Stabilization of high haploid inducer lines
--K. R. Sarkar, A. Pandey, P. Gayen, Jasbir Kaur Madan, Rajesh Kumar and J. K. S. Sachan

The haploid inducer lines developed earlier with 75 percent stock-6 background yielded on an average, about 3 percent maternal haploids in the stock-6 derived tester line carrying appropriate genetic markers. The haploid induction potential was still segregating in the plants within the lines, but further selection was not effective. Therefore, intercrossing among the lines and selection was tried to increase the haploid induction potential still further.

With this in view, the top 15 to 20 high haploid inducer males in each season were carried forward to the next generation and tested. Haploid induction higher than 5 percent was obtained during the last five seasons (Table 1). For the last three seasons haploid percentage induced by selected male families ranged from 3.05% to 18.57%. Further, rigorous selection for the last five seasons resulted in identification and stabilization of a few high haploid inducer C-I lines (Table 2). In the 1992-93 winter, one ear produced as many as 26 haploids out of 140 kernels of the tester female. The earlier maximum number was 23 out of 300 kernels on one ear. During the last winter, 15 ears with more than 20 haploids/ear were obtained as opposed to 5 ears with more than 20 haploids in the 1992 summer. These haploid inducer lines are being tested on breeding populations to explore the possibility of mass scale haploid induction for homozygous line development.

Table 1. Mean haploid percentage over the season.
 
Season Mean haploid % Range of haploid %
1990-91 winter 5.22 2.19-12.50
1991 summer 4.86 2.50-9.23
1991-92 winter 5.81 3.05-14.29
1992 summer 5.22 4.03-13.35
1992-93 winter 5.47 3.76-18.57

Table 2. Selected males from 1992-93 winter.
 
Haploids
Male Total kernels Number Percent
5329 C.1-17 77 10 12.98
-23 140 26 18.57
-28 457 44 9.63
-29 484 25 5.17
5329 C.2-8 95 6 6.31
-12 679 26 3.83
5329 D-6 1006 50 4.97
-10 31 3 9.68
-1 27 3 11.11
-11 161 8 4.96
-12 203 16 7.88
-23 519 28 5.40
5332 C.1-2 581 37 5.43
-11 301 20 6.65
5332 C.2-2 1081 48 4.44
-11 432 22 4.84
-16 339 18 5.31
-18 3015 148 4.91
-27 1099 43 3.76
-28 366 26 7.10
-30 58 6 10.34
5332 D.1-12 1793 90 5.02
5332 D.3-24 589 44 7.47
5332 D.5-4 322 16 4.97
-18 566 27 4.77
-27 882 59 6.69
5332 E.1-9 217 16 7.37

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

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