Clear differences in both autumn and spring vigour between leading winter OSR varieties have been highlighted in Agrii’s national variety trials, with DEKALB breeding standing out for its across-the-board strength to offer particular resilience under challenging conditions.
The fully replicated 2016/17 trials across five sites from Lenham in Kent to Balbeggie near Perth recorded the relative vigour of 39 current and up-and-coming ‘double low’ varieties around 10 weeks after planting, ahead of Christmas and before stem extension in the spring.
Across the sites on the 1-9 scale used (where 9 = very strong) the trial varieties averaged 5.5 for early autumn vigour and 7.3 for late autumn vigour, underlining the extent to which growth improved once the rain arrived. The average spring vigour score on the same scale was 5.9.
Within these averages, varieties ranged from less than 4.0 to nearly 7.0 in early autumn vigour, from 6.0 to 8.0 in late autumn vigour and from less than 4.0 to over 8.0 in spring vigour.
On average, hybrids showed a vigour advantage of around 1.0 over conventional varieties in the early autumn, 0.5 in the late autumn and 1.0 in the spring. All 11 varieties scoring 6.0 or more for early autumn vigour were hybrids; as were 17 of the 20 varieties (85%) scoring 7.5 or more for late autumn vigour and 10 of the 12 varieties (83%) scoring 7.0 or more for spring vigour.
Some conventional varieties proved more vigorous than many hybrids, however, while some hybrids were noticeably less vigorous than many conventionals.
At all three stages, DEKALB varieties were amongst the most vigorous varieties, comprising 55% of those with early vigour scores of 6.0 or more, 40% of those with late autumn scores of 7.5 or more and 50% of those with spring vigour scores 7.0 or more (Figure). And the only varieties with a spring vigour score of more than 8.0 were DEKALB-bred.
Experience shows that most varieties are likely to establish well enough and go into the spring in good enough heart given reasonable seedbeds, soil moisture levels, winter weather and pest and disease pressures.
The superior vigour shown by DEKALB varieties is considered especially valuable in ensuring the greatest crop resilience wherever conditions prove more challenging at any stage as a result of later drilling, less-than-ideal seedbeds, inclement weather or particular insect, slug, pigeon or early phoma pressures. It also gives growers additional confidence in employing the lower seed rates found to produce the most productive and manageable crop canopies.