Field Crop 2018, Vol.1, No.3, 9-14
10
1 Materials and Methods
The experiment was laid out in two factors factorial randomized complete block design during April to September
2017 with five replications and four treatment combinations. The treatments consisted combinations of factor A
(two rice varieties namely, Sabitri and Radha 7) and factor B (
Trichoderma viride
, 5 ml/lit. and 0 ml/lit.).
Individual plot size comprised of 6 m ×1 m, the row to row and plant to plant spacing was 20 cm. The space
between two replications and border was one and half meters (Table 1).
Table 1 Treatment combinations of this experiment
Factor A
Factor B
Treatment combinations
V
1
R
1
V
1
R
1
= Radha 7 (Local) + 0 ml/lit. of
T. viride
T
1
R
2
V
1
R
2
= Radha 7 (Local) + 5 ml/lit. of
T. viride
T
2
V
2
R
1
V
2
R
1
= Sabitri (Improved and blast resistant) + 0 ml/lit. of
T. viride
T
3
R
2
V
2
R
2
= Sabitri (Improved and blast resistant) + 5 ml/lit. of
T. viride
T
4
Transplanting of seedlings were done during 1
st
week of June, 2-3 seedlings/hill were transplanted with 20 ×20
cm of spacing. In case of treated plot, rice seedlings were dipped in the
Trichoderma viride
(10
9
cfu/ml) solution
of 5 ml/litre of water for 30 min. and dried under shade for 10-15 minutes before transplanting. FYM and N:P:K
were applied at 6 ton/ha, and 100:30:30 kg/ha respectively. Total amount of phosphorus and potash and half
amount of nitrogen were mixed in soil at the time of final land preparation. Remaining half doses of nitrogen was
applied in two split doses; one at the tillering stage and the other at the head emergence stage. Weeding was done
two times before the top dressing of urea.
10 plants were randomly selected from each plot excluding border line and tagged by a piece of ribbon for
identification while taking data. The disease was scored three times at 5 days interval starting from the first
appearance of leaf blast symptoms i.e. 75 days of sowing. It was taken on the basis of symptom appearance of the
leaf blast which was graded in 0-9 scale (IRRI, 2002). The disease incidence and severity were recorded treatment
wise by using the following formula:
Incidence(%) =
Number of infected plant
Total number of plants rated
× 100%
Severity(%) =
Sum of all numerical ratings
Number of plants rated × Highest rating scale
× 100%
The effect of disease severity on rice variety was integrated into area under disease progress curve (AUDPC)
(Campbell and Madden, 1990). Area under disease progressive curve (AUDPC) determines the intensity and
progress of disease development and calculated by using the following formula (Das et al., 1992).
AUDPC =∑(
+1
+
2
n
i=1
)(
+1
− )
Where Yi = disease scored on first date, Ti = date on which the disease was scored, n = number of dates on which
disease was scored. Data of disease scoring and then disease incidence and severity were tabulated in excel data
sheet. The data were processed to fit into R-studio and analyzed using R 3.0.3 (Program, 2013). The ANOVA table
was developed and different treatments were compared by Duncan’s multiple range test.
2 Results
2.1 Leaf blast incidence
Leaf blast incidence was found maximum at 80 DAT. Disease incidence was found least in Sabitri and
Trichoderma viride
treatment on this date.
Disease incidence was observed at 75, 80 and 85 DAT after the first appearance of disease symptoms. At 80 DAT,
