IL112796A - Fibrous substrate based on cellulose ester for growing plants - Google Patents

Abstract

Substrate for the culture of plant reproduction material, said substrate essentially consisting of a lower aliphatic ester acid and cellulose-based non sterile fibrous material. The substrate of the invention can contain an agrochemical active material.

Description

Ref : 3497/95 112796/2 OTITIS VlPJ TOD ITNJl "IIDDN "7U 0ΊΌΌ13Τ]Π ϋ'ΊΓΌ Ώ^\?1 FIBROUS SUBSTRATE BASED ON CELLULOSE ESTER FOR GROWING PLANTS Fibrous culture substrate based on cellulose ester The present invention relates to a novel substrate which can be used for growing plants, to a process for obtaining and using it, and to the plants grown with the aid of this substrate.

In particular in market gardening, horticulture and forest nurseries, it is known to use techniques for germinating seeds on clumps which are subsequently planted mechanically rather than by direct sowing. They can thus guarantee a regular plant stand, shorten the vegetation period or else, if the plants are grown in a glasshouse, improve productivity by better handling of the input factors (fertilizers, trace elements ... ) which are delivered by the irrigation water.

The clumps used are mainly composed of mixtures of peats dug from bog areas. They can be mixed with other fibres (wood, coconut) or with materials of mineral origin (pozzolana, schists, clay, vermiculite, rock wool, glass wool ...) .

It has also been proposed to use pulp or cellulose acetate granules as culture substrate.

It has also been proposed to use sterile cellulose and sterile cellulose acetate as sterile culture substrates for micropropagation.

In certain areas, the intensification of glasshouse cultures is expressed by a great increase in input factors, a proportion of which is dispersed in the soil. The soil-free methods in non-sterile medium are thus now in demand since they favour the reduction of water and (recycled) input factor consumption and limit discharges into the soil. However, these methods involve the use of inorganic substrates and plastic materials, whose disposal, which is increasingly required by regulations, is difficult and costly.

Moreover, intensification of the cultures and the demand by the customer for plantlets which can be pricked out and are in excellent plant health increases the need for substrates which allow good anchorage of the plantlets' roots and which have all the following particularly demanding characteristics: freedom from toxicity, good state of health, good distribution of air and water, good resistance to settling in the course of time, and good storage and good release of nutrient elements (cation exchange capacity) .

It is therefore an object of the invention to provide a novel non-sterile substrate of controlled biodegradability which exhibits these characteristics and allows the plantlets raised to be transplanted to a completely different natural (soil) or artificial culture medium.

The subject of the invention is therefore a non-sterile culture substrate for plant propagation material, of controlled biodegradability, characterized in that it is essentially composed of a fibrous material based on a cellulose ester.

Plant propagation material is to be understood within the scope of the present invention as being any plant tissue capable of giving rise to a whole plant when placed under suitable culture conditions, such as, for example, a natural or artificial seed, a plantlet, a cutting or a meristematic tissue.

Meristematic tissue is to be understood as being any plant tissue or association of plant cells capable of developing into a whole plant or part of a whole plant when placed under suitable conditions. This term is to include any type of plant tissue, especially: somatic tissue, somatic embryo, zygotic tissue, germ, adventive bud, shoots, shoot primordium, protocorm analogues (also known under the term protocorm-like body) , the tissue known under the term green spot, germinal cells and natural seeds (also known under the term germ line) .

The plant material thus defined may belong to any species of, especially, annual or perennial food crops, such as sugar beet or fodder beet, maize, oilseed rape; vegetable crops, such as celery, lettuces, cabbage, cauliflower, carrot, eggplant, bell pepper, tomato, onion, garlic, ginger, strawberries, melons, watermelons, cucumber, asparagus; food or industrial crops, such as sugar cane or tobacco; crops of medicinal plants, such as belladonna, ginseng or yew; ornamentals for mass plantation in containers in glasshouses such as chrysanthemums/ gladioli, lilies, orchids, amaryllis, geraniums, begonias, African violets or poinsettias; trees, shrubs or tree-like species with hardy or deciduous foliage such as conifers, maples, palms, the coffee tree, the cocoa tree, fruit trees and grapevine.

