STUDIES ON THE EXPRESION OF GENERAL AND SPECIFIC COMBINATION CAPACITY AT SEVERAL INBRED LINES IN A DIALLEL SYSTEM AND THE MANIFESTATION OF HETEROSIS IN NEW MAIZE HYBRIDS OBTAINED.

Of great importance for the extension of the practice of corn amelioration, of quantitative genetic analysis methods, was the enunciation of the general combination capacity (CGC) and specific combination (CCS) concept. By CGC, according to the concept, is meant the additive genetic component transmitted by the crossing of all the descendants by a parent. By CCS is meant that genetic component that is transmitted to the descendants only when a genitor is specifically crossed with a particular partner. The two components equate to the effect of the action of the aditive genes in the genetic point of view, in the case of the general combinatorial capacity, and in the case of the specific combining capacity, it is equivalent to the effect of the interactions of nonadjusted dominant genes and epistaxis. In the second half of the 20th century, in the creation of maize hybrids, this concept had some remarkable results (Căbulea 2004). The overall ability to combine inbred lines is particularly important in making valuable corn hybrids. Crossing known inbred lines through the general combination ability (for production or other character) in a dialell system, it is normal to perform a hierarchy of the respective inbred lines. The study of the effects of the general combining ability in the expression of heterosis in the characters: the height of insertion, the total height, the length of the ear, the number of grains per row, the grain weight, the weight of the ear, the dry matter, the MMB, the number of erect plants, using experimental data from a dialel system of type p (p-1) / 2. Regarding the analysis of variants of hybrid combinations obtained in the dialell system, it is observed that for all the studied characters the ratio between the specific combining capacity and the overall combinaton capacity is superunit, which means that in these cases the effect of nonadjusted dominant gene interactions and epistasis is stronger than the additive effect. High values for heritability coefficient were recorded for the number of rows per ear, grain production, and the percentage of erect plants, which means that transmission of these characters to other genotypes can be done efficiently. The majority of characters are mainly dominated by dominant genes, with a dominance ratio greater than 1, except for the percentage of erect plants. [ABSTRACT FROM AUTHOR]