Delredovisning - Strategi för säker tomatodling-kombinerad sjukdomskontroll genom gödsling, biofumigering och biologisk bekämpning Dnr 4.1.

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1 Delredovisning - Strategi för säker tomatodling-kombinerad sjukdomskontroll genom gödsling, biofumigering och biologisk bekämpning Dnr /13 Inom ramen för projektet har följande arbeten (Steg 1 i huvudansökan) initierats Inventering och bakgrundsorientering utfört enligt projektplanen. Förtest, infektionsförmåga hos jord avsedd för större studie. Genom rådgivar- och odlarkontakter har lämplig jord som utnyttjats för kommerseill tomatodling insamlats, ca 500 kg. Jorden har analyserats avseende såväl näringsinnehåll som förekomst av korkrotröta. Avsikten är att utnytta insamlad jord för det plaenrade växthusexperimentet och det har därför vairt viktigt att först och främst konstatera att orden faktiskt varit infekterad med korkrotröta. Detta har gjorts genomatt provodla en mix av olika tomatersorter i den insamlade jorden. Som kontroll utnyttjades samma jord men steriliserad genom autoklavering. Efter tre månaders tillväxt har förekomst av korkrotröta på tomatrötterna graderats visuellt. Prover har också tillställts docent Sofia Ekengren på Stockholms universitet som har möjlighet göra en molekylär analys avseende förekomsten av korkrotröta, dessa är dock i nuläget inte klara. Hon har problem med RNA bakgrund i proverna vid kontakt nu i maj och resultaten dröjer därför. Inverkan av ph, kalcium och kvävgödsling på utbrott av korkrotröta-en växthusstudie För detta ändamål har den plan som redovisades i huvudansökan följts, se nedan. Avsikten är att utreda hur korkrotrötan påverkas av kväenivåer, ph och kalcium. Nedan följer en material och metodbeskrivning på engelska (den avses ingå i den internationella vetenskapliga publiceringen av projektet). Materials and methods Plant material The plant material used was the greenhouse tomato Solanum lycopersicon cv. Arvento RZ Bio F1 hybrid due its common use amongst Swedish organic tomato growers. Substrate A naturally highly infected corky root substrate from an organic tomato grower in which tomatoes had been grown the previous season was used as growth medium for the greenhouse experiments. The main constituents of the infected substrate was peat, compost, sand and mineral soil (3:2:1:1 in volume parts). Before the start of the experiment, the substrate was analysed with respect to apparent density, ph, nitrogen, phosphorus, potassium, calcium, magnesium and sodium concentration. Nitrogen was quantified colorimetrically in potassium chloride extracts (2M) by an auto analyser (TrAAcs800, Bran & Lubbe, Hamburg, Germany). All other nutrients were measured in ammonium acetate lactate by ICP (Perkin Elmer Optima 300 DV, Perkin Elmer, Norwalk, CT, USA) (Table 1). The soils was brought from the grower directly after the greenhouse was emptied and kept at 15 o C for three weeks prior to the start of the experiment. Sterilisation of treatments according to the experimental set up was made by autoclaving at 120 o C for 5 h and then

2 leaving the soil to stabilize for two weeks at 15 o C, taking care to keep same conditions as for the unsterilised soil. Nitrogen effects on disease severity in tomatoes Tomato seeds were double grain sown in trays with a commercial sowing soil (S jord, Econova Garden AB, Åby, Sweden), kept hencefort in a greenhouse (25 o /20 o C day/night temperature) and manually irrigated. After 85% of the plants had developed germination leaves, the day temperature was reduced to 22 o C and a 16 h light period was provided. The relative humidity was kept at 70% and artificial light complemented day light. The plants were irrigated once a day with normal tap water. Twelve days after sowing, the plants were thinned to give one plant per pot. Three weeks after sowing, equally sized plants were chosen to be transplanted into 5 litre containers each supplied with 5 L substrate consisting of the naturally infected corky root substrate, either unsterilised or sterilised. In table 2 the experimental set up is shown and included three ph levels combined with three N levels. The ph treatment was lowered by mixing a 5:1 ratio of the infected soil with poorly humified peat (H2 H4), while the higher ph values were achieved by addition of 15.0 g CaCO 3. l substrate 1 and 12.6 g MgCO 3. l substrate 1 respectively to reach ph values of 5.8 (peat addition), 6.5 (no additions) and 7.5 (CaCO 3 or MgCO 3 additions respectively). The N additions were based on N uptake by tomato plants and yields, assuming an average tomato yield of 12 kg. m 3 (Bioland 2005) which resulted in an application of 2.5 g N. plant 1 (low), 5 g N. plant 1 (medium) and 10 g N. plant 1 (high) respectively. The N amendments consisted of the organically certified organic N fertilizer Biofer All N was added by incorporation of the fertilizer in the upper 7 cm of the pots ten days before planting, keeping the pots at 22 o C before that. The experiment was laid out as a complete randomized block, every treatment had seven replicates except for the sterile treatments which each consisted of three replicates. To ensure similar conditions for all plants and to avoid fringe effects, border plants were placed around the blocks. The greenhouse experiment continued for ten weeks after transplanting of the tomato seedlings, as previous experience had shown that the plants required ten weeks to develop characteristic corky root disease symptoms on the roots. At harvest, shoots were cut off at the soil surface. The roots were separated from the soil by gentle shaking and rinsed with tap water to remove soil particles. Disease severity in each plant was evaluated by collecting the following three 3 cm sections of root sample: leaving a segment of 5 cm from the root base and then taking a 3 cm sample, leaving 5 cm and then taking another 3 cm sample, leaving 5 cm and then taking another 3 cm sample. Then the three root samples from the three distances were pooled and mixed. From these root samples, 100 pieces from each plant were examined under a stereomicroscope and grouped into three categories as white (healthy roots), light brown (initially infected roots) and dark brown (severely infected roots). Statistical analysis

