Tm. De La Rosa et al., Does far-red light affect growth and mycorrhizas of Scots pine seedlings grown in forest soil?, PLANT SOIL, 211(2), 1999, pp. 259-268
We studied the response of Scots pine (Pinus sylvestris L.) to supplementar
y far-red sidelight in seedlings grown in a forest soil substrate without a
dditional nutrient supply. Our aim was to determine possible changes in the
accumulation and allocation of dry weight and mineral nutrients and the pr
esence of mycorrhizas. Half of the seedlings were grown in light conditions
simulating reflected far-red light (FR) from neighbouring plants and the o
ther half were controls not receiving additional FR. PAR irradiance was kep
t constant in both treatments. At the first harvest (41 d of treatment), FR
+ had no effect on stem height, biomass accumulation or allocation. However
, at the end of the experiment (93 d of treatment), an increase in stem ext
ension rate and stem dry weight was observed in FR+ seedlings when compared
to controls. Both control and treated plants had several morphological typ
es of ectomycorrhizas, but no effect of FR+ on the frequency of these morph
otypes was observed. Nor was the concentration of ergosterol or estimated m
ycorrhizal fungal biomass affected. Nutrients were more responsive to the l
ight quality treatment: P concentration in roots and N and P contents in st
ems and roots were higher in FR+ plants than in control seedlings. These re
sults are in contrast to those of a previous study in which the root system
of pine seedlings, which were fertilised and had less developed mycorrhiza
s, was reduced by FR+.