Forewarning Rice Blast in India

Forewarning Rice Blast in India
Pooled regression models for leaf blast at Palampur during different years
were developed from the historical data for the years 1991-1996, 1997-2000, 1991-
2000 and 2001 (Table 5). Out of all these equations, the regression equation of the
duration 1997-2000 (Y = -20.53+3.16X 1 –7.28X 2 +0.60X 3 +0.54X 4 -0.36X 5 +1.60X 6 )
was observed to be the best fit equation. Validation of this model was made on the
data of 2001 and found more realistic on farmers’ field data (Fig.3).
Table 5. Pooled regression models for leaf blast at Palampur during different
years developed from the historical data
Year Equation R R 2
1991 – 1996 Y = 5.66+3.39X -9.75X +1.09X +0.47X - 0.25X -1.13X 1 2 3 4 5 6 0.49 0.24
1997 – 2000 Y = -20.53+3.16X -7.28X +0.60X +0.54X - 0.36X +1.60X 1 2 3 4 5 6 0.64 0.41
1991 – 2000 Y=11.543+1.749X -5.950X +0.211X +0.696X - 0.233X +1.760X 1 2 3 4 5 6 0.60 0.36
2001 * Y = -2.41 + 0.26 X1 0.85 0.72
Y = Disease variable, X = T maximum, X = T minimum, X = RH maximum, X = RH minimum,
1 2 3 4
* X = Rainfall, X = Rainy days/week, X = Leaf wetness, R = Multiple correlation coefficient,
5 6 1
R2 = Coefficient of determination
16
Fig. 3. Validation of leaf blast model for Palampur and
Farmers' field (Pharer) data
Y = -20.53+3.16X1-7.28X2+0.60X3+0.54X4-0.36X5+1.60X6
Year 2001, Palampur
Y = -20.53+3.16X1-7.28X2+0.60X3+0.54X4-0.36X5+1.60X6
Year 2001, Pharer