Cellulose ester is to be understood as being any material based on cellulose which is esterified with the aid of a lower aliphatic acid to various degrees, as described in Ullmann's Encyclopedia of Industrial Chemistry, 8th completely revised edition. Vol. A5, VCH Verlags GmbH, einheim, RFA 1986, which not only describee the fibrous materials based on these esters but also the processes for their preparation. The cellulose ester is preferably a cellulose acetate. In a preferred manner, esters, especially acetate, are used which can have undergone treatments which impart an at least partial, controlled biodegradability to the ester by reducing the content of aliphatic acid, preferably acetic acid, to under 53 %, preferably under 49 %, by a variety of degradation processes, for example by hydrolysis, as described in the unpublished German Application P 43 22 965.4, or by alkali treatment with the aid of ammonia or a base comprising at least one NH or NH2 group, as described in the unpublished German Application No. P 43 22 966.2, preferably urea or urotropine. "Content of lower aliphatic acid (acetic acid) " is to be understood, within the scope of the invention, as being the proportion of lower aliphatic acid (acetic acid) bonded in the cellulose ester (acetate) and expressed in per cent by weight. The biodegradability is controlled by adjusting the degradation level of the cellulose ester to suit the intended purpose (type of culture, nature of the species grown and the like) .

The fibrous material is in the form of continuous threads, discontinuous fibres or tows, flat or textured, of diverse cross-section, such as round, in Y-shape or other shapes, in random or orientated arrangement, preferably in the form of tows, in bulk or compacted to give individual compacted structures, of reduced size, such as mini-clumps, also termed plugs, or aggregations, more importantly such as blocks or slabs. The threads are generally obtained by spinning a solution, called collodion, of cellulose acetate in a suitable organic solvent, such as acetic acid or acetone, by the processes described in the reference hereinabove. "Mini-clumps" are generally to be understood as being supports substantially in the form of a cylinder, in truncated form or in the form of a parallelepiped 2 to 4 cm in length and 2 to 5 cm in diameter; equally, "blocks" are understood as being supports which have a greater volume, substantially in the form of a parallelepiped, 10 to 100 cm in length, 10 to 15 cm in width and 5 to 10 cm in thickness, while the term "slab" is used rather for supports of even greater volume. It is worth noting that the shapes described hereinabove are the most customary, but that any other convenient shape of a support is also part of the invention.

Preferably, the substrate according to the invention can additionally contain various additives: - either placed between the fibres: water, nutrient elements or protective elements for the plant (agrochemical active ingredient) - or deposited on and fixed to the surface of the fibres, or, preferably, incorporated into their bulk, non-phytotoxic spinning adjuvants or cohesion adjuvants between the fibres themselves, or else elements which are useful for the culture of the plant material, such as an agrochemical active ingredient, in particular insecticide or fungicide. As fungicide there may be mentioned, for example, fungicides from the families of the triazoles such as, for example, triticonazole, or phosphorous acid, its salts and its esters, or from the family of the 2- (3, 4-dimethoxy-phenyDbenzamides . More generally, any agrochemical active ingredient, especially from amongst those known, may be used.

The substrate according to the invention can also be mixed in various proportions with culture substrates known per se such as, for example, dark or light peat, cellulose-derived fibres and threads (cotton, paper ...), wood fibres, coconut fibres or else mineral supports, such as rock wool or glass wool.

The invention also relates to a process for obtaining a substrate as described hereinabove, characterized in that a fibrous material based on a cellulose ester, preferably of controlled biodegradability, is produced and packaged in compact and non-sterile form.

The invention also relates to a culture method for agricultural or horticultural plants, characterized in that a substrate as described hereinabove is used, and to the plants obtained by this method.

The invention will be understood better with the aid of the examples hereinbelow which are given by way of illustration, but not by way of limitation.

Example 1: glasshouse trial: A plug, namely a cylinder composed of cellulose acetate fibres, 1 cm in length and 1 cm in diameter, is used as substrate, the cellulose acetate fibres having been obtained as follows: a spinning solution containing 28 % by weight of cellulose acetate and 0.5 % of titanium dioxide in acetone was prepared. The water content of this spinning solution is adjusted to 3 % by weight. The cellulose acetate used has an acetic acid content of 55.4 % and a degree of polymerization (DP) of 220. The spinning solution is filtered and dry-spun using a conventional tow spinning apparatus. The cellulose acetate filaments are combined to give a tape, crimped using a pressure-crimping machine and dried in a drum dryer. As the tape enters this crimping machine, it has an entry speed of 550 m/min. The residence time of the tape of cellulose acetate filaments in the drum dryer is 5 minutes. As the filter tow of cellulose acetate filaments leaves the crimping machine, it is deposited free from tension with the aid of a packing machine and is baled; this bale has a residual moisture content of 5.5 % by weight. The tow thus obtained has a linear density of 38,500 dtex, and the filament linear density is 3.3 dtex, the cross-section of the filaments being Y-shaped.

