2.3. Field experiments
Two field experiments were conducted at Alameda del Obispo
experimental farm at Córdoba, Spain.
2.3.1. First field experiment: quantifying the effect of rust infection
on yield components
The first field experiment was performed over two consecutive
field seasons, 1999e2000 and 2000e2001. Cultivars ‘Baraca’ and
‘Amcor’, known to be very susceptible to faba bean rust were used
in this experiment. Sowing was performed on 28 November 1999
and 2000. The experimental units were plots consisting of four
rows 3 m long at 0.7 m distance among rows. All the plots were
surrounded by triticale plants and the distance among plots was
1.5 m. Each faba bean cultivar was represented by eight plots
following a randomised design. Four plots of each cultivar were not
inoculated and additionally were fungicide protected to be used as
controls. A first application of Oxycarboxin 75% WP at 300 L ha1
(Mansour, 1980) was made the same day in which neighbouring
plots were inoculated. Applications were repeated at two-weak
intervals until mid-May to ensure a complete protection from rust
infection. The remaining four plots per cultivar were inoculated
with U. viciae-fabae to ensure high and uniform levels of rust
infection. Inoculation was performed by spraying with an aqueous
suspension of rust urediospores from a bulk population collected at
Córdoba. The urediospores were suspended in tap water (5 105
spores ml1), to which Tween 20 (0.03%, v/v) was added. Inoculations
were repeated three times from mid-January, at two-weak
intervals. Plants were inoculated after sunset to benefit from the
darkness and high relative humidity at night.
Disease severity (DS) was visually estimated at plant maturity as
the percentage of whole plant tissue covered by pustules. Later on,
plants were harvested and the numbers of pods per plant, numbers
of seeds per plant, seed yields, 1000-seed weights and production
were assessed.