Chromosomal polymorphism in local maize of Kashmir

Meiosis was examined in PMC of 181 plants of 37 varieties of local maize grown in three districts of Kashmir Valley for observing the extent of variation in the chromosome morphology. Besides differences in relative length of chromosomes, differences were also observed in the presence of B chromosomes, satellites on the short arm of chromosome 6, heterochromatic blocks on the long arm of chromosome 2 and abnormal chromosome 10.

The maize varieties used in the present study were collected from the sub-mountainous areas of the three districts (Anantnag, Pulwama and Baramulla) of the Kashmir Valley. The collections were made during September-November, 1972: Tripachi (4), Badeh (4), Vozij (2), Niver (2), Mishri (1), Kani (1) and Ferozpur (1) - Group I; and 1977 Chiteh-safed (8), Vozij (6), Lidder (4) and Dabher (4) - Group II from the Gujars' fields. However, no two varieties were collected from the same location or the same farmer. A distance of at least one km was maintained from field to field. The list of varieties collected from each district is given in Figure 1.

Group I and Group II varieties were grown in Srinagar to give 5 plants from each variety during the 1973 and 1978 growing seasons respectively. Young tassels at the proper stage were fixed in 1:3 acetic acid and ethyl alcohol for 48 h and stored in the refrigerator till worked. Squash preparations were made in 2% acetocarmine.

Chromosome morphology was studied at the pachytene stage of meiosis. In order to avoid any discrepancy in the results, which would arise due to differential condensation of the chromosomes, all results pertaining to total chromosome length were transformed into relative lengths (Tables 1 and 2). The cells were also studied at diakinesis for the presence or absence of B chromosomes, and at anaphase and telophase for tracing the course of 8 chromosomes and for other cytological observations. In the case of Mishri, only one plant could be studied.

No consistent similarity was observed in relative length of certain chromosomes within various varieties in a group, among different groups of varieties or within different districts. However, no differences were observed in arm ratios and hence in the arm lengths. These were in conformity with the results of other workers.

B chromosomes, abnormal chromosome 10, satellite and heterochromatic blocks were found variable from district to district (Table 3) and also within various varieties in a group. However, there was some consistency in these observations on a group basis, e.g., B chromosomes were observed in 100% of Ferozpur, Niver and Mishri groups, while these were observed in 50% of Chiteh-safed and Dabher groups. The frequency was the same in the case of Tripachi and Lidder groups (Table 4).

Except for the Badeh group (75%), the percentage in the remaining two groups ranged from 0 to 8.3.

Abnormal chromosome 10 was observed in 100% of Kani and Badeh groups of varieties; Vozij and Tripachi, Lidder and Niver, and Chiteh-safed and Dabher had 75, 50 and 25% respectively. It was totally missing in the remaining two groups.

The satellite was present with a high frequency in the Ferozpur group but was absent in Niver, Mishri and Kani groups. Vozij, Tripachi and Lidder groups had it in 50% of varieties only. However, the frequency was very low in the Chiteh-safed group.

The heterochromatic block was not observed in Chiteh-safed, Kani and Ferozpur groups. In the remaining groups its percentage frequency ranged from 16.6 to 100.

From the above-mentioned observations it was clear that no two varieties, whether having the same varietal name or otherwise, were identical. One of the important factors for this difference seems to be the hybridization between genetically diverse populations, as maize areas in a locality are contiguous and there is a possibility of free exchange of genetic material from one variety to another.

Figure 1.

Tables 1 and 2.

Tables 3 and 4.

P. N. Jotshi and K. A. Patel
 
 


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