INSTYTUT DENDROLOGII

Abstract: A vigour test that can predict the field emergence percentage of tree seeds accurately has long been a wish from growers. A new test method, the Critical Root Length (CRL) vigour test, was developed for beech seeds on the basis of the length of primary roots, germinated seeds can produce during a specified test. Pretreated, imbibed seeds were germinated in a vertically positioned moist paper roll during 20days at 15°C in 12 hour light daily. Root length of normally germinated seedlings was recorded and correlated with field emergence percentage to obtain a critical root length for the ability to emerge in the field. Critical root length for Fagus sylvatica was found to be 45 mm. The percentage of normally germinated seeds with roots longer than 45 mm in the CRL test is a predicted estimate of the field emergence percentage of a seed lot. Results of two tests on 5 and 10seed lots showed generally good correlation between CRL predicted emergence and actually obtained field seedling emergence. Large variation in root length was found between and within seed lots, thus displaying large differences in seed vigour. The new test is an applied, easy and inexpensive vigour test developed for nurserymen and seed technicians in order to predict field emergence more accurately.

Additional key words: critical root length, CRL test, paper roll, predictability