Australia
May 8, 2007
Six years of field experiments
have shown lint yield was higher when cotton was planted close
together in narrow rows less than 40 centimetres apart.
The research – completed by Rose
Roche at Narrabri as part of her PhD with
The University of Queensland
and CSIRO Plant Industry –
is unravelling the complexity of ‘ultra-narrow row’ (UNR)
cotton’s growth and development.
“Previous experiments across Australia and the USA have been
inconclusive about the yield and maturity benefits of UNR, so we
wanted to once and for all pin down the facts,” Ms Roche says.
“Across all our experiments the average lint yield in UNR
plantings was 15.9 per cent higher than in conventionally spaced
cotton, which is planted one metre apart.
"However, yield differences were not consistent, ranging from 4
bales per hectare higher to no difference at all.
“While UNR looks like a promising option for higher yields for
growers, further research and evaluation of agronomic
requirements and economic benefits are needed to understand
under what circumstances growing UNR would be a consistently
better option than one metre spaced cottons,” she says.
Data from the experiments revealed that boll size in UNR
plantings was reduced by nine per cent, but this was more than
compensated for with a 21 per cent increase in boll numbers in
UNR plantings.
“We also found no difference in the time it took for the crops
to mature, a previously reported benefit associated with UNR,”
Ms Roche says.
A key finding of this research is that competition between
plants occurs very early and is much higher than expected in UNR
plantings – as a result plants don’t grow as quickly or as big.
Ms Roche is now working as a Post Doctoral Fellow with CSIRO
Plant Industry investigating if early competition can be
overcome by increasing inputs to the crop early in growth.
“We are comparing row spacings of 38 and 25 centimetres with
different plant populations to identify the critical factors
driving competition – such as early season water, nitrogen and
light use – that may slow early growth in UNR plantings,” she
says.
“We aim to be able to make some specific recommendations on row
spacings and associated management so farmers can choose the
most suitable option for their situation.”
This research was supported by the Cotton Cooperative Research
Centre, the Cotton Research and Development Corporation and
grower collaborators.
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