EFFECT OF RYE (SECALE CEREALE L.) AS A COVER CROP ON HEALTH OF UNDER-GROUND PART OF FIELD TOMATO

Agnieszka Jamiołkowska
Department of Plant Protection and Quarantine, Faculty of Horticulture and Landscape Architecture, University of Life Sciences in Lublin, Poland

ABSTRACT

No-tillage method with various cover crops has become popular recently in vegetable production [3]. The aim of a study conducted in 1998-2000 was evaluation of the effect of rye (Secale cereale L.) as a cover crop on the health of roots and stem base of tomato cultivated in the field. The rye decreased the number of Fusarium oxysporum and increased the number of antagonistic fungi Trichoderma spp. and Penicillium spp. on the roots and stem base of tomato. The numerical classification method [19, 22] applied to compare fungal communities from the roots and stem base of tomato grown conventionally and in field with rye as cover crop showed that similarity coefficient ranged from 10% to 82%.

Key words: cover crop, rye, tomato, Fusarium oxysporum, Fusarium spp.,.

INTRODUCTION

Environment protection necessitates a search for new cultivation methods, which might replace traditional cultivation and intensive protection with chemicals [13]. One of such alternative methods is direct sowing into cover crop [1,2,3,7,18]. Use of cover plants facilitates weed control and increases yield of tomato [8]. This production method ensures higher content of post-harvest remnants of cover plants and better soil properties [13]. It affects soil environment by increasing number of saprotrophic microorganisms, which contribute for reduced infestation of crop plant by pathogenic fungi [9,14]. Grass crops protect the soil against erosion and nutrient leaching. By improving water infiltration they are conductive to early cultivation of vegetables in temperate climate. Rye is one of grass crops recommended both as off-season crop and as mulch for many cash crops [26].

The aim of the study was to evaluate effect of rye as cover crop on health of under-ground part of field grown tomato.

MATERIAL AND METHODS

The research was conducted during 1998-2000 in the Felin Experimental Farm (near Lublin), on experimental plots with field tomato cultivated with rye as a cover crop or without it (control). The experiments were carried out on tomato plants cv. Rumba planted at two experimental plots, each with area of 100 m². Health status of tomato plants cultivated with rye as a cover crop or traditionally was studied. Rye of cv. Dankowskie was sown the previous autumn and in the spring, when plants were 50 cm high, it was treated with gliphosat (Roundup 360 SL 3 l·ha^-1). After two weeks, when dry rye covered fully the surface, tomato seedlings were planted directly into the cover plant. Tomato transplants were planted into hand-made holes spaced 0.45×0.50 m. Control field was prepared in the traditional way. In 2^nd and 5^th weeks tomato plants were fertilized with Norway and lime salpetre (50 kg·ha^-1). During vegetation period no plant protection chemicals were used and all cultural treatments were conducted manually.

Stem base and roots of tomato were analyzed in laboratory. During full fruiting (July/August), 5 randomly selected tomato plants were sampled from each plot. Plant material was precleaned, rinsed with running water for 20 min. and then surface disinfected with 50% ethyl alcohol and 0.1% sublimate for 1 minute. Disinfected plant material was rinsed 3 times in distilled water. Next, 3 mm fragments were prepared and placed on Petri dishes on mineral medium of the following composition: saccharose – 38 g; NH₄NO₃ – 0.7 g; MgSO₄×7H₂O – 0.3 g; KH₂PO₄ – 0.3 g; FeCl₃×6H₂O – trace; ZnSO₄×7H₂O – trace; CuSO₄×7H₂O – trace; MnSO₄×7H₂O – trace; agar 20 g supplemented with distilled water up to 1000 ml. For each experimental treatment 50 dishes with plant material, 10 plant fragments per each dish, were prepared and incubated in thermostat at 20-22°C for 7 days in darkness. Obtained colonies of fungi were transferred to potato-dextrose medium (PDA-Difco) and identified to the species with the keys and monographs [5,6,12,21,23,24,25].

The obtained fungal communities were compared according to numerical classification method using statistical program SYN-TAX 5.01 [19,22]. This similarity analysis bases on determination of general similarity or dissimilarity of samples, which are individual objects (communities). To determine complete structure of dissimilarity for a set of "n" objects it is necessary to calculate n(n-1)/2 dissimilarity coefficients. Dissimilarity coefficient may be defined as a sum of absolute differences between elements of two data vectors [10]. In this study analysis of communities similarity was carried out basing on similarity coefficients i.e. percent differences showed on axis in 0-1 scale. In this case 0.1 percent difference between communities corresponds to 90% similarity of these communities [19]. Analysing the data, which describe studied communities, with SYN-TAX program 1 diagram (dendrogram) showing relation (variations) between compared communities was obtained.

