 for Tuber magnatum. In any case, both methods 1) and 2) do not ensure, in the critical phase that precedes the onset of mycorrhizal symbiosis (mycorrhizal synthesis phase), a total and continuous relationship between the expanding root system and inoculation. The method n.3, although patented, proved to be impracticable for large-scale nursery productions given the difficulties in maintaining the conditions of axenia on large surfaces for a long time.

The use of natural soils coming from areas already naturally truffle or suitable for truffle cultivation introduces in the delicate phase of mycorrhizal synthesis the telluric microorganisms of the soil that are not always adequately eliminated with hot sterilization (stove or steam under pressure) or with fumigations with ethyl bromide. With the use of natural soils there is therefore the risk of establishing mycorrhizal symbiosis unrelated to those of the truffle. The use of MELFERT largely prevents this possibility, as it has a very low microbial load and is more easily sterilized as it does not have clayey lumps. Its relatively high nutritional content, both organic (fragments of bark and peat) and inorganic (lignite ash and osmotic fertilizer) and the difficulty in achieving a stable pH over time due to the different solubility of alkaline substances present in the ash of lignite and the substances acidity of the fine fragments of peel and peat, limits the percentage of mycorrhization with Tuber. Furthermore, this substrate, like the previous one in the planting phase, is not sufficiently competitive as regards the entry of foreign mycorrhizal fungal organisms. In fact, these are substrates which in relation to the surrounding soil where the planting takes place represent a volume of soil that can be colonized by the native microbial flora, as it is richer or less exploited than the latter.

In fact, it has been shown that truffle mycorrhizae have poor competitiveness against most other mycorrhizal fungi, so in the planting phase the eventuality of colonization of the substrate of the synthesis vessel by the autochthonous microflora should be limited as much as possible. .

The present procedure is the result of a laboratory, nursery and field experimentation, begun in 1982 and has as its object the innovation of the inoculation technique and the formulation of the mycorrhizal synthesis substrate.

The results obtained indicate:

1) that the inoculation technique identified maintains a continuous contact between the growing roots and the inoculation of the truffle;

2) that the quantity of inoculum necessary to obtain an optimal percentage of mycorrhization is considerably reduced compared to the known processes, about 500 mg instead of 3-5 gr;

3) that the substrate used for the synthesis ensures a high degree of axenicity even in the absence of sterilization; 4) that said substrate ensures a stable neutral pH optimal for the physiological needs of tuber mycorrhiza

5) that said substrate due to the lack of nutrients forces an intimate relationship of collaboration between the two partners of the symbiosis (plant and truffle);

6) that during the planting phase, again due to the very scarce availability of nutrients, the colonization of the synthesis substrate by the autochthonous microorganisms of the soil does not occur, but it is the mycorrhized roots and the mycelium of the truffle that grow rapidly towards the surrounding land.

D E S C R I Z I O N E D E L M E T O D O

The seedlings of the arboreal and shrub species to be mycorrhized are obtained under axenic conditions, by sterilizing the seeds in an aqueous solution of 1.53⁄4 of NaClO for 15'-20 'and then washing them repeatedly in distilled water.

Sowing is carried out in sterile vermiculite in factory new polystyrene boxes with an adequate content of controlled release fertilizer.

The germination and production of the seedlings takes place in a protected environment until the third leaf is reached (May-June).

The inoculum comes from sporophores of various species of selected Tuber, carefully washed and brushed, placed in containers with sterile sand at 4 ° C until use. INOCULATION AND MYCORRIZATION PREPARATION

The sporal suspension for the inoculation of the seedlings is prepared by homogenizing about 100 g of truffles in a liter of 0.7-1.0% aqueous solution, depending on the type of root system, of high viscosity carboxymethylcellulose.

The root systems of the seedlings are immersed in the suspension thus prepared and then immediately placed in phytocells in black polyethylene with holes 5 cm from the bottom.

The phytocells contain the following substrate: vermiculite, Russian blond peat of sterile sphagnum, calcareous gravel of quarry of 0, l-2 irai in diameter in the volumetric ratio 3: 1: 1.

USE OF HIGH VISCOSITY CARBOXIMETHYL CELLULOSE

The quality of the carboxymethylcellulose (high viscosity) was identified after tests and checks with other thickening substances: low and medium viscosity carboxymethylcellulose, carboxyethylcellulose, xanthan gum, agar-agar, carrageenins, glucose, maltose, sucrose, starch at various concentrations.

The concentration of carboxymethylcellulose was identified after tests and checks at various concentrations: 0.1-0.25-0.5-0.7- 0.9-1.0-1.5-2.0% weight / volume .

The use of the sporal suspension in a high viscosity carboxymethylcellulose solution:

a) improves the adhesion of truffle spores over the entire surface of the root system by reducing the inoculum load;

b) the carboxymethylcellulose coating remains on the roots for a long time, always keeping them in contact with the spores; c) the gelatinous sleeve increases the survival and vitality of the spores and by concentrating the radical exudates facilitates the germination process of the same;

d) with the beginning of the germination of the spores, the mycelium of the truffle finds in this moist gelatinous muff optimal conditions of development;

e) constitutes a barrier to the entry of any other foreign mycorrhizal mycelia.

SYNTHESIS SUBSTRATE

The efficiency of the substrate made up of vermicuiite-blond peat-brecciolino has been verified with respect to natural soils obtained from natural truffle fields, MELFERT and various mixtures of organic and inorganic compounds.

The components of the substrate and their relative ratios have been verified in relation mainly to the nutritional supply at the initial pH values and to its buffering capacities.

Only the substrate identified responds to the characteristics necessary to ensure optimal development of truffle mycorrhiza. Other types of peat or different granulometries of gravel cause the relationships between the components to change in a complex way.

The three components (vermiculite packed in bags, sterile peat packed in buckets and calcareous gravel from quarry) can already be considered almost sterile at the origin and therefore do not require further treatments.

Given the lack of easily available nutrients, the truffle mycelium is forced to quickly establish the mycorrhizal relationship and, on the other hand, the same type of relationship is "obligatorily" carried out by the root system in order to access the scarce nutritional resources contained in the peat and vermiculite.

During the planting phase, again due to the poverty of the synthesis substrate, the mycorrhizal root systems and the fungal mycelium invade the surrounding soil, preventing the entry of mycorrhizal fungi already present in the soil.

The substrate also creates a fresher and more aerated microenvironment around the original root system than the soil context, facilitating the rooting of plants.

Claims (6)

CLAIMS 1. Process for the production of truffle plants characterized by the following peculiarities: a) inoculum consisting of a sporal suspension produced by a homogenate of sporophores of the desired Tuber species in aqueous solution of Carboxymethylcellulose; b) post-inoculation culture substrate for mycorrhizal synthesis consisting of vermiculite, Russian blonde sphagnum peat and calcareous limestone gravel of 0.1-2 mm in diameter. 2. Process according to claim 1 (point a) characterized in that the spore suspension is made in a 0.7-1.02 high density carboxymethylcellulose solution; 3. Process according to claims 1 (point a) and 2 also with respect to different concentrations of high, medium and low density carboxymethylcellulose; 4. Process according to claims 1 (point a) and 2 also with respect to different concentrations of the other tested adhesive substances, previously mentioned on pgs. 7 and 8: Carboxyethylcelluse, xanthan gum, agar-agar, carrageenins, glucose, maltose, sucrose, starch; 5. Process according to claim 1 (point b) also with respect to different volume ratios of the components of the substrate; 6. Process according to claim 1 (point b) and 5 also with respect to different types of peat and limestone gravel. All substantially as described and illustrated and for the specified purposes.