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Materials and Methods
Investigations of wheat resistance to scab caused by
Fusarium graminearum Schw. were conducted in field
experiments in the experimental nursery of the Institute for
Breeding and Production of Field Crops in Zagreb. Here were
included 130 wheat genotypes obtained from the world various
centers. The obtained sources of resistance are mainly
extensive genotypes, taller in habit and with less
expression of the resistance to other diseases. They often
possess some undesirable traits, too.
In our investigations we used both natural and artificial
infections. Infected materials were collected from the large
wheat growing area in Yugoslavia to be used for artificial
infection. Fusarium from collected samples were
developed on PDA and used for productions of pure culture by
using infected wheat kernels, namely its juice for
inoculation and for the identification of Fusarium
species as well.
Artificial infection of spikes in field, took place at
flowering stage using "spray-method". The second infection
is falling in a week later. Attack severity was estimated in
two intervals - first at the milk or milk-dough stage and
the second seven days later (at the growth stage 11,1, and
11,3 of the Feekes scale). The rating scale 0 - 5 was used
for estimating fusarium attack (0 = no infection, 5 = more
than 75% diseased plants/spikes).
Using partial diallel crossings with seven sources of
resistance were performed in 1981. The following sources
were used: Toropi, Roazon, Encruzilhada, Bizel, Mironovskaya
808, Balayacerkov and Poncheau. In the year 1982 were made
crosses F1 x F1. Next year we put
offsprings in the experiment paralley with corresponding
F1 generation and their parents (sources of
resistance). The obtained F1 crosses and the
crosses of F1 x F1 were set in trials
using randomized block design in 5 replications. Each
combination was planted in a 1,20m row, 10 kernels/row. The
parents (sources of resistance) were planted paralley in two
rows with 0,30m row spacing. The trial was artificialy
inoculated by using "spray-method" Two ratings of disease
attack in field were taken.
Results and Discussion
Over 130 sources of resistance were collected and tested,
seven were chosen and crossed (using the scheme of partial
diallel) in order to determine the level of wheat resistance
to fusarium head scab. Apart from considering the level of
resistance, efforts were made to select as divergent
material as possible with good agronomic traits.
According to the results from Table
1 the selected materials differ markedly among
themselves in the level of resistance. The level ranged from
0,65 (Encruzilhada) to 3,89 (Roazon) and the selected
materials expressed types of reaction from resistant to
moderately susceptible (R, MS). This level of resistance was
determined using the rating scale 0 - 5. By this scale types
rated 0 - 2 were marked R, MR, while types estimated 3 - 5
were marked MS, S, AS (VS).
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