Crosses of soybean genotypes (cv. Atlanta, MG 0; cv. Romantica, MG 00; cv. Izidor, MG I and cv. Houta, MG I) with different meaning of the trait harvest index (HI) were made (2017) and studied (2018-2020) in the environmental conditions of the region of Central North Bulgaria, the town of Pavlikeni (43°24' N, 25°32' E, 144 m a.s.l.). The objectives of the study were: i) establishment of genotype variance by HI and the traits determined for it in the group of the parent genotypes and in their hybrid populations (F2-F3 generations); ii) assessment of the potential of different parent genotypes and development of the strategy for crosses for the improvement of the HI; iii) assessment of the capacity of the HI as main or additional selection criteria in the breeding programs for seed productivity of soybean. In F2 and F3 generation of each hybrid combination biometrical and variance analyses were conducted for the following traits: total yield of aboveground plant biomass (including seeds, stems and branches, without leaves -BMY, g); seed yield per plant (SY, g) and harvest index (HI). The correlation (r) and regression (b) between F2 and F3 were assessed on the base of the middle values in F3 generation of each hybrid combination and its corresponding individual values per transgressive forms in HI. Based on the results obtained, the application of father component with high meaning of the HI resulted in breeding progress for seed productivity. It is reasonable to use the application of the harvest index as a breeding criterion in progenies of the crosses with father genotype as a donor with high value of the trait aboveground biomass. By phenotypic assessment of the HI as additional selection criteria recombinant lines with increased seed productivity were selected.

Glycine max (L.) Merrill, harvest index, breeding criterion, genetic improvement

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia