Theres more to variety choice than yield alone
Sugar beet growers must
consider more than yield
alone when choosing
varieties, advises an
Hugh Symington reports
THE trend to earlier drilling means bolting, establishment and disease resistance have become increasingly important selection drivers, says NIABs Simon Kerr.
Sugar yield, a characteristic favoured by British Sugar, also helps growers cut transport costs by reducing the number of loads sent to its factories.
"Seed quality is a big consideration and has a critical impact on performance," adds Mr Kerr. "So growers should choose most of their seed order from the fully recommended group as commercially produced seed lots."
Experimental seed lots, which may contribute to provisional list results, can give less reliable results, he explains.
"Where only breeder seed is being tested, the results do not always provide a true reflection of variety performance in a commercial situation."
NIAB trials allow comparisons between varieties with high root yield and moderate sugar content and those with moderate root yield but high sugar content. But other factors to take into account include establishment levels and bolters.
British Sugar is keen to promote varieties with low amino N in the juice, and breeders selecting on this basis have done well in reducing impurities, says Mr Kerr.
Seed quality has also improved greatly in the past decade. But relative yield differences between recommended varieties are now small, and all on the NIAB list are fairly robust, he notes.
Its not just yield that counts when choosing what should fill the drill.
Sugar yield Adjusted tonnes Year listed
(British Sugars main driver) (growers main driver)
Ariana 100.7 100.7 1999
Chorus 98.4 98.4 1998
Roberta 101.6 101.2 1993
Stallion 99.8 100.2 1999
Triumph 99.1 99.0 1992
Wildcat 100.4 100.5 1999
Baron 99.8 99.8 2000
Dominika (new) 105.2 104.9 2002
Giovanna (new) 103.5 103.2 2002
Humber 101.6 101.8 2001
Jessica 100.5 100.5 2000
Latoya 102.1 101.3 2001
Murray 100.9 101.2 2001
Priscilla 101.3 101.5 2001
Sweet (new) 101.8 102.0 2002
Concept 101.3 101.1 2001
Dorena (new) 101.1 100.5 2002
Rayo (new) 102.4 102.3 2002
Newcomers to challenge standard
HIGHEST listed yielder, with a relative adjusted tonnes score of 105%, is Dominika. It has moderate sugar content with low impurity and amino N levels. Establishment is high with very good mildew resistance.
Giovanna is slightly lower yielding at 103% and with low levels of bolters from both early and normal sowings.
The variety Sweet rates 102% for adjusted tonnes with very high sugar content and low impurities.
"Giovanna and Dominika look exciting, and are set to take on the likes of Roberta," says Mr Kerr. "Roberta still leads the pack with Ariana, Stallion and Wildcat coming a close second.
"Ariana has remained consistent throughout commercial trials, and Stallion and Wildcat have maintained high yields and relatively high sugar contents. But poor bolting means they are not early drilling varieties."
The two other newcomers are rhizomania tolerant, essential in areas where the disease has been identified, particularly after loss of the UKs protected zone status.
"Dorena has an adjusted tonnes rating of 101% and very good establishment. But recorded bolters from early sowing suggest it should not be drilled before the end of March," says Mr Kerr.
"Rayo is higher yielding at 102% with even better establishment and lower levels of early sown bolters. But, while its adjusted output is over 1% higher than Concepts, none of the tolerant types yield as well as the new provisionally recommended varieties.
"Both the new rhizo tolerant varieties are susceptible to rust."