SOURCE-SINK RELATIONSHIP AS INFLUENCED BY LATE LEAFSPOT IN GROUNDNUT GENOTYPES
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Date
1997
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UNIVERSITY OF AGRICULTURAL SCIENCES, DHARWAD
Abstract
In an attempt to findout the influence of late leafspot caused by Phaeoisariopsis personata on various morphological, physiological, biophysical, biochemical, histological, histopathological and histochemical parameters and partitioning efficiency, a field experiment was conducted during kharif 1996 at College of Agriculture Farm, University of Agricultural Sciences, Dharwad. The experiment consisted of six treatment combinations comprising three genotypes differing in disease reaction viz., susceptible (TMV-2), moderately resistant (Dh-74) and tolerant (ICGV-86590), raised under both protected and unprotected conditions in four replications. The plants in the unprotected treatments were sprayed with the inoculum of P. personata at 45 days after sowing (DAS) to induce the incidence of the disease.Results revealed that late leafspot caused a significant reduction in plant height, dry weight of leaf, stem, root and pods, growth parameters viz., LAI, LAR, LAD and BMD. The extent of reduction was more in unprotected treatments as compared to protected treatments in all the genotypes. Among the genotypes, there was least reduction in ICGV-86590 and maximum in TMV- 2. With respect to yield and yield components, oil content and shelling per cent, it was observed that there was a significant reduction due to disease incidence in the unprotected treatments and the extent of reduction was maximum in TMV-2 and minimum in Dh-74.Chlorophyll 'a', chlorophyll 'b', total chlorophyll and nitrate reductase activity reduced significantly due to disease incidence. The level of total sugars increased after infection and the extent of increase was maximum in TMV-2. Whereas, total phenols and tannins were significantly higher in protected treatments and in ICGV-86590. Leaf thickness was found to be more in TMV-2 than in ICGV-86590 but. the epidermal thickness and number of epidermal cells were more in ICGV- 86590 than in TMV-2. Polysaccharides. Proteins, and RNA contents were low in healthy leaves and petioles but were rich in disease affected plant parts. It is inferred that the incidence of late leafspot brings about considerable changes in plant morphology, physiology, histology, histopathology and histochemistry which altogether influence the source-sink relationship in groundnut.
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