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Influence of the earthworms Aporrectodea rosea and Aporrectodea trapezoides on Rhizoctonia solani disease of wheat seedlings and the interaction with a surface mulch of cereal-pea straw
0038-0717(!M)EOO45-Z
Soil Bid. Biochem. Vol. 26, No. 9, pp. 1285-1287,I*4 Copyright 0 1994Elsevier Science Ltd Printed in Great Britain. All rights reserved 0038-0717/94 $7.00 + 0.00
SHORT COMMUNICATION
INFLUENCE OF THE EARTHWORMS APORRECTODK-4 RUSEA AND APORRECTQDEA TRAPEZOIDES ON RHIZOCTONIA SOLANI DISEASE OF WHEAT SEEDLINGS AND THE INTERACTION WITH A SURFACE MULCH OF CEREAL-PEA STRAW P .M . STEPHENS,‘* C. W. DAVOREN,’ M. H. RYDER’-~ and B. M. DOUBE'~*
‘Cooperative Research Centre for Soil and Land Management and zCSIRO, Division of Soiis, Private Bag No. 2, Glen Osmond, SA $064, Australia (Accepted
18 February
Rhizoclonia “bare patch” disease (caused by Rhizoclonia soluni Kiihn) is an important disease of wheat (Triticum oestivum L.) and barley (Hordeurn vulgare L.) in Australia
(Banyer, 1966; MacNish, 1983). Davey and Papavizas (1959) and Singh et al. (1981) reported that the incorporation of organic matter into soil may cause a decrease or increase in the disease severity of R. solani. We have shown that the severity of disease due to R. soluni on wheat can also be reduced in the presence of the earthworm Aporrectodea trapezoides, at a density equivalent to 471 mm2 (Stephens et al., 1993a). As organic matter may be incorporated into soil by certain species of earthworms (Lee and Foster, 1991), we have examined the interaction between earthworms, a surface mulch comprising mostly cereal-pea straw and Rhizoctonia root rot on wheat. Surface soil (O-10 cm) was taken from a site at Kapunda (approx. 75 km north of Adelaide, South Australia). The __ soil was classified as a red-brown earth (Northcote, 1979) and a thermic Calcic Natrixeralf (Soil Survev Staff. 19901. The equivalent of 400 g air dried soil was added to’ 500 r& plastic pots. A full 2 x 2 x 2 factorial experiment was made with pots containing soil with or without R. solani, a surface mulch comprising predominantly cereal-pea straw and A. trapezoides, with 6 replications of each treatment. Concurrently, this experimental design was repeated with the earthworm A. rosea replacing A. trupezoides. Inoculum of R. solani Kiihn AG-8 (McDonald and Rovira, 1985) was produced on autoclaved wheat chaff (Harris et al., 1993), with the fungus being present in the form of hyphae. A total of 12 particles of this wheat chaff were added to the appropriate pots, with 6 particles added at soil depths of 3 and 6cm. Pots were placed randomly in a water bath (maintained at 15°C) in a greenhouse, with natural light. After 4 days, either 0, 1,2 or 3 adult earthworms (equivalent to 0, 157,314 or 471 m-*) of A. rrapezoides or A. rosea were added to the appropriate pots. In addition, the equivalent of 5 g (air dried weight) of Ezi-mulch@ [comprising 60% green pea (Pisum satiuum cv. Dunn) straw, 3@-35% green barley or wheat straw, with the balance (S-IO%) made up of rice hulls (Heywood Stockfeeds, Victoria, Australia)] was ground (< 1 mm), compressed into a disk (4,3 cm dia), adjusted to - 1 kPa matric potential and added as a surface mulch to the soil surface of the appropriate pots. This *Author for correspondence.
