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Ratnambal (1979)

proportion of the chromosome that are acro-, meta-, and telocentric. An asymmetrical karyotype of "1B" was found in all cultivars except in cvs. Bangkok and Jorhat, which have a karyotype asymmetry of 1A (Ratnambal, 1979). The karyotypes of various cultivars exhibited only minor differences (Table 2.4.). The total chromosome length varied from 22.4 jxm in cv. Jorhat to 37.4 ^m in cv. China. The length of the longest chromosome ranged between 2.8 fxm (in cv. Jorhat) and 4.8 ^m (in cv. China). The length of the shortest chromosome ranged between 1.2 fxm (in cv. Rio de Janeiro) to 2.2 fxm (in cv. China).

Ratnambal (1979) used the karyotype data in a generalized distance-D2 statistics analysis. Based on the D2 values, the cultivars were grouped into different clusters. Thirty-two cultivars fell into eight groups, A—H (Table 2.5). The relative distance between each group is a measure of the extent of divergence of the cultivars constituting the group. Cultivars Tafingiwa, Jamaica, Rio de Janeiro, Thinladium, Thingpuri, Maran, and Himachal Pradesh did not fall into any cluster, indicating their independence as well as divergence from the rest of the cultivars. Z. zerumbet and Z. casummunar did not fall into any group, but Z. machrostachyum fell into group B. It was also seen that geographical distances did not influence the clustering. This is expected in a strictly vegetatively propagated species, the planting materials that have been transported from

Figure 2.11 Mitotic metaphase showing 2n — 22 chromosomes.
Table 2.4 Karyotype variability in ginger cultivars

Sl. No.

Karyotype character

Range

Cultivars with lowest and highest values

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