Putting down roots in oilseed rape
Root density in an oilseed rape crop has been shown to be linked to its final yield and the use of the triazole fungicide Caramba in the spring has been shown to have a positive and unique effect on both rooting and crop yields, according to a three year project on optimising winter oilseed rape root systems carried out by ADAS.
"Good rooting at depth is important in oilseed rape in order to maintain the yield potential of the crop. The roots system needs to be able to scavenge for soil moisture and nutrients effectively and so be able to satisfy the crop's demands at the critical pod filling stage. At this time drought can be a problem resulting in premature crop senescence and reducing the length of the seed filling period, as some growers found out to their detriment last year," says Diane Heath, BASF Oilseed Rape Product Manager.
Recent information from HGCA and BASF funded work has shown that oilseed rape crops frequently have insufficient roots at depth (below 40 cms) to fully explore the soil. The project found that around 50% of crops suffering sub-optimal rooting below 50cm depth, which could be limiting and ultimately be affecting yields. "In a dry summer when the crop is reliant on extracting soil water from depth, those crops with a poor root system will therefore suffer from the effects of drought," says John Spink, Head of Crop Physiology for ADAS.
The use of the growth regulating fungicide Caramba has been shown to encourage greater root exploration at depth. Preliminary work carried out in 2005 in an HGCA funded project was confirmed in 2006, he reports.
Root Length Density, which is the length of roots (in cms) within each cubic centimetre of soil (cm root /cm3 soil) was used as a key measurement. The use of Caramba has improved Root Length Density in both years. By reducing lodging and by enhancing root growth, it also enhanced yields over other treatments.
"This work really sets Caramba apart from all other fungicides which have a growth regulatory effect, such as tebuconazole. Caramba combines excellent disease control with a significant yield building effect on roots and canopies. With over half of UK crops suffering from restricted rooting, management strategies to produce large root systems and moderate canopy sizes are needed. This will be a particularly relevant this year with the many advanced crops we are currently seeing," says Diane Heath.
