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Newsletter December 2017

Iron deficiency in rhododendrons? Development of rhododendrons for non-acidic soils

Why do rhododendrons like acidic soil? How can you test plants regarding their tolerance for a higher pH? As a partner of the RHODOLIME project, ILVO paves the way for a more efficient, faster breeding of rhododendron. The market for rhododendrons can expand considerably if cultivars can be developed that can also grow in less acidic soils.

rhodolimeEvery year millions of young rhododendron plants are produced at Flemish companies and sold worldwide. Nevertheless, there is still potential for expansion, especially regarding development of rhododendrons that can also be used in non-acidic soils. Rhododendrons, including pot azaleas, require acidic soils to grow. Because low soil pH does not occur in many gardens, development of rhododendron types adapted to a higher pH, would help them to find their way to the average garden. In the context of breeding and selection, ILVO is looking for a good testing method for the development of adapted rhododendron types. In addition, we are investigating why rhododendron plants prefer acidic soil. The answer to that question can support the development of rhododendrons for less acidic soils.

The aim of the RHODOLIME project is a research tool for a more efficient, faster breeding of the popular rhododendron garden plant (Rhododendron spp.). In order to be able to select rhododendron genotypes that can also grow on less acidic soil, a bioassay is being developed. The intention is to be able to carry out the selection according to suitable genotypes at the seedling stage. The parent plants are also tested in order to make cross combinations, whose seedlings are expected to grow well in a soil with a higher pH. The tests are developed and executed in plant tissue culture and subsequently validated for rhododendron plants under normal growing conditions.

The underlying mechanism for pH preference is also unraveled. There are already indications that the iron and calcium uptake of the plant are involved. When the pH changes, the absorption of these elements changes. The hypothesis to be tested is that rhododendron does not like calcareous soils (high pH) because it prevents the absorption of iron.

Project: RHODOLIME
Term: 2016 - 2020
Funding: China Scholarship Council doctoral grant
Partner: Ghent University
Contact: Leen.Leus@ilvo.vlaanderen.be