COMBINING ABILITY OF EARLY RIPERING SELF - POLLINATED LINES OF MAIZE AND TESTERS IN THE SYSTEM OF TOP-CROSS HYBRIDIZATION
The value of the initial material for selection for heterosis is primarily defined by the combining ability in respect to the main economically valuable characteristics. Combining ability with respect to “grain productivity” has been studied among fourteen self-pollinated lines of maize of early ripening and three testers in the system of hybrid combinations. We have proved that weather conditions have an influence on the variability of the estimates of the combining ability. We have identified the new self-pollinated lines of maize SP 165 and SP 175, which are characterized by invariably high evaluations in the effects of GCA (gi) in different years. The new self-pollinated line SP 167 has got high variants of SCA (δ2si). The new lines SP 161, SP 163, SP 167 and SP 174 have been characterized by the variability of the evaluations in the effects of GCA. They are related to the first or second rank in respect of GCA, depending on the year of the conducted evaluation. These are SP 163, SP 164, SP 170, SP 171 and SP 173 that have differed by their variability of the variants of SCA (from the low variants to the high ones). The highly productive testcross hybrids: Madonna M × SP 165 (4.88 t / ha), Madonna M × SP 171 (4.85 t / ha), Madonna M × SP 167 (4.80 t / ha), T 7M × SP 165 (4.78 t / ha) have been obtained based on the self-pollinated lines having invariably high figures of GCA and SCA