Maize
Genetics Cooperation Newsletter 80. 2006.
Instituto Fitot�cnico de Santa Catalina (FCAF, UNLP)
During the 2004/05 growing seasons, Andinas-Patagonicas inbreds were evaluated for response to the attack of the fungal pathogen responsible for maize rust and other leaf diseases. The selected lines were from the Institute Fitot�cnico de Santa Catalina: SC1, SC3, SC4, SC6, SC7, and SC9 were harvested from the west Patagonica zone in Argentina and X Region in Chile. Also included were one early line, F2 (France), and two lines of average cycle, B73 and Mo17 (USA). The materials were sown on 2 dates, with the second 20 days after the first. The severity of attack was determined for three leaves: Leaf 1: under ear, Leaf 2: ear leaf and Leaf 3: above the ear. Plants with one pustule or less were considered to be tolerant (t).
Most lines present a high incidence (>70 %) of P. sorghi for both plantings, with the exception of SC1 (46%) (Table 1). Lines SC4 and SC6 exhibited reduced severity (Table 2). We also observed the presence of other diseases, such as leaf spot caused by Helminthosporium sp. and also corn smut, caused by U. maydis. These were of lesser severity. In the majority of cases, the incidence was more obvious for the first planting (Table 2).
Table 1. Frequency of Puccinia sorghi
infection.
|
Lines |
1st Planting % infected |
2nd Planting % infected |
|
SC1 |
46 |
100 |
|
SC3 |
87.7 |
100 |
|
SC4 |
96.9 |
88.4 |
|
SC6 |
76.4 |
86 |
|
SC7 |
85.1 |
81 |
|
SC9 |
95.2 |
85.6 |
|
F2
|
76.9 |
100 |
|
B73 |
47.5 |
89.4 |
|
Mo17 |
100 |
47.9 |
Table
2. Severity of Puccinia sorghi infection in leaves.
|
1st Planting |
P. sorghi leaf 1 % |
P. sorghi leaf 2 % |
P. sorghi leaf 3 % |
Other diseases |
|
SC1 |
0-t |
0-t |
0-t |
Helminthosporium spp |
|
SC3 |
0-1 |
0-1 |
0-1 |
Helminthosporium spp |
|
SC4 |
0-1 |
0-1 |
0-1 |
U. maydis, Helminthosporium spp |
|
SC6 |
0-1 |
0-1 |
0-1 |
Helminthosporium spp |
|
SC7 |
0-1 |
0-1 |
0-1 |
U. maydis, Helminthosporium spp |
|
SC9 |
0-5 |
0-5 |
0-5 |
Helminthosporium spp |
|
F2 |
0-10 |
0-15 |
0-10 |
------ |
|
B73 |
0-10 |
0-10 |
0-10 |
------ |
|
Mo17 |
0-15 |
0-10 |
0-10 |
U. maydis |
|
2nd Planting |
P. sorghi leaf 1 % |
P. sorghi leaf 2 % |
P. sorghi leaf 3 % |
Other diseases |
|
SC1 |
0-20 |
t-30 |
t-30 |
------ |
|
SC3 |
0-5 |
t-10 |
t-10 |
Helminthosporium spp |
|
SC4 |
0-t |
0-1 |
0-1 |
------ |
|
SC6 |
0-t |
0-1 |
0-1 |
------ |
|
SC7 |
0-1 |
0-1 |
0-1 |
U.
maydis |
|
SC9 |
0-1 |
t-5 |
0-1 |
------ |
|
F2 |
t-5 |
t-5 |
t-5 |
------ |
|
B73 |
0-t |
0-t |
0-t |
------ |
|
Mo17 |
0-1 |
0-1 |
0-1 |
------ |
Scoring: None ------ ; average:
0-30% ; t : tolerant.
The
lines SC4 and SC6 were selected to continue improving tolerance to maize rust
and other diseases in the materials employed in this breeding.
_________________________________________________
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note:
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