24 July 1998

Variety purity is tricky to detect, warns NIAB

MAKE sure you know what varieties you are sowing, NIAB warns farm-saved seed enthusiasts.

Distinguishing varietal purity in the field can be quite a challenge, says seeds certification officer Tony Chapman. "But if end users like millers and maltsters are demanding purity it is important to know what you have saved."

Mr Chapman demonstrated the difficulties with a series of known mixtures at the recent Varieties and Seeds day.

A 5% admix of bearded Soissons is easy to detect in a crop of Riband, he notes. But the exercise becomes progressively harder with other potential field mixtures caused, perhaps, by volunteers.

Five per cent of short-strawed feed type Buster is easily overlooked in taller potential breadmaker Spark. "That could have a significant effect on crop quality," he says. "Hereward and Rialto are also pretty hard to tell apart."

Identifying Harrier and Madrigal, even in a 50:50, mix is far trickier, the roughness of the glumes being the only give-away in the field. Soaking the grains in phenol, which colours them differently, is the straightforward answer, but not particularly farmer-friendly, says Mr Chapman. &#42