Location of factors influencing grain yield by means of isoenzyme markers under different year conditions
--Chernov, AA; Mihailov, ME

The objective of the present study was to establish the genotypic effects of the chromosome 1 segment marked by the Adh1 locus and the chromosome 7 segment marked by the Sod2 locus on a number of agronomic traits. The study was carried out on a widely cultivated high-yielding hybrid, Moldavsky 291. The parental lines, F1 and F2 plants were estimated for the following quantitative traits: 1) time from emergence to the flowering of panicles; 2) time from emergence to the flowering of top ears; 3) time lag of the onset of flowering between panicle and top ear; 4) time from flowering to the maturation of top ears; 5) time from emergence to the maturation of top ears; 6) number of stems; 7) plant height; 8) stem length; 9) panicle length; 10) top ear position on the stem; 11) diameter of the bottom first internodes; 12) number of above-ground nodes; 13) number of ears with kernels; 14) internode mean length; 15) stem volume parameter; 16) ratio of stem length to bottom first internode diameter; 17) weight of top ear at harvest; 18) weight of the remaining ears at harvest; 19) total weight of ears; 20) the proportion of second top ears in total ear weight; 21) daily increment in ear weight; 22) weight of the cob of top ear; 23) number of kernel rows on the top ear; 24) number of kernels on the top ear; 25) number of kernels in row on the top ear; 26) ear length; 27) ear diameter; 28) ratio of stem length to diameter; 29) weight of 100 kernels; 30) grain index and others.

The enzyme electrophoresis extracts from pollen were run in 14% starch gel (buffer system "G", pH=7.0) (Wendel and Stuber, 1984). The gel staining was performed using reaction mixtures from Levites` (1986) list.

Isoenzyme analysis has shown the parental lines to differ with respect to the Adh1 and Sod2 loci. This allows 3 genotype classes to be distinguished in the F2 population for each locus: FF, FS and SS. For the quantitative traits studied, the following statistically significant differences between the above classes were observed for locus Adh1: 1) panicles and ears of SS enter flowering later than those of FS (for ears - FF and FS); 2) larger time lag of the onset of flowering between panicle and ear compared with FF; 3) top ear position on the stem of FF higher than of FS and SS; 4) number of ears with kernels of FF less than of SS; 5) lower weight of the top ear and cob of FS compared with FF; 6) number of kernel rows on the top ear of FF more than of FS and SS, of FS more than of SS; 7) number of kernels on the top ear of SS is more than of FS; 8) number of kernels in row on the top ear of SS more than of FS and FF, of FS more than of SS. Next year the results were reproduced only for the number of ears with kernels, which suggests the essential influence of year conditions. So for the Adh1 locus and year conditions a two-factor ANOVA was computed to evaluate the significance of the variation attributed to these factors (Table 1).

Table 1. Phenotypic variation explained by the Adh1 locus and year conditions.
 
Phenotypic variation (%) explained by
Numbers of the traits
Adh1 locus
Year conditions
Adh1 locus-year conditions interaction
Rest
1 0.6 18.8** 2.8* 77.8
2 0 14.4** 0 85.6
4 0 4.2* 0 95.8
5 0 0 0 100.0
7 0 9.0** 0.6 90.4
8 0 2.2* 0.2 97.6
9 0 24.7** 0.6 74.7
10 0.4 40.8** 0 58.7
11 0 0.4 0 99.6
12 0 0.3 0 99.7
13 2.3* 0 0 97.7
14 0.1 11.0** 0 88.8
15 0 0 0.2 99.8
16 0 4.2* 0 95.8
17 0 0 1.6 98.4
18 0.5 6.5** 0 93.0
19 0.7 0.1 0 99.2
20 0.1 8.8** 0 91.1
21 0.6 3.3* 0.5 95.6
22 0 5.9** 1.1 93.0
23 1.3 9.9* 4.6* 84.3
24 0 0 2.5 97.5
25 0 3.6** 3.5** 92.9
26 0 0 0 100.0
27 0.3 4.0* 0 95.7
28 0.2 0 0 99.8
29 0 15.5** 0 84.5
30 0 5.6** 0.2 94.3

For locus Sod2 F2 segregation the only effect was observed for the time from emergence to the maturation of top ears.

The results suggest that the chromosome 1 segment marked by the Adh1 locus and the chromosome 7 segment marked by the Sod2 locus genetically affect the above traits in maize. The effect manifestation depends on year conditions. Future research is needed to ascertain the nature of the effects observed. 


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