Effects of non-chemical soil fumigant treatments on root colonisation with arbuscular mycorrhizal fungi and strawberry fruit production Darinka Koron a, * , Silva Sonjak b , Marjana Regvar b a Agricultural Institute of Slovenia, Department of Fruit and Vine Growing, Hacquetova ulica 17, SI-1000 Ljubljana, Slovenia b University of Ljubljana, Biotechnical Faculty, Department of Biology, Ve cna pot 111, SI-1000 Ljubljana, Slovenia article info Article history: Received 12 November 2012 Received in revised form 16 September 2013 Accepted 18 September 2013 Keywords: Arbuscular mycorrhizal fungi (AMF) Biofumigant plants Glomus Temporal temperature gradient gel electrophoresis (TTGE) abstract The effects of biofumigation and soil heating on arbuscular mycorrhizal fungi (AMF) colonisation, strawberry growth and strawberry yield in pot experiments compared with untreated soil and chemical fumigation with dazomet were tested. Three different Brassicaceae species (Brassica juncea, Eruca sativa, Sinapis alba) were used as biofumigant plant green manure and soil heating was applied to simulate soil solarisation. Half of the plants were inoculated with indigenous arbuscular mycorrhizal fungi inoculum. With one exception (E. sativa) among the uninoculated plants, the treatments significantly decreased the mycorrhizal colonisation parameters compared with the untreated control. Dazomet displayed the greatest inhibitory effects on AMF establishment. In addition, the intensity and number of bands cor- responding to Glomus spp. obtained with temporal temperature-gradient gel electrophoresis were lower for strawberry plants from biofumigant treatments than from the control. For the inoculated plants, there were almost no significant differences among the mycorrhizal colonisation parameters. The mass of leaves for the uninoculated and inoculated plants was higher for almost all non-chemical soil fumigant treatments compared with the control, except for heating of the uninoculated treatments. The number of strawberry fruits for the uninoculated biofumigant treatments was the highest, being higher than the values observed for the heating treatments, the chemical disinfection treatments and the control. There were no significant differences among the inoculated treatments. Biofumigation with Brassicaceae species resulted in higher soil organic matter and mineral nutrients and had a relatively small effect on AMF colonisation (F% ¼ 59.0, 80.3, 47.3 for Bj, Es and Sa, respectively) compared with uninoculated controls (F% ¼ 84.3). Despite the reduced AMF colonisation, biofumigation resulted in a higher fruit number and mass of leaves. Therefore, it represents a non-chemical soil fumigation method that should be applied in sustainable strawberry production. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Strawberry (Fragaria  ananassa Duch.) is one of the most intensively produced fruit crop. However, yields often suffer from soil-borne fungal pathogens (Mass, 1998). Therefore, chemical disinfection of the soil is widely used by growers. Methyl bromide was the most frequently used chemical disinfectant in the past (Martin and Bull, 2002; Shaw and Larson, 1999). In 2005, its use was prohibited due to its depletion of the ozone layer (U.S. Environmental Protection Agency, 1999; EC No, 2037/2000). Therefore, methyl bromide has been replaced by less harmful chemicals, such as 1,3-dichloropropene, which was phased out in 2009 in the European Union, chloropicrin (which will be phased out in 2013), dazomet, and others (Ajwa and Trout, 2004; García- Méndez et al., 2008; Mark and Cassells, 1999). Therefore, the use of non-chemical control approaches has been encouraged as a sustainable alternative to chemical methods in agricultural plant defence. These approaches include various cul- tural practices (e.g., solarisation, biofumigation), induction of plant defence responses and application of biological control agents (Linderman, 1994; Charron and Sams, 1999; Fageria et al., 2005; Alabouvette et al., 2006). For soil solarisation, the soil is covered by a transparent plastic foil, which facilitates heating by solar ra- diation to temperatures that are detrimental to soilborne patho- gens (Pinkerton et al., 2002). Biofumigation is used to suppress soilborne pests by taking advantage of toxic compounds that can be released from soil-incorporated tissues of plants. The biofumigant Abbreviations: AMF, arbuscular mycorrhizal fungi; Bj, Brassica juncea; DSE, dark septate endophyte; Es, Eruca sativa; HPLC, high-performance liquid chromatog- raphy; Sa, Sinapis alba; TTGE, temporal temperature gradient gel electrophoresis. * Corresponding author. Tel.: þ386 1 280 5142; fax: þ386 1 280 5255. E-mail address: darinka.koron@kis.si (D. Koron). Contents lists available at ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro 0261-2194/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cropro.2013.09.009 Crop Protection 55 (2014) 35e41