RESULTS

Mycological analysis of roots and stem base of tomato, conducted in the years 1998-2000, revealed in total 782 isolates of fungi belonging to 24 species and non-sporulating mycelia (Table 1).

Among the species regarded as pathogenic, fungi from Fusarium genus were isolated most often (Table 1). Within Fusarium genus the most numerous was Fusarium oxysporum, which made 14.19% of all isolates. It occurred in higher number on plants from control plot than from the plot with rye, and its occurrence depended on cultivation year. During mycological analysis of stem base and roots also F. solani, F. equiseti and F. culmorum were noted and they made 0.51% to 4.09% of all isolates (Table 1). F. solani was isolated more often from plants grown on control plots than on rye plots, with the exception 1999 year (Table 1). F. equiseti was isolated more often from plants grown on plots with rye than on control plants, but its share in total number of identified fungi was only 4.09% (Table 1).

From the plant material many saprotrophic fungi from genera Acremonium, Aspergillus, Penicillium and Trichoderma were isolated. Their number was higher on roots and stem base of tomato grown with rye cover crop that on control plots (Table 1).

Analysis of similarity of fungal communities conducted by the method of numerical classification with SYN-TAX program showed similarity of the studied communities at the level of 10–82%. Similarity of 82% was observed for communities originated from plants from the control plots in 1998 and 1999 (Fig. 1). High similarity of communities, of 68%, was also noted for communities obtained from tomato plants cultivated with rye in 1999 and ones from control plot in 2000 (Fig. 1).

DISCUSSION

Cover plants increase organic matter content in soil and modify soil microbiological environment of cultivated plant [15,17]. Plant residues and their decay products are foodstuff for soil microorganisms [20]. As a result of three-year study of stem base and roots of tomato grown with rye as a cover crop or without it (control plot), it was found that fungi from genus Fusarium were the most numerous group of fungi developing on stem base and roots of tomato. This genus is considered by many authors [6,27] especially important as it includes pathogenic species. Among fungi obtained from plant material, Fusarium oxysporum was isolated in the highest amount. Number of pathogenic species as well as other soil microorganisms depends on cover crop [15]. Rye could influence soil mycoflora both as living crop and as mulch. Root exudates of rye contain some compounds that can directly induce plant resistance [11]. From tomato cultivated with rye as a cover crop less colonies of F. oxysporum were isolated, than from plants cultivated traditionally. So, rye used as a cover plant in field production of tomato reduced infestation of tomato roots with F. oxysporum. Presence of cultivated plant determines not only its infestation of cultivated plant by pathogenic species but affects also presence of other microorganisms, mainly saprotrophs from the genus Trichoderma and Penicillium. These fungi occur in environments rich in organic matter [15]. They are capable to inhabit fresh and decomposed organic matter [4,14]. Jamiołkowska and Wagner [15] inform that fungi from genus Trichoderma show highly positive biotic coefficient with pathogens. Presence of these fungi on the roots of cultivated plant is especially important as they compete with pathogens for food and space. Communities of soil fungi developing in the presence of rye were more favorable for growth of antagonistic species than these from conventional cultivation [16].

CONCLUSIONS

Rye as a cover crop reduced number of Fusarium oxysporum while increased number of saprotrophic species on roots and stem base of field grown tomato.

REFERENCES

1. Abdul-Baki A.A., Morse R.D., Devine T.E., Teasdale J.R., 1997. Broccoli production in forage soybean and foxtail millet crop mulches. Hort Science 32(5), 836-839.

2. Abdul-Baki A.A., Teasdale J.R., 1993. A no-tillage tomato production system using hairy vetach and subterranear clover mulches. Hort Science 28(2), 106-108.

3. Abdul-Baki A.A., Teasdale J.R., Korcak R., Chitwood D.J., Huettel R.N. 1996. Freshmarket tomato production in a low-input alternative system using cover-crop mulch. Hort Science 31(1), 65-69.

4. Baker K.F., Cook R.J., 1974. Biological control of plant pathogens. W.H. Freeman and Co., San Francisco.

5. Barnett H., 1960. Ilustrated Genera of Imperfect Fungi. Minneapolis.

6. Booth C., 1971. The genus Fusarium. Commonwealth Mycological Institute, Kew Surrey, England.

7. Borowy A., Jelonkiewicz M., 1999. Zachwaszczenie oraz plonowanie ośmiu gatunków warzyw uprawianych metodą siewu bezpośredniego w mulcz żytni [Weedy state and field of eight vegetable species sown directly In the mulch]. Zesz. Probl. Post. Nauk Roln., 466, 291-300 [in Polish].

