Abstract

There is an ongoing shift in the paradigm concerning weed control – from the traditional method of attacking weeds by artificial means, to increasing the competitive ability of the crop and thereby reducing yield losses caused by weeds. The ability of a crop to inhibit the development and growth of weeds is one of the most important factors in a weed control strategy. With current research providing new knowledge concerning plant defence mechanisms, for example allelopathy, we can now anticipate a whole new field of research regarding weed control in agriculture. It may be possible to utilise weed-suppressing factors secreted by crop species as a weed control strategy that is beneficial to the environment. Increased knowledge in this area may also lead to production of more effective bioherbicides, suitable for use in both conventional and organic cultivation. Barley cultivars and landraces have been shown in biotests to have different allelopathic effects on test species, with correlations to weed suppression in field studies. In the Swedish research project ‘Isolation and Identification of Weed Suppressing Factors Secreted by Barley’, the aim is to isolate, identify and characterise the allelochemical compounds released in root exudates of barley landraces and cultivars with allelopathic effects. Identification of individual active substances provides the potential to develop DNA-markers, map the genes responsible for the allelopathic effect, make plant production of allelochemicals resource-efficient and perhaps also lead to production of bioherbicides. In one of the studies, the aim was to investigate whether barley plant density in pure stands influenced the production of allelochemicals in root exudates from the barley. To collect the root exudates, the direct resin adsorption method was used. Three-day-old barley (cv. Lina) seedlings were transplanted into a previously autoclaved pot (diameter 13 cm) containing XAD-4 resin and a Mes-Tris buffer. The pots were then placed in a growth chamber. After 14 days the seedlings were separated from the resin. The root exudate was then extracted from the resin. The density of the barley plants in the experiment varied between 1 and 32 plants per pot. To examine the active compounds collected in the root exudate, a bioassay was performed with three test species, Stellaria media, Viola arvensis and Lolium perenne, using multidishes where each test plant could be tested separately. The root exudate extracts were diluted with distilled water and distilled water was used as a control. The test species were pregerminated for 7, 9 and 3 days, respectively, before being placed in the multidishes with diluted root exudate extract. The multidishes were kept in a growth chamber for one week and the root lengths of the test plants were measured before and after the test period. The experiment was repeated. The results showed that the allelochemicals extracted from the barley root exudates at all plant densities inhibited the root growth of the test species compared with the control. Preliminary results indicated also that the density of barley plants affected the production of allelochemicals from individual plants

Published in

Title: Proceedings 14th EWRS symposium, Hamar, Norway

Conference

14th EWRS Symposium

SLU Authors

• Didon, Ulla

  • Department of Crop Production Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/16629