Cotton planting rate guidelines

13 August, 2003

___A four-year INGARD®/Bollgard®II planting rate research trial by CSD has found no difference in yield or fibre quality from plant stands of 9 through to 15 plants per metre, but a statistically significant decline in yields below that level of plant population._

Speaking on the weekly Web on Wednesday (6/8/03) video on the CSD website, extension and development agronomist, John Marshall (pictured), said these same trends were evident in all cotton growing districts where the trials had been conducted, which included Emerald, Dalby, St George and Wee Waa.

This finding differs from previous plant population studies, all of which have been conducted on conventional varieties. In these, little yield difference was evident from 5 through to 10 plants per metre, with a slight yield decline evident either side of this range.

Mr Marshall said the different response seems to be related to a change in crop architecture in INGARD®/Bollgard®II fields, where plants have higher fruit retention throughout, are less tipped out, and factors such as peak nutrient demand, light penetration and insecticide coverage have changed.

He said that using a seeding rate of 16 seeds per metre for Bollgard® varieties, would ensure that a field invariably ended up with a plant stand in the peak yield range of 9-15 plants per metre.

If the field experienced very difficult plant establishment conditions ( i.e. final field establishment of 55%) it would end up at around 9 plants per metre, whereas if it experienced ideal conditions, with a 90% final field establishment, at 14 plants per metre, this would still be within the optimum yield range.

John Marshall said further that seed rates could come back in situations that regularly gave enhanced final field establishment, such as watering up in late plant situations. Establishment of 80-90% was regularly achieved last season under this scenario.

Further Information: *"Robert Eveleigh**, John Marshall, Greg Kauter or Craig McDonald":showstaff.asp?staff=1