Oilseed rape yields have stagnated at just under 3.5t/ha yet research suggests higher yields are achievable. James Andrews looks at what’s holding us back
Pushing oilseed rape yields beyond 3.5t/ha is simple, in theory, yet the national average has plateaued and growers are failing to make headway. Is this because the crop has reached its natural limit or can growers do more to squeeze extra potential from their crop?
According to ADAS’s Pete Berry, yields topping 6t/ha are achievable given the right variety, growing conditions and importantly, canopy management. “Trials show that the crop’s genetic potential isn’t a limiting factor and static yields are most likely a result of crop husbandry and a warmer climate.”
This season oilseed rape crops have established well and have the potential to achieve high yields providing they are managed effectively, he says.
Careful canopy management in the spring can compensate for over-zealous growth coming out of the winter, says Agrovista agronomist Peter Dews. Managing spring nitrogen and using plant growth regulator fungicides effectively is the key, he says. “There’s plenty of time to deal with canopy management in the spring. I will aim to measure green area index (GAI) in early March to assess nitrogen and growth regulator fungicide requirements.”
This helps decide whether tebuconazole or metconazole is applied. Crops with a GAI over one in early March will receive metconazole as it has the most effective growth regulatory effects, he says. “Crops with a GAI of less than one will receive tebuconazole as the plant growth regulator effects are less pronounced.”
Assessing your Green Area Index
Accurately measuring green area index is an essential starting point for spring oilseed rape canopy management, according to BASF’s Clare Tucker.
GAI is the ratio of plant green area to the area of soil the crop is grown on and helps growers predict how the crop will look at harvest and allow them to manage the canopy accordingly.
• See 13 February edition of Crops for the full story.