Heterosis Studies for Response to Aphis fabae Attack in Calendula

  • Adriana-Daniela BACIU
  • Doru PAMFIL
  • Adriana F. SESTRAS
  • Lucica MIHALTE
  • Radu E. SESTRAS
Keywords: aphids, hybrids, response to attack, dominance, overdominance


The main objective of the present study was to estimate the heterosis in F1 and F2 Calendulahybrids for their response to Aphis fabae attack, as a result of crosses between genetically differentparents. The aphids attack was examined as Attack Degree (AD%) on five pot marigold cultivarsbelonging to the C. officinalis L. and three different species (C. arvensis 121GE, C. stellata Cav., C.suffruticosa), used as genitors, as well as twenty F1 and fourteen F2 hybrid combinations of intra andinterspecific crosses, obtained by cyclic and diallel crosses and through self-pollination. Negativeheterosis calculated as mean of AD% per hybrid combination, which was desired for the trait, wasidentified and explained by different genetic interaction and phenomenon of heterosis (e.g. dominance,overdominance, pseudo-overdominance). Absolute heterosis values were close in most intraspecificand interspecific hybrid families in F1 and F2 generations. The highest desired negative value ofheterosis, both in F1 and F2 hybrids, was resulted after self-pollination of ‘Rech.f.’ cultivar, the mostsensitive genitor. The result was explained by the idea that partial dominance causes heterosis, becauseinbred descendants of this cultivars belonging to C. alata species become fixed for recessive orpartially recessive deleterious alleles.