J. Le Gouis et al., Genetic differences for nitrogen uptake and nitrogen utilisation efficiencies in winter wheat, EUR J AGRON, 12(3-4), 2000, pp. 163-173
Due to economic and ecological factors, European agricultural practices are
likely to go towards extensive systems with lower inputs of nitrogen (N) f
ertilisers. The objective of this study waste assess varietal differences f
or N use at two nitrogen levels. A set of 20 winter wheat (Triticum aestivu
m L.) genotypes was studied over 2 years in northern France on a deep loam
soil without (NO) and with 170 kg ha(-1) N fertiliser (N +)as ammonium nitr
ate. Results were consistent on both years as the genotype x year or genoty
pe x year x N level interactions were not significant. The genotype x N lev
el interaction was highly significant except for total N utilisation effici
ency (total above-ground dry weight/total above-ground N) and grain N conce
ntration. The genotype x N level interaction for grain yield was mainly due
to three contrasting genotypes: Cappelle, a cultivar from the 1940s, had t
he same yield at NO and N +; Arche had a high yield at both N levels; and R
ecital had a high yield with added N and a very low one without N. The numb
er of kernels/ear explained most of the variations of grain yield at NO (48
%) and N + (80%), and of the interaction (67%). N uptake efficiency (total
above-ground N/soil N supply) accounted for 64% of the variation in N use e
fficiency (grain yield/soil N supply), while at NO and at N + it accounted
for only 30%. N utilisation efficiency (grain yield/total above-ground N) w
as then more important at N + than at NO. Grain N explained most of total p
lant N variation at both N levels. The interaction for N use efficiency was
best explained by the interaction of N uptake (63%). The applications of t
hese results to a breeding programme to create varieties adapted to low-inp
ut management systems are discussed. (C) 2000 Elsevier Science B.V. All rig
hts reserved.