Saratov State University
The occurrence of haploids on the second ears of parthenogenetic lines
--Smolkina, YV, Tyrnov, VS

Methods vary for the generation of seed from parthenogenetic lines. These include hybridization, backcrosses and self-pollination. Sometimes it is necessary to have the material for embryological analysis or for culture in vitro. Generally, these techniques concern only one individual. In such cases it would be advisable to use the second ears. The use of the second ear makes it possible to either reject the individual or accept the individual following an identification of its frequency of parthenogenesis. In performing this method, it is possible to obtain information regarding the frequency of parthenogenesis on the different ears of the same plant.

We have examined the parthenogenetic maize lines AT-1 and AT-3, described earlier (Tyrnov, MNL 71:73-74, 1997), as well as their analogies, having the cytoplasms of M, S and C type.

The parameters investigated are as follows:

1) the simultaneous pollination of the 1st and 2nd ears by the different dates of appearance in their silks - 1 and 3-4 days;

2) the pollination of the second ear 3-4 days after pollination of the first one.

The parameter was used to answer the question about stimulation or inhibition of parthenogenesis in the second ear by embryological processes of the first.

The conclusion from this research is as follows:

1) On both ears the kernels with parthenogenetic haploid embryos can form with the same frequency. The difference in frequencies of parthenogenesis is within the limits of the values as recorded before by the delay of pollination. This variation is inevitable because of the difference in flowering and timing of ear development between the first and second ear. Consequently, the frequency of parthenogenesis in the second ear can be lower. From this research, we have found that the second ear can be successfully used in breeding, taking into account that their frequency of parthenogenesis can be lower than in the first ones.

This work was supported by a grant from the Russian Foundation for Basic Research.

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