Browsing by Author "Diwakar, Y."

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    Colletotrichum kahawae subsp. cigarro causing leaf spot disease on arecanut, Areca catechu L. in India: A first report
    (2024) R. Thava Prakasa Pandian; Shivaji Hausrao Thube; Bhavishya; Merin babu; H. Rajashekara; T.N. Madhu; Diwakar, Y.; P. Santhoshkumar; B.J. Nirmalkumar; Balanagouda Patil; V. Hegde
    Arecanut is a prominent cash crop in India, known for its potential to significantly boost per capita income. The presence of fungal diseases poses a significant constraint to arecanut cultivation. In October 2019, a severe outbreak of leaf spot disease with 90°% disease incidence was recorded in the farmer's arecanut gardens from Kalasa hobli, Chikkamangaluru, Karnataka, India. Leaf spot symptoms started as small, irregular, light-dark brown spots (3–10 mm in diameter) with a yellow halo on the leaf lamina, which later coalesced to form larger necrotic lesions and a blighted appearance. The symptoms were also observed on leaf sheaths and nuts. In the present study, we identified and characterized the pathogen causing leaf spot disease using cultural, morphological, molecular characterization using multi-gene phylogeny, and pathogenicity assays. Microscopic, and molecular identification of CPCRICkc7G isolate retrieved from the leaf spot infected sample established the association of Colletotrichum kahawae subsp. cigarro as the causal agent. Pathogenicity assays confirmed the Koch's postulate by reproducing the field observed symptoms. To best of our knowledge, this confirms the first report of C. kahawae subsp. cigarro causing leaf spot disease on arecanut in India. The findings from this current study play a pivotal role in enhancing the knowledge of arecanut diseases in India, and lay an essential foundation for devising effective disease management approaches to curtail the disease spread.
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    Exploring reproductive traits of indigenous coconut (Cocos nucifera L.) accessions: Implications for crop improvement.
    (2024) Diwakar, Y.; Niral, V.; VishVenkatesh, J.; Halesh, G.K.; Ramesh, S.V; Maruthi Prasad, B.N.; Harish, B.S.
    Coconut (Cocos nucifera L.) is an economically significant crop in tropical and subtropical regions, and understanding the variability in its reproductive traits is essential for enhancing breeding programs aimed at improving productivity and adaptation. This study characterized 31 indigenous coconut accessions conserved in National Coconut Gene Bank of ICAR-CPCRI Research Centre, Kidu that hosts ICG, SA&ME in Karnataka, India, to assess key reproductive traits. The study revealed significant diversity in several traits, including inflorescence length, which ranged from 96.33 cm in Horned Coconut Tall to 148.50 cm in Kodiaghat Brown Tall. Similarly, the number of male flowers per inflorescence varied from 4,460 in Ponnani Yellow Tall to 9,085 in Indian West Coast Tall, while pollen output ranged from 3.30 g in Ponnani Yellow Tall to 14.02 g in Dugong Creek Tall. Number of female flowers per inflorescence ranged from 12.92 in Kutiadi Tall to 57.87 in Champin Micro Tall. Correlation analysis identified several significant associations among the reproductive traits in the studied population. Inflorescence length was positively correlated with the length of spikelet bearing portion (r = 0.841**) and the length of stalk (r = 0.821**), suggesting that larger inflorescences are associated with longer spikelet-bearing portions and stalks. Notably, number of female flowers per inflorescence was negatively correlated with length of spikelet (r = -0.444*). Moreover, a significant positive correlation was observed between male flower production and pollen output (r = 0.694**), indicating that genotypes with higher male flower production tend to produce more pollen. These findings underscore considerable variability in reproductive traits across the evaluated accessions, highlighting the potential for selecting superior coconut genotypes that exhibit larger inflorescences, enhanced pollen production, and optimal flower production. Such traits are valuable for improving breeding strategies focused on increasing coconut yield, quality, and adaptability to varying environmental conditions.
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    From coast to Isle: exploring the morphological diversity of tender coconuts in selected Indian accessions
    (2024-08-01) Diwakar, Y.; Vishnuvardhana; Niral, V.; G. K. Halesh; J. Venkatesh; Ramesh, S.V.; Neenu, S.
    Coconut (Cocos nucifera L.) is an economically and nutritionally important tropical crop, particularly renowned for its oil and tender coconut water, a beverage known for its hydrating properties and health benefits. This study investigates the morphological diversity of tender nuts from various coconut accessions collected from coastal and island ecosystems in India. A total of 31 coconut accessions, including the Indian West Coast Tall (WCT) as a reference, were evaluated for tender nut traits. Significant variability was observed, with tender coconut weights ranging from 831.67 g in Andaman Horned Tall to 2940.83 g in Kodiaghat Brown Tall. Quantity of tender coconut water varied from 85.55 mL in Andaman Horned Tall to 545.58 mL in Kodiaghat Brown Tall followed by Dugong Creek Tall (495.83 mL) and Nicobar Tall AuckChung (485.0 mL). The average TSS was 5.0° Brix, with Andaman Horned Tall recording the highest TSS at 5.98° Brix. Accessions such as Kodiaghat Brown Tall and Dugong Creek Tall demonstrated superior traits, suggesting their potential in varietal breeding programs. The study underscores the genetic diversity present in coconut accessions, with implications for improving tender coconut production. The findings highlight the importance of understanding these traits for developing varieties that meet consumer and market demands, ultimately contributing to the sustainability of coconut.
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    New Distribution Record of Palm Whitefly, Aleurotrachelus atratus Hempel in Kerala, India
    (2022-07) Jilu V. Sajan; Prathibha, P.S.; Diwakar, Y.; Joseph Rajkumar, A.
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