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G'day Dave
If it's perennial ryegrass, there are 2 requirements for seeding. Plants
first have to be exposed to low temperatures (this is known as
'vernalisation') and/or short day length for a period of time. This
'programs' the tillers to go to seed. Then to actually go to seed, the
plants need exposure to longer days and higher temperatures.
Both of these requirements must be met for perennial ryegrasses to seed,
however biennial ryegrasses ('short rotation grasses') don't abide by these
rules as strongly, and annual ryegrasses don't at all.
This is why we often see more seeding of perennial ryegrass in spring
following a colder winter than following a mild winter (i.e. more
vernalisation), and why perennial ryegrasses don't seed in northern
Australia (i.e. no vernalisation in subtropical/tropical winters - less
than 8% of my hundreds of marked tillers went to seed over 4 years in
northern NSW). Spring-sown perennials also don't go to seed (no
vernalisation), whereas spring-sown biennials will go to seed straight
away, and will seed just as prolifically in the subtropics/tropics.
Flowering/seeding is also sped up in most plants when they are under
stress, think of it as plants trying to secure the next generation (through
viable seed), before they die. White clover's a classic, as soon as
paddocks start to dry out, white clover flowers like mad.
So - your observations look like they're on track. The milder winter may
have meant that less tillers would have been 'programmed' to go to seed
than previously, but the milder spring may have brought forward what
seeding there was going to be. If this is true, it will mean a condensed
period of seeding, so rather than some seeding occurring sporadically over
the next few months, it's all coming now. We'll have to wait and see how
the season pans out to know if that's true or not.......
One other scenario, which came as a question from Andrew Wright when he was
here in Tassie the other week, is that with a wet winter/early spring in
Tassie compared with previous seasons, plants' root systems may be
shallower than normal (due to waterlogging and low oxygen levels in the
soil), and now that the soil is drying out, this is placing more stress on
plants than normal (i.e. under these conditions in previous years, plants
would have a deeper root system and cope better). The stress is causing
faster seeding (and more seeding in one go) than previous years.
Two other thoughts before I leave you - there has been an increasing fad in
the last couple of years to sow short rotation grasses everywhere (which
fit in the biennial category), so is what we're seeing just a reflection of
more paddocks of grasses that seed more than the previous grasses did?
And the last comment, not sure where this has originated from as I heard it
last year and it's even more prevalent this year, is the misconception that
nitrogen fertiliser (e.g. urea) causes ryegrass plants to go to head more
than normal. Nitrogen will increase growth - if plants are ready to seed,
then maybe expect bigger seed heads on overall bigger plants, but apart
from that, nitrogen has no effect on seeding.
Hope that's helped, happy farming
Danny
At 11:57 AM 30/11/2005 +1100, you wrote:
>Danny,
>Just a question that resulted from our last Walking Through the Seasons
>day relating to stalky pastures. Some in the group have noted that the
>pastures seem to be going going stalky or seedy earlier than last year.
>There have been some dry conditions but they were also wondering that
>because we had a milder winter early spring whether this has led to the
>seed head being produced earlier than normal. Are ther other factors like
>the stem elongation period being shortened by the onset of dry conditions.
>Less leaf production etc.
>
>What do you make of this observation and is there any research or science
>behind what has been observed?
>
>Interested to hear of you comments on this.
>
>Cheers
>David Shambrook
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<html>
G'day Dave<br>
<br>
If it's perennial ryegrass, there are 2 requirements for seeding.
Plants first have to be exposed to low temperatures (this is known as
‘vernalisation’) and/or short day length for a period of time. This
'programs' the tillers to go to seed. Then to actually go to seed,
the plants need exposure to longer days and higher temperatures.<br>
<br>
Both of these requirements must be met for perennial ryegrasses to seed,
however biennial ryegrasses ('short rotation grasses') don't abide by
these rules as strongly, and annual ryegrasses don't at all.<br>
<br>
This is why we often see more seeding of perennial ryegrass in spring
following a colder winter than following a mild winter (i.e. more
vernalisation), and why perennial ryegrasses don't seed in northern
Australia (i.e. no vernalisation in subtropical/tropical winters - less
than 8% of my hundreds of marked tillers went to seed over 4 years in
northern NSW). Spring-sown perennials also don't go to seed (no
vernalisation), whereas spring-sown biennials will go to seed straight
away, and will seed just as prolifically in the subtropics/tropics.<br>
<br>
Flowering/seeding is also sped up in most plants when they are under
stress, think of it as plants trying to secure the next generation
(through viable seed), before they die. White clover's a classic,
as soon as paddocks start to dry out, white clover flowers like
mad. <br>
<br>
So - your observations look like they're on track. The milder
winter may have meant that less tillers would have been 'programmed' to
go to seed than previously, but the milder spring may have brought
forward what seeding there was going to be. If this is true, it
will mean a condensed period of seeding, so rather than some seeding
occurring sporadically over the next few months, it's all coming
now. We'll have to wait and see how the season pans out to know if
that's true or not.......<br>
<br>
One other scenario, which came as a question from Andrew Wright when he
was here in Tassie the other week, is that with a wet winter/early spring
in Tassie compared with previous seasons, plants' root systems may be
shallower than normal (due to waterlogging and low oxygen levels in the
soil), and now that the soil is drying out, this is placing more stress
on plants than normal (i.e. under these conditions in previous years,
plants would have a deeper root system and cope better). The stress
is causing faster seeding (and more seeding in one go) than previous
years.<br>
<br>
Two other thoughts before I leave you - there has been an increasing fad
in the last couple of years to sow short rotation grasses everywhere
(which fit in the biennial category), so is what we're seeing just a
reflection of more paddocks of grasses that seed more than the previous
grasses did?<br>
<br>
And the last comment, not sure where this has originated from as I heard
it last year and it's even more prevalent this year, is the
<u>misconception</u> that nitrogen fertiliser (e.g. urea) causes ryegrass
plants to go to head more than normal. Nitrogen will increase
growth - if plants are ready to seed, then maybe expect bigger seed heads
on overall bigger plants, but apart from that, nitrogen has no effect on
seeding.<br>
<br>
Hope that's helped, happy farming<br>
<br>
Danny<br>
<br>
At 11:57 AM 30/11/2005 +1100, you wrote:<br>
<blockquote type=cite cite>Danny,<br>
Just a question that resulted from our last Walking Through the Seasons
day relating to stalky pastures. Some in the group have noted that
the pastures seem to be going going stalky or seedy earlier than last
year. There have been some dry conditions but they were also wondering
that because we had a milder winter early spring whether this has led to
the seed head being produced earlier than normal. Are ther other
factors like the stem elongation period being shortened by the onset of
dry conditions. Less leaf production etc.<br>
<br>
What do you make of this observation and is there any research or science
behind what has been observed?<br>
<br>
Interested to hear of you comments on this.<br>
<br>
Cheers<br>
David Shambrook</blockquote></html>
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