Thumbnail Image

Thesis

Browse

20221
Reset filters
Subject: Entomology × Author: Khokhra, Shivani × Start date: 2018 × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemRestricted
    Induced host plant resistance in pigeonpea against spotted pod borer, Maruca vitrata (Fabricius)
    (Punjab Agricultural University, 2022) Khokhra, Shivani; Taggar, Gaurav Kumar
    The studies on “Induced host plant resistance in pigeonpea against spotted pod borer, Maruca vitrata (Fabricius)” were conducted during Kharif 2020 and 2021. Field screening of pigeonpea genotypes revealed that the genotype AL 1747 consistently performed better towards M. vitrata infestation during both years (Kharif 2020 and 2021). The exogenous application of Jasmonic acid (JA) (100 µM) and Salicylic acid (SA) (5.0 mM) on pigeonpea plants triggered the induction of biochemical parameters (enzymes and secondary metabolites) after 12 and 24 h of application, respectively. Pre-treatment with JA (100 µM) followed by infestation with M. vitrata after 12 h elicited a strong defense response in both the resistant (AL 1747) and susceptible (MN 1) genotypes. AL 1747 responded better to the exogenous application of elicitors and M. vitrata than the susceptible genotype MN 1. The induced effect was highest one day after the treatment (in both JA and SA) and showed a declining trend thereafter with no changes in the activities of defensive enzymes and secondary metabolites after 7 days of treatment. Both JA and SA induced an antioxidative response in pigeonpea plants against M. vitrata, which, in turn, affected the insect development, nutritional indices as well as the metabolism of M. vitrata. Imbalance in the digestive enzymes significantly reduced the nutritional indices (AD, ECI, ECD and RGR) of M. vitrata in JA-treated plants. Insect, as a counter-response to plant defense, increased the activities of glutathione-S-transferases (GST) and glucose oxidase (GOX). However, a significant negative correlation was observed between the detoxifying enzyme (GST) and larval weight (r= -0.790**). The GOX activity and larval weight exhibited a non-significant negative correlation with each other post-elicitor application. SA also led to an alteration in the activities of digestive and defense related enzymes in M. vitrata; however, the effect was not as pronounced as JA. An alteration in insect defensive and digestive enzymes and upregulation of plant secondary metabolites by exogenous application of elicitors (either in the pre-/or simultaneous application) indicates that modulation of pigeonpea defense can increase the effectiveness of the host plant to defend against M. vitrata herbivory.