By truncating this tow, plugs as described hereinabove are prepared. Seeds of different species (carrot cultivar Nandor; petunia cultivar Nain compact (Royal Fleurs) ; wheat cultivar Talent) are placed in the plugs at a rate of one seed per plug. A control without plug, that is to say with seed alone, is tested simultaneously. 20 plugs per species and per replication are placed on 20 ml of a previously moistened mixture composed of half sand and half standard soil (brand SNEO) , which is based on Care -and Sphagnum-derived peats. The set-up is watered 2 to 3 times per week. The experiment is conducted in a glasshouse. The temperature is 22°C and the relative humidity approximately 60 %. These glasshouses allow use to be made of natural lighting. However, if the natural lighting is too weak (less than 250 μΕ.π."2.β"χ) , booster lighting on a mobile bar is used which is adjusted in such a manner that the illumination is 500 μΕ.Ώχ'2.Β'1 when the lamp is above the plants and 70 μΕ.Ία'3. a'1 when it is opposite. The duration of this booster lighting is limited to 14 hours per photoperiod.

First, the germination rate is observed and then, 7 days after sowing, the plant height is observed. Under these conditions it is observed that the germination rate is, in the case of petunia, 73 % compared with 85 % for the control, in the case of carrot 72 % (80 %) and in the case of wheat 98 % (93 %) . The plant height is, in the case of wheat, 11.9 cm for the substrate according to the invention compared with 12.3 cm for the control. In all these cases, the differences are not significant.

This demonstrates the excellent suitability which the non-sterile substrate according to the invention has for the culture of plants.

Example 2; Glasshouse trial: A plug, namely a cylinder composed of cellulose acetate fibres, 25 mm in length and 20 mm in diameter and with a density of either 100 kg/m3 or of 150 kg/m3, is used as substrate, the cellulose acetate fibres having been obtained as in Example 1, except that the spinning conditions are such that the tow has a linear density of 35,000 dtex and a filament linear density of 3 dtex.

The plugs are arranged in expanded-polystyrene sheets/ marketed by Grodan, which are 40 cm wide and 60 cm long and contain 240 receptacles, at a rate of one plug per receptacle.

The seeds of a variety of species (tomato and French marigold) are arranged on the upper surface of the plugs at a rate of one seed per plug and 48 plugs per species per treatment, in three replications. The seeds are subsequently covered by a fine layer of VERMEX vermiculite.

The set-up is placed in a glasshouse. It is provided with irrigation of nutrient solution every hour, from 6 am to 8 pm, with the aid of a mobile sprinkler bar. The concentrated nutrient solution (Plantin) is diluted upon application in such a way that the final conductivity of the mixture is between 1.5 and 2 mS/cm and the final pH of the solution is between 5.5 and 6.5.

Glasshouse and observation conditions are as in Example 1.

Under these conditions, the following germination rates are observed: Variance analyses show no difference between the results.

All these results demonstrate the excellent suitability of the substrate according to the invention.

Bn-am l <¾ 3. Glasshouse trial ; The procedure of Example 2 is followed, except that seeds of other crops are used and that the sheets are kept tinder frames for 3 days before being cultured with automatic sprinkling.

Under these conditions, the following germination rates are obtained: Species Number of Cellulose Rock wool seeds sown acetate Cucumber 8 100 100 Broccoli 28 93 93 Carnation 8 88 75 Eggplant 8 100 75 Cotton 8 75 38 Gerbera 8 75 50 Radish 8 100 100 Endive 8 100 100 Onion 16 88 100 Melon 16 75 88 Geranium 8 100 88 Chicory 8 75 75 Celery 8 100 88 Cabbage 8 100 100 Leek 8 88 62 Lettuce 8 75 100 Example 4: Culture on cellulose acetate plugs of controlled biodegradabilitv A plug, namely a cylinder composed of cellulose acetate fibres, 20 mm in length and 8 mm in diameter, is used as substrate, the cellulose acetate fibres having been obtained as in Example 2, except that urea and, respectively, urotropine are added to the spinning solution, these being molecules which guarantee the biodegradability of the acetate, in such a manner that their end concentration in the fibres is approximately 5 %. Their density is 125 kg/m3. At the same time, a control plug made of Grodan rock wool, and control plugs 20 mm in diameter and with a density of 100 kg/m3 and 150 kg/m3, which have been described in the preceding examples, are used.

