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Materials and methods
a) Southern Highlands
Two
sets of trials were established in Uyole and Njombe in December 2004.
The first trial consisted of 35 inbred lines received from CIMMYT
Harare. The second trial consisted of 35 varieties and landraces from
CIMMYT Harare, and Tropical Pesticide Research Institute in Arusha
respectively. The trials were layed out in alpha lattice design with
three replications. The experimental area was surrounded by two rows of
a susceptible variety CG 4141 which also served as a disease spreader.
Seeding was done at 75cm x 50cm spacing and thinned to two plants per
hill after emergence. DAP was applied at the rate of 50kg/ha at planting
and Urea at 50kg/ha 6-7 weeks after planting. The trial was left to
natural disease infection. The location at Njombe is known as a GLS
disease high pressure area, and it is where the disease first appeared
in the country. Data collected from these trials included plant height,
ear height, resistance to turcicum blight, GLS, MSV and rust, husk
cover, ear aspect and grain yield. Disease rating was done on a 1-5
scale where 1= highly resistant and 5= highly susceptible. Most of the
other parameters were also accordingly rated on a 1-5 scale. Harvesting
at Uyole was done 6months after planting and that at Njombe 8months
after planting. The data was analyzed by MSTAT statistical package.
b) Madira and Arusha Foundation Seed Farm
Three trials were each established in Madira and Arusha Foundation Seed
Farm. These included a trial consisting of 20 varieties of Early
population material (EPOPO) obtained from CIMMYT Harare, a second one
consisting of 30 varieties from CIMMYT Harare and Tanzania maize
landraces obtained from Tropical Pesticide Research Institute in Arusha
and a third one consisting of 54 inbred lines obtained from CIMMYT
Harare. The trials were layed-out in alpha lattice design with three
replications. The experimental area was surrounded by two rows of a
susceptible variety CG 4141 which also served as a disease spreader.
Gray leaf spot was artificially inoculated to test varieties and to the
spreader rows six weeks after planting. A slight modification of last
season procedure was adopted (Anon.., 2004). Leaves which were infected
with GLS the previous season were air dried in sunlight. After drying,
the leaf spots were cut-out and ground with a grinder to a fine powder.
The powder was applied to the topmost leaf-whorl and also to about 2cm2
areas of the top three leaves. Inoculated areas were immediately sprayed
with water. All the plants in the experimental area were inoculated.
Seeding was done at 75cm x 50cm spacing and thinned to two plants per
hill after emergence. DAP was applied at the rate of 50kg/ha at planting
and Urea at 50kg/ha 6-7 weeks after planting. The experiment was
carried out under partial irrigation. .Data collected from these trials
included plant height, ear height, resistance to turcicum blight, GLS,
MSV and rust, husk cover, ear aspect and grain yield. The data was
analyzed by MSTAT statistical package.
c) Crosses
Inbred lines that appeared superior in terms of grain yield, disease
resistance and other attributes last season (Anon., 2004) were retained
and used for making crosses with testers. The testers were selected
based on resistance or tolerance to the major diseases. They included
the following:
CML 444/CML 202 crossed with 3 best
performing lines
CMLL395/CML 202 crossed with 32 best performing lines
CML 197/CML 390 crossed with 61 best
performing lines
CML 206/CML 390 crossed with 31 best
performing lines
CML 206/CML 312 crossed with 15 best
performing lines and
CML 216/CML 202 crossed with 3 best
performing lines
The
crosses will be harvested in January 2006.
Results and Discussion
a) Southern
Highlands
i) Uyole-Variety Evaluation
Results of the variety evaluation trial at Uyole are shown in Table 1.
Varieties with the highest grain yield per hectare included ZM621A-FLINT
(10.4 t), ZM523 (8.0 t), ZM611-F3 (7.5 t), TZA 1757 (6.9 t), TZA 1756
(6.3 t), TZA 1763 (6.2 t), TZA 1747 (6.2 t), TZA 1743 (5.8 t), ZM 521
(5.5 t), and TZA 1723 (5.3 t). Varieties TZA 1731 and TZA 1737 showed
highest resistance to GLS. There were differences among varieties in
resistance to turcicum blight and common rust. However, such differences
were not significant. Differences among varieties in husk cover and ear
aspect were not significant.
