Íslenskar landbúnaðarrannsóknir - 01.03.1979, Page 55

THE INOCULATION OF LUPINUS 53
greater when the seed was inoculated with
an effective strain (3211) compared with
the uninoculated control. It seems theref-
ore that the lack of suitable Rhizobium
bacteria in the soil is the main limiting
factor for the successful cultivation of
lupin in Iceland.
Recently, low pQpulation size of indig-
enous R. trifolii was also reported in Icel-
andic soil (Hardarson & Jones, 1977).
Although white clover is the most abun-
dant legume in Iceland a high percentage
of the nodules is inhabited by ineffective
bacteria and therefore the importance of
inoculation of white clover seed with ef-
fective nodule bacteria is evident.
Lupin might be of potential value as a
pioneer crop in reclamation. Recent obs-
ervation in Néw Zealand have demon-
strated the nutritional role as well as
physical shelter of Lupinus arboreus in co-
astal sand dune forestry (Gadgil, 1971 a
and b). There, L. arboreus is used to stabil-
ise coastal sand dunes by sowing it into
planted Ammophila arenaria stands and by
this means the lupin plants provide shelter
for young Pinus radiata trees. The increas-
ed nitrogen uptake in P. radiata through
the iníluence of litter and seedling exudat-
es from the lupin plants is also reported
and the best estimate for nitrogen fixadon
rate by the \upin-Rhizobium symbiosis in
the lupin-marram stands was recorded as
160kg/hectareperyear (Gadgil, 1971 c).
The present results clearly indicate the
possibility of using L. nootkatensis for rec-
lamation, by sowing this species after in-
oculation with an effective Rhizobium st-
rain into Elymus arenarius stands in coastal
sand dunes in Iceland and by this means
provide the very necessary nitrogen for E.
arenarius and other vegetation.
ACKNOWLEDGEMENTS.
The authors would like to acknowledge
and thank the staff of the Agricultural
Research Institute in Iceland for their
assistance during the course of this work.
The financial support of the Icelandic
Scientific Foundation (Vísindasjóður) is
gratefully acknowledged.