Germination of annual ryegrass seeds (Lolium rigidum Gaud.) as influenced by temperature, light, storage environment, and age

Abstract

Germination of Lolium rigidum seeds, in the light (12 hr day length) and in the dark, at constant temperatures of 12, 18, and 24°C and an alternating temperature of 24/12" (12112 hr), was studied in freshly harvested seeds and in seeds stored for 18 weeks. In freshly harvested seeds the highest germinability (80%) was recorded at 12' in either light or dark and at 24/12' in the light. After 18 weeks' storage, a germinability of between 95 and 100% was observed at 12" and 24/12" in the dark and at 24' and 24/12' in the light.In another experiment in which seeds from a different source were used, seeds kept in six different environments and recovered at 3-weekly intervals during a 21 week post-harvest period were examined for germinability and germination rate. The six environments were: storage in a room, storage in a 60/15"C temperature cabinet, and four field treatments in which seeds were buried 0 . 2 and 1 . 0 cm under both a bare and a mulched soil surface. Germination was tested in the light and in the dark at an alternating temperature of 24/12". Major increases in seed germinability with age occurred during the first 9 weeks after harvest. The different environments influenced the relationship between seed age and germinability only during the first 9 weeks. Seeds located 0 . 2 cm beneath either a bare or a mulched soil surface during summer germinated at a faster rate than seeds kept in the other environments.These findings are discussed in relation to the germination behaviour of seeds in the field. Ryegrass (Lolium rigidum Gaud.) is a common component of annual pastures in southern Australia. In a ley farming system, a proportion of the seed population can remain ungerminated after the first seasonal rains and during cultivations (McGowan 1970). These seeds may germinate later in crops and create a serious weed problem (Pearce and Quinlivan 1971). Ryegrass infestations as low as 400 plants m-2 can markedly reduce grain yields (Lumb and McPherson 1964).

Dormancy and longevity of annual ryegrass (Lolium rigidum) as affected by soil type, depth, rainfall, and duration of burial

“…In Australia, L. rigidum predominantly occurs in the southern Mediterranean regions with their wet winters and dry summers. As a result, most of the research work related to L. rigidum has been done in these regions e.g burial and longevity studies (Gramshaw 1972;Gramshaw and Stern 1977) and herbicide resistance studies (Preston et al 1999). A survey of the lower Liverpool Plains in northern New South Wales in 2001 showed that glyphosate resistant L. rigidum was present on at least 10 farms, with infestations varying from small patches of plants to being widespread across the whole farm (Storrie and Cook 2002).…”

“…Or will a heavy clay soil from the northern region speed or slow seedbank decline? Lolium rigidum is thought to have a short dormancy cycle (Gramshaw 1972;Gramshaw and Stern 1977) but the factors which directly or indirectly affect dormancy, viability, germination and emergence of L. rigidum require further research.…”

Temperature and Light Requirements for Miscanthus sinensis Laboratory Germination Test

“…Seeds of different crops manifest three distinctive germination requirements regarding light: seeds that require light for germination, those that require the absence of light, and seeds that are indifferent to light (Aiken and Springer, 1995;Cole et al, 1974;Gramshaw, 1972). Seeds of different crops manifest three distinctive germination requirements regarding light: seeds that require light for germination, those that require the absence of light, and seeds that are indifferent to light (Aiken and Springer, 1995;Cole et al, 1974;Gramshaw, 1972).…”

“…The effect of light on seed germination has three main components: quantity, duration, and quality. Seeds of different crops manifest three distinctive germination requirements regarding light: seeds that require light for germination, those that require the absence of light, and seeds that are indifferent to light (Aiken and Springer, 1995;Cole et al, 1974;Gramshaw, 1972).…”

Influence of after‐ripening environments on the germination characteristics and seed fate of Italian ryegrass (Lolium multiflorum)

“…This study revealed both similarities and differences in comparison with previous studies of rigid ryegrass. The first similarity is that after-ripening during summer widens the temperature range for the germination of Italian ryegrass seeds, which also has been observed for rigid ryegrass (Gramshaw 1972). The Italian ryegrass seeds tested soon after harvest generally exhibit a high level of postharvest dormancy (Hides et al 1993).…”