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In this research, the effect of rice blast disease on yield was studied:
During years of 1978—79, a susceptible variety of rice (Cul. Mehr) was transplanted at different intervals under complete randomized block design with 4 replications per treatment.
Neck blasts (x1) and node blasts (x2) were sampled and their correlation coefficient with yield (y) in kg/ha for each experiment were calculated and the following equations were obtained:
y= 4286.35—32.62x1 r= —0.884
y= 4093 — 15.86x2 r= —0.646
y= 4513.06—17.14x1— 13.51x2 r= —0.848
Correlation of the effects of the No. of leaf spots on rice Var. Mussatarum on the yield at tillering stage during years of 1981—84 were as follows:
y 3260.27—0.295x r= —0.519
In experiment on planting date in 1981 with 6 treatments, half of the plants in each plot were sprayed with Benlate fungicide at spikeling stage. Correlation of percentage of neck blast (z) and yield decrease (y1) for spray treatments and the controls were:
y1= 19.84z — 146.2 r= 0.923
The correlation was valid for z>%7, that is for more infection, we yet less Crop. Correlation of percentage of neck blast (z) and percentage of yield decrease
(y) were: y2 —1.45 + 0.409z r= 0.815