Agriculture Reference
In-Depth Information
Table 5.1. Some examples of reduction in disease parameters brought about by horizontal
resistance in various crop-pathogen combinations
Resistance
component
Host
Pathogen
Resistant
response
Susceptible
response
Reference
Latent
period
Potato
P. infestans
5 days
3 days
Guzman-N,
1964
Coffee
H. vestatrix
64 days
20 days
Hakiza,
1997
Barley
B. graminis
13 days
9 days
Asher and
Thomas,
1984
Relative
lesion
number
(per unit
leaf area)
Rice
P. oryzae
8
100
Roumen,
1993
Coffee
H. vestatrix
13
100
Hakiza,
1997
Barley
B. graminis
68
100
Asher and
Thomas,
1984
Spore
production
per unit
leaf area
Potato
P. infestans
700
4900
Guzman-N,
1964
Barley
B. graminis
10934
22787
Asher and
Thomas,
1984
Final
disease
level
Plantago
D. adunca
69%
(logistic
model)
100%
(logistic
model)
Linders
et al ., 1996
66%
(Gompertz
model)
100%
(Gompertz
model)
Rate of
growth
Plantago
D . adunca
0.048
(logistic
model)
0.078
(logistic
model)
Linders
et al ., 1996
0.083
(Gompertz
model)
0.111
(Gompertz
model)
Frequently then, new breeding lines are assessed for their reaction to a particular
pathogen or group of pathogens using a wide range of potential indicators. Kong
et al. (1997) assessed the response of 17 sunflower accessions to Alternaria
helianthi under field conditions. At the same time, each line was also assessed under
controlled conditions to examine variation between them in terms of incubation
period (defined here as the time between inoculation and 25% of lesions becoming
visible), infection frequency (expressed as a proportion of the mean number of
lesions on a susceptible check), mean lesion size and spore production. The resulting
correlation matrix, derived following regression of means of components with field
Search WWH ::




Custom Search