ITC Musa collection characterization data obtained from Field Verification
Conservation strategies rely on the stability and availability of conserved plant genetic resources, both in situ and ex situ. At Bioversity’s International Musa Germplasm Transit Centre (ITC), based at the Katholieke Universiteit Leuven, Belgium, the genetic integrity of the in vitro collection is continually assessed.
The ITC is the largest banana genebank, with more than 1,680 accessions available to researchers, breeders and the larger Musa community. The stakeholders’ needs are to know that the germplasm that they request is true-to-type, and to be able to access all available data on the germplasm. In this assessment, also called field verification, data from the systematic periodical characterization of in vitro plantlets in partners’ field collections ensures the characterization of the ITC collection.
This dataset contains the characterization data of 196 accessions scoring 72 morphological descriptors.
Recorded from the base of pseudostem to emerging point of the peduncle
In relation to the parent plant. Observed on the tallest sucker. Recorded at harvest time
Measured by the number of emitted foliage leaves (or their scars) that are at least 10 cm wide. The scars are the dried-up bases of the petioles of past leaves. Along the pseudostem, the leaves are arranged in two spirals. Count the number along one spiral and multiply by 2. Tip: Mark the number of leaves on the pseudostem as it grows to avoid having to count scars since planting.
Determined by the circumference at 100 cm
Recorded without removing the external sheaths. The colour of oldest dry sheaths should not be considered. (Chart A)
Recorded as in 6.2.3
Remove the outermost sheath from the pseudostem and look at the exposed surface of the underlying pseudostem. The values 5 (pink-purple), 6 (red-purple) and 7 (purple) must be chosen only if the pigmentation is uniform, and green tinges are not observed. (Chart A)
Record the tinge of pigmentation, even if it is only noticeable in places. (Chart A)
Cut the external sheath of pseudostem and record the characteristics of the sap. (Chart A)
Record the number of suckers from soil level to point of emergence of the last leaf (>30 cm height). Recorded only if no desuckering has taken place
Recorded on the third, fully unfolded leaf counting down from the top of the plant. (See Fig. 5)
Record the relative surface area coverage by blotches.
Recorded on the third, fully unfolded leaf counting down from the top of the plant. (See Fig. 5)
Use colour chart A. Observation should be made before shooting, on a developed sucker or on another plant of the same accession. Look at the visible face (future lower face) of the cigar leaf before it is unfurled and before the plant flowers.
Leaf III is the third leaf counted from the last leaf (leaf I) produced before bunch emergence. Cut the petiole half way between the pseudostem and the leaf blade and examine the cross section. (See Figs. 4 and 6)
The third leaf (Leaf III) is counted from the last leaf produced before bunch emergence. Cut the petiole halfway between the pseudostem and the leaf blade and examine the cross section
Margin is the part of the petiole that can be bent outwards/inwards
Observation should be made at shooting. Record on the last developed leaf at flowering stage.
Measured from the leaf crown to the first hand of fruit
Observe only the part of the rachis between the last hand and the male bud
For the following descriptors, observe only that part of the rachis between the last hand of fruit and the male bud
“w” is the broadest width of the male bud. “x” is the length from the base of the male bud to the point of broadest width ‘w’; “y” is the total length of the male bud. As the figure shows, these parameters express the profile of the bud. Do not measure the dimensions along the bud but rather on a projection/outline of the bud (e.g. trace the outline of the bud on paper). Calculate the ratio w/y (see figure)
Note the general shape of the male bud at harvest. (See Fig. 9)
Measure the length (y) of male bud at harvest
“w” is the broadest width of the male bud. “x” is the length from the base of the male bud to the point of broadest width ‘w’; “y” is the total length of the male bud. As the figure shows, these parameters express the profile of the bud. Do not measure the dimensions along the bud but rather on a projection/outline of the bud (e.g. trace the outline of the bud on paper). Calculate the ratio x/y (see figure).
Descriptor state 4 (red/or pink-purple) is green homogeneously tinged with red (purple green appearance). When pigmentation is scattered, use state 5. (Chart A)
(Position of the fruit-bearing part). Angle from vertical to the general axis of the bunch
Angle between the axis of the bunch and the vertical.
Score on fully developed plant with no environmental stress.
The bunch should still be on the plant.
Refers to the last lifted bract. Best to record as bract has lifted up to the horizontal.
Flatten the apex of the bract to observe its shape. (See Fig. 11)
Refers to the first external unlifted bract. Flatten bracts to determine shape.
Alignment of bracts at the apex of the male bud
Observed on the face opposite to the dehiscence split of the anther (dorsal face). (Chart B)
Without considering lobe colour. (Chart B)
For the following descriptors, records should be made on the inner fruit in the middle of the mid-hand of the bunch, at harvest time (first fruit ripening on bunch) / Recorded only on fruits arranged symmetrically around the stalk
(Before joining the crown)
Before they join the rachis at the bract scar. Look up from bottom of bunch.
Recorded on the youngest hand of the bunch, before maturity. (Chart B)
Recorded on youngest hand of the bunch. (Chart B)
(Chart B). (Ripe, but not over-ripe; full yellow stage)
Observed on the mid-hand of the bunch
Measured as the internal arc of the fruit, without pedicel
Observe the inner fruit in the middle of the mid-hand of the bunch. In case of an asymmetric bunch that has straight and curved fruits, please indicate it in the note section and score only the fruit on the upper side of the bunch.
Observe the inner fruit in the middle of the mid-hand of the bunch. In case of an asymmetric bunch, score the dominant fruit shape appearing in the bunch.
Observed at the distal end of the fruit. (See Fig. 22)
Observe before cutting the bunch as relicts may fall off.
List of accessions included in the dataset