cotton - Greenmount Press

FIGuRE 5: A high vegetative growth rate
scenario where the crop is tracking above the
upper limit
Ideally, the VGR should be maintained between the upper
and lower limits of the crop development graphs based on the
seasonal day degrees as seen in Figure 5.
This crop may require an application of Mepiquat Chloride to
control excessive vegetative growth and redirect resources back
into fruiting structures.
Another way of looking at this is using a number of crop
indicators that allow agronomists to make decisions on whether a
crop needs growth regulation.
These indicators can be used at first flower to assess where a
crop is up to in terms of vegetative growth and whether growth
regulation is required. Only having one of these indicators does
not necessarily mean growth regulation is required, but having
several indicates a likely response to growth regulation.
Once in flowering it is important to monitor the crop
internode growth. Another way of looking at ascertaining where
the crop is up to is by looking at the 4th to 5th internode interval
from the top of the plant, which gives a good understanding
of what the crop is doing. This node represents 90 per cent of
its current length. If this node is longer than 7.5 cm, look at the
previous nodes 6th to 7th from the top and the younger nodes
TABLE 2: Some growth parameters that may
indicate need for growth regulation
Growth parameters at first flower that indicate likely
Pix response
Parameter
Pix Indicated
Height
>70 cm
Growth rate
>2.5 cm per day
Node growth rate
7.5 cm
Vegetative nodes >7
Bottom five retention