1994)
material was used as it can act as an inoculant carrier for biocontrol bacteria and be distibuted by earthworms through soil (Stephens et al., 1993b). Clear plastic pots were placed over the surface mulch in order to minimize moisture loss from the mulch during the experiment. Transparent PVC film was attached around the circumference of each pot in order that earthworms did not escape. After a further 12 days, 13 seeds of wheat (Triticum ueslivum cv. Spear) were planted at a depth of 1 cm into each pot. Plants were harvested 16 days after sowing and the roots were rated for disease severity on a scale of &5, where 0 = no disease and 5=maximum disease with 100% of primary roots severely truncated (McDonald and Rovira, 1985). Weights of roots and shoots were measured after drying at 60°C for 48 h. All earthworms added to pots were recovered at the end of the experiment. R. solani significantly (P < 0.05) increased the root disease rating and caused a significant (P < 0.05) decrease in the shoot weight of wheat. In the presence of R. sohni, but absence of earthworms, the addition of a mulch to the soil surface did not alter the root disease rating or shoot weight of wheat. In the presence of R. solani and with no surface mulch, A. wupezoides caused a significant (P i 0.05) reduction in the root disease rating (at a density of 1, 2 or 3 pot-‘) (Fig. I) and a significant (P i 0.05) increase in the shoot weight (at a density of 2 or 3pot-‘) (Fig. 2). In contrast, when an organic mulch was added to the soil surface, A. lrapezoides did not cause a significant (P > 0.05) reduction in root disease (Fig. 1) and was associated with a significant reduction in shoot weight (at a density of 2 or 3 pot-‘) (Fig. 2). The amount of surface mulch removed from the soil surface in pots containing 1, 2 or 3 A. rrapezoides was 1.07+0.28g (*SD), 1.51 *0.4g and 2.45*0.82g, respectively. In the presence of R. soluni with no added surface mulch, A. rosea caused a significant (P < 0.05) reduction in the root disease rating only at a density of 3 pot-’ and did not significantly (P 10.05) influence shoot weight when present at either 1,2 or 3 pot-’ (data not shown). When a mulch was added to the soil surface, A. rosea did not significantly influence the root disease rating or shoot weight of wheat when present at I, 2 or 3pot-‘. The amount of surface mulch removed from the soil surface in pots containing
1285
Short Communication
1286
b e
8 a
Number of Ahp. per pot
0
Minus Rsolani
0
1
4-
2
3
Pius R.so/anl 7
Fig. 1. Influence of the earthworm A. trupezoides on the root disease rating (fk5 scale) of R. solani on wheat, grown in the presence or absence of cereal-pea straw on the soil surface, Columns containing the same letter were not significantly different at the P c 0.05 level.
Number if A.trap. 0 per pot Minus R.solani
1
3
2
Plus /ho/ad
-b
Fig. 2. Influence of the earthworm A. trapezoides and R. solani on the average shoot weight of wheat, grown in the presence or absence of cereal-pea straw on the soil surface. Columns containing the same letter were not significantly different at the P i 0.05 level.
Short Communication I, 2 or 3 A. rosea was 0.12+0.11 g (&SD), 0.20&0.14g and 0.11 f 0.12 g, respectively. Our study showed that A. trapezoides can reduce the disease severity of R. soluni on wheat at lower densities (equivalent to 157 and 314 m-‘) than those used (equivalent to 471 m-*1 bv Steuhens et al. (1993a). The earthworm A. trapezoides’wk more effective (on a numerical basis) than A. roseu in reducing the disease severity of R. soluni on wheat seedlings, under the experimental conditions we used. A. rosea is the most widespread and abundant earthworm under wheat in southern Australia (Mele, 1991; Baker et al., 1993). Should this disease reduction be observed in the field, efforts to increase the number of A. trapezoides, rather than A. rosea, may facilitate a reduction in the disease severity of R. solani in field grown wheat. Our study also showed that the addition of a surface mulch to the soil surface caused A. frapezoides to have a negative, rather than a positive, effect upon plant growth in the presence of R. solani. This suggests that the amount of organic matter on the soil surface should be considered when evaluatng the ability of A. trupezoides to reduce Rhizoctoniu disease of wheat in the field. Further studies are required to determine whether the interaction between A. trapezoides and a surface mulch is dependent upon the type of organic matter present in the mulch and the mechanisms involved.
REFERENCES Baker G. H., Barrett V. J., Carter P. J., Williams P. M. L. and Buckertield J. C. (1993) Seasonal changes in the abundance of earthworms (Annelida: Lumbricidae and Acanthodrilidue) in soils used for cereal and luceme production in South Australia. Australian Journal of agricultural
Research 44, 1291-1301.
Banver R. J. (1966) Cereal diseases and their control. Part 1.. Journal df the’ Department of Agriculture, Sourh Australia 69, 31&315.
Davey C. B. and Papavizas G. C. (1959) Effect of soil amendments on the Rhizoctonia disease of snap beans. Agronomy Journal 51, 493-496.
