Division of Genetics, Indian Agricultural Research Institute, New Delhi-12
*Present address: Agricultural Research Institute, Hungarian Academy of Sciences, Martonvasar, Hungary.
Online published on 25 January, 2012.
Two primitive varieties of maize collected from Sikkim have been compared for a number of quantitative and other characters with genetically improved commercial types of maize and with primitive forms of Mexican and Columbian distribution. It has been found that the two Himalayan varieties are differentiated from the more evolved types with regard to a number of their characters. Thus, the reciprocal crosses between the two groups of evolved and Sikkim varieties show significant differences indicating differentiation at a cytoplasmic level. Also, the primitive varieties show a higher chiasma frequency and some of the hybrids between the two groups provide evidence of heterosis for this character. Heterosis was also observed for a number of quantitative characters in the hybrids between the two groups of varieties. The two Sikkim primitive varieties have relatively smaller chromosomes and a distinctive pattern of knobs. They also show a longer nuclear cycle suggesting a greater content of DNA in their chromosomes. The two Himalayan varieties appeared to be differentiated from the evolved commercial types to a greater extent than the primitive varieties of Mexican distribution. The significance of these observations has been discussed from the point of view of the time scale of introduction of maize in Asia.