8. Borowy A., Jelonkiewicz M., Chmielowiec P., 1998. Zachwaszczenie oraz plonowanie czterech gatunków warzyw uprawianych metodą bezorkową z zastosowaniem żyta sianego jesienią jako rośliny okrywowej [Weedy state and field of eight vegetable species cultivated with non-tillage method with Winter rye as cover crop]. Roczniki AR w Poznaniu – CCCIV, 27-32 [in Polish].

9. Dighton J., Jones H.E., Robinson C.H., Beckett J. 1997. The role of abiotic factors, cultivation practices and soil fauna in the dispersal of genetically modified microorganisms in soils. Applied Soil Ecology 5, 109-131.

10. Dzwonko Z., 1978. Application of Jaccard's and Sorensen's formulas in numerical comparison and classification of phytosociological records. Zesz. Nauk. UJ. Prace Bot. 6, 23-38.

11. Funck-Jensen D., Hockenhull D., 1984. Root exudation, rhizosphere microorganisms and disease control. Vaxtskyddsnotiser 48, 49-54.

12. Gilman J.C., 1957. Soil fungi. Iowa, USA.

13. Hoyt G.D., Monks D.W., Monaco T.J., 1994. Conservation tillage for vegetable production. Hort. Technol. 4(2), 129-135.

14. Hubner D.M., Watson R.D., 1970. Effect of organic amendment on soil-borne plant pathogens. Phytopathology 60, 22-26.

15. Jamiołkowska A., Wagner A., 2003. Effect of field pea (Pisum arvense) as cover crop on fungal communities from soil environment of tomato and their influence on Fusarium oxysporum Growth. Phytopathol. Pol. 30, 37-50.

16. Jamiołkowska A., Wagner A., 2005. Fungal communities from the rhizosphere of tomato cultivated conventionally and with rye as cover crop. EJPAU, Horticulture, 8, 4, www.ejpau.media.pl.

17. Lemańczyk G., Sadowski Cz. K., 2002. Fungal communities and health status of roots of winter wheat cultivated after oats and oats mixed with other crops. Biocontrol 47, 349-391.

18. Liebl R., Simmons F.W., Wax L.M., Stoller E.W., 1992. Effect of rye (Secale cereale) mulch on weed control and soil moisture in soybean (Glicyne max). Weed Technology 6, 838-846.

19. Łaska G., 2001. Metody syntaksonomii numerycznej i sposoby ich wykorzystania w analizie zróżnicowania roślinności [The numerical classification methods and possibilities of utilization of their in analysis of vegetation disparity]. Zesz. Nauk. Polit. Białostockiej. Nauki Techniczne 135, Inżynieria Środowiska 12, 83-119 [in Polish].

20. Mangenot F., Diem H.G., 1979. Fundamentals of biological control: 207-265. [In:] S.V. Krupa, Y.R. Dommergues (eds.) Ecology of root pathogens. Elsevier Scientific Publishing Company.

21. Nelson P.E., Toussoun T.A., Marasas W.F.O., 1983. Fusarium species. An Illustrated Manual for Identification. The Pensylvania State University Park & London.

22. Computer Programs for Multivariate Data Analysis in Ecology and Systematics. User's Guide. Scienta Publishing. Budapest.

23. Ramirez C., Martinez A.T., 1982. Manual and atlas of the Penicillia. Elsevier Biomedical Press Amsterdam. New York. Oxford.

24. Raper K.B., Thom C., Fennel D.J., 1968. A manual of the Penicillium. Heafner Publish. Co., New York, Oxford.

25. Rifai M.A., 1969. A revision of the genus Trichoderma Comm. Mycol. Inst., W. Surr., England.

26. Smeda R.J., Weller S.C., 1996. Potential of rye (Secale cereale) for weed management in transplant tomatoes (Lycopersicon esculentum). Weed Sci. 44, 596-602.

27. Truszkowska W., Pudełkowa Z., 1966. Obserwacje niektórych chorób pomidorów występujących w szklarni i w gruncie [Observation of some diseases of tomatoes in greenhouse taking a stand and in field]. Acta Mycol. 2, 183-202 [in Polish].

Accepted for print: 15.01.2009

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