Normal and C analogues of hybrids were examined during five years in one location in three-factor experiments including: density planting (2-3 densities each in 2-3 replications, plot area 10 sq m); genotype (of 5-19 hybrids in each block); cytoplasm (C and normal).

Table 1. The result of comparative study of corn hybrids in normal and male sterile cytoplasms.

Corn hybrids in C male sterile cytoplasm significantly differ from their normal counterparts only in plant height and tassel length (Table 1). There were not considerable differences between normal and C analogues, for all the rest of the morphological traits of the plant and ear. The C analogue hybrids have the same grain moisture when yielding, growing period, period from seedling to silking, but even more productive than normal one.

We may note that in drought years the yield of cytoplasmic male sterile hybrids was more (6.0%) than the yield of their normal counterparts, whereas in the favourable years differences were insignificant (1.5%). In addition it is necessary to observe, that grain yield of cytoplasmic male sterile hybrids depends upon their ability of pollen formation. In our investigation we concluded that in drought years, male sterile hybrids excel in grain yield (10.6%), while hybrids with restored fertility were only 3.8%. However, in favourable years differences in grain yield between male sterile and normal, as well as between restored and normal analogues were not so considerable.

Therefore we consider the utilization of the C male sterile cytoplasm acceptable in corn hybrid seed production.

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