8th INTERNATIONAL WHEAT CONFERENCE

GENETIC STUDY ON THE EFFICIENCY OF NITROGEN
UTILIZATION IN WINTER WHEAT (TRITICUM AESTIVUM L.)
UNDER VARIED FERTILIZATION REGIMES
Dominika Ratajczak 1* , Bogusława Ługowska 2** ,
Zofia Banaszak 2 and Andrzej G. Górny 1
1 Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479 Poznań,
Poland,
2 Danko Plant Breeding Ltd., Choryń, 64-005 Racot, Poland
E-mail: * dwas@igr.poznan.pl, ** boguslawa.lugowska@danko.pl
Progress in breeding more effi cient winter wheats better adapted to sustainable agriculture
and/or more optimal N-input technology is still limited due to a lack of knowledge
on the mode in which the effi ciency of N utilization in grain mass formation (NUtE)
is inherited. To improve NUtE by breeding, better understanding of the genetic system
governing the physiological trait and its components is needed.
In two factorial fi eld experiments, two separate sets of diallel F 2 -hybrids between parents
of diff erent origins were examined in 2005-2007 and 2008-2009 at two locations
using contrasting N fertilization regimes. Th e range of the additivity-dependent variance
in NUtE components was relatively narrow, especially under N shortage. Usually,
narrow-sense heritabilities for the traits did not exceed 0.40-0.45 under N shortage. Th us,
a broadening and diversifi cation of the current gene pool that wheat breeders would handle
may be recommended. In general, NUtE components were inherited in a complicated
fashion and the used N regimes exhibited essential infl uences on the expression of gene
actions responsible for the traits and their inheritance mode observed. Under high fertilization
only, NUtE and its components were inherited in a manner being favourable for
the breeding practice (preponderance of additive gene eff ects). However, contribution of
non-additive eff ects and degree of dominance substantially increased in nitrogen-limited
plants. Th is should not facilitate breeding eff orts to improve NUtE and adaptation to
less favourable fertilization regimes. Moreover, genotype-by-nutrition interactions were
frequently noticed for NUtE suggesting that an evaluation under diverse N fertilization
levels is needed when searching for improved N effi ciency and adaptation to less favourable
fertilization in winter wheat. Results of the study did not confi rm the potential for
a rapid improvement of NUtE among the current European wheat germplasm and suggest
that non-conventional breeding schemes under reduced N levels and selection prolonged
for later hybrid generations appear to be necessary to fi x additive and additive ×
additive gene actions and to overcome the masking non-additive eff ects. Nevertheless,
the modern and short-statured British cvs. Rapsodia, Kris and Clever were found to exhibit
enhanced combining abilities in the study. Th us, the genotypes seem to be the most
promising sources for wheat breeding dealing with improved NUtE under less favourable
fertilization, and identifying their effi ciency genes and pyramiding these in further crossing
programs appears challenging.
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