ii) Uyole –Inbred Lines Evaluation
Results of inbred line evaluations are shown in Table 2. There were
significant differences among inbred lines in grain yield. Inbred lines
which had the highest average grain yield in tones per hectare included
A1105-8-53 (3.1t), A1150-40-22 (2.7t),
A1150-55-29 (2.7t), A1105-4-50 (2.4 t). At this site, turcicum blight
was more severe than Gray leaf spot (GLS). Inbred lines that received a
rating of below 2 included A1150-32-20 (1.0), A1150-62-31 (1.3),
A1150-14-16 (1.5), A1150-54-28 (1.5), A1150-73-36 (1.5), A1150-64-32 (
1.8), A1150-32-21 (1.8), A1150-9-13 (1.8), A1150-68-35 (1.8),
A1150-77-37 (1.8), and A1105-10-55 (1.8). Differences among lines in
ear aspect between lines were not significant. Lines with the best ear
aspect included A1150-4-11 (3.3), A 1150-10-14 (3.3), A1150-13-15 (3.3),
A1150-14-16 (3.8), A1150-29-19 (3.5), A 1150-77-37 (3.3), A1150-62-31
(3,5), A1150-77-37 (3.3), A 1150-4-11 (3.3) and A 1105-2-48 (3.0).
iii) Njombe-Variety Evaluation
At
this site, varieties with the highest grain yield included TZA 1756 (5.8
t), TZA 1730 (5.4 t), TZA 1747 (5.1 t), TZA 1751 (5.0 t) and TZA 1758
(5.0 t) (Table 3). Varieties with high resistance to turcicum blight
included TZA 1747 (1.5), TZA 1756 (1.8t), TZA 1742 (2.0), TZA 1744
(2.0), TZA 1758 (2.0), TZA 1761 (2.0) and TZA 1763 (2.0). Differences
among varieties in GLS resistance were not significant. The variety with
the best grain texture was TZA 1743 (4.5). Varieties with the best ear
aspect included TZA 1763( 4.0) followed by TZA 1727 (3.8), TZA 1744
(3.8), TZA 1742 (3.7), TZA 1742 (3.7), ZM 623 (3.6) and TZA 1744 (3.6).
Except for husk cover, differences among varieties in the parameters
assessed were not significant. Although the testing site is a GLS high
pressure area, disease rating appeared low because of frost experienced
during the season. The frost masked GLS symptoms and also resulted into
the grains not filling properly or not filling at all.
iv) Njombe- Inbred Lines Evaluation
Results of the inbred lines evaluation at Njombe are shown in Table 4.
There were significant differences among inbred lines in grain yield.
Lines that had the highest grain yield in tonnes per hectare included
A1150-9-13 (2.2 t), A1150-65-33 (2.2 t), A 1150-73-36 (1.9 t),
A1150-55-29 (1.8 t), A 572-64-57 (1.7 t) and A 1150-20-17 (1.6 t). There
were also significant differences among lines in plant height. On a 1-5
rating scale, lines that had a rating of below 2 included A1150-2-10
(1.0), A1150-2-10 (1.0), A 1105-3-49 (1.0), A 1150-30-20 (1.3), A
1105-5-51 (1.3), A 1150-9-13 (1.5), A 1105-10-55 (1.5). Lines with the
best ear aspect included A1150-68-35 (4.0), A 1105-4-50 (4.0), A
1150-4-11 (3.8), A 1150-10-14 (3.8), A 1150-14-16 (3.8), A 1150-78-38
(3.8). However differences among lines in this parameter were not
significant. Nonetheless a few lines will be selected and advanced
through various crosses.
b) Northern Zone
v) Madira- Variety Evaluation
Results of variety evaluation at Madira are shown in Table 5. There were
significant differences in grain yield among varieties. The highest
yielding varieties included ZM 423 (8.2 t), SYN01E2 (7.8 t), ZM 521 (7.4
t), TZA 1774 (6.3 t) and TZA 599-2PC (5.3 t). Differences among
varieties in anthesis date, ASI, GLS resistance, number of lodged plants
and percent diseased cobs were not significant. There were significant
differences among varieties in plant height, ear height, and resistance
to blight and common rust. TZA 1791 had the highest resistance to
turcicum blight (2.0) followed by UH 615 (2.2) and TZA 1784 and
TZA1787 each with a rating of 2.5. The TZA varieties are landraces
and some appeared resistant to turcicum blight. These may have
developed resistance to local populations of turcicum blight. They will
be used as sources of resistance in the crossing work if the noted
resistance is stable. Varieties that were rated resistance to common
rust included ZM 423, ZM 521, Kilima (ST 94)-SS:101 followed by MZ 305,
SYN01E2, ZM 423, M162W, TZA 1766, TZA 1787 and MZ 305.
vi) Madira- Inbred Line Evaluation
Results of the inbred line evaluation at Madira are shown in Table 6.
