2014-05-28   facebook twitter rss

Oilseed Rape Pod Shatter Resistance Proves its Worth

Genetic resistance to pod shattering is providing winter oilseed rape growers across the country with a valuable way of maximising crop yields and minimising subsequent volunteer problems, according to the UK’s leading breeder.

Launching a detailed review of the innovative trait pioneered by Monsanto, Dekalb technical specialist Dr Andrew Smooker pointed out that direct combining, workload pressures and challenging seasons have made OSR losses through pod shattering in the run-up to and during harvest an important issue.

Pod shatter

Pod Shatter

“UK growers involved in most recent national oilseed rape growing study rated pod shatter resistance as one of their three highest priority traits,” he pointed out. “This is not surprising since it can decimate crop yields in extreme cases and frequently causes significant losses where weather or workloads prevent crops being harvested at optimum maturity.

“Our breeders have long recognised that the pods of varieties developed in their particular hybridisation system were substantially more resistant to shattering at maturity than others and have taken care to preserve this character through their programme. Being so influenced by harvest date and conditions, though, it has taken considerable time and effort to characterise and quantify the trait.”

This process has included independent laboratory measurements of the traction force required to open pods; deliberately delayed harvesting trials; recording from field trials affected by adverse weather at harvest; volunteer population measurements in large scale farm trials; and in-field random impact testing with a specially developed device.

All these assessments have shown Dekalb hybrids with pod shatter resistance lose noticeably less seed around and at harvesting than a range of leading varieties. Traction force measurements have, for instance, shown DK ExPower, DK Extrovert, DK Excellium and DK ExStorm to be typically four times more resistant to shattering than other varieties. In delayed harvesting trials yield losses in the shatter resistant hybrids ranged from 0-4% compared to 12-26% in competitor hybrids.

Average yield losses of 26% were recorded from seven Dekalb hybrids hit by a hailstorm during harvesting against 74% in five competitors. And recording in farm strip trials under commercial management conditions has revealed a 10-fold reduction in volunteer problems arising from seed losses around harvesting with DK hybrids even in the absence of weather or harvesting difficulties.

“Altogether recorded yield losses from pod shatter susceptible varieties in 19 recent trials across five European countries have ranged from 0.09 t/ha to 3.15 t/ha,” reported Dr Smooker. “At an oilseed rape value of £300/t, UK figures translate into financial losses of between £1800 and £22,000 for a typical 50 ha winter OSR crop.

“The volunteer pressures that shattering creates in the rotation are even more significant,” he added. “With a typical thousand seed weight of 6g every 100 kg/ha of yield lost is nearly 17 million seeds of 1700 seeds/m2. Even assuming a viability loss of 90% loss over two seasons, this means adding around three times the typical hybrid seed rate in volunteers to the next OSR crop.”

Dr Smooker accepts that the pod shatter resistance carried as a core yield-protecting trait in all DK hybrids will not eliminate all such yield losses and volunteer pressures where particularly damaging weather is experienced ahead of harvest or harvesting is very seriously delayed.

However, he stresses that the large volume of evidence available clearly shows pod shatter resistance provides extremely valuable insurance against inclement weather and harvesting delays.

“The pod shatter resistance trait we have pioneered is proving especially valuable in today’s high pressure production systems and with the climate as variable as it seems to have become,” he concluded. “Growers are also finding it allows them to hold-off on harvesting for as long as possible to maximise the seed yield in their crops while reducing the extra risk they would otherwise incur.”

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