Development of a pot bioassay to screen organic matter or mycorrhiza input

The addition of exogenous organic matter or mycorrhiza in orchard (natural soil) can contribute/promote some biological, physical or chemical processes such as microorganism activity, water management or mineral element availability. Assessment of a range of organic matter in situ is often difficult because of response time and space available in orchard. The development of a pot essay (ex-situ), with natural soil or growing mix, will help to evaluate large number of organic matter. Two experiments were made in 2013 in greenhouse with peach plant (GF305). We compared several organic matter or endomycorrhize additions, four types of soils (natural sandy, silty clay and clay soil, artificial soil) and we measured different variables such as stem length, number of internodes, nitrogen status of plant or fresh and dry matter and mycorhization on trees roots. Three main results were highlight. First, our experimental set-up allows differentiating modalities after 6 weeks of culture. Second, some indictors are useful such as stem length while some are useless (internode). Finally, the origin of soil has an impact on results. This kind of experiment should be a preliminary step before evaluation in orchard condition.