Induced chlorophyll deficient mutants in maize
--Adamu, A. Kasim

Air dried seed of an inbred line of corn (Zea mays L.) was irradiated with a gamma cell 220 cobalt 60 (60Co) source, at 10 to 400 Gray, and thermal neutrons (flux 1.5x10-4 n.cm-2 S-1) for 25 minutes to 12 hrs. The irradiated seeds were sown in the field and pots in a complete randomized block design (CRBD) with four replications.

Among the dominant seedling mutants are sectors of chlorophyll mutants in M1 and M2 plants. Most of these mutant characters were lethal or unfavourable to growth. The type of chlorophyll deficient mutants found are albina, xantha, virescent, lutescent, chlorina (Fig. 1) and striata. Among the chlorophyll deficient mutants albina and xantha were rare, while lutescent and virescent were the most frequent. In the M1 generation, of the total number of mutants observed, 2.73% were albina, 10.38% xantha, 22.95% lutescent, 34.42% chlorina, and 7.38% were striate. However, in the M2 generation, of the number obtained 5.11% were albina, 9.85% xantha, 12.41% lutescent, 44.16% virescent, 16.42% chlorina, and 12.05% striata. When the two mutagens are compared in both the M1 and M2 generation, gamma rays produced higher chlorophyll deficient mutants in the M1 generation than thermal neutrons, while in the M2 generation thermal neutrons produced more chlorophyll deficient mutants than gamma rays cobalt 60 source.

Figure 1. Chlorophyll mutant in maize (i.e. chlorina).

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