The sprinkling and glasshouse control conditions are as in Example 2.

Under these conditions, the following germination rates are observed: Variance analyses show no difference between the results.

All these results demonstrate the excellent suitability of the substrate according to the invention.

Example 5; Gradual release into the water of an agrochemical active ingredient which is included in the cellulose acetate fibres Cellulose acetate fibres, 20 mm in length and 8 mm in diameter, which have been obtained as in Example 1, except that a single or double amount of triticonazole, a fungicidal agrochemical active ingredient, is added to the spinning solution, in such a manner that their final concentration in the fibres is approximately 5 and 10 % by weight, respectively. The filaments obtained have a linear density of 2.2 and 15 dtex, respectively, their cross-section being round. 20 mg of fibres are placed into a flask containing 300 ml of demineralized water. The flask is placed on an orbital shaker whose plate revolves at 100 revolutions per minute. There is one flask per sample per dose.

After a predetermined period, two samples are taken with the aid of a syringe by drawing in an aliquot of the liquid phase. The solution sampled is passed through a filter of mesh size 0.2 μχα.. Assay is carried out by HPLC. The concentrations are determined by comparison with a standard. The results are shown in the graph of Figure 1. g-iram i a 6 ; Powdery mildew test on barley using a mixture of fibres/potting compost Cellulose acetate fibres are obtained as in Example 5, except that the filaments obtained have a linear density of 2.2, 7.8 and 15 dtex respectively. 2.4 g of the fibres thus obtained are incorporated into 100 g of potting compost using a Waring Blender. The mixture is taken up in, and stirred with, 2.9 kg of potting compost. Half of the substrate obtained is divided between pots with a square cross-section, of side length 7 cm, at a rate of approximately 300 ml per substrate per pot.

The rest of the substrate is taken up in, and mixed with, another 1.5 kg of potting compost. Thus, the mixture obtained contains half as many fibres containing the active ingredient as the previous mixture. As previously, half of the substrate obtained is divided between pots of a square cross-section, side length 7 cm, at a rate of approximately 300 ml per substrate per pot. This operation is repeated until the desired concentration of fibres in the potting compost is obtained.

In the same manner, samples containing 15 dtex fibres without active ingredient are prepared as a control.

Other control samples are prepared which contain the active ingredient in other than fibre form by replacing the 2.4 g of fibres by 6.4 g of seed dressing powder containing 2.5 % by weight of triticonazole, the amount of potting compost being reduced from 3 to 2 kg.

Other control samples are prepared by filling the pots with potting compost without cellulose acetate fibres, into which there have been sown untreated seeds and seeds which have been treated with the formulation commercially available under the name Real, a flowable for seed treatment containing 209 g/1 of triticonazole as active ingredient, at a rate of 120 g/hundredweight.

The seeds are placed into pots at a rate of 48 seeds, that is to say 2.16 g per pot, and are then covered by a fine layer of untreated potting compost.

The plants are grown in the glasshouse with manual sprinkling, the glasshouse conditions (temperature, humidity, illumination) being those given in Example 1. 8 days and 16 days, respectively, after sowing, the barley is inoculated with powdery mildew (Eriayphe gramini hordei) by brushing the pots against other pots containing inoculum barley. Visual assessment is effected 8 days after the second inoculation. Under these conditions, the following results are observed (a.i. = active ingredient): These results demonstrate clearly the good protection imparted to the plants by the substrate based on fibres containing triticonazole. Moreover, this treatment imparts better protection than the protection imparted by traditional seed treatment with triticonazole, while avoiding all signs of phytotoxicit .

Example 7; Test for mildew on tomato using a mixture of fibres/potting compost Cellulose acetate fibres are obtained as in Example 5, except that the filaments obtained have a linear density of 2.2, 6.3 and 15 dtex respectively, and that the triticonazole is replaced by N-methyl-N-ethyl-4-trifluoromethyl-2- (3,4-dimethoxyphenyl) -benzamide. 1.84 g of the fibres thus obtained are incorporated into 100 g of potting compost using a Waring Blender. The mixture is taken up in, and stirred with, 0.9 kg of potting compost. Half of the substrate obtained is divided between pots with a square cross-section, of side length 7 cm, at a rate of approximately 300 ml per substrate per pot.

