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Germination of Italian Ryegrass Seeds 1
Author(s) -
Young James A.,
Evans Raymond A.,
Kay Burgess L.
Publication year - 1975
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1975.00021962006700030026x
Subject(s) - germination , lolium multiflorum , agronomy , biology , population , seedling , horticulture , sociology , demography
Italian ryegrass ( Lolium multiflorum Lam.) is widely planted on western California and Oregon rangelands, but it does not persist or spread. Understanding seed germination characteristics may help to explain its rather poor competitive ability as compared to other naturalized annual grasses. We studied the germination of seeds (caryopses) of Italian ryegrass under constant and alternating temperatures, and we studied simulated litter as a germination substrate. Constant and alternating temperature regimes were used from −6, −4, −2, 0, 2, and 5 C and 5 degree increments to 30 and 40 C, with 16 hours at the lower temperatures and 8 hours at the higher temperatures. Seeds used were from a naturalized population and two commercial seed sources. Italian ryegrass germinated over a wider range of temperatures and at more extreme diurnal fluctuations than did other annual grasses from the same environment. Germination of the naturalized population was highest at both relatively cool (5 C) nights and warmer (10 to 25 C) days and at a second peak of 10 C nights and high (30 to 40 C) days. Commercial seed lots had maximum germination over a wider range of temperatures than the naturalized seed lot. Litter‐germinated seedlings were very susceptible to drying and had virtually no root regeneration in comparison to other annual grasses. The limited temperature range at which Italian ryegrass germinates and the inability of roots to resist drying or to regenerate after drying may limit it ecologically.