N. Tsenov1*, T. Gubatov1, E. Tsenova2

1Agronom I Holding, 9300 Dobrich, Bulgaria
2Dobrudzha Agricultural Institute, 9525 General Toshevo, Bulgaria

Abstract. Objectives. The height of the stem of wheat has a direct impact on its productivity. Genetics of the trait is very particular in the country environments in terms of positive effects have only some of the known genes. The purpose of this study was to ascertain which of these genes for short stem (semi dwarf) alone or in combination with other could positively influence the yield of wheat in Bulgarian conditions. Methods. The study is on the relationship between the height of the stem and productivity of varieties with different genetics for their height. Selected two groups consisting of seven varieties (one check in each group), with known genetics of the trait, which differ significantly in its phenotypic expression. There are hybrid populations between selected high-stem varieties and a semi dwarf one – Medea. For two consecutive seasons (2012 – 2013) in the varieties and breeding lines created by hybrid combinations several major traits associated with the height of the stem and productivity, are analyzed. All existing differences in each trait of the groups, and the differences in correlations between them are discussed.

Key results. Productivity is highest in wheat that has medium or short height of the stem. In NPT and NGS there were no differences between “short-stem” and “high-stem” varieties. The most significant difference in favor of varieties and breeding lines with a short stem, the trait NGM (9.3 and 10.9%) and the GY (10.2 and 6.1%) and in HOS (20.6 and 44.1%), respectively. For TGW “high-stem” varieties generally have higher values in both groups studied.
Conclusions. The height of the stem has no significant negative correlations with characters specifying the productivity and grain yield itself. Selection on height of the stem in the hybrid populations towards shorter forms substantially alter the correlations between the traits associated with productivity. All tested varieties and lines are carriers of the gene Rht8. The difference in the specific conditions of about 30 cm in height is arising from the various alleles of gene Rht-B1. The semi dwarf lines carrying the genes Rht-B1e, Rht-B1b and Rht-D1b are the shortest in stem. In terms of gene Rht-D1, all varieties without exception have alleles Rht-D1a, which shortens the least stem. Best is a combination of height and grain yield in a combination of genes Rht-B1d, Rht 8 or Rht-B1e, Rht 8. All varieties with different alleles of these genes in the background of several different alleles Rht 8 are higher of 90 cm.