Weed tolerance and weed-suppressing ability of blue lupin (<i>Lupinus angustifolius</i>)

Abstract

In the joint research project LupiBreed in 2015 the competitiveness of two blue lupin varieties (terminated type: Boruta, branched type: Boregine) and in 2016 additionally eight pre-breedinglines (two terminated, five branched, one intermediate) was examined. Variety-specific weed-suppressing ability and weed tolerance were tested with site-specific weeds and a mixture of “artificial weeds” (rapeseed, buckwheat, phacelia) at two sowing densities. Furthermore, weed suppression in mixed cropping systems with spring wheat, oat and false flax at two sowing densities was surveyed. Field trials were carried out at Thünen-Institute of Organic Farming with 3-fold replications. Plots were sampled at stem elongation, flowering and ripeness.
Weed tolerance, measured by means of lupin yield, differed at each sampling between varieties and prebreedinglines and was dependent on weed infestation at ripeness. Variety-specific weed suppression was only significant at ripeness. Weed tolerance and weed suppression were not distinctive between growth types. In summary, pre-breedingline 1-E, 4-V, 6-V and Boregine-V showed good competitiveness but the effect of the variety was not strong.
Mixed cropping reduced weed biomass dependent of lupin varieties and pre-breedinglines between 15 and 80 % compared to lupin sole cropping. Weed suppression was mainly influenced by partners and was significantly higher in mixed cropping with false flax than with spring wheat and oat.