Heterosis and combining ability for plant height and its components in hybrid wheat with Triticum timopheevi cytoplasm

Abstract

The heterosis and combining ability for plant height and its components of hybrid wheat were investigated in an incomplete diallel experiment including 5 CMS lines and 4 restorer lines. The results showed that heterosis (HS) and heterobeltiosis (HBS) occurred in plant height (PH) and length of the first internode (LFI), second internode (LSI), third internode (LTI), basal internode (LBI) and the spike (LS) of hybrids, but their values varied among crosses and characters; the HS and HBS of LBI were larger than those of other characters, the HS and HBS of LSI and LTI contributed a lot to those of PH. There were significant relationships between internode lengths and PH for specific combining ability (SCA) and general combining ability (GCA), and among lengths of the adjacent internodes for SCA and/or GCA effects. However, the relationships of LS with the lengths of internodes and PH were insignificant for GCA, SCA, HS and HBS. The SCA effects were more important than GCA effects for LFI, the reverse was true for LSI, LTI, LS and PH, and the SCA effects was nearly equal to the GCA effects for LBI. So, LFI was mainly influenced by non-additive effect of genes, while LSI, LTI, LS and PH were mainly controlled by additive gene effects, LBI was controlled equally by additive and non-additive effects of genes. The genes that control the length of specific internode not only affect PH, but also the length of the adjacent internode. The genetic system in charge of lengths of internodes and plant height is independent of that for length of spike. Thus, it is possible to develop new wheat cultivars or hybrid combinations having long spike but dwarf plant height.