Galina NAYDENOVA1*, Tatyana BOZHANSKA2
1 Experimental Station on Soybean, 61 “Ruski” Str., 5200 Pavlikeni, BULGARIA
2 Research Institute of Mountain Stockbreeding and Agriculture, 281” V. Levski” Str., 5600 Troyan, BULGARIA
*corresponding author: firstname.lastname@example.org; Tel: +359 0878229771
Abstract. The purpose of this study is to evaluate the genetic variability between red clover half–sib families in terms of yields of dry forage mass during regrowing, as well as seasonal yield stability and years of use. Ten red clover elite plants selected in the past by one or more breeding criteria underwent a re–pollination in 2014. Their polycross progeny (HSFs) were examined by cuts from the first to the fourth vegetation (2015–2018) for the following indicators: green matter yield, dry matter content, dry matter yield, time for cuts formation. ‘Nika 11’ and ‘Sofia’ 52 cultivars were used as a control for high summer productivity and adaptability. In early spring growth, the polycross progeny of elite genotypes did not significantly differ in dry forage mass. In contrast, as in late spring and summer regrowing, the effect of the family was significant (P<0.05). Genotypic effects are also observed in terms of growth rate. A genetic potential for increasing the yield of dry forage mass for both late–spring and summer regrowing was found for family 2 and 3. Valuable genotypes for the breeding in relation to yield stability over seasons and age of plants, respectively years of use, can be selected in family 7, which originated from a local wild–type germplasm. The high expression in the level and stability of the observed characteristics, as well as the high estimates of general combination ability, determined ‘Nika 11’ as an important genetic source in the breeding for high forage productivity in regrowing. According to these results, ‘NIKA 11’ is used as a major component in the formation of polycross groups with the selected families.
Keywords: red clover, Trifolium pratense, breeding, half–sib families.