1287
Harris A. R., Schisler D. A. and Neate S. M. (1993) Culture of Rhizocronia solani and binucleate Rhizoctonia spp on organic substrates for inoculation of seedlings into containers. Soil Biology & Biochemistry 25, 337-341. Lee K. E. and Foster R. (1991) Soil fauna and soil structure. Australian Journal of Soil Research 29, 745-775.
MacNish G. C. (1983) Rhizoctoniu patch in Western Australia grain belt. Aukdasian Plant Pathology 12, 49-50. McDonald H. J. and Rovira A. D. (1985) Development of an inoculation technique for Rhizocronia solani and its application to screening cereal cultivars for resistance. In Ecology and Management of Soilborne Plant Pathogens (C. A. Parker, A. D. Rovira, K. J. Moore, P. T. W. Wong
and J. F. Kollmorgen, Eds), pp. 174176. American Phytopathology Society, St Paul. Mele P. (1991) What species and how many on local farms. Earthworms, improving soil for agriculture. Proceedings of a conference held at TAFE College, Wangaratta, Vitro ria, Australia. Australian Institute of Agricultural Science,
Occasional Publication No. 62. Northcote K. H. (1979) A Facrual Key for the Recognition of Australian Soils. 4th Ed. Rellim Technical Publications, Glenside. Singh P. J., Nagra P. and Mehrotra R. S. (1981) Effect of organic amendments on root rot of gram Cicer-arietinum and their influence on growth. Plant & Soil 63, 199-208. Soil Survey Staff (1990) Keys to Soil Taxonomy, 4th ed. Soil Management Support Services Technical Monograph No. 19, Virginia Polytechnic Institute and State University, Blacksburg. Stephens P. M., Davoren C. W., Doube B. M., Ryder M. H., Benger A. M. and Neate S. M. (1993a) Reduced severity of Rhizocronia soluni disease on wheat seedlings associated with the presence of the earthworm Aporrectodea trapezoides (Lumbricidae). Soil Biology & Biochemistry
25, 1477-1484.
Stephens P. M., Davoren C. W., Ryder M. H. and Doube B. M. (1993b) Influence of the Lumbricid earthworm Aporrectodea trapezoides on the colonization of wheat roots by Pseudomonas corrugata strain 2140R in soil. Soil Biology & Biochemistry
25, 1719-1724.
Soil Bid. Biochem. Vol. 26, No. 9, pp. 1285-1287,I*4 Copyright 0 1994Elsevier Science Ltd Printed in Great Britain. All rights reserved 0038-0717/94 $7.00 + 0.00
SHORT COMMUNICATION
INFLUENCE OF THE EARTHWORMS APORRECTODK-4 RUSEA AND APORRECTQDEA TRAPEZOIDES ON RHIZOCTONIA SOLANI DISEASE OF WHEAT SEEDLINGS AND THE INTERACTION WITH A SURFACE MULCH OF CEREAL-PEA STRAW P .M . STEPHENS,‘* C. W. DAVOREN,’ M. H. RYDER’-~ and B. M. DOUBE'~*
‘Cooperative Research Centre for Soil and Land Management and zCSIRO, Division of Soiis, Private Bag No. 2, Glen Osmond, SA $064, Australia (Accepted
18 February
Rhizoclonia “bare patch” disease (caused by Rhizoclonia soluni Kiihn) is an important disease of wheat (Triticum oestivum L.) and barley (Hordeurn vulgare L.) in Australia
(Banyer, 1966; MacNish, 1983). Davey and Papavizas (1959) and Singh et al. (1981) reported that the incorporation of organic matter into soil may cause a decrease or increase in the disease severity of R. solani. We have shown that the severity of disease due to R. soluni on wheat can also be reduced in the presence of the earthworm Aporrectodea trapezoides, at a density equivalent to 471 mm2 (Stephens et al., 1993a). As organic matter may be incorporated into soil by certain species of earthworms (Lee and Foster, 1991), we have examined the interaction between earthworms, a surface mulch comprising mostly cereal-pea straw and Rhizoctonia root rot on wheat. Surface soil (O-10 cm) was taken from a site at Kapunda (approx. 75 km north of Adelaide, South Australia). The __ soil was classified as a red-brown earth (Northcote, 1979) and a thermic Calcic Natrixeralf (Soil Survev Staff. 