The rest of the substrate is taken up in, and mixed with, another 0.5 kg of potting compost. Thus, the mixture obtained contains half as many fibres containing the active ingredient as the previous mixture. As previously, half of the substrate obtained is divided between pots of a square cross-section, side length 7 cm, at a rate of approximately 300 ml per substrate per pot. This operation is repeated until the desired concentration of fibres in the potting compost is obtained.

In the same manner, samples containing 15 dtex fibres without active ingredient are prepared as a control.

Other control samples are prepared which contain the active ingredient in other than fibre form by replacing the 1.84 g of fibres by 0.4 g of a wettable powder containing 2.5 % by weight of N-methyl-N-ethyl-4-trifluoromethyl-2 - (3 , 4-dimethoxyphenyl) benzamide .

Other control samples are prepared by filling the pots with potting compost without cellulose acetate fibres.

Tomato plants (cultivar Marmande) which are 10 days old are pricked out into the pots thus prepared at a rate of 1 plant per pot.

The plants are grown in the glasshouse.

The plants are grown in the glasshouse with manual sprinkling, the glasshouse conditions (temperature, humidity, illumination) being those given in Example 1. 15 days after pricking out, the plants are inoculated by spraying them (Fisher sprayer) with mildew (Phytophthora infestans) spores obtained by suspending in water spores which have developed on tomato leaves at a rate of 30,000 spores/ml.

The plants are placed in culture cells in the glasshouse at 20°C and a relative humidity of 90 %.

Visual assessment is effected 6 days after the second inoculation. Under these conditions, the following results are observed (a.i. = active ingredient) : Substrate type Formulated Active Number of product ingredient diseased per pot per pot plants (mg) (mg) Untreated potting 0 0 100 compost Potting compost + 100 0 100 fibres without a.i.

Potting compost + 115 10 23 fibres of 2.2 dtex with a.i.

Potting compost + 119 10 26 fibres of 7.8 dtex with a.i.

Potting compost + 115 10 25 fibres of 15 dtex with a.i.

Claims (22)

1. Culture substrate for plant propagation material, characterized in that it is essentially composed of a non-sterile fibrous material based on an ester of a lower aliphatic acid and cellulose.

2. Substrate according to claim 1, characterized in that the fibrous material is based on an ester of a lower aliphatic acid and cellulose of controlled biodegradabilit .

3. Substrate according to one of claims 1 and 2, characterized in that the fibrous material is based on a cellulose acetate.

4. Substrate according to one of claims 1 to 3, characterized in that the fibrous material is in bulk form.

5. Substrate according to one of claims 1 to 3, characterized in that the fibrous material is in compacted form.

6. Substrate according to claim 5, characterized in that the fibrous material is in the form of a mini-clump.

7. Substrate according to claim 5, characterized in that the fibrous material is in the form of a block.

8. Substrate according to one of claims 1 to 7, characterized in that the cellulose ester has a content of aliphatic acid of less than 53 %, preferably less than 49 %.

9. Substrate according to one of claims 1 to 8, characterized in that it contains, in addition to the cellulose ester, a non-phytotoxic adjuvant for manufacturing the fibrous material.

10. Substrate according to one of claims 1 to 8, characterized in that it contains, in addition to the cellulose ester, at least one agrochemical active ingredient .

11. Substrate according to claim 10, characterized in that the agrochemical active ingredient is a fungicide.

12. Substrate according to one of claims 1 to 11, characterized in that it contains, in addition to the cellulose ester, at least one substrate of a different nature.

13. Substrate according to claim 12, characterized in that it contains, in addition to the cellulose ester, at least one peat-type substrate.

14. Substrate according to claim 12, characterized in that it contains, in addition to the cellulose ester, at least one rock-wool-type substrate.

15. Substrate according to one of claims 1 to 14, characterized in that it contains, in addition to the cellulose ester, at least one nutrient element.

16. Substrate according to one of claims 1 to 15, characterized in that the plant material is a seed.

17. Substrate according to one of claims 1 to 15, characterized in that the plant material is a cutting.

18. Substrate according to one of claims 1 to 15, characterized in that the plant material is a plantlet.

19. Substrate according to one of claims 1 to 15, characterized in that the plant material is a meristematic tissue.

20. Process for obtaining a substrate according to one of claims 1 to 19, characterized in that a fibrous material based on a cellulose ester of controlled biodegradability is produced and in that it is packaged in compact and non-sterile form.

21. Culture method for agricultural or horticultural plants, characterized in that a substrate according to one of claims 1 to 19 is used.

22. Plant grown by the method according to claim 21. LUZZATTO * LUZZATTO