The highest yielding inbreds included entries Nos. 17 (2.5 t), No.40
(2.1 t), No.28 (2.0 t) and No.52 (2.0 t). However, differences in grain
yield were not significant. Although the test materials were inbred
lines, the yields were relatively lower than expected. Nonetheless a few
will be selected based on yield and other attributes for use in making
crosses and to observe if the crosses will result into vigorous hybrids
that can be used for further development. The high cv observed for yield
cannot be explained. There were significant differences in anthesis
date, ASI, plant height, ear height and resistance to common rust among
lines. Although there were significant differences in resistance to
common rust among the test material, none of the lines reached a rating
of 3 (moderately resistant). Thus, rust severity level was not high
enough for clear cut distinction of susceptible and resistance reactions
to be made. Although there were no significant differences among the
inbred lines in blight resistance, entries no. 1 and 50 appeared
resistance and were rated 2.0. These were followed by entries nos. 4, 6,
27, 42 and 46 which were rated 2.3-2.5.
vii) Madiira –Early Population Evaluation (EPOPO)
Results of the early population evaluations are shown in Table 7. There
were significant differences among varieties in grain yield per hectare.
The highest yielding populations included VPO42 (6.7 t), ZM 523 (6.2 t),
01SynZME (5.7 t), Syn01E2 (5.6 t) and 02SADVE (5.5 t). There were also
significant differences among varieties in turcicum blight resistance.
Populations with highest resistance to turcicum blight included
01SynZimE (2.5), ZM 523 (2.5), VP042 (2.6) and 02SADVE (2.6).
Populations with high turcicum blight resistance also had a higher
yield. It seems that this disease reduces yield in proportion to
severity. Differences among populations in common rust and GLS
resistance were not significant. Likewise, there were no significant
differences among populations for the other parameters estimated.
viii) AFSF-Variety Evaluation
Results of variety evaluation trial at AFSF are shown in Table 8. There
were significant differences among varieties in grain yield. The local
check (UH 615) produced the highest grain yield with an average of 11.6
t/ha. It was distantly followed by SYN01E2 (6.5), ZM 521 (4.3 t), KILIMA
(ST97-S5:107 (4.0 t) and TZA 599(2PC) (3.9 t). Most of the varieties in
this trial consisted of local landraces and material from CIMMYT
Zimbabwe. It seems varieties from Zimbabwe are not good adaptors to the
agro-climatic conditions at AFSF. There were also significant
differences among varieties in plant height, ear height and resistance
to common rust. Common rust severity level varied between 1.5-3.2.
Higher variations would have enabled selection for resistance to this
disease to be made more easily. It seems none of the test varieties at
AFSF could compete with the local check UH 615 in terms of yield.
However, the other varieties can still be used for crosses to impart
other attributes to the local check like plant and ear height and
maturity.
ix) AFSF-Inbred Lines Evaluation
Results of inbred line evaluations at AFSF are shown in Table 9. Grain
yield expressed in tones per hectare varied between 0.4 t/ha to 1.9
t/ha. However, differences in grain yield were not significant. The
coefficient of variation for this parameter was quite high due to some
unexplained reason. There were significant differences among varieties
in anthesis date, plant height, ear height, resistance to MSV, turcicum
blight and GLS and also in percent lodged plants For the MSV and GLS
resistance, severity level was quite low for any meaningful selection
for resistance to be made. For turcicum blight, varieties that were
rated resistant included entries No. 49 (1.5), 39 (2.3), 41 (2.3), 44
(2.3) and 45 (2.3).
x) AFSF- Early Population Evaluation (EPOPO)
There were significant differences among the early populations in grain
yield expressed in tones per hectare at Arusha Foundation seed farm
(Table 10). Populations with the highest grain yield included Situka 1
(9.3 t), VP042 (8.1t), 01SynZmE (6.7 t), ZM 523 (6.6 t), VP041 (5.9 t)
and 02SADVE (5.7 t), There were significant differences among varieties
in turcicum blight resistance. Varieties with a high resistance value
included VP042 (2.1), Situka 1 (2.1), 01SADV1 (2.5) and 02SADVE2 (2.6).
There were also significant differences among populations in anthesis
date, plant height, ear height, resistance to common rust and EPP.
Although there were significant differences among populations in
resistance to common rust, selection for resistance was not clear-cut as
most populations had a rating of 1.5 to 2.8 on a rating scale of 1-5.
Differences among populations in GLS resistance were not significant.
The disease level was very low during the season.
Expected/realized outputs and impacts:
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GLS and turcicum blight maize varieties identified
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Identified resistance incorporated into high yielding
susceptible varieties
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High yielding hybrids and OPVs developed
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