Íslenskar landbúnaðarrannsóknir - 01.09.1977, Page 45

THE INOCULATION OF WHITE CLOVER 43
100
80
c
‘5
i 60
<u
^ 40
20
Fig. 1. Frequency distribution (%) of the effective strains, tested at
12 °C and 20 °C.
lcelandic
Welsh
Swedish English
12 20
°C
12 20
°C
12 20
°C
12 20
°C
incubated at 20 °C the first nodules appeared
after 8—9 days, whereas when incubated at
12°C the best combinations took 15—20
days to nodulate.
The results of Experiment 1 clearly show
the adaptation of Rhizobium strains from
northhern strains were in this most effective
for nitrogen fixation at low temperatures
compared with strains from the United
Kingdom (Fig. 1). Of the most effective
strains at 12°C, 94% were from Iceland and
Sweden, whereas at 20 °C only 64% of the
northern strains were in this most effective
group. In particular, there was a difference
between the Rhizobium strains from Iceland
and Wales, all of which originated from
wild white clover plants. None of the 10
strains from Wales were found to be highly
TABLE 4. SUMMARISED ANALYSIS OF VARIANCE FOR NUMBER OF DAYS
TO FIRST NODULE FORMATION
Item d.f. M.S. V.R.
Total......................................... 111
Strains ....................................... 55 51.64 0.596 N.S.
Temperature .................................... 1 34391.02 397.0***
Interaction (S X T).................... 55 55.56 0.641 N.S.
Error.................................. 1125 86.62
*** : P < 0.001, N.S. : Not significant