Abstract
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.
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Claims 9
Claim · model-written summary
Sikkim varieties differ from evolved types in several characters.
- Outcome
- differentiated from the more evolved typese0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two Himalayan varieties are differentiated from the more evolved types with regard to a number of their characters”
t0“maize”
Claim · model-written summary
Reciprocal crosses differed significantly, indicating cytoplasmic differentiation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reciprocal crosses between the two groups of evolved and Sikkim varieties show significant differences indicating differentiation at a cytoplasmic level”
t0“maize”
Claim · model-written summary
Primitive varieties had higher chiasma frequency.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“primitive varieties show a higher chiasma frequency”
t0“maize”
Claim · model-written summary
Some hybrids showed heterosis for chiasma frequency.
- Outcome
- heterosis for this charactere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some of the hybrids between the two groups provide evidence of heterosis for this character”
t0“maize”
Claim · model-written summary
Hybrids showed heterosis for quantitative characters.
- Outcome
- Heterosis was also observed for a number of quantitative characterse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heterosis was also observed for a number of quantitative characters in the hybrids between the two groups of varieties”
t0“maize”
Claim · model-written summary
Sikkim varieties had smaller chromosomes.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two Sikkim primitive varieties have relatively smaller chromosomes”
t0“maize”
Claim · model-written summary
Sikkim varieties had distinctive chromosome knob patterns.
- Outcome
- distinctive pattern of knobse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a distinctive pattern of knobs”
t0“maize”
Claim · model-written summary
Sikkim varieties had a longer nuclear cycle, suggesting greater chromosomal DNA content.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They also show a longer nuclear cycle suggesting a greater content of DNA in their chromosomes”
t0“maize”
Claim · model-written summary
Himalayan varieties were more differentiated from commercial types than Mexican primitive varieties.
- Outcome
- differentiated from the evolved commercial types to a greater extente0
- Comparator
- primitive varieties of Mexican distributione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two Himalayan varieties appeared to be differentiated from the evolved commercial types to a greater extent than the primitive varieties of Mexican distribution”
t0“maize”