Contents - Greenmount Press

FIGURe 4: Significant differences in the
accumulation of bolls between the varieties
FIGURe 5: There are major differences in
fruiting patterns
utilise without having to work too hard. Monitoring of the NAWF
number plus the rate of decline will allow objective evidence to
ensure stress is minimised
Boll number
Significant differences were witnessed in the accumulation of
bolls between the two varieties, in how fruit was accumulated
and the final number. Within these trial sites, the Sicot 74BRF
amassed extra bolls over Sicot 71BRF if it was allowed to.
Sicot 74BRF is slow to begin to amass fruit when compared
to Sicot 71BRF, and it is not till the season progresses to
approximately 1800 day degrees that Sicot 74BRF equals and
finally overtakes Sicot 71BRF. Growers and consultants should
be mindful of this pattern as this difference in fruit accumulation
will affect nutrient and moisture requirements of the crop. It
is also clear that the longer into the season that Sicot 74BRF is
kept growing and producing fruiting sites, the better the yield
potential will be.
The technique of segmented picking of cotton crops has
been a wonderfully effective tool in helping understand the
components of yield and how fruit is stacked on a plant.
What the segmented picking data has shown is that there
are major difference between Sicot 74RF and Sicot 71BRF in the
amount of fruit retained on the bottom fruiting nodes, the upper
and also the vegetative nodes as well. This data backs up the fruit
accumulation curve where Sicot 74BRF is slow to put on fruit but
then finishes the season quite strongly.
If we first concentrate on fruiting branches one to four – not
only are there not as many bolls within this segment of Sicot
74BRF but the weight of these bolls is considerably lower as
well when compared to the other first position bolls on the Sicot
74BRF plant. It is theorised that this deficiency may be overcome
by getting Sicot 74BRF off to a good, vigourous start to the
season. Transition the plant from early vegetative growth into
flowering with more vigour, size and leaf area to support early
boll development and retention.
Interestingly the middle two segments on the plant (fruiting
branches 5 to 12) are very similar in their make up of the final
yield. Boll numbers within these segments are lower in Sicot
74BRF but the boll weight is heavier which therefore makes up
for the lower boll number. Bolls coming from the fruiting branch
nodes 5 to 12 have the heaviest bolls on the plant.
By far the highest percentage of yield in both Sicot 74BRF and
Sicot 71BRF comes from this section of the plant.
When looking at the fruit produced on the upper fruiting
nodes and also on the vegetative branches, Sicot 74BRF has the
ability to retain more fruit on these partitions when compared to
Sicot 71BRF. These segments are important in the improvement
of yield potential over Sicot 71BRF, and all effort should be made
to take advantage of this trait.
The lengthening of the flowering period will have a vital role
on the number of fruit retained in these segments of the plant.
But you cannot grow the crop forever, and the last effective boll
date will need to be determined for a given season and region
to ensure that energy is not wasted in initiating and developing
fruit which will not be picked. It may be more advantageous to
stop additional growth and concentrate the plant’s efforts on
increasing the weight of the retained bolls.
What does this mean for management
Promoting good early growth to encourage retention of early
fruit in the first four nodes, not only improves the contribution to
yield of this segment in Sicot 74BRF but also establishes a robust
plant for the entire flowering and boll development period.
50 — The Australian Cottongrower October–November 2012