Gulerodens farefulde vej fra marken til forbrugeren

Kølelagring af Lammefjords-gulerødder muligør, at der kan leveres danskproducerede gulerødder i perioden fra november til april. Sidst på lagringssæsonen kan mere ed 50% af rødderne dog være kassable på grund af lagersygdomme. I marken angribes rødderne af forskellige jordboende svampe, der allerede ved høst kan resultere i kassable rødder. I lagerperioden kan tilsyneladende raske gulerøder dog også udvikle sygdomme forårsaget af de mikrosvampe der forkommer naturligt på rødderne. Sår på rodoverfladen fremmer angreb under lagring og desuden reduceres gulerøddernes modstandsdygtighed overfor sygdomme i takt med røddernes aldring. I artiklen beskrives de mest betydende sygdomsfremkaldende organismer (patogener), faktorer der er af betydning for udvikling af lagersygdomme samt muligheder for forbedret lagerkvalitet ved hjælp af biologiske forebyggelsesmetoder

Functional Compost

The aim of the research program Functional Compost is to develop and test compost, which have been enriched with chitin, for plant growth promoting properties and to recognise specific mechanisms. Two types of compost were included in the program: source separated biodegradable municipal solid waste compost (DM = 62 %) and garden and park waste compost (DM = 66 %). Chitin was added in trace amounts during the maturity phase, combined with two levels of trace amounts immediately before adding the compost to the growth medium. The research program includes several parallel experiments. In experiment I, compost (20 vol. %) was added to soil (no plants) and incubated at 15 C for 5 month, under regular determination of microbial respiration and gross and net N mineralization. There was a significant increase in respiration due to chitin enrichment, which could not be explained by the amount of C derived from the chitin, which therefore suggest a priming effect. The N analyses are still being processed in the laboratory, but data are expected to be available at the conference. In experiment II, compost was mixed with sand, put into pots in a climate chamber, and spring barley seeds infected with Fusarium culmorum were sown in the pots. After 3 weeks of growth, the health of the plants was determined, and the chitinase activity in the sand was measured. The health of the plants and the chitinase activity was significantly higher in the treatments receiving municipal waste compared to the treatments receiving garden waste compost. However, there was no clear effect of the chitin enrichment. Additionally, the microbial community structure of the two types of compost, with and without early chitin, was determined by Denaturing Gradient Gel Electrophoresis (DGGE). There was a clear separation between compost types, and with or without early chitin amendment. Experiment III is a regular growth experiment, and is running right now. Compost has been incorporated into soil, put into pots in the greenhouse, and spring barley is grown for 2 month before determination for wet and dry weight and N uptake. Data from experiment III is expected to be available at the conference