19901. The equivalent of 400 g air dried soil was added to’ 500 r& plastic pots. A full 2 x 2 x 2 factorial experiment was made with pots containing soil with or without R. solani, a surface mulch comprising predominantly cereal-pea straw and A. trapezoides, with 6 replications of each treatment. Concurrently, this experimental design was repeated with the earthworm A. rosea replacing A. trupezoides. Inoculum of R. solani Kiihn AG-8 (McDonald and Rovira, 1985) was produced on autoclaved wheat chaff (Harris et al., 1993), with the fungus being present in the form of hyphae. A total of 12 particles of this wheat chaff were added to the appropriate pots, with 6 particles added at soil depths of 3 and 6cm. Pots were placed randomly in a water bath (maintained at 15°C) in a greenhouse, with natural light. After 4 days, either 0, 1,2 or 3 adult earthworms (equivalent to 0, 157,314 or 471 m-*) of A. rrapezoides or A. rosea were added to the appropriate pots. In addition, the equivalent of 5 g (air dried weight) of Ezi-mulch@ [comprising 60% green pea (Pisum satiuum cv. Dunn) straw, 3@-35% green barley or wheat straw, with the balance (S-IO%) made up of rice hulls (Heywood Stockfeeds, Victoria, Australia)] was ground (< 1 mm), compressed into a disk (4,3 cm dia), adjusted to - 1 kPa matric potential and added as a surface mulch to the soil surface of the appropriate pots. This *Author for correspondence.
1994)
material was used as it can act as an inoculant carrier for biocontrol bacteria and be distibuted by earthworms through soil (Stephens et al., 1993b). Clear plastic pots were placed over the surface mulch in order to minimize moisture loss from the mulch during the experiment. Transparent PVC film was attached around the circumference of each pot in order that earthworms did not escape. After a further 12 days, 13 seeds of wheat (Triticum ueslivum cv. Spear) were planted at a depth of 1 cm into each pot. Plants were harvested 16 days after sowing and the roots were rated for disease severity on a scale of &5, where 0 = no disease and 5=maximum disease with 100% of primary roots severely truncated (McDonald and Rovira, 1985). Weights of roots and shoots were measured after drying at 60°C for 48 h. All earthworms added to pots were recovered at the end of the experiment. R. solani significantly (P < 0.05) increased the root disease rating and caused a significant (P < 0.05) decrease in the shoot weight of wheat. In the presence of R. sohni, but absence of earthworms, the addition of a mulch to the soil surface did not alter the root disease rating or shoot weight of wheat. In the presence of R. solani and with no surface mulch, A. wupezoides caused a significant (P i 0.05) reduction in the root disease rating (at a density of 1, 2 or 3 pot-‘) (Fig. I) and a significant (P i 0.05) increase in the shoot weight (at a density of 2 or 3pot-‘) (Fig. 2). In contrast, when an organic mulch was added to the soil surface, A. lrapezoides did not cause a significant (P > 0.05) reduction in root disease (Fig. 1) and was associated with a significant reduction in shoot weight (at a density of 2 or 3 pot-‘) (Fig. 2). The amount of surface mulch removed from the soil surface in pots containing 1, 2 or 3 A. rrapezoides was 1.07+0.28g (*SD), 1.51 *0.4g and 2.45*0.82g, respectively. In the presence of R. soluni with no added surface mulch, A. rosea caused a significant (P < 0.05) reduction in the root disease rating only at a density of 3 pot-’ and did not significantly (P 10.05) influence shoot weight when present at either 1,2 or 3 pot-’ (data not shown). When a mulch was added to the soil surface, A. rosea did not significantly influence the root disease rating or shoot weight of wheat when present at I, 2 or 3pot-‘. The amount of surface mulch removed from the soil surface in pots containing
1285
Short Communication
1286
b e
8 a
Number of Ahp. per pot
0
Minus Rsolani
0
1
4-
2
3
Pius R.so/anl 7
Fig. 1. Influence of the earthworm A. trupezoides on the root disease rating (fk5 scale) of R. solani on wheat, grown in the presence or absence of cereal-pea straw on the soil surface, Columns containing the same letter were not significantly different at the P c 0.05 level.
Number if A.trap. 0 per pot Minus R.solani
1
3
2
Plus /ho/ad
-b
Fig. 2. Influence of the earthworm A. trapezoides and R. solani on the average shoot weight of wheat, grown in the presence or absence of cereal-pea straw on the soil surface. Columns containing the same letter were not significantly different at the P i 0.05 level.
