Comparative evaluation of diploid and tetraploid red clover accessions in a flat area of Northern Bulgaria

Abstract

Abstract From the first to third growing season in the field test carried out at the Experimental Station of Soybean (Pavlikeni, Bulgaria) was observed 12 accessions of red clover, including two Bulgarian diploid varieties Nika 11 (standard) and Sofia 52, four local populations and next six foreign tetraploid varieties, i.e. Kvarta, Astur, Carbo, Elanus, Fregata and Larus. The goal of study was to determine the effect of ploidity level of the varieties as well as the effect of adaptive variability of local populations on fresh mass yield, dry mass yields and their persistence in an agro-ecological area with lower summer moisture assurance for red clover. The highest total dry mass yield was observed for Sofia 52 variety (2n), with insignificant differences being inferior to the standard variety Nika 11 (2n) and tetraploid varieties Kvarta and Astur. The productivity of these tetraploids strongly varies depending on the season and the year, as well as the age of sward. According to the obtained comparative production data for cuts and years, the tetraploid germplasm has a stronger adaptation to the limiting moisture. In summer drought, typical for the plains of Northern Bulgaria, tetraploids stops growing and does not compensate for its limited vegetative growth, despite the excellent moisture guarantee in the late summer, as well as in the spring the next growing season. Local wild-type germplasm of the species is characterized by a rapid development and lower yield of fresh and dry forage mass compared to the diploid standard when growing in conditions of optimum moisture but relatively high productivity in the dry conditions of the summer months. The differences in the genotypic productivity response under dry conditions reported in this experiment also suggest that the abiotic limit studied can be successfully responded by the genotype factor.

Keywords

• diploid
• drought
• populations
• red clover
• tetraploid
• variety
• yield