Within the framework of long-term
experiment devoted to cereal production,
the factors variety and fungicide protection
were added during three years (2006,
2008 and 2010) to the factors crop rotation
and soil tillage already studied since 1967.
By this complement, the aim was to
evaluate to what extent variety disease
tolerance and fungicide protection may
compensate for phytosanitary risks due to
high ratio of winter wheat in rotation, and
how far soil tillage interacts.
Monoculture penalized grain yield from
8 to 22 q/ha, mainly because of the
reduction of the grains number produced
per unit of area. Two years out of three,
the effect of soil tillage was significant,
with a variation of 8 q/ha in favor of the
ploughing. The difference between
varieties reached 8 to 15 q/ha, corresponding
to the known variation between the
two types of wheat tested. The additional
yield by fungicide protection varied
between 4 and 7 q/ha. The effects of a
high ratio of cereals in rotation could not
be compensated. The specific contributions
of each factor and many stressed
interactions point out the need for better
integrating the cropping techniques for a
high-level production.