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Subject: Entomology × Author: Giri Naga Harish × Start date: 2017 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Damage potential and bases of resistance in soybean against Bemisia tabaci (Gennadius)
    (Punjab Agricultural University, Ludhiana, 2021) Giri Naga Harish; Ravinder Singh
    The studies on damage potential and bases of resistance in soybean against B. tabaci were conducted during kharif 2018 and 2019. Based on the pooled mean the avoidable yield losses were found to be lowest in variety SL 744 (18.12 %) followed by SL 525 (20.45 %) and SL 958 (27.28 %). Eight soybean genotypes were evaluated against B. tabaci under field conditions. The genotype SL 1074 had recorded lowest whitefly population and was at par with SL 1028. These were followed by genotypes PS 1572 and PS 1347 which were at par with each other. The other genotypes SL 1113, SL 958, SL 688 had recorded intermediatory population and were at par with each other, whereas genotype DS 3105 had recorded highest whitefly population. The leaf injury symptoms due to B. tabaci were categorized into five grades (I-V). The standardization of screening techniques against B. tabaci confirmed that soybean genotypes can be effectively screened at the 3rd trifoliate leaf stage using 125 whitefly adults per plant under screen-house. Evaluation of soybean genotypes against B. tabaci in the multiple-choice test based on the whitefly resistance index (WRI) revealed that genotypes SL 1028 and SL 1074 were categorized as moderately resistant with WRI of 1.50. The genotypes PS 1347, PS 1572 had recorded WRI of 2.38 and 2.50, were categorized as moderately susceptible. The remaining genotypes, SL 1113, SL 958 and SL 688 had recorded WRI of 2.80, 3.00 and 3.11, respectively were categorized as susceptible. Genotype DS 3105 had recorded the highest WRI of 3.70, was categorized as highly susceptible. The whitefly adult population among the three canopies (upper, middle and lower) had showed significant differences. The maximum population was recorded on upper canopy, followed by middle and lower canopies. Leaf area, trichome density, length and angle were significantly and positively correlated with whitefly nymphs and adults, whereas leaf lamina thickness was negatively correlated. Total phenols, o-dihydroxy phenols, flavonols, tannins, superoxide dismutase, peroxidase and polyphenol oxidase were found to be significantly negatively correlated with whitefly nymphs and adults. Whereas total soluble sugars, reducing sugars and total soluble protein contents were significantly positively correlated. Thus, soybean genotypes possessing narrow, less pubescent leaves with short and flattened trichomes with higher phenolic contents and antioxidative enzyme activity contents should be selected for resistance against B. tabaci.