SINGLE-SEED SOWING IN THE TREATMENT OF CONTROLLED MYCORRHIZATION OF SCOTS PINE (PINUS SYLVESTRIS L.) GROWN ON THE PEAT SUBSTRATUM IN CHANNELS

Stefan Kowalski¹, Józef Walczyk², Paweł Tylek^3
1 Department of Forest Pathology, Agricultural University of Cracow, Poland
² Department of Forest Works Mechanization, Agricultural University of Cracow, Poland
³ Department of Forest Work Mechanisation, University of Agriculture in Krakow, Poland

ABSTRACT

If in the site of planting stock production no natural mycorrhization of seedlings can be expected, the controlled mycorrhization of seedlings should be introduced using ectomycorrhizal fungi selected in laboratories. Controlled mycorrhization is, however, associated with a precise dosage and introduction of inoculum of a mycorrhizal fungus to the substratum. Mechanization of this treatment may considerably shorten the whole technological process, and it may have a positive effect on its success. Using a single-seed sowing about 35% of seed material was saved.

Key words: biopreparation, controlled mycorrhization, single-seed sowing, grown in frames.

INTRODUCTION

Technical progress in the forest nursery practice, aiming at production of a high quality planting stock, pays more and more attention to the importance of mycorrhizae for the optimal growth and development of seedlings of forest trees, especially those which are going to be planted on degraded soils [3, 7, 9, 10]. If in the site of production of planting stock no natural mycorrhization of seedlings may be expected, or there have occurred microbiological disturbances eliminating ectomycorrhizal fungi proper for a given tree species, the controlled mycorrhization of seedlings should be introduced using ectomycorrhizal fungi selected in laboratories [8]. A method of production of the biopreparation based on an active strain W40 of the fungus Hebeloma crustuliniforme, developed in the Department of Forest Pathology, Agricultural University of Cracow, makes such a treatment possible, mainly in the case of seedlings grown in containers and those grown on peat substrata in frames or boxes [4, 5]. Under such methods of production of planting stock the substratum is most often devoid of symbiotic fungi proper for a given tree species.

It should be remembered that all our forest trees are mycotrophic, while mycorrhizae occurring on their roots are mostly the ectomycorrhizae [1]. Trees growing without fungal partners able to make a proper contact with a suitable host are susceptible to physiological disturbances, become weakened and even die [2]. Keeping in mind the program of afforestation of degraded lands and former farmlands in Poland, it is necessary to produce planting stock furnished with ectomycorrhizae proper for a given tree species [11].

Research showed that the mycotrophy of Scots pine, planted in soil degraded by air pollution, may be considerably improved by planting seedlings with a properly developed ectomycorrhiza [6]. Controlled mycorrhization is, however, associated with a precise dosage and introduction of inoculum of a mycorrhizal fungus to the substratum. Mechanization of this treatment may considerably shorten the whole technological process, and it may have a positive effect on its success.

RESEARCH AIM

The objectives of this study were to compare the effects of two methods of introduction of the mycorrhizal biopreparation with the fungus Hebeloma crustuliniforme to the substratum on the success of the treatment of controlled mycorrhization of Scots pine seedlings, and to study the effects of two sowing methods, mechanical single-seed sowing and manual broadcast sowing, on production efficiency and quality of planting stock.

MATERIAL AND METHODS

The investigations were carried out in the forest nursery in Olkusz Forest District, in two channels, each 1.5 are in area. The channels, where Scots pine seedlings subjected to controlled mycorrhization with the fungus Hebeloma crustuliniforme were grown, were located in an open area situated between two belts of old Scots pine stand. Before filling them with a new substratum they were carefully cleaned off an old substratum, right to the mineral soil (view of the channels is presented in Figure 1).

It was assumed that 25 m³ of the substratum is needed for one are of the seed plot. The substratum was prepared in two parts. The first part, i.e. 16 m³, was made up of unsterilized high-moor peat deacidificated with dolomite, including 15% of pearlite, and with addition of the “Azofoska” fertilizer. The pH of this substratum was 4.5. The substratum prepared in such a way was spread evenly in the bottom of the seed plot in the channel, and by gradual watering its moisture was brought to a desired level.

The second part of the substratum, i.e. 9 m³, was prepared on the basis of the sphagnum peat, sterilized and deacidificated in a similar way as in the case of the first part. This part contained vermiculite and pearlite, 15% and 5% respectively. Before sowing the biopreparation with the fungus Hebeloma crustuliniforme was added to this part of the substratum, as well as the Osmocote fertilizer, 2.0 kg/m³ of substratum.

PREPARATION OF THE VERMICULITE-PEAT BIOPREPARATION WITH THE FUNGUS HEBELOMA CRUSTULINIFORME FOR THE TREATMENT OF CONTROLLED MYCORRHIZATION OF SEEDLINGS GROWN IN CHANNELS

The biopreparation, till time of its usage in the nursery, was kept in a cold store at stable temperature 8–10°C. A dose of the biopreparation with the fungus Hebeloma crustuliniforme in the substratum in channels was 350 litres of pure preparation per 1 are of the seed plot.

The part of the biopreparation assigned for the treatment of controlled mycorrhization of pine seedlings was manually broken up in a clean container with addition of vermiculate in order to obtain a homogeneous and loose mixture, and then it was screened using a clean sieve with 5 mm mesh. The assumed 15% (by volume) of vermiculate was divided in such a way as to mix 10% directly with the substratum, while 5% with the biopreparation. This made a uniform dosage of the biopreparation possible, and created a favourable environment for the development of the fungus.

