--Elena P. Erygina and A. S. Mashnenkov
It was found that inbreds differed much in frequency of seed set in maize-Tripsacum crosses (MNL 63:87, 1989). In 1989 11 maize inbreds were crossed with Tripsacum dactyloides (2n=72). Ten ears were pollinated in each inbred. Depending on rate of ovary development four types of maize-Tripsacum hybrid kernels were distinguished:
1. kernels with well-developed germs and endosperms (test weight of a kernel--m=30-80mg),
2. kernels with poorly developed endosperms (m=15-30mg),
3. kernels with well-developed pericarps and initiated germs and endosperms (m=6-15mg),
4. kernels with initiation of pericarps, germs and endosperms.
All four types of kernels were included in the index-percentage of developed
|Maize inbreds||Ovaries per ear||Developed ovaries, %||F1 kernels with germs and endosperm, %||Coefficient of kernel development, P||Coefficient of compatible F1 genomes, C1|
Three inbreds, Gk26, Mangelsdorf's Tester 10 (TM10) and T22 showed complete incompatibility with Tripsacumdactyloides genomes. According to rate of kernel development other inbreds may relatively be divided into three groups: P = 0.65-0.92; P = 0.109-0.139; P = 0.144-0.152.
In the case of T. dactyloides ample pollen on cut maize silks, all egg cells are probably fertilized but kernel development stops at different stages of organogenesis.
In this case the value P mainly expresses rate of accumulation of stored substances in kernels. Coefficient C1 considers time that kernel development stops, i.e. stability of organogenesis. Evidently these traits are independently inherited. For instance, for inbreds PLS61 and A344 the most stable organogenesis is observed at moderate rates of stored substance accumulation in endosperms. Inbreds A663 and Gk30 are characterized by a contrasting combination of these traits.
To improve efficiency of hybridization the genetic factors governing
maximum expression of both traits should be combined.
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