Screening of okra (Abelmoschus esculentus) genotypes for resistance to powdery mildew caused by Golovinomyces cichoracearum

LOKESH  RAMACHANDRAN; SUNDARAMOORTHY  SUBRAMANIAM; SATHIYA ARAVINDAN  VENKATESAN; AJAY DESOUZA VINCENT  PAULRAJ; YUVARAJ  MARIYAPPAN

doi:10.56093/ijas.v96i7.170339

Authors

LOKESH RAMACHANDRAN Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu 641 003, India
SUNDARAMOORTHY SUBRAMANIAM Horticultural College and Research Institute (Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu), Periyur, Tamil Nadu, India
SATHIYA ARAVINDAN VENKATESAN Annamalai University, Annamalai Nagar, Tamil Nadu, India
AJAY DESOUZA VINCENT PAULRAJ Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu 641 003, India
YUVARAJ MARIYAPPAN Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu 641 003, India

https://doi.org/10.56093/ijas.v96i7.170339

Keywords:

Disease severity, Percent disease index, Resistant genotypes, Sustainable management

Abstract

Powdery mildew caused by Golovinomyces cichoracearum (DC.) V.P. Heluta, remains a major foliar disease, significantly reducing the yield of okra (Abelmoschus esculentus L.) under conducive environmental conditions. Identification of resistant okra genotypes offers an eco-friendly, sustainable and cost-effective approach for the management of powdery mildew. The present study was carried out at Faculty of Agriculture, Annamalai University, Annamalai Nagar, Tamil Nadu with aim to evaluate okra genotypes for resistance against powdery mildew and indetify resistance resources. The study evaluated 15 okra genotypes, including commercial varieties and hybrids, for resistance against powdery mildew under pot culture conditions during the samba seasons of 2022 and 2023. Disease severity was recorded at 50, 65 and 80 days after sowing (DAS) and quantified as percent disease index (PDI) using a 0–9 disease rating scale. Considerable and statistically significant variability was observed among the genotypes in disease severity and progression, allowing clear discrimination of resistance responses. Four genotypes, namely ‘Arka Nikhita’, ‘Kasi Chaman’, ‘Pusa Makhmali’ and ‘Pusa A4’ exhibited complete resistance, showing no visible symptoms or sporulation during both years of evaluation, confirming stable, resistant sources. In contrast, ‘Sakthi’ was categorised as highly susceptible, recording the highest mean PDI of 76.94%. This high susceptibility was associated with the highest conidial count (511.60/microscopic field) and the fastest apparent infection rate (r = 0.1298). Furthermore, seven genotypes including ‘Raadhika Hybrid Okra’ (72.79% PDI) and Farmers’ variety (63.35% PDI), were classified as susceptible while three genotypes, namely ‘Arka Abhay’, ‘COBH h1’ and ‘Traditional variety- Elephant Tusk Okra’, showed moderate susceptibility. The simultaneous assessment of PDI, disease progression rates and conidial density proved reliable for discriminating genotypic resistance levels. This investigation successfully identified stable and resistant genotypes that can be utilised effectively in resistance breeding programmemes and as components of integrated disease management (IDM) strategies for sustainable management.

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