A Shattering Interest29-Sep-2014
While OSR pods open more easily than those of almost any other brassica, there’s always been natural variation for their resistance to shattering among pure line varieties. But this is nothing compared to the character we recognised from the early on in our advanced hybrid breeding programme.
It actually came as a fortunate by-product of the Ogura hybridisation system forming the basis of much of our breeding programme. The vital fertility restorer gene bred into male parent stock from the radish – to overcome the male sterility essential in ensuring female parents in the programme can only be cross-pollinated – came complete with a complex of genes controlling this species’ far greater resistance to pod shattering.
Unlike several other hybridisation programmes from the same root, we recognised the character early on – mainly from much lower post-harvest volunteer populations in our breeding plots – and made sure to retain it as we bred out other accompanying undesirable characters like high glucosinolate levels. Since then we have been able to track it effectively in our breeding programme and lock it into our lines.
Being so influenced by harvest date and conditions, the pod shatter resistance trait has taken us considerable time and effort to quantify so we can be confident of its effect and the commercial advantages it offers.
However, 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 have all shown our hybrids with pod shatter resistance lose noticeably less seed around and at harvesting than a range of leading varieties.
DK ExPower, DK Extrovert, DK Excellium and DK ExStorm are, for instance, typically four times more resistant to shattering than other varieties, with yield losses in delayed harvesting trials ranging from 0-4% compared to 12-26% in competitor hybrids without the trait. At the same time farm strip trials under commercial management conditions have revealed a 10-fold reduction in volunteer problems arising from seed losses around harvesting with DK hybrids even in the absence of weather or combining difficulties.
So valuable has pod shatter resistance proved that we have made it a core trait in all our DK ‘double low’ hybrids and are rapidly introducing it into our Vistive HOLL varieties.
It will not, of course, eliminate all yield losses and volunteer pressures where particularly damaging weather is experienced or harvesting is very seriously delayed. However, the large volume of evidence available clearly shows the pod shatter resistance we have offers very valuable insurance against inclement weather and ordinary harvesting delays.
It is proving especially important in today’s high pressure production systems and with the climate as variable as it seems to have become; yet another example of the extra reliability that can be provided by breeding for yield-protection alongside gross output.