Contents - Greenmount Press

Sicot 74BRF – What have we
learnt
■■CSD Extension and Development Team with Mike Bange, CSIRO
Sicot 74BRF from its release has moved to dominate the
variety choice of Australian cotton growers. At present
it represents up to 64 per cent of all seed planted within
Australia. It has become popular for its 0.2 to 0.3 bale per
hectare improvement in yield over Sicot 71BRF as well as have a
good fibre quality, disease resistance and being partially regionally
adaptive.
Previously the Australian cotton industry was predominated by
varieties from the Sicot 71 family. A variety suite with high yield
potential, wide regional adaptability and excellent responsiveness
to the inputs of management.
But although there are similarities between Sicot 71BRF and
Sicot 74BRF, it is in the subtle differences between the two
varieties where growers and consultants can fine tune their
management to achieve the most from this excellent variety.
How does Sicot 74BRF differ from Sicot 71BRF
There has been a lot of speculation and comment about the
establishment of Sicot 74BRF in past seasons, due to its lower
seed density. This has resulted in below par establishment in
marginal conditions, but this is widely known and can and should
be compensated for quite easily.
The CSD variety trial program allows an excellent opportunity
to examine the relative establishment between Sicot 71BRF
and Sicot 74BRF. This data compares like with like, the varieties
are planted into the same field, on the same day, at the same
seeding rate and depth. No adjustments are made to the planter
between the varieties. Therefore difference in plant stand is a
direct indication of how a particular seed type has coped with
field conditions. From over 70 comparisons we have witnessed an
average reduction of plants established of 11 per cent between
Sicot 74BRF and Sicot 71BRF.
FIGURe 1: Relative yield of Sicot 74BRF and
Sicot 71BRF and the relationship to difference
in plant stand
In brief…
■■
Aim for and create conditions to get Sicot 74BRF off to a
good start. Have the plant growing strongly into first flower.
■■
Concentrate on minimisation of plant stress during the
flowering period to extend this for as long as possible,
stress minimisation during this period will also improve boll
weight.
■■
Allow the plant to grow out for as long as the season allows.
There are some benefits in aiming to get the plant stand of
Sicot 74BRF equal to what would normally be accepted as a
good stand for Sicot 71BRF on your farm. On average, the yield
differential between Sicot 74BRF and Sicot 71BRF is 0.21 bales
per hectare (in 95 CSD trials). When the plant stands are similar,
Sicot 74BRF outyields Sicot 71BRF by 0.5 bales per hectare.
Over the past three seasons, the CSD extension and
development team has been examining the growth habit and
yield components of Sicot 74BRF to gain further insight into how
to extract the maximum from this variety.
The CSD Extension and Development team has stressed that
it is crucial to get Sicot 74BRF off to a good start. If we can
generate a healthy actively growing seedling into squaring and
first flower than we have set the crop up to achieve its full yield
potential.
Squaring nodes
There is no difference between the two varieties in the
production of squaring nodes. This is not a startling revelation
as squaring node production is temperature respondent. But it
FIGURe 2: No difference between the varieties
in production of squaring nodes
48 — The Australian Cottongrower October–November 2012