MIXING OF THE BIOPREPARATION WITH THE SUBSTRATUM

Two methods of mixing of the biopreparation with the substratum were used. In the first case, the whole amount of the prepared biopreparation was evenly mixed with the second part of the substratum in a concrete mixer, and immediately transferred to a seed plot in the first channel so to make an even layer over the bedding. In the second case, the second part of the substaratum was evenly spread over the bedding in the second channel, and then the biopreparation with the fungus Hebeloma crustuliniforme was scattered over it, and using a soil miller the biopreparation was mixed with the second part of the substratum to a depth of about 15 cm (Fig. 2). The substratum containing the biopreparation with the fungus in seed plots in both channels was slightly compacted with a light roller. In one part of the seed plot a mechanical single-seed sowing was performed, while in the second part a manual broadcast sowing.

SOWING

After mixing the biopreparation with the substratum using a soil miller the substratum was very loose, and this would make the work of the single-seed seeder difficult. For this reason directly after mixing the biopreparation with the substratum, and before sowing, the manual rolling was applied (Fig. 3).

The sowing was carried out on 29 April 2004. Seed of 96% vitality originated from the managed stand, and the weight of 1000 seeds was 6.8 g. The sowing was conducted with the single-seed seeder, the Omega S079 type manufactured by ROLMASZ in Kutno, in rows 0.05 m apart, with spacing in a row 0.037 m. this theoretically would give 540 seedlings/m2. For comparison reasons also a manual sowing was carried out using 6.5 g of seed per m2, which theoretically would give 848 seedlings/m2 taking seed vitality into account. Seedlings in both experimental variants were not additionally fertilized during the whole growing season. Sowing is shown in Figure 4.

During sowing the seeder was moving on the guide so it could travel along the same route many times (Fig. 4). Two rows were seeded in a single passage, then the seeder returned with a lifted sowing section. Next, the sowing section was shifted on the frame for the distance equal to spacing of two rows. After this the sowing section was lowered down and the next sowing passage was performed [12, 13]. The seeder was driven by an electric motor with its current-carrying wire suspended on a cable (Fig. 3).

RESULTS

The investigations carried out at the end of growing season showed that 100% of Scots pine seedlings was furnished with the ectmycorrhizae characteristic for the association of Scots pine with the fungus Hebeloma crustuliniforme. In this respect there were no differences between different methods of introduction of the biopreparation into the substratum. While the mechanization of this technological process undoubtedly simplified procedures used in the treatment of controlled mycorrhization , considerably shortened the time of the operation, and affected its costs. In both cases the substratum was well penetrated by mycelium of Hebeloma crustuliniforme, and in various places in the seed plot there appeared numerous fructifications of this fungus (Fig. 5).

Scots pine seedlings were very well developed, had a dark green assimilation apparatus, and they did not show any symptoms of nutrient deficiency in spite of a very low level of mineral fertilization. Taking their morphological features into consideration about 80% of them was qualified to the quality class one. The seedling developed from seed sown by the single-seed seeder had a very well developed root system with numerous branches of the first and second orders, and they were amply furnished with ectomycorrhizae (Fig. 8). In most cases these mycorrhizae assumed the single and dichotomic morphological forms with evident ample white fungal mantle and hyphe spreading from it (Fig. 6).

On 22 October 2004 the number of seedlings per one m2 of the seed plot was determined on the basis of the seedling count within a frame 0.25 x 0.25 m randomly placed in each experimental variant (Fig. 7). Counting of seedlings in each plot was repeated 10 times.

The numbers of seedlings are shown in Figure 8. They show that the single-seed sowing created better conditions for seed germination. Under the assumed technology of the single-seed sowing the number of seedlings was by only about 6% lower than the estimated number of seeds sown. While this percentage in the case of the manual sowing amounted to as much as 42%. It is supposed that in the latter case the main reason for such a low efficiency was a poor contact of seeds with the substratum (seeds were not pressed to the soil), and also uneven depth of a layer covering seeds. Therefore, it may be concluded that using the single-seed sowing about 35% of seed material is saved at the same number of seedling per a unit of area as in the case of the hand sowing.

DESTINATION OF SCOTS PINE SEEDLINGS SUBMITTED TO THE TREATMENT OF CONTROLLED MYCORRHIZATION WITH THE FUNGUS HEBELOMA CRUSTULINIFORME

Seedlings submitted to the treatment of controlled mycorrhization should be planted in all places where there is a lack of ectomycorrhizal fungi able to associate symbiotically with seedlings of forest trees. Therefore, the mycorrhized seedlings should be produced mainly for afforestation of former farmland, wastes, reclaimed lands, lands degraded by air pollution, large area burns, etc.

Scots pine seedlings grown in the nursery of the Olkusz Forest District and submitted to the treatment of controlled mycorrhization with the fungus Hebeloma crustuliniforme were used for the afforestation of the sand excavation. Sand was used for coal mine backfilling.

CONCLUSIONS

1. This study showed that the utilized technology of the treatment of controlled mycorrhization of Scots pine seedlings grown on the peat substratum in channels in the open forest nursery was successful. At the end of the growing season 100% of Scots pine seedlings was furnished with ectomycorrhizae characteristic for the association of Scots pine with the fungus Hebeloma crustuliniforme.

2. The introduction of a mechanical mixing of the substratum with the biopreparation did not make the development of H. crustuliniforme mycelium worse, while the technological process connected with the treatment of controlled mycorrhization was considerably improved.

3. The single-seed sowing permitted to obtain a better area covering with seedlings, lowering spontaneity in their distribution occurring in the case of manual sowing.

4. Using the single-seed sowing about 35% of seed material was saved.

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