3 For evaluation of the greenhouse experiment, mean and standard deviation were calculated for shoot dry matter for all treatments. To identify differences between treatments significance test were conducted (Wonnacott & Wonnacott 1972). Resultat Alla analyser är ännu inte klara. Table 1. Status of the infected corky root substrate used as growth substrate Parameter Apparent density 610 ph in CaCl NH + 4 N (mg. l 1 ) 4 NO 3 N (mg. l 1 ) 377 K 2 O in ammonium acetate 524 lactate (mg. l 1 ) P 2 O 5 in ammonium acetate 374 lactate (mg. l 1 ) Table 2. Experimental design of the greenhouse study on the impact of N levels and ph on the corky root disease of tomatoes ph (MgCO 3 ) 7.5 (CaCO 3 ) Total N added (g. N plant 1 ) Naturally infected substrate Sterilised substrate Table 3. Effects of various ph levels on growth of organically cultivated tomato grown in restricted substrate chambers in green house recorded as above ground dry matter production. Used substrate was collected from a tomato grower prior to use. ph value of substrate Naturally infected substrate Above ground dry matter (g. plant 1 ) Number of replicates Substrate sanitised by autoclaving prior to use Above ground Number of dry matter (g. replicates plant 1 ) aB bA aB aA aA bA 18

4 Different capitals within the columns and different lowercase within the rows indicate Tendens till att högt ph minskar skörden i ickesterilt system Högt ph icke sterilt sänker skörden Tomaterna gillar alltså lägre ph, vid det höga ph:t så har kanske svampen bättre förutsättningar infektera pga tomaternas fysiologiska preferens för lägre ph, de mår inte bra vid höga ph och kan infekteras lättare. Table 2. Effects of various N levels on growth of organically cultivated tomato grown in restricted substrate chambers in green house recorded as above ground dry matter production (g. plant 1 ). Used substrate was collected from a tomato grower prior to use. Total N added as organic N at start of the experiment (g N. plant 1 ) Naturally infected substrate, n=28 Substrate sanitised by autoclaving prior to use, n= aA bA aB bB aC bB Different capitals within the columns and different lowercase within the rows indicate Ökad skörd vid högre N, högre skörd sterilt ssytem inte oväntat Table 3. Effects of increasing ph level in substrate to 7.5 by addition of CaCO 3 and MgCO 3 respectively on growth of organically cultivated tomato grown in restricted substrate chambers in green house recorded as above ground dry matter production. Used substrate was collected from a tomato grower prior to use, initial ph 6.5. (g. l substrate 1 ) Naturally infected substrate, n=21 Substrate sanitised by autoclaving prior to use, n= (CaCO 3 ) aA aA 12.6 (MgCO 3 ) aA bA Different capitals within the columns and different lowercase within the rows indicate ph effekten (minskade skördar vid högre ph ) kan inte förklaras som kalciumbrist eller måste veta växtinnehållet av Ca, Mg här, analyserna inte klara Under 2015 planeras följande Steg 2 forskningsplan

5 Gödslingsexperimentet avslutat och utvärderat enligt projektplanen. Biofumigeringsstudier igångsatta i samarbete med Hanna Friberg. I bifallen projektplan anges att dessa också ska ha avslutats, detta kan ha varit överoptimisk. Ambitionen är dock denna men det kan flaggas för att detta inte kan vara fullt avslutat under 2015, med tanke på att projektet under 2014 inte drog igång förrän i mars 2014 så blir en fördröjning naturlig.