Developing crop descriptor lists - Bioversity International

32 BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Example #39
Quantitative descriptors using a discrete scale
1 Very low
2 Very low to low
3 Low
4 Low to intermediate
5 Intermediate
6 Intermediate to high
7 High
8 High to very high
9 Very high
Sometimes this list is abbreviated by listing only states 3, 5, and
7. Where this has occurred, the full range of codes is available for
use by extension of the codes given or by interpolation between
them.
Example #40
Density of oil glands on fruit surface [no. per sq. cm]
3 Low (< 40/cm 2 )
5 Intermediate (50 – 80/cm 2 )
7 High (>90 cm 2 )
The validity of exact measurements should be emphasized
again because of their potential for data analysis and because
transformation is minimal compared with discrete scale data.
There is also a ‘limited’ range of states comprising a 1 to 5 scale. It
is used where the range of expression of a trait is physically limited
at both ends and it is not appropriate to divide the expression into
more than three intermediate states.
Example #41
Stem growth habit
1 Erect
3 Semi-erect
5 Prostrate
When defining descriptors for different intensities of the same
colour hue, the descriptor and descriptor states may be presented
as pseudo-quantitative data (if they fulfil the requirements for a
quantitative characteristic).