Abstract
Effect of Pythium aphanidermatum (damping off/root rot pathogen) on the physiology of Luffa cylindrica (sponge gourd) and its management by microbial antagonists were studied. In this regard, plants were exposed to P. aphanidermatum suspension (@1 × 10−3cfu/ml) to initiate disease. Later, suspension of three biocontrol agents, i.e., Paecilomyces variotii (3 × 10−1cfu/ml), Bacillus subtilis (0.65×10−1cfu/ml), and Trichoderma harzianum (2 × 10−1cfu/ml) were employed for disease control and management. Non-destructive chlorophyll “a'' fluorescence assay was used to assess photosynthetic performance of the infected plants. The study reveals that biocontrol agent enhanced photosynthetic performance due to better chlorophyll quantum yields (ΦPSII and Fv/Fm), photochemical quenching (qP), electron supply (rETR) for PSII systems in infected plants. Biocontrol has greatly reduced energy loss in terms of heat dissipation and increased quantum efficiency, electron transport rate, and OJIP values in diseased plants. The study demonstrates that the application of biocontrol agents in the infected plants also covered up the root colonization of P. aphanidermatum suppressing disease intensity. T. harzianum greatly suppressed pathogen invasion due to more root colonization as compared to P. variotii and B. subtilis. Moreover, the biocontrol application decreased H2O2 and MDA concentrations in the infected plants due to adequate CAT and SOD activities during disease management. The role of biocontrol agents in disease management were varied and are discussed in detail.
Published Version
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