cotton - Greenmount Press

Germinating
ideas
By CSD Extension and Development
Team
IN this edition of Germinating Ideas, we address the key
cotton plant growth phases from flowering to cut-out and
the management required through this period to produce an
efficient crop.
Since the introduction of Bollgard II technology, effectively
controlling the major pest of cotton (Heliothis), cotton growers
have been afforded more time to concentrate on some of
the intricate management practices that if gotten wrong can
cost yield. These are in the form of irrigation and nutrition
management and the monitoring of vegetative growth rate
and node production. The most important time is through the
development of fruit, which ultimately will determine the yield of
the crop.
Irrigation management
The crop as it moves towards flowering does two things. It
starts to develop fruiting structures and with warm temperatures
FIGuRE 1: Seasonal water use in mm/day for
cotton production
occurring through most regions in December the vegetative
growth rate accelerates and the demand for water increases. This
can be seen in Figure 1.
Once flowering occurs the water demand increases steadily to
a point at peak flowering where the crop is using up to eight mm
a day. The impact of water stress through this period can have a
major impact on yield as seen in Figure 2.
It is for this reason that it is essential that bores and pumps
have been serviced pre season and that pumping capabilities
are not restricted through the season, particularly at flowering.
FIGuRE 3: Segmented picking comparison of
Sicot 71BRF managed under differing irrigation
regimes
Crop A is a normal
Bollgard II field
where Sicot 71BRF is
managed for Bollgard
II.
Crop B is a
conventional field
where Sicot 71BRF has
been inserted into the
trial and the field is
being managed as a
conventional field.
FIGuRE 2: The impact of one day’s water stress
varies with growth stage
Source: Hearn and Constable, 1984.
December 2012–January 2013 The Australian Cottongrower — 55