DEVELOPMENT OF EMPIRICAL CROP LOSS MODELS IN GROUNDNUT (Arachis hypogaea L.) AFFECTED BY LATE LEAFSPOTAND RUST
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Date
2000
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University of Agricultural Sciences, Dharwad
Abstract
"In the present study, an attempt was made to have am insight into
the yield loss mechanism in groundnut [Arachis hypogaea L.) in presence
of the fungal diseases viz., late leafspot and rust. Analysis of variance of
yield and disease variables, revealed th a t there existed significant
variations among the genotypes under study, both for yield potential and
response to diseases. Moreover, disease severity was more in late sovra
trial and th u s low yield, as compared to the early sown trial.
Simple linear regression models of 3deld loss on disease variable at
each stage, revealed that in early sown trial for pod, kernel and fodder
loss, disease a t 85th day after sowing (DAS) was having more explanatory
value compared to other stages, while it was 65th DAS for oil loss (based
on r2). In late sown trial, explanatoiy value of the models were low,
comparatively and better results were obtained with disease at 95th DAS
for all yield loss variables. AUDPC models, polynomial and non linear
models could not explain the variations in yield loss more precisely than
the models with single point disease variables. Multiple point linear
regression models of yield loss on disease a t different stages taken
together, improved the explanatory value, b u t could not explain the
variation precisely.
Stepwise regression analysis on disease variable and physiological
traits like leaf area index, harvest index, partitioning coefficient and
growth rates improved the value of the models considerably, both in
early and late sown trials. Grouping of genotypes with pod loss and
disease variables using Mahalonobis D2 showed similar results in both
trials, where variety TAG 24, which show moderate yield loss even at high
disease severity, was grouped separately."
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No. of Reference 91