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 %|
Table 2. Selected males from 1992-93 winter.
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