Ársrit Ræktunarfélags Norðurlands - 01.01.1974, Page 32

SUMMARY
This paper deals with the cultivation of ryegrass (Lolium pirenne)
for grazing or silage making. The results of two paired experiments in
north Iceland, Akureyri and Hólar, ar presented. The following rye-
grass varieties were compaired:
Tewera, Westerwoldic ryegrass (tetraploid).
Tetila, Italian ryegrass (tetraploid).
Dasas 486, Italian rygrass (diploid).
The main results were as follows:
Tewera grows faster and gives a greater crop of hay in one cut than
the others, both when harvested early in the growing season or in the
fall. The Italian ryegrass (Tetila and Dasas) grows most rapidly during
the latter part of the growing season, and preserves its digestibility
much longer than Westerwoldic ryegrass, such that after 75 or niore
days of growth the Italian rygrass yielded more in f. f. e. (Scand. feed
units for fattening) per hectare.
Comparison of the growing behaviour of the Italian diploid and the
tetraploid showed that the diploid grows somewhat faster in the be-
ginning, but is surpassed by the other concerning growth period of just over
100 days. Regrowth of the diploid is also greater in the beginning, but is
surpassed by the tetraploid later.
After about 90 days heading was complete with Tewera, where as
just 50% and 20% headings had appeared within the Dasas and Tetila
varieties respectively.
In about a growth period of 50 days 1,3' kg hay (15% DM) were
required per f. f. e., about the same for all three varieties. After 110
days 1,7, 1,5 and 1,4 kg hay were required per f. f. e. for Tewera, Dasas
and Tetila respectively.
The results of these experiments show that the varieties in question
may be ranked by their growth periods with respects to yield in f. f. e.
per hectare as follows:
Up to 75 days: Tewera, one cut.
75 to 100 days: Dasas, one cut.
Over 100 days: Tewera, two cuts and Tetila one cut.
With increasing maturity of the ryegrass its concentration of protein,
P, Ca, Mg, Mn, Zn an Cu decreased, where as its Iv concentration
changed irregularly and that of Na increased. As a rule, the concent-
rations of protein and the above minerals were greater in the case of
the diploid, than the Italian tetraploid.
I
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