PECULIARITIES OF FORMING ELEMENTS OF THE MAIZE YIELD STRUCTURE DEPENDING ON THE EXISTENCE OF THE GENETIC MARKERS IN THEIR MATERNAL COMPONENTS

Abstract

Maize is one of the major grain and forage crops. Biological peculiarities of  its growth and development contribute to growing both in Ukraine and far beyond its borders. For a long period mainly varieties-populations were grown. And because of high adaptive potential and higher productivity heterotic hybrids drove them out of  the production in the middle of the last century.

Due to the shortage of qualitative domestic seed the percentage of imported planting material was increased, which according to the adaptive ability is worse adapted to our growing conditions. Therefore, the development of methods for obtaining hybrid seeds of maize for specific soil and climatic conditions will provide an opportunity to simultaneously reduce the cost and increase the production of grain through the full disclosure of the genetic potential.

The most common way to reduce the cost of producing heterosis hybrids seeds of agricultural crops, in particular maize, is the use of maternal lines with different forms of cytoplasmic sterility as the most common variants of the genetic system of  the controlled reproduction (GSCR) of maize. It is well known that the most common way of reducing costs in the production of maize heterotic hybrid seeds is the use of mechanisms of cytoplasmic male sterility (CMS) as one of the most studied variants of the genetic systems of the controlled reproduction (GSCR). Now M- and C-type of sterility are dominated in the maize hybrid seed production in Ukraine.

However, the problem of unification of plasma encourages for the search for new GSCR primarily on the basis of functional male sterility genes Vg – (Vestigial glume), without violations of the genetic mechanisms of microsporo- and microgametogenesis. The simplification of controlling seeds hybridity, and hence the cheapening of its production, is achieved due using marker genes of the maize grain colouring, suggested by F. M. Parm with the co-authors, which are closely linked with the mentioned functional male sterility gene, as well as on the basis of the concatenated nuclear genes of male sterility (Ms5/ms5 and Ms13/ms13) with marker genes (A2/a2) of maize grain colouring.

To establish effective methods of the genetic controlling of the purity of maize hybrid seeds, using genetic markers in different genetic systems of the controlled reproduction (GSCR), to create high quality hybrid seeds with preservation of the harvest and sowing qualities and high typicality of hybrid seeds we have tested coisogenic analogues of simple hybrid Pioneer-Grand 3978 and three-way cross hybrid Grand-6 in two localities with different soil and climatic conditions of Right-Bank Forest-Steppe and Southern Steppe.

In the experiment coisogenic analogues of simple hybrid Pioneer-Grand 3978 were studied (it is obtained by crossing sterile maternal component П3Са2а2 with the genetic marker a2 (Antocianinless), which in the homozygous state determines the absence of anthocyanin coloration in aleurone, and parental component П5СВСІСІ with the genes of fertility restoration and marker CI (Dominant colorles), which suppresses the expression of purple or red color): П3зМ×П5СВСІСІ (maternal form in a hybrid combination of fertile fixer of M-type of sterility); П3зМACR×П5МВСВР-RR (maternal component - fertile fixer of the M-type of sterility with the genetic markers ACR, which in the homozygous state determine the presence of anthocyanin coloration in the aleurone and pericarp, the paternal line — with fertility restoration genes has a marker of P-RR, which causes the red color of the pericarp). Analogues of three-way cross hybrid Grand-6 were also studied (in the seed production of which maternal component of С-type of sterility is used, and a paternal - with the fertility restoration genes and genetic marker a1): П7зС×П26СВа1а1 (a hybrid combination with the maternal line — the fertile fixer of С-type of sterility); П7зСACR×П26СВСІСІ (a hybrid form with the same maternal lines and markers ACR, and the paternal line — with the genes of fertility restoration has the marker CI).

The analysis of our research showed that under unfavourable growing conditions (drought during the formation and ripening of grains, insufficient rainfall, extreme temperature conditions which negatively influenced the fulfillment of genetic potential of the maize hybrids yield) researched coisogenic analogues compared to basic control hybrids, had higher productivity. The presence of a maternal component in the dominant genetic markers ACR did not lead to a decrease in yields of the analogues П3зМACR×П5МВСВР-RR and П7зСACR×П26СВСІСІ, but on the contrary contributed to its increase. The highest grain productivity provided the same coisogenic analogues respectively to 6.58 t/ha and 7,41 t/ha in Forest-Steppe areas, whereas its analouges had the yield to 8.19 and to 8.41 t/ha in the Steppe.

A significant increase in harvest grain moisture had analogues of three-way cross hybrids П7зС×П26СВа1а1 and П7зСACR×П26СВСІСІ under the conditions of Right Bank Forest-Steppe. Harvest grain moisture of the simple hybrid analogues did not increase significantly. When growing analogues in the southern Steppe moisture did not exceed the data of the control options, therefore, the grain did not need to be dried.

The analogue of the hybrid Pioneer-Grand 3978 with the maternal line fertile fixer of the M-type of sterility and the gene markers ACR had the highest cob length indexes and number of grains in a row under the Right-Bank Forest-Steppe and southern Steppe conditions. When growing coisogenic analogues of three-way cross hybrid Grand-6 with the maternal line of P-type of sterility and the same markers, an increase in the number of rows of grains in both areas of research was noted.

Therefore, the results, obtained in our experiments, indicate the possibility of introducing genetic markers of grain colouring linked to the genes of male sterility into hybrid maize seed production for simplification of controlling seed hybridity without negative effects on the yield qualities of the seeds.