Short Communication I, 2 or 3 A. rosea was 0.12+0.11 g (&SD), 0.20&0.14g and 0.11 f 0.12 g, respectively. Our study showed that A. trapezoides can reduce the disease severity of R. soluni on wheat at lower densities (equivalent to 157 and 314 m-‘) than those used (equivalent to 471 m-*1 bv Steuhens et al. (1993a). The earthworm A. trapezoides’wk more effective (on a numerical basis) than A. roseu in reducing the disease severity of R. soluni on wheat seedlings, under the experimental conditions we used. A. rosea is the most widespread and abundant earthworm under wheat in southern Australia (Mele, 1991; Baker et al., 1993). Should this disease reduction be observed in the field, efforts to increase the number of A. trapezoides, rather than A. rosea, may facilitate a reduction in the disease severity of R. solani in field grown wheat. Our study also showed that the addition of a surface mulch to the soil surface caused A. frapezoides to have a negative, rather than a positive, effect upon plant growth in the presence of R. solani. This suggests that the amount of organic matter on the soil surface should be considered when evaluatng the ability of A. trupezoides to reduce Rhizoctoniu disease of wheat in the field. Further studies are required to determine whether the interaction between A. trapezoides and a surface mulch is dependent upon the type of organic matter present in the mulch and the mechanisms involved.
REFERENCES Baker G. H., Barrett V. J., Carter P. J., Williams P. M. L. and Buckertield J. C. (1993) Seasonal changes in the abundance of earthworms (Annelida: Lumbricidae and Acanthodrilidue) in soils used for cereal and luceme production in South Australia. Australian Journal of agricultural
Research 44, 1291-1301.
Banver R. J. (1966) Cereal diseases and their control. Part 1.. Journal df the’ Department of Agriculture, Sourh Australia 69, 31&315.
Davey C. B. and Papavizas G. C. (1959) Effect of soil amendments on the Rhizoctonia disease of snap beans. Agronomy Journal 51, 493-496.
1287
Harris A. R., Schisler D. A. and Neate S. M. (1993) Culture of Rhizocronia solani and binucleate Rhizoctonia spp on organic substrates for inoculation of seedlings into containers. Soil Biology & Biochemistry 25, 337-341. Lee K. E. and Foster R. (1991) Soil fauna and soil structure. Australian Journal of Soil Research 29, 745-775.
MacNish G. C. (1983) Rhizoctoniu patch in Western Australia grain belt. Aukdasian Plant Pathology 12, 49-50. McDonald H. J. and Rovira A. D. (1985) Development of an inoculation technique for Rhizocronia solani and its application to screening cereal cultivars for resistance. In Ecology and Management of Soilborne Plant Pathogens (C. A. Parker, A. D. Rovira, K. J. Moore, P. T. W. Wong
and J. F. Kollmorgen, Eds), pp. 174176. American Phytopathology Society, St Paul. Mele P. (1991) What species and how many on local farms. Earthworms, improving soil for agriculture. Proceedings of a conference held at TAFE College, Wangaratta, Vitro ria, Australia. Australian Institute of Agricultural Science,
Occasional Publication No. 62. Northcote K. H. (1979) A Facrual Key for the Recognition of Australian Soils. 4th Ed. Rellim Technical Publications, Glenside. Singh P. J., Nagra P. and Mehrotra R. S. (1981) Effect of organic amendments on root rot of gram Cicer-arietinum and their influence on growth. Plant & Soil 63, 199-208. Soil Survey Staff (1990) Keys to Soil Taxonomy, 4th ed. Soil Management Support Services Technical Monograph No. 19, Virginia Polytechnic Institute and State University, Blacksburg. Stephens P. M., Davoren C. W., Doube B. M., Ryder M. H., Benger A. M. and Neate S. M. (1993a) Reduced severity of Rhizocronia soluni disease on wheat seedlings associated with the presence of the earthworm Aporrectodea trapezoides (Lumbricidae). Soil Biology & Biochemistry
25, 1477-1484.
Stephens P. M., Davoren C. W., Ryder M. H. and Doube B. M. (1993b) Influence of the Lumbricid earthworm Aporrectodea trapezoides on the colonization of wheat roots by Pseudomonas corrugata strain 2140R in soil. Soil Biology & Biochemistry
25, 1719-1724.